Research

Experiences Report

V.P.R. ARIYADASA

REPORTONCEB EXPERIENCEV.P.R. ARIYADASAOPERATIONS ENGINEERLAXAPANA POWER STATIONCEYLON ELECTRICITY BOARD16TH JULY 2014TABLE OF CONTENTS21 PERSONAL DATA

2INTRODUCTION23trainig at power station34 RESPONSIBLE EXPERIENCE6

4.1. Operation Engineer as at Laxapana power station (from May 2013 onwards)6

4.1.1. Scope of work6

4.1.2. Duties and responsibilities6

4.1.3. Major problems and critical decisions encountered7

4.1.3.1. Spilling of Maussakelle reservoir7

4.1.3.2. Castlereigh needle valve operation8

4.1.3.3. Cleaning of Polpitiya and Canyon intakes9 4.1.3.4. Water management of Laxapana Complex10

4.1.4. Involvements to rectify machine failures and continuity of power generation10

4.1.4.1 New Laxapana No.1 Machine failed to start on 26th April 201310

4.1.4.2 Old Laxapana Stage II machines trip on 7th June 201311

4.1.4.3 Old Laxapana Stage I machines isolation issue on 6th of May 201311

4.1.5. Other involvements for the safety operations of the machines12

4.1.5.1 Establish a pest control system in the power station12

4.1.5.1 Implement a log note system on the machine components12

4.1.6. Other relevant experiences12

4.1.6.1 Opportunity to observe the New Laxapana tunnel12

4.1.6.2 OPPORTUNITY TO OBSERVE N/L UNIT NO.02 REHABILITATION 13 4.2. Site Engineer as at Uthuru Wasanthaya Northern Electrification Project 13

4.2.1. Scope of work13

4.2.2. Achievements 13

4.2.3. Other Relevant Experiences14 4.3. Extra Curricular Activities14

..1. Personal dataName

:V.P.R. AriyadasaE.P.F No:37982Date of birth:20th October 1983Nationality:Sir LankanEducation: Bsc(Hons) in Electrical Engineering in 2008

University of Moratuwa, Sri Lanka

Membership ofProfessional societies:Member of the Institution of Engineers Sri Lanka Work Experience:

July 2009 to date

Ceylon electricity board,

Electrical engineer

December 2008 July 2009

Bank of Ceylon,

Electrical Engineer

May 2008 December 2008 Temporary Instructor,

University of Moratuwa2.

IntroductionI, V.P.R. Ariyadasa currently appointed as the Operations Engineer in Laxapana Power Station. I joined the Ceylon electricity board on 15th of July 2009 and I was appointed for the current position from 20th May 2013 onwards. Before I come to the Generation Division I worked as the Site Engineer for Mannar District in Uthuru Wasanthaya Electrification project under Distribution Division Region 01. I am pleased to submit this CEB experience report for the consideration of K3 interview to be held in 14th of July 2014 at the generation headquarters.

3.

Training at Power StationsBefore appointed for the current position, I had to undergo four and half months of training period to get familiarized about the power stations and duties in Laxapana complex. That Helped a lot to carry out my duties in various difficult times.Laxapana complex consist of five power stations named canyon, Wimalasurendra, Samanala, New Laxapana and Old Laxapana power stations. The oldest power station in CEB which was commissioned in 1950 was the Old Laxapana Power station. Consist of 3 number of 8.33MW generators (Now those were rehabilitated and improved to 9.5MW) in Stage I and 2 number of 12.5MW generators in stage II (1958). New Laxapana Power Station was commissioned in 1974 with 100MW total capacity. In 2012, the New Laxapana Unit no. 01 was rehabilitated to 57MW generator from 50MW old generator. Currently the New Laxapana Unit No.02 undergoes a rehabilitation work (by ALSTOM) which will upgrade the full capacity of the generator to 57MW from 50MW. Altogether 167MW of power can be supplied to the national grid at once. Pelton turbines are used in all of Old and New Laxapana.

