Psp Notes for 5 Questions

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POWER SYSTEM PLANNING

Prepared by | ANILKUMAR K.M., Assistant Professor in E&EE, BIET,

Davangere-04.


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ANILKUMAR K.M.,Assistant Professor in E&EE, B.I.E.T, Davangere.

AS PER VTU SYLLABUS

SUBJECT - POWER SYSTEM PLANNING

Subject Code: 10EE761 IA Marks: 25 Exam Hours: 03

No. of Lecture Hrs. / Week: 04 Total No. of Lecture Hrs. 52 Exam Marks: 100

PART - A

UNIT - 1

INTRODUCTION OF POWER PLANNING, National and regional planning, structure of

power system, planning tools, electricity regulation, Load forecasting, forecasting techniques,

modeling. 8 Hours

UNIT - 2 & 3

GENERATION PLANNING, Integrated power generation, co-generation / captive power,

power pooling and power trading, transmission & distribution planning, power system

economics, power sector finance, financial planning, private participation, rural electrification

investment, concept of rational tariffs. 10 Hours

UNIT - 4

COMPUTER AIDED PLANNING: Wheeling, environmental effects, green house effect,

technological impacts, insulation co-ordination, and reactive compensation. 8 Hours

PART - B

UNIT - 5 & 6

POWER SUPPLY RELIABILITY, reliability planning, system operation planning, load

management, load prediction, reactive power balance, online power flow studies, test estimation,

computerized management. Power system simulator. 10 Hours

UNIT - 7 & 8

Optimal Power system expansion planning, formulation of least cost optimization problem

incorporating the capital, operating and maintenance cost of candidate plants of different types

(thermal hydro nuclear non conventional etc), Optimization techniques for solution by

programming. 16 Hours

TEXT BOOK REFERRED FOR NOTES:

1. Electrical Power System Planning, A.S.Pabla, Macmillan India Ltd, 1998

2. Electrical Power Distribution System, A.S.Pabla, Macmillan India Ltd, 1983


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POWER SYSTEM PLANNING

UNIT-1: INTRODUCTION OF POWER PLANNING

V.T.U.Syllabus

National and regional planning, structure of power system, planning tools, electricity regulation,

Load forecasting, forecasting techniques, modeling.

SYNOPSIS

The basic process of planning & its application to the power system has been illustrated. The

history of the planning & its increasing importance in present & future scenarios of power system

has been analyzed. The power growth & national & regional planning & development of national

grids have been brought out. Least cost planning is discussed, the regulatory process of power

development which includes various rules, acts & policies are illustrated. The various techniques

for forecasting & its modeling are explained.


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POWER SYSTEM PLANN ING

ANILKUMAR K.M.,Assistant Professor in E&EE, B.I.E.T, Davangere.-1 -

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UNIT-1: INTRODUCTION OF POWER PLANNING

1. INTRODUCTION

1.1POWER PLANNING

Electricity plays a key role in the modem society because of its versatility with respect to input

energy form. The annual per capita consumption in India is about 335 kWh (1996). A rise in this

consumption to three times the value is likely to substantially raise the standard of living of the

people in the country with respect to education, health, transport, communication, media,

productivity etc. Electricity can be produced with coal, nuclear fuels, oil, gas, hydro power, diesel,

geothermal energy, biomass, wind energy, solar energy or fuel cells. Electrical supply also offers

the opportunity of total environmental enhancement compared to other energy use patterns.

For increasing the supply of electricity, new power projects will have to be installed.

Expansion, modernization, and maintenance of the electricity utility industry will require increased

capital costs, financial and environmental restraints, increasing fuel costs and regulatory delays.

All these factors lead to the necessity for a more comprehensive understanding and analysis of

electric power systems. Recent developments in system analysis and synthesis as well as in related.

Digital, analog, and hybrid computer techniques provide important tools which will aid the

planning engineer in meeting these challenges.

Some of the questions to be explored are:

1. Where and how much generating capacity should be added?2. What should be the optimum size of the generating units?

3, what types or combinations of generation types should be used - nuclear, gas turbine,

conventional steam, pumped hydro, solar, wind etc.

4. What will be the environmental impact of various generation alternatives?

5. What should be the size of the interconnections with neighboring systems?

6. What voltage levels are most economical and what transmission lines should be constructed?

7. What will be the impact of major facility additions upon the financial structure of the utility?

8. How will utility requirements affect targets of performance for new technologies?

9. How will the energy conservation and load management measures help to reduce generation

capacity requirements?

10. How much reliability of power supply to consumer is required?

1.2PLANNING PROCESS

Planning is the process of taking a careful decision. The main input in Planning is the quality of

systematic thought that goes into a decision.

The process of establishing the power industry is capital intensive and time consuming.

Planning saves project time and ensures that resources are used most economically.


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Planning is the process of selecting vision, values, mission and objectives and deciding what

should be done to attain them.

Planning should take into account: uncertainty about the future, many alternative action

choices and many goals and constraints. Planning can be seen as consisting of three cyclical

componenents

1

Learning about the environment, the relevant issues and possible future scenarios in order

to identify:

(i) Strategically goals

(ii) The decision criteria and constraints

(iii) Technological needs and opportunities

2

Thinking about available strategic options, the associated costs and risks and their

implications. This involves:

(i) Investment of resources

(ii) Possible unforeseen factors

(iii) Reliability of outcome.

3

Action that involves choosing preferred plans or strategies on the basis of supporting

analysis.

Once an action has been selected and the process of implementation begins, the cycle is

renewed. The following characteristics make this planning process particularly challenging for

power systems.

1. The power system is highly capital intensive.

2. Rationales and experiences developed in advanced countries are difficult to apply for expanding

a large system with diverse options in developing countries.

3. The learning and thinking activities often tend to diverge broadly before finally converging.


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1.3POWER SYSTEMS

Ever since electrification began in the world around 1880, electrical utilities have gradually

consolidated into larger units to generate, transmit and distribute electricity. In India,

electrification started with the commissioning of small hydro-electric station (130 kW) at

Darjeeling in 1897. Followedby commissioning of a hydropower station at Sivasamudram in

Karnataka during 1902.

The regulatory systems have consequently changed over time. The planning of power systems

must fit with the overall energy policy with due respect to public opinion and reliability of

power supply. This makes power system planning difficult. The problem of ensuring adequate

future electricity supply varies from country to country depending on the peoples' expectations,

technological development, and availabilities of resources.

Under the Electricity Supply Act, it is the duty of the Central Electricity Authority to adopt a

systematic approach to formulate policy and optimize resources.

