Training Report

Industrial Training Report

Preface

This Industrial Training Report is prepared after completion of 23 weeks of Industrial

training at Hemas Power PLC., Ceylon electricity Board and Lanka Electricity Company

(Pvt.) Ltd.

Completion of 22 weeks Industrial Training is compulsory for the award of the Degree of the

Bachelor of Science in Engineering from the University of Moratuwa, Sri Lanka and it is

conducted after the completion of level 3 semesters 1. Industrial Training program was

carried out by the National Apprentice and Industrial Training Authority (NAITA) in

collaboration with the Training Division of the University of Moratuwa.

This report contained with my experiences and knowledge I gathered during my training

period from 15/02/2010 to 23/07/2010.

Chapter 1 is included with introduction of my three training places. And chapter 2 is included

with my experiences which are learned during my training. And finally Chapter 3 is

conclusion which gives a summary about the training.

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Acknowledgement

I grant my gratitude to all who helped me to get a proper training. I should thank to NAITA

and Industrial Training Division for conducting an Industrial Training Program with this

success. Furthermore, I should thank to the Department of Electrical Engineering for

restructuring the training program for this worth, collaborating with the Industrial Training

Division.

And also I thank Mr. Kishan Nanayakkara, who is the managing director of Hemas Power

Plc. for preparing us the opportunity to have training in Hemas Power, and Mr. Krishantha

Wimalasiri for presenting the helping hand when we were in an ocean of unknown. I thank to

all the staff members in Hemas Power for helping me on gathering the knowledge of their

fields.

Special thanks to Dr. Narendra de Silva for offering us the opportunity to have training in

LECO. And I grant my gratitude to all the engineers in System Development Division,

System Operations, and Nugegoda Branch Office. Furthermore, I thank to the staff in Ekala

meter repairing and testing lab and Transformer repairing lab, and Boralasgaamuwa

Customer service Center.

My special thanks to Mr. Buddhadasa, electrical engineer in internal training for preparing a

training opportunity in CEB. And I should give my gratitude to Mrs. Mendis, who is the

DGM of Other Hydro Complex, for giving us the chance to be in S’wawa power station and

gather knowledge. And also thankful to all the chief engineers in Transmission, Operation

and Maintenance, Samanalawewa Power Station, Kalanithissa Power Station and

Kalanithissa Combined Cycle Power Plant, Generation Planning Branch and System Control

Center. And also I thank to the engineers and other staff members in CEB, who helped us

sharing their knowledge.

S. R. M. D. T. S. Wijesekara

Department of Electrical Engineer

Faculty of Engineering

University of Moratuwa.

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Content

Preface.................................................................................................................................i

Acknowledgement.....................................................................................................................ii

Content......................................................................................................................................iii

List of Figures............................................................................................................................v

List of Tables............................................................................................................................vi

1 Introduction....................................................................................................................- 2 -

1.1 Hemas power..........................................................................................................- 2 -

1.1.1 Organizational Structure..................................................................................- 3 -

1.1.2 Strength............................................................................................................- 3 -

1.1.3 Weaknesses......................................................................................................- 4 -

1.1.4 Profitability......................................................................................................- 4 -

1.1.5 Usefulness to society.......................................................................................- 4 -

1.2 Ceylon Electricity Board........................................................................................- 4 -

1.2.1 Vision..............................................................................................................- 4 -

1.2.2 Mission............................................................................................................- 4 -

1.2.3 Present Performances of CEB.........................................................................- 5 -

1.2.4 Strength of the CEB.........................................................................................- 5 -

1.2.5 Weaknesses of CEB........................................................................................- 5 -

1.2.6 Profitability......................................................................................................- 6 -

1.2.7 Usefulness to the society.................................................................................- 6 -

1.3 Lanka Electricity Company....................................................................................- 6 -

1.3.1 Organizational structure..................................................................................- 7 -

1.3.2 Present performance........................................................................................- 7 -

1.3.3 Profitability......................................................................................................- 7 -

1.3.4 Strength of the company..................................................................................- 8 -

1.3.5 Weaknesses of the company............................................................................- 8 -

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2 Training Experience.......................................................................................................- 9 -

2.1 Hemas power..........................................................................................................- 9 -

2.1.1 Hemas building power system.........................................................................- 9 -

2.1.2 Mini Hydro Plants.........................................................................................- 12 -

2.1.3 Designing a mini hydro plant........................................................................- 15 -

2.1.4 Trash rack design...........................................................................................- 20 -

2.1.5 Financial Structure of a company and evaluation for acquire a company.....- 21 -

2.1.6 Gidddawa mini hydro power plant................................................................- 22 -

2.1.7 Maintenance schedule........................................................................................28

2.2 Ceylon Electricity Board...........................................................................................29

2.2.1 Hydro Power Generation – Samanalawawa Power Station...............................30

2.2.2 Kalanithissa Power Station & Kalanithissa Combine Cycle Power Plant.........34

2.2.3 Transmission Operation and Maintenance Branch............................................37

2.2.4 System Control Centre.......................................................................................40

2.2.5 Generation Planning...........................................................................................43

2.3 LECO.........................................................................................................................48

2.3.1 System Development Division...........................................................................49

2.3.2 System Operations.............................................................................................51

2.3.3 Branch Office.....................................................................................................54

2.3.4 Customer Service Center (Depot)......................................................................56

3 Conclusion........................................................................................................................58

Annexes....................................................................................................................................61

Annex 1 – MATLAB Program on flow duration curve.......................................................62

Annex 2 – MATLAB Program on turbine selection-1.........................................................63

Annex 3 – MATLAB Program on turbine selection-2.........................................................64

Annex 4 – Trash rack design................................................................................................65

Annex 5 – Teamwork workshop certificate.........................................................................66

Annex 6 – Maintenance schedule.........................................................................................67

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List of Figures

Figure 1.1-1 - staff of the Hemas Power PLC.....................................................................................- 9 -Figure 1.3-1- LECO Distribution Areas.............................................................................................- 12 -Figure 1.3-2 - LECO Organizational Structure..................................................................................- 12 -Figure 2.1-1 - Power system of Hemas building..............................................................................- 16 -Figure 2.1-2..................................................................................................................................... - 19 -Figure 2.2-1 - Annual Hydrograph...................................................................................................- 22 -Figure 2.2-2 - Flow Duration Curve..................................................................................................- 22 -Figure 2.2-3 Turbine Selection Chart...............................................................................................- 24 -Figure 2.2-4 - Turbine Efficiency Curve............................................................................................- 24 -Figure 2.5-1 - Waterway of Giddawa MHP......................................................................................- 28 -Figure 2.5-2 - Electrical System of Giddawa MHP............................................................................- 29 -

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List of Tables

Table 2.1-1 - Hemas Building Electricity Expenditures.....................................................................- 17 -Table 2.6-1.1 - CEB training schedule * the LECO period. Not relevant to this section...................35Table 3.5-1.1 - LECO training Schedule................................................................................................54

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1 Introduction

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1.1 Hemas power

Hemas Power PLC is a strategic investment company, which invests in power sector,

generation area. The company is a sub company of Hemas Holdings PLC and functions as the

holding company of the group’s power sector investments. The company has currently

invested in one thermal power plant and three mini hydro power plants.

The company was formed in 2003 and public listed some time after Hemas Holdings

was public listed. Currently, 75% of the capital of the company is owned by Hemas Holdings

and remain 25% are issued as the public shares. The price of the share on Hemas Power is

about 23.00 LKR currently.

Hemas Power invested in Heladanavi 100MW thermal power plant as the first

invested project. In this project, 15% of the capital was invested by Hemas Power and

another 15% was by Lakdanavi Ltd. The rest 70% was collected as loans. Te capital cost of

the plant was 6.2M LKR. Currently 50% of the voting shares are owned by Hemas Power.

The operations and maintenances are conducted by Lakdanave Ltd, who is the operation and

maintenance contractor of the plant. The plant was commissioned in 2004. The unit cost of

the plant is about 16 to 18LKR.

As the second project and as the first renewable energy project of hemas power,

Giddawa Hydro Power was established. It was located in Giddawa, Theldeniya in Kandy

district. From the feasibility to the operation all the procedures in this plant, was done by the

Hemas Power. The plant was registered as Giddawa Hydro Power. More details about this

project will be discussed in later chapters.

As the third project the Magal Ganga Small Hydropower plant was set up. The pre-

feasibility and feasibility studies were done by Okanda Power Grid (Pvt.) Ltd. The

documents were acquired by Hemas Power in the feasibility stage. The plant is located at

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Daraniyagala in the Kegalle District and it is fed from the river Magal Ganga. The capacity of

the plant is 2.4MW. The power plant is supposed to be commissioned in 2011.

The Senok Mark Hydro power plant which is located at Lindula, Thalawakale was

acquired by Hemas power in operation level. The capacity of the power plant is 2.6MW. And

the power plant is fed from Agra Oya.

1.1.1 Organizational Structure

The company is acted as a

sub-company of Hemas holdings as

said above. The organizational

structure could be shown as figure

1.1. Currently Electrical Engineer

and Mechanical Engineer are

working as the project managers. The complete staff is about 60 personals with the project

staff who are working in the project sites.

1.1.2 Strength

Hemas power achieved to more than Rs.5 billion as the annual revenue with a

minimum number of staff like 60. And also, the staffs in the plants as well as in the

managerial level are very much loved to the company and the power plants. Having such a

staff is the greatest strength the Hemas Power have.

1.1.3 Weaknesses

Even though the staff is very much love to the company, the employees in the lower

levels like labors are leaving the company due to the insufficiency of the salary. This is an

improper management practice. Through this the lack of the sufficient staff to the power

plants could be occurred.

1.1.4 Profitability

When considering the power generation, the renewable power generation is an

extremely profitable field. Because, the electricity is classified as an essential item and the

foul cost in renewable plants are very low. Due to that reason the company is in a stable

financial state.

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Figure 1.1-1 - staff of the Hemas Power PLC.


1.1.5 Usefulness to society

In a time, which the country is facing a relatively downcast financial state, and

spending a high price to the thermal energy, invest and encourage the renewable power sector

could be considered as a great service to the country. And also, the company always tries to

help to the people who are living nearby the plant area.

1.2 Ceylon Electricity Board

Ceylon Electricity Board, which is commonly known as the CEB was established by

the Ceylon Electricity Board act in 1969 under the Ministry of Irrigation and Power. Later on,

the CEB was transferred to the Ministry of energy and power. Currently this institute is

governed by the Ceylon Electricity Board act 1969 and Sri Lanka Electricity act 2009. The

CEB has divided into three divisions; Generation, transmission and Distribution. Currently,

the license for generation and distribution are issued for IPPs as well as the CEB and CEB is

the only one who is having the license for transmission.

1.2.1 Vision

“Be an internationally recognized efficient utility providing high quality service to all

its stakeholders.”

1.2.2 Mission

“To provide reliable quality electricity to the entire nation at internationally

competitive prices effectively and efficiently through a meaningful partnership with skilled

and motivated employees using appropriate state-of-the-art technology for the socio

economic development of the country in an economically sustainable manner while meeting

acceptable environment standards”.

1.2.3 Present Performances of CEB

CEB is the largest organization related to the power sector in Sri Lanka and the main

controller of the power sector. 74% of the installed capacity in Sri Lanka is owned by CEB.