Wimalasurendra Power Station commissioned in 1965 and having two number of 25MW generators. Samanala Power Station which also called as Polpitiya power station was commissioned in 1969 and having two numbers of 37.5MW generators. Canyon Power Station commissioned in 1983 and 1989 having two vertical fransis turbines with total of 60MW. The total capacity of the Laxapana complex is 345 MW now. Laxapana complex has two main reservoirs called Catlereigh and Maussakelle and three ponds called Norton, Canyon and Laxapana. The two reservoirs are fed from Kehelgamu Oya and Maskeli Oya which form the Kelani river. The power stations are in a cascaded system and generation of one power station depends on the annual rainfall, machine outages and running period of the other power stations. Therefore the operations of all the power stations are interrelated and those are carried out according to the system demand by communicating with system control centre. Also, due to the cascade system and non-requirement of water release for the irrigation purposes, many pond balancing systems are developed in order to optimize water usage and the power generation.A comprehensive diagram of laxapana complex is as follows. After the general training in the Hydro Power Station I trained in the Laxapana Power Station as a parallel Operation Engineer for about two months. The important areas that I covered in this training period are: General arrangement of Laxapana power station turbines, generators, connecting transformers, switchyard, distribution feeders etc. Machine & transformer capacities of old Laxapana and new Laxapana power stations Water discharge rates, reservoir/pond capacities and spill & operation levels Spill gates and needle valve operation Operation processes automatic or manual starting and shutdown procedures and machine loading Auxiliary services cooling water system, service water system, auxiliary power supply, bearing oil circulation & cooling system, substation lighting. Switchyard equipment identification and operation procedures Protection schemes for machines, transformers and lines alarm and tripping settings Organization structure of Laxapana complex, line of authority Responsibilities of technical assistants, technical officers, control room operators etc. Documentations log sheets, water level and rainfall book, daily machine and line outage, monthly statically data, weekly spill data, duty assignment to junior staff. 4.

Responsible experience4.1Operation Engineer at Laxapana power station (from May 2013 onwards)4.1.1. Scope of workTo ensure safe and smooth operation of power station while maintaining efficiency of the plants and equipment in the power station up to the switch yard line isolator and to ensure personally that the power station contributes its share of the system load as required and planned up to the maximum at all times.4.1.2. Duties and responsibilities Personally responsible for all operations in the power station and the switchyard when on shift duty. To startup, synchronize and load generating units as and when required. To shut down generating units as and when required. To report immediately to the chief engineer or engineer in charge of the power station any serious defect or breakdown of plant or equipment and to furnish a complete report of the breakdown. To inform system control of any plant non availability/breakdown in proper time. To conduct switching operations of feeders in case of breakdown/interruptions. To restore supply in the shortest possible time in the event of partial or total failure due to plant of feeder failures. To isolate and make safe any plant, equipment, switchgear or feeder back into commission after the maintenance or repair work is over. To operate an agreed scheme whereby all operating personnel not up to the required standard could be trained effectively and efficiently to acquire the required competence in the shortest possible time. To ensure that the CEB and the factory safety rules and regulations are strictly adhered to. To maintain records of attendance of operating staff and all statical data (loading of sets, feeders, water levels etc). To approve leave of the operating staff and cover-up arrangements.

4.1.3. Major problems and critical decisions encountered

4.1.3.1. Spilling of Maussakelle reservoir During the middle of last year there was heavy rain in catchment areas of the Maussakelle Castlereigh reservoirs. On 8th of June, 2013 the Moussakelle reservoir was at its peak water level and ready for the spilling after about 12 years of time. I just happened to be the operation engineer on that day and had to take prompt actions to prevent damage for the public as well as CEB property and to make coordination between relevant parties.

Reservoir water storage is the main source for the hydro generation so that the water should not be wasted by spilling but excessive water may damage dam and the public. Though the generation of canyon and N/L were at their peak generation, the water inflow for the reservoir was too high actions had to be taken to limit the water.Pre - arrangements for the operation of Maussakelle gates: For a about 12 years there were no river like water flow from Moussakelle reservoir to Canyon pond. So the people may used do their day today activities through the water flowing areas which was very dangerous for them and should be prevented. So the public awareness was very much important so we kept in touch with the Dissaster Management Coordinating officer and the relevant police stations to inform our status for the public awareness. If the radial gates of the Maussakelle dam are opened, the downstream water level will be increased at once with a considerable margin. Therefore we had to more careful with levels of two downstream ponds, i.e. canyon and Laxapana. If we keep the water levels of these ponds at higher levels at the instance of Maussakelle gate opening, levels of two ponds could not be controlled to keep at a safe level. Due to canyon and N/L power generation at their peak level and due to the side flows the water in their ponds were in spilling condition we had to open spill gates more for the incoming water flow from Moussakelle reservoir. However we had to keep on mind that water released from Maussakelle would take 15 minutes to reach canyon pond and same will take 45 minute to reach Laxapana.