Planning should consider the needs of the system - existing, new or refurbished generation,

new transmission or upgrades, demand-side management and so on - and the resources that

may be available to meet them. Where additional generation is required, like site, size, the fuel

type including back-up fuel requirements (if any), technical and environmental characteristics

and mode of dispatch (base load, intermediate, peaking), should be identified.

Environmental and resource constraints are forcing us to approach the future with better

planned and researched projects. The major goals for the future are to develop least cost

projects, identify new primary resources, find better means of distribution, transmission and

generation, emphasize on better and less wasteful use of electricity, and develop demand side

management. Pumped hydro power and superconducting magnetic coils represent a possible

solution for storage of electricity Planning should identify the project with decision & clarity.

Power aspects in developed and developing countries

ITEM DEVELOPING COUNTRIES DEVELOPED COUNTRIES

Load Growth Fast Slow

Reliability Low Stringent

T&D Losses High Low

Power Planning Poor Adequate

Grid System Weak Strong

Public Acceptance Lacking Pursued

Services Non-Market Market oriented


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1.4STRATEGIC PLANNING

1.4.1 Strategies & its classification

Strategy is a unified, comprehensive and. integrated plan.

It is designed to ensure that the corporate goals are achieved. Comprehensive intelligence about

the nature and extent of the likely trends of power development and demand is essential for a

successful strategy.

Strategic planning is the process of determining the long-term goals and courses of action and

the allocation of resources necessary to accomplish these goals.

The broader planning horizon of strategic planning has significant implications for resource

planning, for example, planning to influence demand in order to reduce the need to build new

generating capacity.

There are many means available to reduce demand, such as by

(i) Changing the tariff structure, e.g., time-of-day tariff.

(ii) Demand billing.

(iii) Implementation of load control by shifting peak load to off peak period.

(iv) Encouraging co-generation/captive generation.

(v) Promotion of conservation of energy.

Functions of planning

Function Time Frame (Yrs) Organizational Level

Perspective 10-20 Corporate vision, mission, Values

Strategic 5-10 Utility, Regional and National level

Tactical 1-5 Utility/corporate level

Operational 0-1 Utility level

The first step in developing a strategy is the identification of the problems and opportunities

that exist. A successful utility will have a fertile idea generating environment. To attain the vision,

perform strengths, weaknesses opportunities and threats (SWOT) analysis and benchmarking

exercises within the power utility. The second step is to set goals (objectives). Goal setting is not

independent from identification of opportunities. The next step is to have a procedure for providing

possible solutions. Tactical and operational planning involves this step. The fourth step in strategic

planning is to choose the best solution, given possible solutions and the objectives. On what basis

the solutions be chosen is a difficult job, depending upon various constraints. The components of

planning are shown in the next page.


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Flow chart showing the Components of Planning

The last step is to have some type of review procedure to check how the best solution hasactually performed. The nature of this review function will depend on the performance and style of

management. To implement a strategy, develop the specific action plan.

Long-Term Strategy

Some technological, managerial and geopolitical issues require long-term policy and

administrative decisions and include, among others:

(i) Directions for capacity augmentation to meet the projected demand need for accelerating hydro

development.

(ii) Environmental issues in power development.

(iii) Inter (state/regional issues in water resources development.

(iv) Functional and commercial issues in integrated operation.

(v) Land and water availability for thermal power development.

(vi) Fuel (coal, oil etc.) quality and transport in thermal power development.

(vii) Energy costs and prices and resource mobilization.

(viii) Organizational deficiencies in power development, i.e., re-engineering of power industry to

bring efficiency in the management process.

(ix) Private participation in power generation, transmission and distribution.

Medium-Term Strategy

The broad aims are:

(i) Renovation, modernization, upgrading and extension in the life of existing ageing power plants.

(ii) Reduction of transmission and distribution losses.

(iii) Construction of shorter gestation power plants like gas turbine based combined cycle, co

generation schemes etc.

(iv) Energy conservation and load management.


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(v) Adoption of non-conventional energy sources particularly for rural decentralized energy

systems.

Short-Term Development Strategy

Short-term strategies aim at:

(i) Improving the performance of existing power plant capacity and maximizing its utilization.

(ii) Seeking even power sharing over circuits of similar ratings.

(iii) Establishing new circuit connection as required, if possible without recourse to displacing.

lower voltage circuits, and at the highest possible capacity.

(iv) Routing new circuits so that they may readily be used for connection of future power stations,

or for supply points to regional grids.

(v) Reducing the number of levels of system voltage used.

(vi) Maintaining uniformly high, but acceptable fault levels.

(vii) Installing capacitors at various voltage levels (HT and LT.)

(viii) Computerizing work management system for tracking recurring problems, materials

movement and maintenance history and to forecast maintenance schedule.

The planning engineer's contribution to a project is to prepare a detailed project report giving a

time frame for site clearance, and for starting, completing, and finishing construction of a project.

The report sets the limits of resources and sequence of activities and phases etc.

1.4.2Detailed project report (DPR)

Planning of power project facilities undergoes the following stages:

(i) Preliminary investigations for establishment of need proposed to be achieved through the

implementation of a project.

(ii) Project identification and formulation which involves examination of various options to meet

desired needs and selection of one for preparation of feasibility report.

(iii) Detailed Feasibility Report (DFR) regarding technical, demand, organization, and

environmental aspects, and financial and economic viabilities.

(iv) Appraisal of Detailed Feasibility Report keeping in mind the following aspects:

(a) Technical analysis to determine whether the specifications of technical parameters chosen are

realistic and optimal.

(b) Demand analysis to determine the demand availability gap of power for a particular

region/state/site and arrangement for evacuation of power thus generated.

(c) Organizational aspects to determine whether the organization has the managerial capability to

implement and operate the project.

(d) To check if the environmental guidelines are fully covered in the project cost(e) Financial analysis to determine whether financial costs are properly estimated, funding is

ensured and the project is financially viable.


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(f) Economic analysis to determine the cost generation/transmission and whether the project is

economically worthwhile.

(v) Preparation of Detailed Project Report: It comprises technical details running into several

volumes for large projects. After the appraisal of DFR, detailed engineering conducted. A Detailed

Project Report indicating the firmed-up cost estimates and project implementation schedule is

prepared. Between the DFR and DPR stage, there may be some further studies required to improve

information about site conditions and other project parameters.