And the current total capacity which is owned by CEB is about 1902.1MW. And also, it

serves more than 90% of area in Sri Lanka through the transmission and distribution lines

owned by CEB.

Due to the large size and the complexity of the organization, even though the

organizational structure is well structured, the management had become a problem. There are

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many inefficiency in CEB and it was categorized as an institute, run in a loss state. To

overcome this problem and to generate reliable operation out of CEB, a restructuring for CEB

was proposed. According to that, the CEB is supposed to divide into three individual sectors

and privatize them was proposed. But, due to the criticisms of the trade unions, the proposal

was failed from the parliament.

1.2.4 Strength of the CEB

The assets, which is owned by CEB is about billions of rupees. Due to that asserts it

keeps the control over the power sector in Sri Lanka. And also, it is having the all three

license for Generation, Transmission and Distribution. Furthermore, the only licensee of

transmission is CEB. This makes CEB, the most powerful institute in power sector.

1.2.5 Weaknesses of CEB

CEB is an organization which is operated under the Sri Lanka Government. So the

rights of the employees are significantly strong. So the employees, who are not taking a part

of the critical decision makings and the critical issues, are acted in an unproductive manner.

This makes CEB a loss counting organization. And also, because of CEB is operated under

the government, some important decisions like building plants are taken through the

government. So the control of the CEB is gone out of its hand, sometimes to the people who

are not having the proper understanding of the field’s important areas. This makes the

operation difficult to CEB.

1.2.6 Profitability

As said above, the CEB is conducted under huge losses. This had made the

organization unprofitable. Proposals to improve the profitability had come out time to time.

But due to some reasons, these attempts have been restrained.

1.2.7 Usefulness to the society

The electricity, as said above, is an essential service. Manipulating such a sector in a

reliable manner is a great social service to the country. Even though the distribution ends are

having come problems, as a macro scale picture, CEB provides a quality vice very good

service through the generation, transmission and satisfactory service through distribution. The

staff in key positions of the institute are always try to conduct a safe and reliable service to

the country. As an example, the number of blackouts is minimum and the voltages in the

transmission ends are usually kept within the range.

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1.3 Lanka Electricity Company.

Lanka Electricity Company, commonly known as LECO is an electricity distribution

company. This company is the only company which is having the power distribution license

instead of CEB. The LECO distribution areas are extended from Negombo to Galle, in the

west coastal area of the island.

LECO was established in 1983, as a solution for the inefficient electricity supply in

above mentioned areas. Before 1983, the electricity distribution of these areas was controlled

by the local authorities. By considering the inefficiencies, the government decided to

establish a private company for the electricity distribution. Then LECO established, but the

full ownership of the company is belonged to the

Government authorities.

15% of the electricity distribution is owned by LECO.

For the administration simplicity, the LECO distribution

network is divided into seven branches. They are Negambo,

Kelaniya, Kotte, Nugegoda, Moratuwa, Kaluthara and Galle

respectively. There is a LECO training school is established

in Ekala. Each branch is consists several depots. And the

staff is about 1500 personals.

Currently LECO is operating is 39 local Government

areas and over 500,000 consumers are having the service of

LECO.

LECO purchases the electricity from the primary substations as

11kV power. Then it distributes as 11kV high voltage for bulk consumers

and 400V low voltage power.

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Figure 1.3-2- LECO Distribution Areas

Figure 1.3-3 - LECO Organizational Structure


1.3.1 Organizational structure

The LECO organizational structure could be shown as figure 1.2

1.3.2 Present performance

LECO maintains the distribution network in a good state. The distribution losses are

kept below 6% while the distribution loss in CEB is having higher value like 14%.

Furthermore, LECO maintains a GPS based geographical information system, which helps

LECO in asset management in a highly accurate manner. LECO always tries to gather the

new technology to the Sri Lankan power distribution area.

Currently, LECO has invested in a meter production factory in Bandaragama. The

projects like net-metering and broadband service via power lines could be taken as the future

steps, willing to be taken by LECO.

1.3.3 Profitability

As said above, LECO maintains the network in a loss-minimum manner. This makes

the company loss reduced profitable one. Furthermore, the components used in the LECO

distribution network, prevents stalling the electricity in a higher degree.

The distribution business is operated under a tariff system. So the profits should be

gained mainly by reducing the losses and maintaining the network in a good condition.

1.3.4 Strength of the company

The company is having a well structured, technological system to maintain the

network. So supplying a quality vice good service has become simple. Furthermore LECO

areas are having a high density of consumers. This has become an extra profit to LECO.

1.3.5 Weaknesses of the company

The interconnection between the employee levels of the company has become

minimum. So the disagreement between the managerial level and the other employee levels

are occurred. This might caused to the reduction of the satisfactory of the employees.

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2 Training Experience

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2.1 Hemas power

2.1.1 Hemas building power system.

As our first assignment, we were assigned to analyze the power system of the Hemas

building, Colombo.

The building was locates adjacent to the Bristol street and York street itself, and the

workplaces are located facing the both streets and the corridors inside the building in upper

floors. Eusifully Trust, the owner of the company, conducts all the maintenances of the

building including provide the requirements like electricity, water, maintain the buildings

systems etc. It charges for the services from the residents. Hemas holdings and Eusifully trust

are shareholders of each other. The building was constructed about 50 years ago and since

then Hemas has resident it.

In understanding the electrical system of the Hemas building, as our first step, we went

to meet Mr. Jeffry Mohomad, who was the manager of Eusifully trust. He and Mr. Piyasiri, a

maintainer of the electrical system, helped us on understanding the electrical system.

The power system of the Hemas building could be divided into two, the main power

system and the alternative system. The main power system is containing a 1000kVA

transformer, a bus bar, metering gauge units and main switches. The power is taken from

CEB as 11kV to the transformer. Then the electricity is transformed to 400v and taken to a

bus bar. The residents in Hemas building could have the postal address belong to either

Bristol Street or York Street. Due to these two kinds of addresses, the power distribution

system in the building is too divided into two sections; Bristol street side and York street

side. Through the above bus bar, the power is divided to above sections. Those section lines

are then connected to another two bus bars, through metering units and main switches. As the

alternative power system, a 640kVA diesel generator is placed. The generator is connected to

a different bus bar through switching units.

Then the main and alternative systems are joined together to supply the power to

consumers. Each feeder in the main lines busses are joined with a feeder from generator bus

bar through changeover switches and connected to the consumer through metering units.

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The system could have optimized if the alternative system joined with the main lines

before the distribution bus bars. This will reduce the cost for individual changeover switches

and reduces the respond time. It improves the performance of the system.

We observed the main

control room. The bus bars

were double bus bars and the

meters were digital meters,

which were capable of

measuring the maximum

demand. In addition, there are

two measuring instruments,

which are capable of measuring

the power factors, Voltages,

Currents and reactive and

active powers for separate

phases. In order to improve the

power quality those parameters

were measured.

We observed the

generator too. It is a diesel

generator, which an engine

runs as the prime mover. It had

the following characteristics.

Prime mover speed – 1500rpm

Rated Power - 512kW 565kW (stand by)

640kVA 706kVA (stand by)

Rated Current 924A 1019A (stand by)

The generator is maintained by Trade Promoters Ltd. Sri Lanka.

The CEB prepares two separate bills to the two sides of the building. The billing details

relevant to December 2009 are given below.

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Figure 2.1-4 - Power system of Hemas building


Table 2.1-1 - Hemas Building Electricity Expenditures

For Bristol street Cost – Rs For York Street Cost – Rs

kWh 57900 700902 kWh 35371 488119.80

kVA 242 181500 kVA 202 151500

Total 882402 Total 639619.80

Total 1522021.80

This amount is divided among the consumers according to their usage. Eusifully Trust

staff does this billing. Energy meters belong to each consumer is placed in the control room.

According to the above data, Eusifully Trust pays about 333,000 LKR for the reactive

power. And also the power factor of the building is about 0.2 due to the usage of the air

conditions and florescent lamps. We took the readings of the power factor. To save that

expenditure and improve the system performance, it is willing to install a capacitor bank in

the building. We met Mr. Lalith Athugoda, who has a contract about the improvements of the

building electrical system on this matter. According to his calculations about 1 million LKR

will be spent to install the capacitor bank. Through this the power factor could be improved

up to 0.85. The cost for the installation of the capacitor bank could be recovered within 2

years and the profits could be gained from the third year. The capacitor bank is scheduled to

install in 2011.

On the third day of the training we were attend to a trip switch testing of the building,

which is conducted to improve the safety of the building. The testing is scheduled for once

three months. We attend to the tests with Mr. Vajira.

There are three tests were done in the testing procedure; No-trip, rated trip and fast trip.

It uses an instrument called RCCB digital tester to conduct the tests, which facilitates to all

above tests. As the first step of the testing procedure, the power is cut off from the main

switch. Then the tester is attached to the bus bars. Then, for the given currents, the respond

time of the trip switch is checked. In no-trip the trip switch should not operate and in the fast

trip test the trip switch should operate immediately.

In the beginning of the 2nd week, we presented a presentation about the electrical system

of hemas building.

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2.1.2 Mini Hydro Plants

We learnt about the mini hydro plants in the first week onward.

The hydro plants, which the power generation is below 10MW and above 1MW, are

roughly categorized into the category, Mini Hydro Plants. This kind of power plants is

generally considered as a most cost effective and reliable power producing power plants.

Because,

Mini hydro power plant uses the kinetic energy of the flowing water to

produce the power. Therefore, the fuel cost for this kind of plant is nil. And also the

source is renewable. Therefore, the risk of lacking the fuel is minimum.

This kind of pants are not releases the green house gasses or any kind of

hazarders gas. This will improve the environmental friendliness.

In hydro power plants, the efficiency is high (about 70%-90%) relative to the

other power producing technologies.

The power of the power plant varies with the water flow of the river. The

water flow varies with the annual rainfall. Therefore, the predictability of this kind of

power plants is high relative to the other renewable power producing technologies.

The water flow of a river varies slowly in most cases. So, the power output

varies slowly. Therefore, the power output is said to be stable in this kid of power

plants. So, the reliability is relatively above to the other renewable power producing

technologies. And also, the plant could be designed to meet a higher plant factor.

In hydro power plants, the power is generated using the kinetic energy of a water flow.

This energy could be mentioned using the head and flow terms

P = ρ g Q H

By including the efficiency, the power output could be presented.

P = η ρ g Q H

Therefore, the parameters of the hydropower generation are head (H), Flow (Q) and

Efficiency (η). By matching those parameters in an appropriate power generating technology,

the mini hydro plants are designed.

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The structure of a mini hydro scheme is slightly different from the other hydro plants.

In most cases, these power plants are run-off-river type. That means the water storage of this

kind of scheme is minimum. A mini hydro plant could be designed to either divert the water

flow and run the plant or construct the plant in the river. Canal and penstock type could be

taken as an example for the diversion type and Barrage type and Syppen type could be taken

for the non-Diversion type. When there is a sufficient head, the diversion type is used.

Construction in this type is relatively easier than the non-Diversion type. In Sri Lanka,

because of the commonness of the sites, diversion type mini hydro plants are common. All

the mini hydro plants belong to Hemas Power are Diversion type.

The components of the mini hydro plant

A sketch of a waterway of a mini hydro plant is shown in fig 2.1.

Weir – The water flowing in

the river is collected to a

small reservoir

Inlet – the water collected in

the reservoir is diverted to

the channel. In most of the

times, there is a gate to

control the inlet.