Normally reservoir water levels are taken every six hours. When the water level is high, the level readings are taken more frequently. Required personal were arranged at the dam to take tape level in every half an hour with the assistance from canyon station engineer.

Radial gates are electrically operated. Power is supplied by a normal distribution line and standby power is supplied by a diesel generator. After discussing with canyon electrical engineer, condition of the standby generator was tested for availability. Consumer service centre of CEB at Maskeliya was informed to send maintenance crew in a flash, if there is any breakdown at the supply lines to the dam area. Since the water coming from long time it may contain lot of debris which may block in the canyon intake. That may prevent full loading of N/L machines and Polpitiya machines which is a large income loss for the CEB. As per instruction from CE (LAX) relevant mechanical engineer was informed to get service from master divers and let them ready for emergency maintenance. With the coordination of EE ( Canyon ) gates were opened slowly ( by 1 each ) and counter the situation as expected.

4.1.3.2. Castlereigh needle valve operation

During the high raining situation in the middle of last year the water level in castlereigh reservoir went higher so as operation engineers we had to take coordinated activities to cater the situation. There are no dam gates in catlereigh reservoir but there are 4ft high flash boards (since 1981) to store more water and to increase more power generation ( around 10 GWh extra). That favors to the CEB but also brings a risk of instant high water release if the flash board trips. On 12th June,2013 the water level of Castlereigh reservoir was reached +0.3 m with WPS machines were run at full loads so the needle valves were opened for 100% since the water rising speed was too high. Before opening the needle valve as per instruction of CE ( Lax ) coordinated actions were taken with relevant Mechanical Engineer to check the condition of needle valve and the flash board so that it wouldnt provide unexpected failures. Like in moussakelle reservoir, if the water is released from Castlereigh reservoir, a new large water path would create in between Castlereigh and Norton pond. So the public awareness was very much important to avoid further damage. So before opening of needle valve we made contacts with DMC coordinator and the relevant police stations and made them aware of our condition.

On 23rd June the water in the reservoir started to spill above the flash boards. Teams were set to monitor the conditions of the flash boards and the generator continuously. Also tape measurements were taken for every half an hour for more awareness. By 24th of May the spilling was at the maximum level of 8.5 inches above the flash board which was a critical condition since the flash boards must be tripped for 1 feet above the flash board according to the guide line. The public awareness was at the maximum level. Luckily, the heavy raining condition disappeared and the water level dropped from its danger situation. On 28th of June needle valve was fully closed when the water level was 2 feet and 6 inches.

4.1.3.3. Cleaning of Polpitiya and Canyon intakes.This had to be done in several times when i was working as operation engineer. When Polpitiya intake screen of Laxapana pond and N/L intake screen of Canyon pond were blocking, the water level in the intake was decreasing very rapidly even though the pond level was close to spill level. This was due to the trash collected at the intake screens. In most cases both intakes are blocked by debris at the same period of time due to same river water.

This situation becomes uncomfortable if the intake water level reaches to their MOL values. The machines shouldnt be operated below MOL values since the pressurized air bubbles can cavitate the tunnel walls and the turbine blades. Only options were to deload the machines which may lead to waste of water hence we loss the income to CEB. So we informed this to CE and arranged to clean the intake as the intake loss getting higher to avoid such scenarios. As a result an arrangements were made to get the service from master divers (pvt) ltd with coordination of system control centre and with the mechanical engineer for laxapana complex. For this purpose all the generators at old Laxapana, new Laxapana and Polpitiya have to be kept in minimum load (some time shutdown some machines) if the intake cleaning is in Laxapana pond. This should be planned from the previous day and all three ponds should be at minimum level when the machines are stopped. Arrangement of auxiliary supply during this period for both N/L & O/L power stations is also a major consideration for operations engineer.It is an important duty of the operation engineer to coordinate with the system control centre to reduce the water level from previous day by generation so the water may not get wasted as well as the cleaning will be done according to the time plan. In some cases where we were unable to arrange the service from divers company, sudden deload of relevant machines would clear the debris for a while and run the machines for higher loads for some times.