(vi) Implementation involves implementation planning as per detailed project report, obtaining

various clearances, getting investment approval or financial close, detailed designs and drawings,

specifications, tendering/contracting, execution of various activities leading to commissioning of

the project and monitoring throughout.

1.4.3Project implementation

Good project management is necessary to avoid time and cost over runs. Rigorous project

planning and management practices should be applied for the project to be completed in time and

within budget. PERT must define an overall project management framework under which all

implementation activities will have to be performed. It should contain:

(i) A detailed schedule of all project activities and their estimated durations.

(ii) A statement on the methods to be used to complete all the project activities.

(iii) A quality statement which identifies all quality control and quality assurance steps to be

applied.

(iv) A statement on the organizational requirement and impact within the utility organization, so

that it can be managed effectively.

Well researched, clear and good quality Detailed Project Reports (DPRs) for power

development are important. Research and Development should be an in-built part of the project for

the entire duration of the project. The one important reason for the present conditions of power

supply in India is the delays in the addition of power generating, and transmission and distribution

capacity mainly due to DPR deficiencies.

1.4.4Role of consultants

Consultants have important role in Power industry. The consultant can take up the turn-key

projects and Consultancy services such as feasibility reports, detailed project reports, detailed

engineering, total project management, commissioning, financial systems, manpower management,

R&D etc. The primary business of a consultant is;

(i) To provide solution to their client's problems. The consultant should be able to define the

problems and constraints and analyze them to arrive at a solution.(ii) To help the client to accept and implement the solution.

(iii) Consolidate consultants' knowledge base.


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1.5 POWER DEVELOPMENT

The development of power is closely linked with the growth of gross national product. The

economic strength of a region in the next century will be greatly dependent on the availability of

power. In the planning of power system development, priority is given to regional systems and

generation load balances are maintained. Also, keeping in view that different transmission lines are

not too 'redundant' but are sufficiently robust regional links, there must be strategic planning to

foresee, evaluate and co-ordinate future requirements and concentrate resources to dovetail with

medium and short-term objectives.

The overall time leads to the various planning activities are given below,

Time ahead Planning Activity

5-20 years Long-term planning Vision, values, mission, load forecasting regional system

and National grid expansions scheme

2-5 years Medium-term

planning

Medium-term utility generation schemes such as coal,

thermal, gas turbines, hydro etc. Renovation andmodernization of existing generating plants

1-2 years Short-term planning System improvement of transmission and distribution

systems, Small generation schemes, small hydro, gas

turbines diesel power projects, non-conventional sources

of generation

15days-1year Operational planning Maintenance scheduling of units and fuel requirements

1-7 days Operational planning Generation scheduling and network switching

2-12 hours Operational planning Economic dispatching instruction and power purchases /

selling

0-2 hours Operational planning Network switching Economic Dispatch Control

The starting point in the planning process is to develop clear vision, good values and

mission. The other processes follow, such as to develop load forecasts in terms of annual peaks and

energy needs for the entire utility area as well as for each region consisting of many utilities.

The system expansion is determined by load-flow studies under steady state and abnormal

conditions. The load-flow studies are made for calculation of currents, voltages, and real and

reactive power flows taking into account the voltage regulating capability of generators and

transformers, capacitors, generation schedules, power interchange etc. By changing the location,

size and number of transmission lines, the planner can achieve. To design an economical system

that meets the operating, design, environmental and cost criteria. After determining the best system

configuration from the load-flow studies, the planning engineer studies system behavior under

fault conditions by carrying out Short-circuit studies as a short-term plan to determine design

parameters of protection systems. Finally the planner performs the stability studies to ensure that

the power system will remain stable following severe fault.


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1.6 POWER GROWTH

The electricity generation capacity in India is the fifth largest in the world. India is also the

sixth largest consumer of electricity, and accounts for 3.4 per cent of the global energy

consumption. Over the past thirty years, the countrys energy demand has grown at an average

of 3.6 per cent per annum. Growth in the installed capacity of power generation has been

spectacular, having risen from 1,712MW in 1950 to 84,087MW ending 1995-96. During the

financial year 2011-12, the highest ever capacity addition of 20,501 MW (thermal, nuclear and

hydro) was achieved (CEA). A capacity addition of 17,956 MW during the year 2012-13

comprising 15,154 MW of thermal, 802 MW of hydro and 2000 MW of nuclear powerhas

been envisaged.

Indias Installed Generation Capacity stands at 210,951.72 MW as on December 31, 2012. And

the electricity sector in Indiahad an installed capacity of 225.133GW as of May

2013. Captive power plants generate an additional 34.444 GW. Non Renewable Power Plants

constitute 87.55% of the installed capacity, and Renewable Power Plants constitute the

remaining 12.45% of total installed Capacity. India generated 855 BU (855 000 MU i.e.

855TWh)electricity during 201112 fiscal.

In terms of fuel, coal-fired plants account for 57% of India's installed electricity capacity,

compared to South Africa's 92%; China's 77%; and Australia's 76%. After coal,

renewalhydropower accounts for 19%, renewable energy for 12% and natural gas for about

9%.

The Power Ministry has also proposed an outlay of Rs 37 crores for the Central Electricity

Authority (CEA) for various initiatives of strengthening its institutional framework. Sixty-three

per cent will be spent on new and ongoing projects while twenty-nine per cent is on renovation

and modernization, and the rest is on renewable energy projects. The overall investment

required for the power sector in the 12th Plan is about 12 to 14 lakh crores of rupees. The

investment pattern should focus on generation, transmission and distribution segments in order

to achieve balanced growth in the power sector.

The Central Electricity Authority (CEA), in its fifteenth Electric power Survey has estimated

that the gross energy generation required by the year 2020 is to the order of 1325TWh/annum

and the corresponding generation capacity requirement is 3,85,770MW.

The transmission network comprises of about 98,367 circuit kilometers of transmission lines at

800/765kV, 400kV, 220kV and 132kV EHVAC and +500kV HVDC levels and 160 sub-

stations. A new transmission line of 1200 KV has become operational in India recently,

whereas the highest transmission voltage level in China is only 1100 KV. The transformation

capacity is about 1,57, 158 MVA as on January 31, 2013. This gigantic transmission network
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spread over the length and breadth of the country is consistently maintained at an availability

of over ninetynine per cent (PGCIL).

The transmission and distribution loss is another ill afflicting the power sector in the country.

The main reasons for high transmission and distribution losses are weak and inadequate sub-

transmission and distribution system, improper load management, inadequate reactive load

compensation at load points, low quality of construction, inadequate maintenance of

equipments, and unmetered supply of agricultural pump-sets and pilferage/theft of energy.