Channel – The water, which

is diverted from the weir, is

carried to the forebay tank.

The channel could be an

open channel, a closed

channel and a combination of

both. In most cases, the filtering methods like trash rack and desilting tank are

placed in the channel. By the trash racks the heavy floating parts like plant parts,

which is coming with the water, is collected and by desilting tank the heavy

particles like sand are collected.

Forebay Tank – The water carried through the channel is collected to the

forebay tank. The water flow relative to the water storage in the channel is

relatively high. So, in a sudden stop, the water is collected in the forebay tanks

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Figure 2.1-5


and channel. The excess water is spilled from the banks. To create a safe way to

exit the excess water the spillways are constructed. The spillways are placed in

the forebay tank and in the channel.

Penstock – The water, which is coming through the forebay tank, is carried to

the turbine creating a high head difference and high kinetic energy. Duo to the

sudden variations of the flow in stopping and starting, heavy pressure currents

could be generated through the penstock. To survive those currents, the penstock

is usually made by steel.

Turbine – The turbine is the most important part of the waterway of the mini

hydro plant. It converts the kinetic energy of the water flow to kinetic energy of

the coupled shaft.

Tailrace – The water, which is used by the turbine, is released to the river

through the tailrace.

The electrical system is consists the following components.

Generator – The kinetic energy of the rotating shaft is converted to the electrical

energy by the generator. Typically, the output voltage of a generator varies from

400V to 15kV. The synchronous type generators are generally used in mini

hydro plants.

Breaker s and bus bars – The breakers and bus bars too installed in the system to

provide the protection and reliability.

Transformer – The transformers are used to convert the power from generator

output voltage to transmission voltage (33kV in Sri Lanka). Generally, the

number of transformers is equal to the number of generators units.

Measuring instruments - to measure the power output from the plant, an Energy

meter is installed.

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2.1.3 Designing a mini hydro plant

We learned the procedure of designing a mini hydro plant.

The first step of designing a mini hydro plant is selecting the site. In this, the flow of the

river and the head could be gain is considered. As the primary need, a place, which could

gain a head as high as possible, is selected. The place should have the higher head with a

maximum slope, because, when the slop is high, the length of the penstock becomes low.

Therefore, the loss in the penstock reduces. Furthermore, the ability to carry water to the

selected area is checked too. This means, there should be a point to tap the river, which is

above in height, to the highest point of the selected area.

Then a place to build the weir should be select. In this, the ability to carry a sufficient

amount of water to the plant is considered. If the tapping point is lower in height to the

selected designed penstocks highest point, the ability to bring the water to the penstock

becomes impossible. If the tapping point is very high, the flow is become low and due to the

slope, the channel will washout. So the tapping point is selected slightly above the penstock

start. In this tapping point, a weir is build and diverted to the plant site.

As the second step, the flow of the river in the tapping point is measured. In measuring

the flow of the river, two criteria could be used. First criteria is measure the cross section and

the speed of the river at the tapping point. In this method, the instant accurate flow could be

measured. However, gathering hydrology data about a long period like a year is difficult. In

this case, an approximate method is used.

In this method, the catchment area of the river for the tapping point is calculated. The

area, which the rainfall collects to the given point of a river, is simply referred as the

catchment area. The area is selected using maps of the area. The hydrology data about the

rainfall is collected then. Through this rainfall data, a fair rainfall model along the year could

be developed. Then the catchment area is divided to the areas according to the manner of the

environment like forest cover and the appearance of the soil. Then the rainfall is multiplied

by the sub areas of the catchment area weighted by the factor, which represents the amount of

water collected to the river per unit rainfall and get the sum of the flows. From this method,

an annual hydrograph is created.

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In annual hydrograph (Figure 3.1),

the day-by-day flow variation Vs the day

of the year is plotted. However, in

designing process, to calculate the energy

and other facts, the annual hydrograph is

not sufficient. Therefore, the Flow

Duration Curve (Figure 3.2) is plotted. In

this graph, the flow Vs the number of

days which the floe is available is

plotted. This curve is more useful in

choosing the design flow.

We were given an assignment to

study the flow duration curve and create

a program to calculate the critical

parameters for various design flows.

2.1.3.1 Criteria

In diverting the water flow, an amount of water is released to go through the natural

river for environmental and ecological reasons. This flow is called the compensation flow or

by-pass flow. In energy calculation, this flow is subtracted from the flow duration curve.

Then, for few design flows, the following calculations were done.

1. Plant factor- the term ‘plant factor’ is referred to the portion of the annual

energy output to the produced energy output.

Plant factor = Energy generated per year

Maximum output * 8760

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Figure 2.2-6 - Annual Hydrograph

Figure 2.2-7 - Flow Duration Curve


This could be converted to the terms related to the flow duration curve as

follows.

Plant factor = Area under the FDC and resign flow

Area under the design flow

2. Excedance – The term ‘excedance’ is referred to the portion of the number of

days, which the plant could be operated in full load, to the number of days the

plant operated.

Excedance = full load operated days

Plant operated days

This could simply extracted by taking the point, which the FDC and design flow

is intersected.

3. Annual energy output- the annual energy output could be calculated using the

area under the FDC and design flow.

Annual energy output = η ρ g H Area under curve 86400

By optimizing the above values with the cost for the equipments and project, the

design flow is selected.

We modeled the above criteria in a MATLAB Program. In it, for different design

flows, the plant factor, excedance and the annual energy is calculated. The efficiencies of

different turbines are different. To make the calculation fairer, the turbine type is too taken as

an input. The MATLAB program has been attached as the annex 1

Then using the above flow and head, the turbine is selected. We were given an

assignment to understand the turbine selection criteria and create a program to select the

turbine according to the flow and head.

Turbines

In hydropower generation, there are two types of turbines are used; impulse type and

reaction type. In impulse type, high-speed water jets are used to run the turbines. In reaction

type, the pressure difference of the input and output is used to run the turbine. In mini

hydropower schemes, the following turbines are used.

Pelton – Pelton wheel is an impulse type turbine. In this turbine, water-jets are

directly focused to the buckets of the turbine. This turbine is suitable for the

high head low flow applications.

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Turgo – Turgo turbine is too an impulse type turbine. In this turbine, water-

jets are placed slightly angled from the wheels plane. This turbine is used in

high and medium head applications.

Francis – This is a reaction type turbine. This is used in medium head

applications. In Sri Lanka the sites with medium head is common. So these

kinds of turbines are widely used in Sri Lanka.

Crossflow – This is an impulse type turbine; but used in low head high flow

applications. When the plant is constructed as non-diversion plant, this turbine

is used.

Propeller – These turbines are used in low head turbines. This is a reaction

type turbine and like a propeller in the boats in shape. The water flow is

moving in the shafts axis direction in this turbine.

Kaplan – This turbine is too a reaction type turbine. It is used in low head

applications.

The efficiency variation of the turbines with the flow percentage is plotted in the fig

To fulfill the assignment, we created a MATLAB program (m file) based on an

algebraic method. The relevant m file is attached as the annex 2-a. But in evaluation the

program, it malfunctioned. So, our training engineer gave us a graphical method, which

Hemas power uses as a source, and the relevant chart. Therefore, we modeled the chart to a

MATLAB m file. The relevant MATLAB files are attached as the annex-2 and annex-3

While after those selections, the projects feasibilities were evaluated. In this, the

following facts are considered.

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Figure 2.2-8 - Turbine Efficiency Curve Figure 2.2-9 Turbine Selection Chart


Summery – in this section a quick representation of the following chapters are

given. Furthermore, all the key data and the comparisons with the other energy

options are described.

Environmental impact analysis – in this chapter, the environmental impacts

could be occurred is discussed. Generally, the information about the living

creatures of the site area, the methodology used in the survey relevant to

environment and other environmental factors are considered. Furthermore, the

bypass release is too decided in this chapter.

Socio-economic viability – in this chapter the social and economical states of

the people who are living in relevant site area is discussed. Furthermore, the

impact of the living style of the relevant people is too described.

Hydrology analysis – In this, the hydrological analysis is included. The flow

analysis method, flow analysis data and the energy calculation results are

represented in this chapter.

Cost/profit analysis – in this chapter, the economical analysis about the costs

and profits are described.

Component details – in this chapter, the equipment provider details, all the

equipment details and the cost analysis is included. Furthermore, the details

about the quotations considered and the reasons for the selection are too

described.

Annexes – relevant materials like the rainfall data, the Flow Duration Curve,

the site maps and the reports taken from the relevant authorities and analyzers

are attached to the

During the training period, we had the chance to refer the feasibility report of

Giddawa project.

2.1.4 Trash rack design

In the 7th week, I was given an assignment to design a trash rack for the Thalawakale

power plant (Senok Mark Hydro)

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The filter, which is used to filter the large floating parts in the water, is called the

trash rack. As a practice, the trash racks are designed fitting bars vertically to a frame. So

then the trashes remain could remove using the rakes.

The trash rack whish was to design, was supposed to be placed in the desilting tank.

The following data was given,

The dimension of the channel – to calculate the cross section of the

flow.

The dimension of the desilting tank.

The width of the bars of the trash rack.

The width should be kept in the holes of the trash rack

20% extra space from the cross section of the channel for make the

flow continues and 150 angles.

The medium height of the water flow.

As the first step, I modeled the site area in AutoCAD, and measured the effective

cross section area of the channel (A). Then the effective cross section of the trash rack will be

120% into (A)

Effective cross section of the trash rack (Atr) = A 1.2

Thos is the cross section of the holes. Therefore, the effective cross section of the

trash rack would be the Atr into width of a hole and a bar over width of a hole. In here the

effect of the angled edges are neglected.

Under water cross section of the trash rack (AUw) = A 1.2 (Wh+ Wb)/ Wh

Then, a plane of an angle 150 to the z direction is drawn in the AutoCAD file and the

intersection cross section area was taken for few places in the trash rack. Then the place

which gives the AUw was found and decided it as the proper place to place the trash rack. The

drawing of the assignment is attached as the annex 4

2.1.5 Financial Structure of a company and evaluation for acquire a company.

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We met Mr. Ravi, who is the economist of Hemas Power, to learn about the financial

structure of a company. He learnt us about the power business, capital structures of a

company and the economic evaluation for an acquirement of a company.

There are two kinds of capital collection methods; Lendership and ownership. The

lendership is referred to the investments with an interest. In this relationship, the investor is

not having any ownership to the capital and company and the invested money should be paid

with a fixed interest. The ownership is referred to the investment, which makes the investor

own a part of the profit and a risk. In calculating the profits, the share of the landership is

taken as a liability and subtracted from the gross profit. Then a share for the future usage is

saved and the rest is divided among the owners. These decisions are taken by the board of

directors.

In acquiring a company, an economic evaluation is done. While after getting known

that a company is about to sell, the financial state and the future revenues are evaluated and

the revenues are projected to the present value. Then the cost of equity is evaluated. The cost

of equity reflects the opportunity cost of the purchase. The cost of equity could be evaluated

by the following equation.

Cost of equity = riskless rate + premium factor risk factor

If the cost of equity is lower than the forecasted present value of the company, the

purchasing is viable.

In power purchasing by CEB, they create an account for the power plan, not the

owner. This will simplify the accountings of the CEB side. Se the power plants should be

registered as individual companies by law. Then the payments for the power purchasing are

paid for the individual power plant. And also, the changes of the managements are not

affected to the CEB procedure. Because of the power plants are considered as companies,

acquiring a company is relevant to the field.