4.1.3.4. Water management of Laxapana ComplexAs Laxapana, Norton and canyon ponds are regulating ponds, balancing the water level of the ponds during the day time to meet the night peak of the system is a major requirement. The regulation of the pond levels are carried out by the operation staff under the instruction of system control centre. The operations engineer is considered to be at full awareness about the pond levels and load of the generators of the complex. Necessary day to day information about the weather pattern, side flows to the pond etc are given to the system control centre, and in some occasions necessary changes to the day to day operating pattern is done with the co-ordination of the system control centre.In some occasions there is unexpected rain. As a result, within 2-3 hours, all regulatory ponds may get spilled. In this kind of situation we have to take immediate action for the safety of dams, proper operation of Polpitiya machines and the people in the downstream. There are some polices stations and disaster management centre which operation engineer is responsible to inform prior to gate openings. When canyon gates opened, the water level will rise at Laxapana pond within 45 minutes time. If Laxapana pond is at the top level at that time sudden rise of water may damage the dam. So we should prepare that situation by opening the gates at Laxapana.4.1.4.Involvements to rectify machine failures and continuity of power generation. 4.1.4.1 New Laxapana No.1 Machine failed to start on 26th April 2013The N/L Unit No.01 was taken for the R/M and tried to restart the machine at 16.45p.m. A quick shutdown appeared indicating TSLG minor fault of high level in pressure tank. The oil level must be brought down within the range of 568mm 441mm in order to satisfy the condition.What I did was, drain some oil from the bottom of accumulator pressure tank. That draining oil goes to governor oil sump tank though the existing oil path. When the oil draining occurs, the accumulator oil pressure reduces accordingly. The air pressure should be within 26-28 bars in order to satisfy the condition. Since it was dropping (about 25 bars) I had to manually open the air ( from the air compressor tank ) in order to bring the air pressure to satisfactory level. We observed that ( using historical data on ALSTOM SCADA system) the accumulator oil level always goes high in some extend. That was because of the compressor air releasing valve opening time was not enough in that time. (nominal setting was 60s for 600s) We asked the ALSTOM officer to increase the opening time for some more time. ( now the setting is 100s for 600s period) The problem solved and prevented further tripping due to accumulator oil level high conditon.

4.1.4.2 Old Laxapana Stage II machines trip on 7th June 2013 The O/L Stage II machines no. 04 and no. 05 suddenly tripped on 7th of June 2013 at 5.00 a.m. indicating inverter supply fault. It was very important to restart the machines due to the spilling of Norton pond and wasting of water because of the heavy rainy situation. The machine AC auxiliary pumps were fed by three main supply paths. Default is the feeding AC supply from the DC battery supply inverted using AC inverters and feed the pumps. Second is getting AC supply from auxiliary transformer supply and perform AC-AC conversion and feed. The third and last option is the bypass mode which directly supplies the AC from auxiliary transformer supply.

In this situation, the initial two options were not supported since the fault remains and preventing restarting of generators. Later it was found that the fault was from inverter controller card. Only bypass mode was supporting and hence restarted the machines using that mode and load immediately to reduce the water wastage. Due to change of auxiliary transformer lead to trip the machine again instruct operation staff to be on alert. Later new inverter controller card was installed and rectified the issue.4.1.4.3 Old Laxapana Stage I machines isolation issue on 6th of May 2013

When the system frequency dropping ( due to failure of major power plant in any other place ) the O/L Statge I machines changed to isolation mode from power mode showing an alarm called speed controlled isolated N/W and reduce the output power to 1 MW. The alarm is not resetted only way to bring the machines SNL condition and then to the power mode.It was found that the alarm appears when the system frequency drops below 49.5Hz which was not desirable. Informed to CE (LPS) and the project engineers to alter the alarm pickup frequency and to prevent further disturbances. 4.1.5. Other involvements for the safety operations of the machines