India's network losses exceeded 32% in 2010 including non-technical losses, compared to

world average of less than 15%. Both technical and non-technical factors contribute to these

losses, but quantifying their proportions is difficult. But the Government pegs the national

T&D losses at around 24% for the year 2011 & has set a target of reducing it to 17.1% by 2017

& to 14.1% by 2022. Some experts estimate that technical losses are about 15% to 20%.

2. NATIONAL AND REGIONAL PLANNING

2.1 ADVANTAGES & DISADVANTAGES OF NATIONAL AND REGIONAL

PLANNING

There is a lot of diversity in the country in topography, daily peak due to day time differences,

annual peak load timings (winter or summer) & resources in the various regions. Hence five

electricity regions have been established. The economic argument in support of regional

coordination is Advantages,

Such coordination allows joint planning & operation of facilities,

It makes the exchange of economical energy easier,

It prevents the constructions of unnecessary facilities by isolated systems & increases

reliabilities.

More specifically, as a result of transmission interconnections, coordination offers distinct

economic & the non coincidental occurrence of the peak of the participation systems.

It might be possible to reduce the total generating capacity requirements that would otherwise

apply if each utility system were to fully meet its needs.

By combining the existing capacity of generation in the region & to make economic use of the

generating resources such as hydro & fossil fuels etc

Disadvantage,

One of the problems in regional planning relates to coordination among the various utilities in

the region with respect to tariff and backing down Of generating units in merit order. HVDC

links for transfer of power between various regions is desirable in order to utilize surplus

power in some regions and for stable grid operation.


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2.2 INTEGRATED RESOURCES PLANNING

This is an aspect of least cost planning. The utilities have to evaluate all the Supply side and

demand side options like energy conservation programmes, direct load control, interruptible or

time of use pricing and system improvement

SUPPLYSIDE OPTIONS

1. The technology related to conventional fossil fuels is predominant at present. Many utilities

have turned to combustion turbines fueled with natural gas with new capacity which are highly

efficient, have low emission, and are well adapted for intermittent use. Moreover, as the focus

is now on cleaner, more efficiently cost-effective, coal-fired generation technologies, washed

coal, gasification based generation options like Integrated Gasification-Combined Cycle

(IGCC), etc., are found more effective over applying Flue Gas Desulfurization units and

Fluidized Bed Combustion because the former have a potential to minimize solid waste in

addition to cutting airborne emissions.

2. Increasing role of renewable: While technological advancement continues in the use of fossil

fuels, several new options have started to emerge which broaden the scope of non-conventional

sources of energy in the future. Wind power generation costs have fallen dramatically, by a

factor of 10, and photovoltaics by a factor of 4, over the last two decades.

3. Increase in the availability of generating station.

4.

Efficient operation of the regional and national grid.

5.

Strengthening the existing transmission and distribution system such as by adding new links

and capacitor banks at suitable points and thus reducing system losses and improving voltage

profiles.

DEMAND SIDE OPTIONS

1. Taking energy conservation 111asureTs:here is a potential for energy saving to the extent of

30 per cent in agriculture pump-sets, 25 per cent in industrial motors, and 10-15 per cent in

commercial and domestic lighting.

2. Minimum consumer power factor of not less than 0.95 lagging.

3. Consumer load management such as rural, agriculture and urban load staggering, individual

large consumer load control, and thereby improvement in generating stations load factor.

4. Time-of-day metering with three tariffs for peak time (higher rate), night time (lower rate) and

other times of the day (medium rate).

2.3 LEAST COST UTILITY PLANNING

There are two fundamental problems inherent in traditional planning. The first is that demandforecasting and investment planning are treated as sequential steps in planning, rather than as

interdependent aspects of the planning process. The second problem is that planning efforts are


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inadequately directed at the main constraints facing the sector, namely, the serious shortage of

resources.

Demand forecasts are little more than extrapolations of past trends of consumption; no attempt

is made to understand neither the extent of unmet demand, nor the extent to which price would

influence demand .growth. Greater attention should be paid to end-use efficiency, plant

rehabilitation, loss reduction programme etc as these have a potential for much more economic

use of investment resources.

Least cost planning is least cost utility planning strategy to provide reliable electrical services

at the lowest overall cost with a mix of supply side and demand side resources.

The LCUP uses various options like end-use energy efficiency, load management, transmission

and distribution options, alternative tariff options, decentralized non-conventional sources

power generation and conventional centralized generation sources. The magnitude of the

various components depends upon the detailed outcome of the exercise.

This planning process can yield enormous benefits to consumers and society because it affords

acquisition of resources that meet consumer energy service needs in ways that are low in cost,

environmentally benign, and acceptable to the public. Such benefits occur because of the

diversity of resources considered, public involvement in the planning process and cooperation

among interested parties.

Least costs utility planning as a planning and a regulatory process can greatly reduce the

uncertainties and risks faced by utilities. System expansion detailed project reports (DPRs)

must be based on least cost planning and need to be made mandatory by amending the

Electricity (Supply) Act, 1948. The logic for least-cost planning is shown in below Figure.

For an investment to be least cost, the lifetime costs are considered. These include capital cost,

interest on capital, fuel costs, and operational and maintenance cost.

To fully realize the benefits, a complete analysis of the options is necessary and simulation

study according to a programming can be necessary and simulation study according to a

programming can be helpful for a complete analysis of attributes. The process of least cost

planning is shown in next page.


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The process of least cost planning

Evaluation

1. All options, whether supply or demand, should be assessed in a comparable and consistent

manner.

2. Once the initial evaluation has been completed, other factors (economic, environmental, and

societal) should be considered individually. Such revaluation prevents the rejection of options with

high costs in one set of factors, such as economics, but strong benefits in others, such as

environmental impacts.

3. The evaluation and integration of options can also be accomplished through the use of various

commercially available computer programs.

4. A linear programming model (India ELITE) based on an earlier version of a power planning

model developed in Canada has been prepared. It has been used in identifying least cost electric

power system development options for India for the 1991-2021time frame.

5. EGEAS packages have been used by CEA for preparing the National Power Plans.

6. Other softwares or packages available for simulation or least cost planning are PROMOD,

ELFIN, MIDAS, EGEAS, UPLAN, MARKAL-ELGEM etc which are used in different countries.

3. STRUCTURE OF POWER SYSTEM

An electrical power system can be considered to consist of generation, transmission, sub

transmission systems and distribution parts. In general, the generation and transmission

systems are considered as bulk power supply and the sub transmission and distribution systems

are considered to be the final means to transfer the electric power to the ultimate consumers.