2.1.6 Gidddawa mini hydro power plant

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Giddawa mini hydro plant is the first renewable power plant, which started by Hemas

Power. The site is located at the village called Giddawa in Theldeniya, Kandy. This is the

fourth cascade placed power mini hydro plant in the river. Followings are the details relevant

to the power plant.

Gramasewaka division – Ambalagala & Giddawa

Divisional secretarial division – Theldeniya

Pradeshiya Sabha – Mada Dumbada

Provincial council – Central Province (Kandy)

The gross head of the power plant is 27m and the net head is 26.3m. The rated

discharge is 4.3m3/s. In the 10th week I was given a chance to get training in this plant for a

week in plant training. I was given an assignment to prepare a maintenance schedule for the

plant. About that assignment will be described in a later chapter.

The plant is constructed crossing the river ‘Hulu Ganga’. A weir is constructed

crossing the river about 800m above the plant area. It is 15m in long and 2m in height. The

weir is constructed using rocks and concrete. There is a bypass to keep the river live. The

channel is constructed in the left bank of the weir. The intake is constructed in a left most

position of the weir.

The channel is constructed

through the left bank. It is 2m high

and 3m wide. The length of the

channel is about 800m. The inlet gate

is constructed about 20m after the

intake. And a desilting tank is

constructed in the middle of the channel. Its

dimensions are 3m 4m 6m. There is a spill

way in the desilting tank and a gate to remove

the sands is placed in the bottom. A trash rack

is too placed in the end of the tank.

In the end of the channel, the forebay

tank is placed. It is 6m wide, 8m high and 9m

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Figure 2.5-10 - Waterway of Giddawa MHP


long. There are two spillways placed in the forebay tank. The spillway in the tank is the first

designed spillway. But it couldn’t be able to provide enough space for the whole spill in a

sudden stop. So a spillway outside the forebay was constructed. There is a sand gate similar

to the desilting tank is placed in the end of the forebay tank. There is a trash rack too.

In the end of the forebay tank, two penstocks were placed. The penstocks are 70m

long. They are 1.5m in diameter and 12mm in thickness, steel. From the penstock the water is

transferred to the two horizontal spiral Francis turbines. Through this two synchronous

generators were driven. The rates speed of the turbine is 500 rpm and manufactured by

Gugler Hydro Energy, Australia. The rated output of the turbine is 1012kVA.A hydraulic

system, which is coupled with a weight, is used as the auto-closing method of the guide

vanes. Then the used water is released to the river through the tailrace.

The generator is a 12 pole salient pole

rotor synchronous generator. The technical details of the generator are given below.

Rated power – 1150kVA

Power factor – 0.85

Rated current – 1160A

Output voltage – 400V

Excitation – 90V 3.6A brushless

excitation.

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Figure 2.5-11 - Electrical System of Giddawa MHP

Figure 2.5-3 GHP Weir Figure 2.5-4 - GHP channel

Figure 2.5-5 - GHP Forebay Tank Figure 2.5-6 - GHP Electrical Equipments

Figure 2.5-7 - GHP tail race Figure 2.5-8 - GHP Penstock

The power output of the generators is then transferred to the transformer through

breakers. There are two 1250kVA transformers are placed in the plant. Through this the power is

transformed to 33kV. Then the transformer outputs are connected to a bus bar through breakers.

These breakers are the ones, which were closed in synchronization. Then the bus bar output is

sent to the national grid through a 33kV transmission line. An energy meter is coupled with the

line through a Current Transformer. From this the power output and the reactive power usage is

measured.

The transmission line is proposed to connect the Theldeniya gantry. But currently the line

is connected to a feeder of the Karandeniya gantry.

2.1.6.1 Experience in plant

I reported to the power plant about 12.30pm on Monday. I started to refer the manuals of

the power plants components in the evening.

On Tuesday and Wednesday, I studied about the waterway system and the other systems

of the power plant, the hierarchy of the staff and the works done by those staff members. And

also I gathered the information for the assignment of preparing a maintenance schedule.

The staff of the power plant is consisting one plant supervisor, four plant operators and

eight labors. All of the staff is lived nearby the plant area except supervisor.

The supervisor; Mr. Pramathilaka, controls and supervises the plant. The administration

part is completely done by the supervisor. The plant operators are worked in an 8-hour shift

manner. The shifts are changed at 6am, 2pm and 10pm. The operations of the power plant

machinery are completely done by the plant operators. The maintenance of the power plant is

done by the labors under the supervision of the supervisor or operator. And also, the cleaning of

the plant is done by the labors. They also worked in a shift schedule, two personals in a one shift.

Dering my training in Giddawa; I attended to the works done by operators. I

synchronized a generator once tripped due to the phase shift failure. I got the readings of the

power output, reactive power input and power factors. I got the opportunity to attend few night

shifts with the power plant operators.

Moreover, I studied the works done by labors. I attended to clean the trash racks twice.

2.1.6.2 Teamwork – leadership development program.

In Thursday, there was a teamwork and leadership development program in the plant.

The program was organized by Hemas Power, to develop the leadership and mutual

understanding of the staff of Giddawa hydro power plant. The program was conducted by

corporate training division, Academy of Adventure, Belihul Oya. I was too had the chance to

attend to this function.

The function was conducted as a one-day course. The whole staff was divided into two

groups as about six personalities per group. Both the groups had to go through the activities and

complete them. There were eight challenges and are focused on the abilities like self confidence,

commitment, leadership. The tasks had named as team building, trust challenge, lava crossing,

magical turtle, key punch, human knot and blind walk. Those activities were focused on

developing different attitudes and abilities on the staff of the power plant. The concentration,

mutual understanding and the strategy were became the essential abilities in this tasks. That

experience was a real fun. The certificate, I was given for the participation is attached as the

annex 5

In the last day of the Giddawa, Mr.

Premathilaka thought me about the power

distribution system around the Theldeniya

area. And the power flow of the power

plant. I was given the chance to travel

around the Theldeniya area and see the

Karandeniya gantry and Rajawaka Air

Break Switch. A single line diagram of the

area is shown in the figure 4

2.1.6.3 Review

The plant is facing a large difficulty in the incoming water flow. The forest cover in a

part of the catchment area has been removed few years back. So the water flow is not regular

throughout the day and sudden water flows are generated at the rains in the upper part of the

Figure 2.5-9 Single line diagram of Theldeniya Distribution Area

river. So the controlling has become difficult and due to the large spill out in the sudden flows,

the energy is wasted. Due to that, the plant factor has been reduced to the designed value.

Furthermore, the plant output is connected to a feeder. So the voltage fluctuations and phase

shifting are generated. This has made the increase of the number of tripping in the plant. The

plant is a run-off-river type one and for each tripping the water is spilled from the forebay tank.

This makes a huge energy waste.

Throughout the week, I was given the chance to stay in the plant in the night as well as

the day. Through this I had the chance to learn about their duties in the plant, their lifestyle, and

there relationship with the power plant. The villagers are deeply bounded with the power plant in

the re lifestyle. And the power plant administration and Hemas itself too became more helpful

for the villagers, and tries to improve the living condition of the villagers through the social

servicing activities like improve the conditions of the village school. And also, because of the

plant, the sudden floods generated have been limited.

Furthermore, I observed that the staff working hard to do their duties as best as possible.

They extremely cared about the power plant. And also, became more helpful for the visitors too.

I should be more thankful for the plant staff for helping me out in letting me get experiences and

helping me out in various ways throughout the week.

2.1.7 Maintenance schedule

I was given an assignment to create a maintenance schedule for Giddawa power plant in

the 9th week of the training. As the first step of the assignment, I gathered the information about

the mini hydro plants, the components using in the plants and the maintenance of the

components. Then I organized the information found. End of the week, I gave a presentation on

the assignment progress – the gathered information about the maintenance of the mini hydro

plants.

In the week, which I was in Giddawa, the maintenances which are conducted by the staff

were gathered. The information gathered before the Giddawa week was mainly based on the

electrical and mechanical equipments. The information about the civil constructions like the weir

and channel, are gathered during the in plant training.

Then I combined the maintenance in a schedule such that, not to be clash with each other.

And matched them with the appropriate period, for example cleaning the tanks are not scheduled

in the wet period.

And also I gathered the information about the safety of the personals who is doing the

maintenance.

As the final presented item, I had to prepare a booklet for the maintenance and the

maintenance schedule. The booklet is attached as annex 6

2.2 Ceylon Electricity Board

During the CEB Training period, we had to gather knowledge about power generation

and transmission. The Distribution is supposed to be covered in the Lanka Electricity Company

period. We had the chance to attend five training places during eight weeks period covering two

regions; Generation and Transmission.

We got the training schedule for the CEB training period as follows

Period Training area Place

03/05/2010 – 14/05/2010 Transmission

Operation & Maintenance

Pannipitiya, Kotuoda,

Veyangode & Kolonnawa GSS

17/05/2010 – 11/06/2010 *LECO

14/06/2010 – 25/06/2010 Hydro Power

Generation

Samanalawewa Power

Station

28/06/2010 – 09/07/2010 Thermal Power

Generation

Kalanithissa Power Station,

Kalanithissa Combine Cycle

Plant.

12/07/2010 – 16/07/2010 Generation

Planning and design

branch

Generation Planning Branch,

CEB Head Office, Colombo.

19/07/2010 – 23/07/2010 System Control

Center

CEB, Kent road,

Dematagoda.

Table 2.6-2.1 - CEB training schedule * the LECO period. Not relevant to this section

From this, Hydro Power Generation and Thermal Power Generation are belonging to

Generation section and Transmission, Operation & Maintenance, System Control Center and

Generation Planning & design branch are belonging to Transmission section. To make it clear,

the chapters about the CEB Training is organized as in section relevant manner, instead of the

order of attend.

2.2.1 Hydro Power Generation – Samanalawawa Power Station.

Samanalawewa Power Station is a most important power plant in Sri Lankan power

generation. It generates and releases a 120MW maximum power generation to the national grid.

And it is the largest power producer in the southern part of the power grid. The plant is placed in

Walawe basin and operated using the water which is collected at Samanalawewa, in Balangoda

area. The construction of the power plant was started in 1989 and it was commissioned in 1994.

The plant is operated under the Deputy General Manager (DGM) of other hydro complex. The

plant is located at Hapugala, Balangoda. We had the opportunity to attend and learn about the

power station and the systems and operations through these two weeks.

2.2.1.1 The waterway

The Samanalawewa reservoir is built by building a dam crossing the Walawe River at

Pambahinna. The reservoir is fed from Diyawini oya and Katupath oya, which are the branches

of the Walawe River. The dam is 107m in height and 500m in length. And it is clay core rock

filled type dam. It is having three spillways with radial gates placed on it .The gross storage of

the reservoir is about 274106 m3. The reservoir is designed to spill at 460 m above MSL. But

due to the leak in the right bank, now a decision to spill the reservoir at 455 m above MSL has

been taken.

The intake, which is used to take the water to the powerhouse, is located about 5.5kms

away from the dam site. The intake structure includes a screen to filter the water and two

hydraulic controlled gates; the control gate and the emergency gate. The minimum intake water

level of the reservoir is 424 m above MSL. And the live storage capacity is 215 106 m3

Through the intake the water is entered to the power tunnel. The power tunnel is a

horseshoe type 5.35km long tunnel and it is having a slope about 1:100. The diameter of the

tunnel is 4.5m. The power tunnel is ended with the surge chamber. It is about 12m high from the

ground level and about 18m in diameter.