4.1.5.1 Establish a pest control system in the power station

It was noted that the rat population was increased due to unavailability of pest control system for a very long time. Also noted that the rat bites may lead unfavorable conditions, so took immediate action to implement pest control system for one year period and to prevent damage to the workers and the machineries. 4.1.5.2 Implement a log note system on the machine components

The generators of the power station have various types of pumps ( governor pumps, oil lubrication pumps, MIV pumps, etc. ) air compressors and filters in where condition monitoring and operation priority changes are required over some times of operation. Also sometime the some activities ( like compressor oil change, filter change by mechanical section on R/M) done by some staff was not known to any other section. Due to this implementation any minor activity done on that particular component is written on the log note on the site itself hence its visible to everybody who are responsible.

4.1.6 Other relevant experiences

4.1.6.1 Opportunity to observe the New Laxapana tunnel

After about 40 years of operation the N/L tunnel was dewatered for the first time to clean out the rock traps, concrete the cavitated tunnel areas and specially to prevent water leakage from tunnel. The tunnel works started with the N/L unit no2 rehabilitation works on 14th January 2014 and finished ( by filling water ) by 29th of July 2014. The tunnel consist with two parts which is a 7 degree angled fist area of about 1170 feets with steel piped area ( ~ 400 feets ), restricted orifice surge shaft and a rock trap ( of 60 feet length ) It was found that the main leakage area was from the first section where surge shaft and 3rd rock trap is located. There is a weak marble area in which the cavitation is most and noted that the leakage was mainly from. It was calculated that the leakage was about 300l/s. This water lead to loss of power generation, hazardous rupturing on the tunnel and the land slides in nearby villages. The concreting of the leakage area came to top priority.

The other part is a 0.14 degree angled 16,870 feet long area. This area consists with two adits and two rock traps. Those two rock traps were filled with 100% fine sands and tree parts. The other rock trap was filled about 40% of them. All were removed and cleaned well.

Other than those establish new intake ladder, add new rock bolts, etc. were done during the tunnel repair works. 4.1.6.2 Opportunity to observe N/L Unit No.02 rehabilitation

The N/L U # 02 rehabilitation works were started with the tunnel outage so that the time can be efficiently spent. This includes placing a new stator, refurbishment of rotor poles, refurbishment and repairement of MIV, placing new servo motors for needle operation, new cooling water system, fire alarm and CO2 system, new excitation system, battery bank, new inverter system, etc. As operation engineers we assisted the project engineers to electrically isolate the components, issuing various permits quickly and witness some commissioning tests in order to proceed the project according to the time plan. 4.2 Site Engineer as at Uthuru Wasanthaya Northern Electrification Project (from July 2009 to December 2012)4.2.1. Scope of work

To perform the power line construction works soon, ensuring the construction standards, the safetiness of the workers as well as the public and to utilize the fund allocation more effectively.

4.2.2. Achievements Before starting the project, the electrification level in Mannar district was 35%. Within that period we could increase that level to 76%. In some villages, the villagers experienced the benefits of electricity for their first time. To achieve that level we had to utilize about 726 Million rupees. All the constructions were carried out by private contractors under the supervision of CEB staff.

4.2.3 Other Relevant Experiences

Other than normal construction works, we could achieve plenty of experiences on other relates subjects as well.

Testing of Concrete Poles

The main cost component of the project was the cost for concrete poles. All the poles were purchased locally and prior to that a CEB official should test the materials whether those are according to the standards and approve. The testings were mainly done for 8.5m/100kg, 11m/300kg, and 11m/500kg poles.

Other than that, some testings on Galvanised cross arms, Stay assemblies, etc. were done on request.

Way leaves clearing

Before energising a scheme, way leaves must be cleared according to the standards. Due to the community participation is a must we get together with the villagers and arrange a campaign to cut way leaves with a guidance of the CEB official.

When the community participation was not available, quotations were called and arrange contractors to cut the way leaves ensuring the standards.

Extra Curricular Activities Joined the Officers Recreation Club and participated for the events made.

Arrange and participate for a donation program on a primary school in Kebithigollewa when working in Vavuniya.

Extend support for the other social activities such as funding and participating for the events such as dan sel on poya days, funding to build new house for a worker, etc.

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