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The standard system voltages used in India for transmission and distribution are as per IS: 12360-

1988are given in the below table.

Standard system KV Voltages (IS: 12360)

Nominal Voltage in KV Maximum System Voltage Remarks

0.240 0.264 Distribution

0.415 0.457

3.3 3.6

6.6 7.2

11.0 12.0

22.0 24.0

33.0 36.0 Distribution & Sub

transmission66.0 72.5

132.0 145.0 Sub transmission &

Transmission220.0 245.0

400.0 420.0 Transmission & Tie

line765.0 800.0

The basic system consists of energy resources such as hydro, coal, gas etc., a prime mover, a

generator and a load. Some sort of control system is required for supervising it.

The prime mover may be a steam driven turbine, a hydraulic turbine or an internal combustion

engine. Each one of these prime movers has the ability to convert energy in the form of heat,

falling water or fuel into rotation of the shaft which in turn drives the generator.

The generator may be are alternator or a d.c. machine. The Electrical load on the generator may

be lights, motors, heat or other devices, alone or in combination etc.

The control system functions to keep the speed of the machine constant, the voltage within

prescribed limits to meet varying conditions of the load by adjusting fuel/water, and generator

excitation within the generator capability.

The active power (MW) is regulated by frequency (speed) control. The reactive power (MVAr)

and voltage is regulated by excitation control.

The components of an electric power system include generators designed to convert

mechanical energy into electricity, transformers, which change the voltage or current of electric

power supply, transmission lines used to transfer power from one location to another, and

auxiliary equipment intended to vary the system controls.


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System performance is determined at an instant of time and is characterized by its functional

parameters such as levels of power, voltage, frequency, wave shape, phase balance, and

amperes. Physical properties of interconnected systems are characterized by resistance of

components, inertia moments and time constants determining the change of electrical and

mechanical quantities. The electric power system is closely connected to other systems by tie

lines or links.

Power System Components

The power transmission and distribution network may be of the following types

1. The radial systemis as in Figure shown in next page. Here the lines form a 'tree' spreading out

from the generator. Opening any line results in interruption of power to one or more of the loads.

2. The loop system is as in Figure shown in next page. With this arrangement all loads will

continue to be served even if one line section' is put out of service. In normal operation the loop

may be open at some point at Aas shown in the figure. In case a line section is to be taken out, the

loop is first closed at Aand the line section is put on shut down. In this way no service interruption

occurs.

Radial System Loop System

Network of Lines


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3. In Network of linesthe same loads being served by a network. This arrangement has a higher

reliability as each load has two or more circuits of supply.

The sub transmission and distribution circuits are commonly designed as radial or loop circuits.

The high voltage transmission lines are generally laid as interconnected or networks.

In this case interconnection of major power stations creates networks made of many line

sections. As the demand for load grows, generating capacity and transmission and distribution

must grow as well. Transmission and distribution are distinguished by their voltage levels. In

general, transmission systems have bulk power handling capability, and relatively long lines

connecting generating stations to load centres of the utilities.

The model of transfer of power (P)by transmission line (having line reactance XL) between

two distance buses, (1 and 2) fed by generating machines with terminal bus voltage V1 and V2

respectively with phase angle difference is generally represented as,

1 2| || | sin

L

V VP

X

=

Distribution systems including sub transmissions, branch out from and Under lie the

transmission systems. They handle lower levels and have relatively short lines. The power

level that transmission and distribution systems are being called upon to handle, are increasing

with time. The economies of scale need large generating stations and higher voltage levels for

transmission and distribution. Electricity cannot be stored and has to be supplied instantly.

The component installed capacity, say in MVA p.u., expands progressively as one moves from

generation to transmission, sub transmission, distribution and the consumer end. Typical value

for the Indian power system is,

Generation capacity (1 p.u.) =Transmission capacity (1.5 p.u.) + Sub transmission

capacity (2p.u.) + Distribution capacity (3 p.u.) + Connected load (6p.u.)

The reduced p.u. values on the right hand will indicate better electricity efficiency of the

system but in the interest of reliability and future expansion p.u. values may be higher for some

sectors. With rapid advancements in the field of electronics and its applications in innumerable

domestic, commercial and industrial sectors, the demand for quality power supply has

increased. 'Computers and other high-tech electronic process technologies require clean,

precise, transient free and uninterrupted power supply.

Rule 54 of the Indian Electricity Rules, 1956, states that a supplier shall not permit deviation in

voltage at the point of supply in consumer premises

1. In the case of low or medium voltage, by more than 6 per cent, or

2.

In the case of high voltage, by more than 6 per cent on the higher side or by more than 9percent on the lower side, or


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3.

In the case of extra high voltage, by more than 10 percent on the higher side 0r by more than

12.5 percent on the lower side.

4. Rule 55 states that the frequency of the alternating current should not vary from the declared

frequency by more than 3 percent.

4. POWER RESOURCES

The electricity sector in Indiahad an installed capacity of 225.133GW as of May

2013. Captive power plants generate an additional 34.444 GW. Non Renewable Power Plants

constitute 87.55% of the installed capacity, and Renewable Power Plants constitute the

remaining 12.45% of total installed Capacity.

The share of electrical energy in total energy consumption in India is 13.0% which is at 10th

place in world ranking.

India is endowed with economically exploitable and viable hydro potential assessed to be about

84,000 MW at 60% load factor. In addition, 6,780 MW in terms of installed capacity from

Small, Mini, and Micro Hydel schemes have been assessed.

Indias coal reserves will outlast other fuels for there are known coal reserves for another 200

years. India is the third major coal producing country in the world. Coal and lignite accounted

for about 57% of India's installed capacity. However, since wind energy depends on wind

speed, and hydropower energy on water levels, thermal power plants account for over 65% of

India's generated electricity. India's electricity sector consumes about 80% of the coal produced

in the country.

India's share of nuclear power plant generation capacity is just 1.2% of worldwide nuclear

power production capacity, making it the15th largestnuclear power producer. Nuclear power

provided 3% of the country's total electricity generation in 2012.