The surge chamber is connected with the portal valve house through a steel tunnel. Due

to this steel structure, the damage to the tunnel in a sudden trip becomes minimum. The

waterway is divided into two from the portal valve house. There are two Butterfly valves placed

in this valve house, for the two outlets of the water. One outlet of the portal valve house is

currently blocked and kept for the future expansion of the plant and the other outlet is connected

to a penstock.

The penstock is about 670m in length and made with steel. The elevation of the penstock

is about 364m. The internal diameter varies from 3.85m to 2.85m on the bottom. The penstock is

divided to two in the end and supplied the water to the two turbines through spherical type

valves. The valves are operated by high pressure oil servo motor with weigh assisted closure.

The diameter of the inlet valve is 1500mm and the designed pressure is about 440m. There is a

by-pass valve with the diameter of 200m to equalize the pressures of the both sides of the valve

before open the valve.

The turbines are spiral case vertical Francis type. The rated output of the turbine is

70200kW when operating at the net head of 320m. The speed of the motor is 500rpm. The guide

vanes are operated by a ring which is coupled with two servo mechanisms governed by

hydroelectric governor system. The water used by the turbines is then released to the Walawe

river trough the tailrace.

2.2.1.2 The electrical system

There are two vertical shafted salient pole 3 phase generators which are driven by the two

Francis turbines. The rated output is 60MW and the output voltage is 10.5kV. The power factor

of the turbine is 0.85 and the rated speed is 500rpm. The output of the generator is carried to the

transformer through isolated phase busbars (IBPS) filled with dry air. It was tapped to take the

power to the excitation system and the auxiliary system.

Then the power generated by the generators is transformed to transmission voltage

(132kV) through two three phase 10.5/138 kV transformers. They are rated at 71MVA. The

tapings of the transformer are manually operated. The windings are oil cooled and the cooling is

classifies as ONAN/ONAF.

The power transformed to 132kV is then send to the switchyard. There is a UI bus bar

system is placed in Samanalawewa Power Station switchyard. To save the space and create a

reliable system the bus system is constructed in that manner. The two double circuit transmission

lines from Balangode & Embilipitiya and the two generator outputs are connected to the

switchyard. The bus bars are coupled using a bus coupler.

The auxiliary of the power plant is provided in three ways. As the primary method two

unit transformers are used. The power output of the generators are tapped and converted to

400V. In the power plant not operated situations, the power is taken through a 33kV feeder from

Balangode GSS. If it’s also not possible, the diesel generator placed in the plant is used. The all

auxiliary supplies are gathered to a busbar with interlocking to each other.

The excitations of the generators are done using excitation transformers and thyristor

banks. There is a battery bank placed as the back-up method of excitation.

The S’wawa is become more famous because of the leak in its right bank. Due to the

composition of the soil in the reservoir area, an amount of water collected to the reservoir is

leaked through the right bank of the dam. The leaking rate is about 2.5m3/s. The water is leaked

through the mountain and collected inside the mountain. Then this water leaves the mountain

from a single place in the right bank. The leak is used as an irrigation outlet to the Kalthota area.

We reported to S’wawa power station in 14th June about 2.00pm. We met Mr. Sepala

Karunasena, who was the chief engineer of the S’wawa plant. He gave us a presentation about

the S’wawa power station and gave us a schedule to be followed in next two weeks. In the

second day we visited to the sections of the power plant and learned about the important

components of the power plant. In the third day we visited to the switchyard and learnt about the

electrical system in S’wawa. The following is a brief description about S’wawa power scheme.

In Friday we had the chance to attend a routine maintenance of the unit two. These kinds

of maintenances are conducted once a month for a unit. In this, the following inspections and

maintenances are done.

1. A visual inspection is done for the inlet valves, the turbine outside, the cooling

water pumps, hydraulic systems and all the pumping systems in the power plant,

for cracks, leaks or any other troublesome situations.

2. The outside of the components are cleaned for dust.

3. The cover of the generators are removed and the parts inside are cleaned for the

dust.

4. A visual inspection for the components like breaking pads and the excitation

brushes are done.

During the maintenance, we had the chance to inspect the components of the hydraulic

and waterway systems. And also we had the chance to go inside the generator and identify the

parts of the generator.

2.2.1.3 Fire Protection

In Monday of the next week we learned about the safety procedures and the fire

protection schemes. As the fire protection of the generator there is a CO2 bank placed in the

power plant. When a fire is occurred in the generator the bank is actuated by the heat detector

sensors which are placed in the generator inside. Then, the generator is filled with the CO 2. In

maintenances the bank is deactivated through a manual interlocking system.

As the fire protection in the transformer, a high pressure water injection system is placed.

When a fire is occurred the sensors are actuated and a high pressure water jets are injected to the

transformer.

2.2.1.4 Emergency

In an emergency, all the staff is trained to leave the building through the front door. There

were many path marks to identify the way t o leave the building. And also there are fire fighter

materials placed in the most suitable places around the power house. And also there are

emergency tripping switches are placed around the generator. An emergency drill is take place in

the plant every year.

2.2.1.5 Dam site

In Wednesday we had a chance to visit the S’wewa dam site and Intake. In this visit, we

observed the intake, the Dam and the Barges – the boats used in wet blanketing. We also had the

chance to visit the tunnels used to take the readings of the pressures inside the right bank, and to

see the leak.

2.2.2 Kalanithissa Power Station & Kalanithissa Combine Cycle Power Plant.

As the 9th and 10th weeks of the training second half, we had the chance to attend and

learn about Kalanithissa power plants. The first week is for the Kalanithissa Power Station and

the second week for Kalanithissa Combined Cycle Power Plant.

Kalanithissa Power Plant, which is commonly known as KPS, is located in Paliyagoda,

Colombo. This is a major thermal power plant belong to CEB. The installed capacity of the

power plant is 215MW. This power plant is considered to be a key power station in blackout

situations. In blackouts, the KPS are taken to the system and the Colombo area is powered as an

individual unit.

2.2.2.1 Gas turbines

KPS is having six frame-5 gas turbines and one Feat gas turbine, which is similar to

frame 9 in size and capacity. The frame 5 GTs commonly known as small GTs are having the

rated capacity of 20MW, a small GT has been out of operation for a long time, and dissembled.

We had the chance to observe the parts of this GT. A special feature of this GTs is that, it can

operate in the synchronous compensator mode.

2.2.2.2 Synchronous compensator mode

The synchronous compensator is a component, which consumes the reactive power and

releases reactive power. In GT’s case, this term refers to the no-load running of the generator. To

bring the generator to the sync. comp. mode the following procedure is followed; first the

generator is started and brought to the full speed. Then the generator is synchronized to the

system. Then the power input of the generator is reduced by decreasing the fuel input. At this

time, the generator is started to run using the power in the system. Due to the special gear

system, which is used in the GT, between the turbine and the Generator, the turbine is

disengaged from the generator and the generator started to run as a synchronous motor. In this

state, by varying the excitation current, the reactive power could be generated.

The Feat GT is a gas turbine which is having a rated capacity of 115MW. The unit cost of

this GT is about 26 LKR/kWh while the small GTs are having a unit cost about 40 LKR/kWh.

There were two 25MW steam turbines in KPS and they were out of operation since 2003.

2.2.2.3 Switchyard

The switchyard in KPS is having the both 132kV and 33kV. The small GTs except GT1,

are connected to the 33kV busbar through 10.5/33kV transformers. The 33kV busbar is a bus

section type. The GT1 and the GT7 are connected to the 132 busbar through 10.5/132kV

transformers. This busbar is a UI type busbar system. The 633kV busbar is connected to the

132kV busbar through 33/132 kV inter bus transformer. The power generated in KPS is

transferred to the Kolonnawa through 132kV double circuit transmission line and to Biyagama

through 220kV double circuit transmission line. The Biyagama lines are connected to the

switchyard through 220/132kV step-down transformers and a gas insulated substation.

As the second week in the thermal generation we had the opportunity to visit and learn

about the Kalanithissa combined Cycle power station. The full capacity of the power plant is

165MW; 110MW from Gas turbine and 55MW from steam turbine.

The gas turbine of the KCCP can use diesel or naphtha as the fuel. But in the starting,

only diesel is used as the fuel. The energy in the exhaust is used as the source to the steam

turbine. The exhaust is dent through the Heat Recovery Steam Generator (HRSG). The energy in

the exhaust is then transferred to the steam carried through the HRSG, in two stages. Low

pressure and high pressure steam. This steam will be sent through the turbines. The high pressure

steam is sent through the high pressure turbine and the low pressure steam and used high

pressure steam is sent through the low pressure turbine. The high pressure turbine runs at

9000rpm and the low pressure turbine runs at 3000rpm. The low pressure turbine is directly

coupled to the generator shaft and the high pressure turbine is coupled using a gear system. Then

the generator shaft speed becomes 3000rpm. The used steam is condensed in the condenser and

reused to generate the steam. The output of the high pressure turbine is 25MW and the low

pressure turbine is 30MW.

Because of the combined cycle uses the exhaust energy, energy to be wasted is saved. So,

the efficiency increases. The unit cost of the power plant with the steam turbine is about 16 to 18

LKR. But, when the plant runs without the steam turbine, the unit cost increases to 26 to 28LKR.

2.2.2.4 Water Treatment

KCCP uses the water from the Kalani River for the usages like generate stream and

cooling water. The water pumped from the Kalani River are treated and made up before use.

Following steps are used in this process.

As the first step Cl is applied to the water. This chlorine is generated using the sea water.

NaCl + H2O NaOCl + H2

Then Al2(SO4)3 and NaOH is applied to the water. Al2(SO4)3 is generated by reacting a

conjugant aid and an amid. through this the Al(OH)3 is generated.

Al2(SO4)3 + 6NaOH 3Na2SO4 + 2Al(OH)3

With this Al(OH)3 precipitate an amount of suspended particles are removed from the

water. Through this the water is purifies to meet 5NTU.

This water is then filtered using pressure filters (3NTU) and multimedia filters (2NTU).

Then to remove the excess chlorine NahSO4 is applied. To remove the ions, the water is send

through Reverse Osmosis Membranes. From this the conductivity of the water is meet 100µSs-1.

Then the water is sent through an ion exchange bed. From this, the anions and the cations

are replaced with H+ and OH-. After all of this procedure, to keep the ph amount to 9, NH4OH is

added.

Electrolysis

2.2.3 Transmission Operation and Maintenance Branch

In the first two weeks of the training second half, we were assigned to Colombo region

in Transmission operation and maintenance branch for the training. During the period we had the

chance to visit the Pannipitiya, Kotugoda, Veyangoda and Kolonnawa grid substations.

In the third day of training, we went to the Pannipitiya GSS. Pannipitiya GSS is a GSS

which is having 220kV system, 132kV system 33kV system and a capacitor bank. This GSS is

one of the most important Grid Sub Stations.

The substation is connected to Biyagama GSS through a 220kV double circuit

transmission line. The incoming power through the 220kV line are taken to 220kV busbar and

transformed to 132kV through six singe phase auto transformers. The capacity of an

autotransformer is 83.3MVA and 500MVA is build together. Then it is fed to the 132kV busbar.

There are seven feeders connected to the 132kV busbar. Two double circuit transmission lines

from Kolonnawa and Ratmalana, two single circuit transmission lines from Horana and

Mathugama and an underground cable transmission line from Dehiwala.

The 132kV power is then transformed into 33kV through three 3-phase transformers. The

rating of the transformers is 90MVA. The transformed power is then carried to the 33kV GIS

(Gas Insulated Substation). From this GIS 12 feeders are taken out and two of them are

considered as the special feeders (Feeder 11 and 12). Then the power is taken to the outdoor

busbar. This is a special type of busbar. Any feeder could be connected to this busbar and also

have the ability to transfer the power without connecting to the busbar. If a failure is occurred in

the 33kV system, the outside busbar is used to feed the faulty feeder.

The autotransformers are coupled to create two 3-phase transformers. The 33kcv outputs

of the transformers are connected in delta configuration. The terminals of the delta are connected

to the capacitor bank. The capacitor bank is now out of operation.

In the next two weeks, we visited to the Kolonnawa GIS, Kotugoda GSS and Veyangoda

GSS. Throughout the week, we identified and observed the components of a grid substation.

2.2.3.1 Circuit Breaker

To connect or disconnect power lines in either no-load or on-load conditions without

developing arcs, the breakers are used. In earlier systems, the Oil circuit Breakers are used. But

later they were replaced by the SF6 filled Circuit Breakers. The special reason to use this type of

breakers is, the high arc quenching property and insulation property of SF6 gas under high

pressure. The breakers which are placed in 220kV switchyard at Pannipitiya are rated as 245kV.

The normal allowable current is 4000A and the breaking current is 50kA. The maximum

wording pressure of SF6 is 0.8 Pa.

2.2.3.2 Isolators

Isolator is a mechanical switch which is operated in no load condition. This is an open

type switch and, it could be seen whether the isolator is open or closed physically. If an isolator

is operated in on-load condition, the arks could be generated. So, as a practice the isolators are

operated after the breaker. Most of the isolators are provided with an earthling switch in it. So, in

maintenance, the earthling could be too done through the isolator.

2.2.3.3 Current transformers

The current transformers are generally used as a measuring instrument in the areas like

protection and measurement. In here the power line is used as the primary winding and a

secondary winding is created around the power line. The current generated in the secondary

winding is proportional to the current carrying through the power line. There might be multiple

cores used in different purposes, in a single CT. The secondary windings of a CT should always

in a closed circuit during the operation. Otherwise, the CT could be destroyed with huge blasts.

2.2.3.4 Voltage Transformer

The voltage transformers, commonly known as VTs are generally used in protection and

instrumentation purposes, as a measuring instrument for voltage. One end of the primary

winding of VT is connected to the power line and the other end is connected to the ground. The

secondary winding is placed such that, the voltage is lower than the primary winding’s. One

terminal of the secondary winding too connected to the ground.

2.2.3.5 Surge arrestors

Surge arrestors, which are commonly known as lightning arrestors are used in protection

from the higher voltage surges. As a practice this equipment is applied to protect the high

reliable and high cost equipments. As a practice, SAs are used in connection point of every

power line connected to the GSS and the both primary and secondary sides of the power

transformers.

2.2.3.6 Bus bar

In power systems, the bus bars are acted as the modes or vertices of the network. There

are various kinds of busbars used in Grid substations. Single bus, double bus and main & transfer

bus could be taken as the examples. In double bus bar systems, bus couplers are used to connect

the busses. But in single bus systems, most of the time, bus sections are used.

2.2.3.7 Carrier equipments

In the SCADA system, which is used by the CEB in communication, in PLC technology,

the Y phase is used as the communication line. This is called as Power Line Carrier system and

in this purpose the carrier equipments like wave trap and CVT are used.

Most of the switchgears of substations are built as outdoor open switchgears. But in the

situations where, there is no room for bulky switchgears, as a more reliable option, Gas Insulated

Substations are used. GIS is an indoor compacted model of switchgear, which is in a SF6 filled

environment. GIS are more reliable because, the maintenance of the switchgear is minimum and

the operation of this kind of switchgear is relatively easier than the outdoor switchgears. But, the

cost of this kind of assembly is relatively higher than the outdoor type.

2.2.4 System Control Centre

In controlling and keeping the Sri Lankan power system live, The System Control Center

ants a key role. It is established to conduct a safe and reliable service in power generation and

transmission. Through this the above areas are monitored and controlled. Mainly the following

tasks are performed by SCC. In the 12th training week of the second half, we had the chance to

attend and learn about the SCC and its main functions.

Decide the power plants should be dispatched.

Decide the amount of power should be supplied to the system by those power

plants individually.

Monitor the parameters like voltage in the transmission lines and maintain them in

the acceptable limits.

Schedule and monitor the maintenance of the system

Etc.

2.2.4.1 The operation policies

In order to conduct a safe and reliable service, the operation policies for SCC are

declared. It includes the priority order, thermal and hydro dispatch guidelines, the voltage ranges

should be maintained in transmission lines and spinning reserve and maximum generation unit

guidelines.

2.2.4.2 The load curve

The plot of the active and reactive power usage Vs time is considered as the load curve.

In CEB the load curve is plotted using the values, which are measured from the major power

stations. The special places like the night peak, the day peak, the morning peak and the off peak

could be easily identified in this curve. And also the \lifestyle of the Sri Lankan population is too

described using this plot. Using this plot, the power generation during the day could be

forecasted and planed.

2.2.4.3 Voltage drop

If the voltage of a transmission end lies out of the acceptable range, it is said to be a

voltage outrange in the system. There are two kind of voltage outranges. Voltage drop and

voltage rise. Generally, when the load centers are located far away from the power stations

voltage outranges are occurred. When the inductive loads are connected to the system in a bulky

manner, with the power stations are far away, the voltage drops could be occurred. In this

situations, add reactive power to the system from power stations, improve the power factor using

the components like capacitor banks and static Var compensators and change the tap setting of

the transformers are the actions could be taken in this situations. When the transmission line is

too long and the delivering power is low, due to the capacitance of the transmission lines, the

voltage rises could be occurred. This effect is called the Ferranti effect. In these situations, the

reactive power injection to the transmission line is limited as much as possible. Furthermore, the

tap settings are changed to limit the consumer voltage to the acceptable limits. In our training

period in SCC, we had the chance to see a voltage drop in western area substations. In this

period, the hydropower generation is maximized. Therefore, a situation, which the load centers

with reactive power and far away from the power stations, is occurred. The result was a huge

voltage drop in Biyagama Grid Substation. Therefore, a thermal plant, which is located around

the Colombo area had to be taken to the system.

2.2.4.4 Power generation

Power generation in Sri Lanka could be categorized into two as thermal and hydro. The

hydropower generation too could be categorized into three complexes.

Mahaweli complex is a cascade complex which is mainly operated in accordance with the

irrigation requirements. The irrigation department makes the decisions of the energy production

by these power plants. Rantambe, Bovatenna powerhouse outlet and Bowatenna reservoir is the

main irrigation outlets of this complex.

Laxapana complex is mainly operated to meet the power requirements. This is too

cascade system and there are three reservoirs and two ponds in this complex. The complex is

designed in a manner such that, when all the power plants are operated in full load, the lover

ponds are filled. In order to get the maximum output, a concept called pond regulating is

performed. According to this concept, when the full load is not requires to the system, the upper

power plants are stopped and the pond levels are let reduced. When the full load is required, the

full complex is operated in full load. So then, the decreased water levels are increases without

spilling the reservoirs. The complex is operated too to supply the water to Ambathale water

treatment plant in dry seasons.

The major hydro plants which are not belong to those complexes and the IPPs are

gathered to the Other Hydro Complex. There is one irrigation outlets in S’wewa to Kaltota area.

The thermal generation could be divided into two categories, CEB owned and IPPs, the

IPPs supply the power under the power purchasing agreement.

A weekly meeting to plan the power availability for a typical day is held in every week.

The irrigation department and CEB are participated to this meeting. The power availability of

every plant and the operating instructions are decided to the next week in this meeting.

In decision making to dispatch the power plants the following facts are considered,

The reactive power requirement to the system and the maintenance requirements.

The opportunity cost and the capacity charge if the plant is thermal IPP.

The drinking water, environment and irrigation requirement priorities if the plant

is hydro.

The availability of the water (position of the reservoir and the water level) if the

plant is a hydro.

2.2.5 Generation Planning

The electricity demand of the country is increasing with the time because of the growth

of the users as well as the growth of usage of the electricity. So to conduct a reliable service the

planning becomes a necessary item.

We were supposed to be in the System Control Center in our last two weeks. However,

our schedules were changed and we got the chance to learn the generation planning in

Generation Planning Branch. This branch is operating under the transmission division of CEB.

Its main responsibility is to prepare and implement the plans to meet the future demand. The

tasks of this branch could be listed as below,

Forecast the future demand.

Prepare the long term generation expansion plan

Conduct the Pre-feasibility, feasibility and site surveying studies.

Financing

2.2.5.1 Demand forecasting.

To create a trustworthy plan, the accurately forecasted date becomes a vital source, so the

demand forecasting in an accurate manner, becomes an important section in the planning

procedure. There are three demand forecasts, which are conducted by the CEB.

1. System Demand Forecast. – By System Control Center.

2. Forecast in Distribution Planning – By all four distribution regions.

3. Long Term National Demand Forecast – By Generation Planning Branch.

From these forecasts, first two forecasts use the trend analysis method. These forecasts

are not discussed in here. Meanwhile, the forecast which is used in Generation Expansion Plan

uses an econometric model.

In this, the forecast is conducted for 20 years and it is updated per one year. The demand

is divided into three categories to increase the accuracy of the forecast; Domestic, Commercial

and religious & Street lighting. In the domestic demand forecasting, a linear regression formula

is created. In this the following variables are used,

Previous year demand

Gross Domestic Product per capita

Population

Avg. electricity price

Leading demand

Domestic consumer accounts

Leading domestic consumer accounts

Leasing GDP per capita.

Etc.

The variables used could be changed according to the demand pattern. From these

variables, the independent variables are determined. After that, the regression formula is

prepared.

The linear regression formula for the domestic demand for 2008 as follows.

Ddom (t)i = b1 + b2GDPPCi + b3Ddom(t-1) + ei

Where, Ddom(t)i – Domestic demand for ith year.

GDPPCi - Gross Domestic Product Per Capita for ith year

b1, b2, b3 - constants

ei – error for ith year

The Industrial and General Purpose tariff categories are gathered to the Commercial

category. This also uses the same procedure as the Domestic category, but the variables are

changed.

Previous year demand

Gross Domestic Product

Average Electricity Price

Leading demand

Leading GDP

Population

Industrial Consumer Accounts

Leading industrial Consumer Accounts

The leaner regression formula for commercial category for 2008 as follows,

Di&gp(t)i = b1 + b2GDPi + ei

Where, Di&gp(t)i – Industrial & General Purpose demand for ith year.

GDPi - Gross Domestic Product for ith year

b1, b2 - constants

ei – error for ith year

In the Religious and Street Lighting category, because of the share of this for national

demand is relatively small and only one variable is identified, a trend analysis is done. The

formula for this category is as follows.

St = b1(1+g)t

ln(St) = B1 + tln(1+g)

After building the formulas, they are tested and verify for the accuracy. Then they are

used to forecast the future demands. The sum of these three for a year is taken as the forecasted

demand for the year.