In India, the known reserves of oil will last for about 30 years & the Natural Gas can last up to

AD 2050 at the present rate of consumption. Natural gas is basically methane which contains

one carbon atom for every four hydrogen atoms. Therefore, after combustion it gives out less

CO2 for every energy unit derived. Besides, gas has little or no sulfur compounds or suspended

particulate matter, & the percentage of nitrogen is much less than in coal or oil. As a natural

policy, the use of oil & gas has been allowed for power generation.
http://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Nuclear_power_by_countryhttp://en.wikipedia.org/wiki/Nuclear_power_by_countryhttp://en.wikipedia.org/wiki/Nuclear_power_by_countryhttp://en.wikipedia.org/wiki/Nuclear_power_by_countryhttp://en.wikipedia.org/wiki/Watt


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5. PLANNING TOOLS

Planning engineer's primary requirement is to give power supply to consumers in a reliable

manner at a minimum cost with due flexibility for future expansion.

The criteria and constraints in planning an energy system are reliability, environment,

economics and electricity pricing, financial constraints, and society impacts and value ofelectricity.

Reliability, economic; financial and environmental factors can be quantified. However, societal

effects are evaluated qualitatively. Some of these criteria conflict, making the planning

decisions more complex. For example, meeting higher reliability levels may be constrained by

financial limitations to build new facilities. Achieving lower environmental impact is likely to

increase the cost of electricity to consumers (economic factor).

The system must be optimal over a time period from first day of operation through the planned

lifetime. Today, the planner numerous analysis and synthesis tools at his disposal.

Various computer programs are available and are used for fast screening of alternate plans with

respect to technical, economic and environmental performance of power system.

The available tools for power system planning can be split into three basic techniques: simulation,

optimization and scenario Techniques,

1. Simulation Tools -

These simulate the behavior of the system under certain conditions and/or calculate relevant

indices. Examples of (simulation tools) are load flow models, short-circuit-models, transient

stability models etc., in transmission; production costing, adequacy calculations, estimation of

environmental impact etc.

In power generation, corporate models can simulate the impact of various decisions on the

financial performance of the power utility company.

The use of simulation tools for strategic planning need voluminous data and requires the

results from various models to be integrated such typical simulation programs is shown.

2.

Optimization Tools

These minimize or maximize an objective function by choosing adequate values for decision

variables. Examples of these are optimum power, least cost expansionplanning, generation

expansion planning.

3. The Scenario Techniques -

This is a method for viewing the future in a quantitative fashion.

All possible outcomes are investigated. The sort of decision or assumptions which might be

made by a utility developing such a scenario might be: should we Computerize and automate

the management of power system after a certain date.


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The process of Planning Electric Energy Systems consist of generating a set of planning

Scenario,

Scenario can be optimistic/ambitious or optimum or Pessimistic.

In India, the various types of scenarios for electric power are drawn by the Planning

Commission, CEA, State Electricity Boards, research organizations, individual research

workers Etc.

Electrical utilities should prepare integrated resource plans. These Long term plans seek to

develop the best mix of demand and supply options to meet consumer needs for electric energy

services.

Simulation programs for system planning

ANALYSIS

PROGRAMS

APPLICATION

Generation reliability Generation reserve requirement to meet specified reliability criterion,

System reliability

Generation cost Cost of fuel, operation and maintenance

Risk analysis Resource uncertainties

Optimum generation

mix

Best combination of different types and sizes of generating units

considering capital and production costs and minimizing revenue

requirements

Power flow Steady-state system studies

Transient stability System stability assessment

Dynamic stability Possibility of cascade tripping, system isolation and blackouts

Short circuit To design protective relaying systems and to select the circuit breakers

Sub synchronousoscillations

To determine damaging generator shaft torques

Loop flow To determine possibility of unauthorized use of transmission lines of a

particular utility

Transmission

expansion

Optimum range for transmission line expansion


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6. THE ELECTRICITY REGULATIONS

Regulations shape and influence the functions and processes.

The regulations generally concern,

1. Price setting: consumer tariff, wheeling charges, long-term bulk-power Purchase agreements.

2.

Quality of service standard and monitoring.3. Compliance with public service obligations.

4.

Dealing with consumer complaints.

5.

Ensuring fair and open competition or the harnessing of competitive forces, as appropriate.

6. Monitoring investment in and repair of infrastructure.

7. Third party use of networks.

The current regulations enacted by the Government of India are primarily administered by

CEA in its role as technical and economic advisor to the Minister of Power, with input from

state, regional and central government entities.

For example, there is need for rules regarding transmission access to private generators and for

checking the potential for anticompetitive use of monopoly power.

Tariff regulations at the bulk power level are primarily covered under section 43A of the

Electricity (Supply) Act of 1948.

ELECTRICITY ACTS

INDlAN TELEGRAPHICACT, 1885

This act covers the privileges and powers of the government to place the telegraphic lines and

posts. Penalties and certain other supplementary provisions regarding electric power lines.

INDIAN ELECTRICITY ACT, 1910

This is an act to amend the law relating to the supply and use of electrical energy. It regulates:

1. Licences: Grant of licences; revocation or amendment of licences; purchase of undertakings;

annual account of licensees.

2. Works: Provision as to opening and breaking up of streets, railways and tramways; notice of

new works; laying of supply lines; notice to telegraph authority; overhead lines; compensation for

damage.

3. Supply: Point of supply; powers of lincences to enter premises, restrictions on licensees;

obligation on licensees to supply energy; powers of the state governments to give direction to a

licensee, power to control the distribution and consumption of energy; discontinuance of supply to

consumers; meters.

4. Transmission and Use of Energy by Non-licensees: sanctions required by non-licensees in

certain cases; control of transmission and use of energy.


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5. General Protective Clause: Protection of railways, aerodromes, canals, docks and piers;

protection of telegraphic and electric signal lines; notice of accidents and enquiries; prohibition of

connection with earth and power to government to interfere in certain cases of default.!

6. Administration and Rules: Advisory boards; appointment of electrical inspectors.

7. criminal Offences and Procedure: Theft of energy; penalty for maliciously wasting energy or

injuring works; penalty for unauthorized supply of energy by non-licensees; penalty for illegal or

defective supply or for non-compliance with order; penalty for interference with meters or

licensee's works and for improper use of energy; offences by companies; institution of prosecution.

8. supplementary Provisions: Exercise in certain cases of power of telegraph authority; arbitration;

recovery of sums; delegation of certain functions of the state government to the inspection staff;

protection for acts done in good faith; amendment of Land Acquisition Act, 1884;repeals and

savings.

THE ELECTRICITY (SUPPLY ACT) ACT, 1948

This act rationalizes the production and supply of electricity and generally provides for taking

measures conducive to its development. It provides for:

1. The Central Electricity Authority: Constitution ; powers to require accounts, statistics and

returns; direction of central government to the Authority; power of central government to make

rules; powers of Authority to make regulations.