Final Energy Demand Forecast = Ddom(i)i + Di&gp(t)i + St

Then the final energy generation is forecasted adding the total losses to the energy

demand forecast.

Final Energy Generation Forecast = Final Energy Demand Forecast + Total energy Losses

Then the peak is forecasted by dividing the energy demand by the load factor.

Peak Forecasted = Final Generation Forecast

Load Factor 8760

2.2.5.2 Generation planning

After the demand is forecasted, the plan for next 15 years is prepared. In planning the

future generation, the following parameters are considered.

2.2.5.2.1 Capacity required for ith year.The capacity of the country in a particular moment should be higher than the instant

demand of the country. So, as the worst case, the full capacity of the country should be higher

than the maximum demand. The difference between the maximum demand and the full capacity

is referred as the reserve margin. Hence, the full capacity is built by adding the maximum

demand to the reserve margin. After forecasting the maximum demand, the reserve margin for

the year is too decided. By adding those two, the capacity requirement is calculated.

2.2.5.2.2 Existing GenerationThe current generation of the country is taken as the existing generation. This is

expressed in the capacity terms.

2.2.5.2.3 Retirement scheduleDue to the reasons like the technology developments and the fuel price changes, the

power plants are considered as aging elements. So a date for the retirement of the plant is

decided. Then a schedule for the retirements is prepared and used for the generation planning.

2.2.5.2.4 Committed plantsThe plants, which are fixed to develop, are called the committed plants. The dates of the

commissioning of these plants are fixed and the capacities of these plants will be added to the

system in the given period in a certain manner. So the flexibility to adjust these plants is

minimum.

2.2.5.2.5 Candidate plantsThe plants which are having the capability to build and not yet decided to build is called

ad the candidate plants. In planning, the only type of plants, which are having the capability to

adjust, is candidate plants.

The above parameters are interconnected to each other in the following manner.

= - + +

In the planning process simply, the candidate plants are adjusted to meet the capacity

requirement. To make this planning reasonable, the generation is planned in the most technically

feasible, economically feasible and least cont manner. This is practically done using the software

called WASP. In this planning the following options are considered as the candidate plant

options.

Candidate hydro projects.

Hydro capacity extends

Candidate thermal projects

Pump storage – Demand

shifting method

LNG – liquid natural gas

Nuclear

Dendro

Mini hydro

Wind

HVDC – Hi-Voltage Direct

Current transmission lines.

Capacity required for ith year

Existing capacity

Retirement for ith year

Committed plants

Candidate plants

2.3 LECO

As the second part of the training second session we had the chance to attend and learn

the distribution division from Lanka Electricity Company Ltd. for 4 weeks period. Within this

training we had the chance to learn the distribution functions and distribution planning and we

had the exposure to the experience in distribution sector. In this training period the following

schedule had to be followed.

Period Training area Training place

17/05/2010 – 21/05/2010 System Development

Division

SDD in LECO Head Office

24/05/2010 – 28/05/2010 System Operations System Operations division in Head

Office, Training center in Ekala

31/05/2010 – 04/06/2010 Customer Service Center Boralasgamuwa CSC

07/06/2010 – 11/06/2010 Branch Office Nugegoda Branch Office

Table 3.5-3.1 - LECO training Schedule

2.3.1 System Development Division

As the first week in LECO, we had to train in the System Development Division. This

division is responsible for the High voltage planning (in LECO the term high-voltage is referred

to 11kV), procurement and network data controlling. Throughout the week we learnt about those

areas.

2.3.1.1 High Voltage Planning

With the time, the demand for the electricity is increased. With that increment, the

performance of the electricity distribution network is decreased. To overcome this matter, the

distribution network is planned for next few years. The planning process for the LECO

distribution network is done for 5 years and the plan is updated in 3 years. In this following

process is followed.

2.3.1.2 Load forecasting

The demand is increasing continuously. So, forecast the load for the next few years is an

essential step in planning process. There are two kinds of load forecasts conducted in LECO;

general load forecast and special load forecast. In spacial load forecast, the future trends for load

changes relevant to the space, is considered. The future trends of establishing an industry in an

open space could be taken as an example. In general demand forecast only the past data are used.

In forecasting the demand, a time trend for the demand is constructed using the past data.

Using this formula, the future demands for next five years are forecasted iteratively.

2.3.1.3 Load flow analysis

In load flow analysis, the loads are categorized into three categories.

1. Constant impedance loads

2. Constant power loads

3. Constant current

Using this legend, the high voltage network is modeled. Then the current flows and

voltages are calculated for the maximum demand.

In planning the forecasted values are used and the modeled network is simulated for the

voltages and feeder loadings. Is there are problems with the voltages and feeder loadings,

following solutions are applied.

1. Load transfer – the load transfer is the first option the situations like voltage drops and

feeder and transformer loadings. Because, the cost for this kind of option is minimum

2. New feeder construction – when the voltage is dropped, but the PSS loading is in the

acceptable limits, this option is used. In this, a new feeder is connected to the problematic

loads.

3. New substations construction and upgrades– when the PSS is overloaded this option is

considered. In this either the existing PSS upgrade or construct a new PSS and transfer

troublesome load is done.

The network is simulated using PSS/ADEPT software. In this, with and without the

solutions given for the last year is simulated. After the simulations the proposals are gathered to

the plan.

2.3.1.4 GIS – Geographic Information system

LECO manages a geographic information system and a database in asset management in

the network. In this all the properties and the geographical position about each component placed

in the network is gathered to a database. Using this, a geographical map for the network is

constructed.

The system updates in the following manner. A draftsman from each branch collects the

data about the changes in the network according to the system alternation form. This form is

filled when a change to the system is done. The draftsman reaches to the location and records the

geographical location and the relevant information about the component in a GPS recorder. Then

those data is transferred to the computer and corrects the GPS data using base files. After that the

network is plotted in a map. Then the data is sent to the head office in every month. After every

three months, a booklet containing the maps is prepared and sent to the branches.

2.3.2 System Operations

As the second week in LECO we had the chance to learn in System Operations. The

system operations section is responsible for maintaining the current situation of the network. In

this the following tasks are done.

2.3.2.1 Scheduling the interruptions in the network

In this the following procedure is followed. First, the information about the planned

interruptions of the Branches for maintenance and new constructions, and the interruptions for

the CEB maintenance are gathered. Then they are scheduled in a practically feasible manner. In

this, the facts like giving priority for necessary feeders, demand variations and the human

resource availability are considered. Then, after the approval for the schedule, the necessary

details about the interruptions are publicized through the printed media and LECO web site.

2.3.2.2 Issuing work permits and monitoring the maintenances

The safety of the personals is considered as the most prior necessity of the electricity

sector. So when the maintenances are occurred, they are monitored in personally by the system

Control. In this first all the switching instructions for the interruption is given by SO. These

switching should be personally observed by the relevant officer. Then, after verifying that all the

given instructions are followed the permit to work is issued. After that, the maintenance is

started. After the relevant maintenance is finished and all the personals are reported to the safe

place, the officer requests for cancel the permit. In this, the permit is cancelled and the switching

instructions for retrieve the network is given by the SO.

In Tuesday and Wednesday we had the opportunity to visit the training center in Ekala. In

this, we learned about the meter testing and meter repairing, transformer testing and repairing

and observed the components used in LECO network.

2.3.2.3 The energy meter testing and repairing

When the accuracy of meter readings is kept out of the appropriate region of ±2.5%, the

relevant meter is said to be malfunctioned. The energy meters could be malfunctioned due to

following reasons

Binding the dirt in the disks and air gaps.

Burnouts and short circuits of the windings

Decrease of the magnetism of the damping magnets

Malfunctions in the bearings ( Gummy oils and dirt, decrease the magnetism in magnetic

bearings, improper adjustments)

Disk rubbing and Creeping.

Vibration of the mounting

In meter repairing, if the malfunction is occurred due to an outage of a component, the

relevant component is replaced with the proper component. If the malfunction could be

recovered b adjusting the parameters of the meter, then the meter is tested and calibrated to meet

the proper functioning.

In meter testing following procedure is used.

The cover is removed and the meter is connected to the testing bench. There are two

testing benches places in LECO meter testing lab, which are capable of testing 10 and 20

parallel meters respectively.

Then the meter is left to preheat by applying the power to the meter

Then the following tests are conducted.

o Error test – this is conducted to test the error in disk rotation. The meter is tested

in following conditions.

1. 5% of Ib and 1 pf

2. 100% of Ib and 1 pf

3. Imax and 1 pf

4. 100% of Ib and 0.5 pf

Then the error is calculated and if the error is not in acceptable limits, the meter is

calibrated using the Full load adjustment (Adjust the position of permanent

magnet), the Low load adjustment (Adjust the position of potential coil) and the

Inductive load adjustment (Adjust the resistor connected in series with the

shading coil)

o Dial test – check whether the counter is functioning properly

o Creep test – check whether the meter is not running in no-load condition

After gaining the meter to the satisfactory limits, the meter is sent to re-use.

We had the chance to dissemble an energy meter and observe the components of the

meter.

2.3.3 Branch Office

As the forth week in LECO training, we had the chance to attend and learn about the

Branch functions and the structure of a branch. The branch, which we had the chance to visit,

was Nugegoda Branch. Boralasgamuwa, Nugegoda and Maharagama CSCs are operated under

this Branch. Billing, job costing and constructions could be taken as some of functions of the

Branch office.

2.3.3.1 Billing

The billing procedure is conducted as follows,

The electricity bills for all the customers are prepares and printed in branch office. And it

keeps the records of all the consumers as different accounts in PRONTO system. These accounts

are completely managed by the Branch office. Then the printed bills are sent to the Depots or in

other words CSCs.

The revenue officers in the Depots issue the electricity bills for the consumers keeping

the branch office copy-1 with them. The bundles of these copies are returned to the branch office

after issuing the bills. The consumer accounts could be referenced through the PRONTO system.

The payments could be done to the CSCs, branch office itself, and authorized agents and

through the banks. The payments done through the banks are updated through the Head Office.

The customer copy is returned to the customer and the branch office copy-2 and

agent/Bank copy is kept with the agent. Then the branch office copy-2 is too sent to the branch

office. From this the payment is registered and deposited to the customer account.

2.3.3.2 New connections

When a new connection is establishing the following procedure is followed.

First the customer applies a new connection through an application. The details including

the name, address, connection type, map and the equipments in use are forwarded with the

application. The Gramasewaka certificate is an essential document out of the above documents.

Then a technical officer, who is responsible of estimation preparation, goes to the site and

gathers the relevant information like the service wire length, transformer no, etc. The nearest

customer number is too noted down in case of the easiness of the identification. Then the

estimate is prepared.

The customer has to pay the estimated amount to CSC and sign a contract. After that, the

LECO employees in CSC provide the connection and issue a meter seal docket. Then the file of

the new connection is sent to the branch office and updates the PRONTO system.

2.3.3.3 Constructions

While the high voltage constructions are being done by SDD, the low voltage

constructions are done by the branch office. There are two kinds of constructions; LECO

initiated and Customer initiated. In here the LECO initiated constructions are considered. LECO

initiated constructions are mainly focused on upgrading the network performances.

In this, following quality vice parameters are considered.