2. State electricity boards, generating companies; state electricity consultative councils and local

advisory committees; constitution and composition of state electricity boards; interstate agreement

to extend board's jurisdiction to another state; formation, objects, jurisdiction etc., of generating or

transmission companies.

3. Power and duties of state electricity boards and generating or transmission company,

coordination with regional electricity boards and regional load dispatch centres.

4. The board's finance accounts and audit.

5. Miscellaneous items such as effects of other laws; water power concessions to be granted only

to the board or a generating company; coordination between the boards and multipurpose schemes;

powers of entry; annual reports, statistics and returns arbitration; penalties; cognizance of offences;

direction by the state government; provision relating to income-tax; members officers and other

employees of the board to be public servant; protection of persons acting under this act; saving of

application of Act.

THE INDIAN ELECTRICITY RULES, 1956

It contains 143 rules along with detailed annexure and covers:

1. Authorization to perform duties2. Inspection of electric installations: Creation of inspection agency; entry and inspection;

inspection fees; appeal against an order; submission of records by supplier or owner.


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3. Licensing: Application, contents and form of draft license; advertisement of application and

contents thereof; approval of draft licence and a notification for grant of licence; commencement

of licence; amendments of licence; preparation and submission of accounts and model conditions

of supply.

4. General safety precautions: Regarding construction, installation, Protection, operation and

maintenance of electric supply lines and apparatus; service lines and apparatus on consumer's

premises; identification of earthed conductors; accessibility of bare conductors; provisions

applicable to protective equipment; instructions for restoration of persons suffering from electric

shocks; intimation of accidents; precautions to be adopted by consumers, owners, electrical

contractors, electrical workmen and suppliers; periodical inspection and testing of consumer's

installations.

5. General conditions relating to supply and use of energy: Testing of consumer's installation;

precaution against leakage; declared voltage and frequency of supply; placing and sealing of

energy and demand meters; point of supply; precautions against failure of supply.

6. Electric supply lines, system and apparatus for low, medium, high and extra high voltages:

Testing of insulation resistance; connection with earth; voltage tests systems; general conditions as

to transformation and control of energy; approval by inspector; use of energy; pole-type

substations; discharge of capacitors; supply to neo-signs; supply to HVelectrode boiler; supply of

X-ray and high frequency installations.

7. Over headlines: Materials and strength; joints; clearances and supports, erection of or alteration

of buildings; structures; conditions to apply where telecommunication lines and power-lines can be

carried on the same supports; lines crossing; service lines; protection against lightening; unused

overhead lines.

8. Electric traction: Additional rules for electric traction; voltage of supply; difference of potential

on return; current density in rails.: size and strengths of trolley wires; records.

9. Additional precaution for mines and oil fields.

10. Miscellaneous Provisions.

Rules relaxation by the government; relaxation by the inspector; supply and use of energy by non

licensees and others; penalty for breaking seal and other penalties for breach of rules; repeal

FOREST (CONSERVATION) ACT, 1980

The Act stipulates the forest clearance requirement for the forest area where hydro plants

(reservoir etc.), and transmission lines are planned. The guidelines for taking power lines through

the forest area are,

1. Where routing of power lines through the forest areas cannot be avoided, these should bealigned in such a way that it involves the least amount of tree cutting.

2. As far as possible, the route alignment through forest areas should not have any line deviation.


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3. The maximum width of right-of-way for the power lines on forest land shall be as follows:

Line Voltage (KV) Width of Right Of Way

11 7

33 15

66 18

110 22

132 27

220 35

400 52

800 85

4. Below each conductor, width clearance of 3m would be permitted for taking the swinging of

stringing equipment.

5. In the remaining width, right-of-way up to a maximum of 8.5 metres (for 800kV lines), trees

will be felled or looped to the extent required, for preventing electrical hazards by maintaining the

Following, The sag and swing of the conductors are to be kept in view while working out the

minimum clearance mentioned below.

Line Voltage (KV) Minimum clearance between conductors & trees (m)

11 2.6

33 2.8

66 3.4

110 3.7

132 4.0

220 4.6

400 5.5

6. In the case of lines to be constructed in hilly areas, where adequate Clearance is already

available, trees will not be cut.

7. Where the forest growth consists of coconut groves or similar tall trees, widths of right-of-way

greater than those indicated above may be permitted in consultation with the CEA.

TOWN AND COUNTRY PLANNING ACTS

These acts are of interest before erecting a plant, a substation or overhead line. It is necessary to

seek approval of planning authorities whenever these acts are applicable

ENVIRONMENT LAWS

Environment laws such as Water (Prevention and Control of Pollution) Act, 1974; Air (Prevention

and Control of Pollution) Act, 1981; Environment (Protection) Act, 1986are important for getting

pollution clearance from the competent authorities in case of generating plants


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7. LOAD FORECASTING

7.1LOADS

Throughout the world, electrification is an ongoing process. The reason for this phenomenon is

the preference for electrical energy.

The increasing demand in the Asian region is due to several factors such as population growth,growth of per capita income, migration to urban areas and increase in energy using product.

Demand forecasts are used to determine the capacity of generation, transmission and

distribution

System and energy forecast to determine the type of generation facilities required.

There are five broad categories of loads-domestic, commercial, industrial, agricultural and

residential. Commercial and agricultural loads are characterized by seasonal variations.

Industrial loads are considered base loads that contain little weather dependent variation. Their

generation characteristics are given below,

1 Domestic - This type of load consists mainly of lights, fans, domestic appliances such as

heaters, refrigerators, air conditioners, mixers, ovens, heating ranges and small motors for

pumping, and various other small household appliances. The various factors are: demand factor

100 percent, diversity factor 1.2-1.3 and load factor 10-15 percent.

2 Commercial - This type of load consists mainly lighting for shops and advertisement

boardings, fans, air conditioning;" heating and other electrical appliances used in commercial

establishments, such as shops, restaurants, market places, etc. The demand factor is usually 90-

100 percent, diversity factor is 1.1-1.2 and load factor is 25-30 per cent.

3 Industrial -These loads may be of the following typical power range,

Small Scale Industries 0-20kW

Medium Scale Industries 20-100kW

Large Scale Industries 100kW & above

The last type of loads needs power over a longer period and which remains fairly uniform

throughout the day. For large-scale industrial loads the demand factor may be taken as 70-80

percent and the load factor 60-65 per cent. For heavy industries the demand factor may be

taken as 85-90 per cent with a load factor of 70-80 per cent.