The voltage of the consumer end should be within the range 230±6%V.(216.2V–243.8V)

The Frequency should be within the range 50±1%Hz (49.5Hz – 50.5Hz)

The power should be available 24hours.

From this, in Branch office constructions, the voltage is used. Furthermore, the feeder

loadings and transformer loadings are taken into account as the performance vice parameters.

Using the consumer data the transformers are modeled as individual networks and

simulated using the “LV design” software, for the voltages and feeder loading for the next 5

years. Through this, the matters of the network are identified.

Then the most feasible and cost effective solutions out of the followings are identified.

Load transfer

New feeders

Feeder rearrangement

Tap position change

New transformer

2.3.4 Customer Service Center (Depot)

As the third week of the LECO training, we had the chance to learn about the CSC

and the functions of it. And also we had the chance to attend the tangible works done by

CSC, like maintenances and reconnections. The CSC which we had the chance to attend is

Boralasgamuwa CSC.

2.3.4.1 The tariff categories

Some of the tariff categories have been mentioned in the earlier chapters. But the

exposure to the tariff categories is mainly gained during the LECO CSC period.

The electricity is categorized as an essential item. So the electricity is sold to the

customer in a tariff format instead of a price deciding method. In tariff format, the consumers

are divided into few categories. They are,

Domestic – this category is the one which is having the largest category in consumer

count. The consumers who are using the electricity for domestic usage are belonging

to this category. The cost of a unit in this category is relatively high, because, the

consumers in this category are not contributing to the GDP.

General purpose – The consumers, who are using the electricity for commercial

applications and the temporary connections are considered ad the GP consumers.

They are having the highest rate.

Industrial – The consumers, who are using the electricity for industrial usage, are

taken into this category. They should be registered in Ministry of Industry. The rate in

this category is relatively low.

Hotel – The consumers, who are registered as hotels in ministry of tourism and having

at least three star rating, is gathered to this category. They are having a relatively

lower rate to the domestic.

Religious – the consumers who are registered as religious or social servicing

organization in Social Service Department is gathered to this category. The rate for

this category is relatively low.

Street lighting – the payable for street lighting is collected in an estimated manner

from the relevant provincial council.

2.3.4.2 Experiences

During the week we had the chance to attend the reconnection visit. In this, five

disconnections ate reconnected. When disconnecting a supply, the phase line is removed from

the meter, and seals it. When the approval for reconnection is given, the removed phase line

is connected to the meter again. If the disconnection is difficult due to the consumer matters,

the line is disconnected from the pole. The maintenance gang uses an identical tool for the

gang, to seal the meters. After all the works with the meter sealing, a docked is issued.

And also, we had the chance to attend a service maintenance visit. In this, we had the

chance to attend two meter shiftings, service wire replacement and a meter box replacement.

The MCB which is used instead of the fuse in CEB is used to protect the meter. Therefore, it

should be connected before the meter. But, what we observed is, connect the MCB after the

meter to prevent stealing the electricity from the MCB position. And also, the service wire

should be placed in a clearly visible manner, to the revenue officer.

We too had the chance to prepare connections of the meter box. Furthermore, the

maintenance personals worked in the on-load. They removed the conductor in the live wire

for some length for the safety purposes. They used the electricity in the phase for the drilling

purposes of the walls.

3 Conclusion

In this training session the training is restructured for the Electrical Engineering

students by dividing the 6-month training period into two and allowing all the students have

two different trainings experiences in the same training session. Furthermore, each and every

student had the exposure for the government sector as well as the private sector. Through

this, we had the chance to acquire the complete knowledge about the field. The knowledge I

gathered is a great.

As my first training place I had the chance to training in Hemas Power. This company

is a great path to acquire knowledge about power generation as an IPP. Because, the company

has invested in thermal as well as the mini-hydro fields. We had the exposure to learn about

the IPP role in power sector.

In my training period I could be able to visit Giddawa mini-hydro plant and Senok

Mark mini-hydro plant. This gave me the exposure to the life-style of yet-suburbanized

villagers. It was a great experience to be with such a community. Furthermore, I enjoyed the

environment very much. Being in the beneath of Knuckles mountain range is a great pleasure.

Opportunity to participate in the programs like Teamwork workshop gave a different

experience to me.

Hemas Power is a company which does a great job with a lesser staff. So facilitating

to three trainees and teaching them is a great deal. But they gave their maximum effort to

teach us when we wanted, by managing their time too. Hemas Power is a worth place to have

an electrical engineering training in IPP sector. We should thankful to Hemas Power for

giving us the chance and proper guidance to have a better training.

The second session of the training was CEB and LECO training.

I had the opportunity to get the knowledge about various sections, in generation and

transmission during CEB period. During the training, we had the chance to visit different

places and gather the knowledge about different section. Being with a group of colleagues

and gather knowledge by moving around the country was a great experience.

What I observed in CEB is, the personals in the above level like Engineer and AGM,

tries to keep the service provided by CEB in a quality vise good manner. But in the below

levels, in most of times, this attitude is not represented. I strongly suggest looking into the

matter of inefficiency through this degree. Furthermore, the developments and the

improvements of the Generation and the transmission too, are done through the government

decisions, this makes the improvements delayed. We have the experiences of these delays in

earlier 2000s. So, create a criteria to accelerate the decision making process through the

government could be a very effective step. The attitude I had about the CEB before the

training period was completely changed to a great one during the training period, after having

the experiences in CEB.

LECO was more helpful in understanding the distribution area. In this period we had

the exposure to the new technologies could be used for the power sector. The creative ideas

use the other fields too, instead of only the electricity related technologies.

The major areas, like planning and administrating too learnt during this period. So the

LECO period gives us a great knowledge. Furthermore, we had the opportunity to visit

service repairs during the CSC week. In this week we had the exposure to the lifestyle of the

employees, employed in heavy works like maintenance, in additional to the practical

experience. Understanding these employees and their problems leads to the easiness of

creating good relationships in engineering future.

Moving on to the training establishment again, due to the training, the application of

the theories increased the interest of learning them. So, if it’s possible to create an

opportunity for the younger generations, to attend to, at least one month training in the earlier

years, it would be a great help for them to get the knowledge well. Theory makes the

understanding of the exposed; exposure makes the interest of the theory.

Annexes

Annex 1 – MATLAB Program on flow duration curve

function details=analizerainfall(FDC,lowermargine,head,TE)%FDC order is [days,values]FDC(2,:) = FDC(2,:)-lowermargine;FDC_Size = size(FDC);for i=0:FDC_Size(1,2) A_days = [A FDC(1,:)'^(FDC_Size(1,2)-i)]; %#ok<AGROW> A_vals = [A FDC(2,:)'^(FDC_Size(1,2)-i)]; %#ok<AGROW>endcoff_days = inv(A_days)*FDC(1,:)';coff_vals = inv(A_vals)*FDC(1,:)';disp('1 - Pelton');disp('2 - Francis');disp('3 - Kaplan');disp('4 - Small');turb = input('enter the turbine type:');turbdet = [.9 .5 .6 .4];minFlow = min(FDC(2,:));maxFlow = min(FDC(2,:))/turbdet(1,turb);details1 = [];for i = cast(minFlow,'int16'):1:cast(maxFlow,'int16') x1 = polyval(coff_vals,i); flow = x1*i + quad(@(x)polyval(coff_days),x1,max(FDC(1,:))); power = TE*9.81*flow*head; max_power = TE*9.81*max(FDC(1,:))*i; plant_factor = power/max_power; excedance = x1/max(FDC(1,:)); annual_energy = power*60*60*24*365; dindet = [i power plant_factor excedance annual_energy]; details1 = [details1 dindet']; %#ok<AGROW>enddetails = details1;

Annex 2 – MATLAB Program on turbine selection-1function turbine = selectturbine(head,flow)turbine_headmin = [30 6.6 136 62 4 2 1.3 3 2];turbine_headmax = [734 72 1230 1150 186 27 23 27 147];turbine_flowmin = [8 34.5 2.5 .1 .8 2.7 2.5 6 .1];turbine_flowmax = [781 618 52 27 25 170 530 290 12];turbine_efficiency_mean = [.92 .92 .89 .87 .85 .87 .89 .89 .81];selected_turbines = ones(1,9);turbinedetails = [];disp('Turbine Order:')disp('1-Vertical shaft Francis')disp('2-Vertical shaft Kaplan')disp('3-Vertical shaft Pelton')disp('4-Horizontal shaft Pelton')disp('5-Small Scale Francis')disp('6-Small Scale Kaplan')disp('7-Bulb turbine')disp('8-Tubular turbine')disp('9-Cross-flow turbine')disp('')for i=1:9 if head<turbine_headmin(1,i)||head>turbine_headmax(1,i)||flow<turbine_flowmin(1,i)||flow>turbine_flowmax(1,i) selected_turbines(1,i) = 0; turbinedetails = [turbinedetails ones(4,1)] else power = 9.806*head*flow*turbine_efficiency_mean (1,i); diameter = 0.168*(power/head)^.447; speed = 80.387*(head^.5/diameter)^.828; no_of_poles = 120*50/speed; syn_nop = 4*cast(no_of_poles/4,'int8'); rec_speed = 120*50/syn_nop; rec_diameter = head^.5/(rec_speed/80.387)^(1/.828); valuemat = [i power rec_speed rec_diameter]; turbinedetails = [turbinedetails valuemat']; endenddisp(turbinedetails)[val,idx] = min(turbinedetails(4,:));switch idx case 1 turbine = 'Vertical shaft Francis'; case 2 turbine = 'Vertical shaft Kaplan'; case 3 turbine = 'Vertical shaft Pelton'; case 4 turbine = 'Horizontal shaft Pelton'; case 5 turbine = 'Small Scale Francis'; case 6 turbine = 'Small Scale Kaplan'; case 7 turbine = 'Bulb turbine'; case 8 turbine = 'Tubular turbine'; case 9 turbine = 'Cross-flow turbine';end

Annex 3 – MATLAB Program on turbine selection-2function turbine = selectturbine(flow, head, speed)ssn = 10*(flow/1000)^.5*head^-.75*speed;turbines = [];if ssn<91.287 d = [1;.75]; turbines = [turbines d];endif ssn>45.643 & ssn<213.003 d = [2;.75]; turbines = [turbines d];endif ssn>60.858 & ssn<197.789 d = [3;.75]; turbines = [turbines d];endif ssn>114.401& ssn<457.604 d = [4;.65]; turbines = [turbines d];endif ssn>88.388 & ssn<1178.511 d = [5;.8]; turbines = [turbines d];endif ssn>883.883 d = [6;.8]; turbines = [turbines d];endlngth = size(turbines);if lngth(1,2)~=1 cost = []; for i=1:lngth(1,2) %select type, calc power, selectdia, evaluate cost/profit turbines(2,i); power = 10*head*(flow/1000)*turbines(2,i); specificspeed = 1.2*(head^-1.25)*speed*(power^.5); diameter = selectdia(head , flow , specificspeed); cost = [cost diameter]; end [val,idx] = min(cost);else idx = 1;endswitch idx case 1 turbine = 'pelt_s'; case 2 turbine = 'pelt_m'; case 3 turbine = 'turgo'; case 4 turbine = 'crossflow'; case 5 turbine = 'franecis'; case 6 turbine = 'axial';end

Annex 4 – Trash rack design

Annex 5 – Teamwork workshop certificate

Annex 6 – Maintenance schedule

Training Report

Documents

Transcript of Training Report