4 Agriculture - This type of load is required for supplying water for irrigation by means of

suitable pumps driven by electric motors. The load factor is generally taken as 15-25 percent,

the diversity factor is 1-1.5 and the demand factor is 90-100 per cent.

5 Other loads - Apart from the loads mentioned above, there are other loads such as bulk

supplies, street light, traction and government loads which have their own peculiar

characteristics.


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7.2 ELECTRICITY FORECASTING

Forecasting of electric load basically consists of,

o Long-term forecasting which is connected with load growth and supply / demand side resource

management adjustments.

o Mid- / short-term forecasting which is connected with seasonal or weather variations in a year,

weekly or daily load forecast etc.

The planning for the addition of new generation, transmission and distribution facilities is

based on long-term load forecasts and must begin 2-25 years in advance of the actual in

service.

In India, electricity load forecasts at the national, the Annual Power Survey Committee under

Central Electricity Authority prepares regional and state levels.

Load demand of states and regions must be forecasted. The pattern of Their typical monthly

load curves must be determined and the mix of base load and peaking power stations for

efficient integrated operation must be fixed. Locations and power station capacities must also

be identified to give optimum results.

Tie-up of all necessary inputs; and matching transmission and distribution systems must also

be a part of the full plan.

Forecasting techniques must be used as tools to aid the planner, along with good judgment and

experience.

7.3

FORECASTING HORIZON

Load forecasting is required in all three facets of power system operation, viz., long-range

system planning, operational planning and operational control, generally in the following time

frames,

(i) Long-term forecasting (periods ranging 245.years).

(ii) Medium-term forecasting (periods from one month to two years) for operational planning.

(iii) Short term forecasting (periods from one day to a few weeks) for operational planning.

(iv) Very short term forecasting (a few minutes to 24 hours) for operational control.

7.4 TYPES OF FORECASTS & THEIR IMPORTANCE

Long Range Forecasts

Long-range forecasts involve Identification of both energy and demand forecasts for a utility

over a period exceeding two years. Whereas the energy requirements decide the type of generating

units (i.e., peaking or intermediate or base-load units), expansion and the demand of peak power

requirements decide the utility's investment in generation and the resultant transmission capacity

additions.Long-term forecasts are used for,

(i) Exploration of natural fuel and water resources.


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(ii) Development of trained human power.

(iii) Reinforcement planning of generation transmission and distribution equipment.

(iv) Establishing future fuel requirement.

Forecasts based on either past trends or on very broad based factors do not provide sufficient

confidence level for long-range planning. Forecasting in today's environment has increased in

complexity due to rapid and random changes in the factors that influence load consumption.

The following factors are relevant for their impact on utility's growth,

(i) The country's economic policy, developmental plans, technological development in production

of products and services.

(ii) Growth pattern in domestic, commercial, industrial and agricultural loads.

(iii) Population growth and electrification plan (urban and rural).

(iv) Political, developmental and environmental decisions.

Statistical methods with adaptive techniques are employed to forecast long-range load

requirements, as the method chosen shall have to use past data, growth patterns and human

judgment.

Mid-Term Forecasts

These forecasts are aimed to determine yearly or monthly peak, minimum load and energy

requirements for one to few years for the purpose of:

(i) Deciding rat~-structure for billing of different consumer categories.

(ii) Power exchange contract with neighboring utilities and interchange schedules.

(Hi) annual planning and budgeting for fuel requirements and other operational requirements.

(iv) Maintenance scheduling of generation and transmission equipment.

(v)Scheduling of captive plants.

(vi) Scheduling of multi-purpose hydro plans for irrigation, flood control, cooling water

requirements etc., apart from generation.

Short-Term Forecasts

Short-term load forecasting is required for operational planning for,

(i) Unit commitment and economic dispatch calculations.

(ii) Maintenance scheduling updates.

(iii) On-line load flows.

(iv) Spinning reserve calculations.

(v) Short-term interchange schedules with neighboring system.

(vi) System security analysis.

(vii) Scheduling of pumped storage units.(viii) Load management scheduling.

(ix) Optimization of fuel stocking.


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Utilities use past normalized data, weather data, and information on known random phenomena

like popular TV programmes, school vacations, factory strikes etc., for short-term forecasting of,

(i) Peak load conditions for system in a day.

(ii) System load at various intervals of time (half hour /hour) in a day.

(iii) Hourly or half-hourly energy requirements.

(iv) Individual bus load prediction.

(v) A few minutes to several hours ahead forecast and is useful in utility's systems operations to

deal with economic load dispatching & security assessment.

7.5 FORECASTS TECHNIQUES WITH EXAMPLES

The need to understand the proper use of forecasting techniques has increased as the computing

capability has moved out o the hands of the experts in to those of the users in an organization.

Forecasting continues to gain in importance due to the increasing scarcity of electrical energy

along with the availability of lower cost and more powerful computing equipment and

softwares.

Here techniques used are called Deterministic and Statistical.

Deterministic techniques are further classified as extrapolating, econometric, end use and

strategic. For example

1. For extrapolation, Sheer's formula is used which is based on the hypothesis that for every one

hundredfold increase. In per capita generation, half will reduce the rate of growth of power

generation. The following relation was developed after studying load growth in a number of

countries.

0.15

10CG

U=

Where G is annual percentage growth in power generation, U is per capita generation, and C is

constant which is 0.02 multiplied by population growth rate plus 1.33. The formula is used

iteratively to forecast power consumption growth for each year with the preceding value used

to forecast the next year's growth.

2. In the end use method, the consumption of each category is projected, based on expected

changes in production (industrial), traction, irrigation, water works and sewerage pumping etc.

This technique is adopted where sufficient data regarding the programme for future is

available.

3. Trend method, is suitable in case of other sectors such as domestic, commercial and public

lighting. For example, an exponented trend using energy consumption data in India the

calculated regression equation is shown below:Y =- 3411.39+ 8555.05 x e

O.O988X

X =time in years with 1950-51as base year, Y= GWh requirement for the year


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Trends identified nowadays are,

(i) Industrial to information society (ii) national to world economy

(iii) Short-term to long-term thinking (iv) centralization to decentralization

(v) Either/or to multiple options

4. Time series analysis, is a good technique involving the necessity of Using sound judgments

along with an analysis of past history. The history of past loads might be forecasted by a utility

using a time series analysis program, which uses monthly data and yields an analysis of trend,

cyclical variation, seasonal variation, and irregular movement. A recomposition of these four

factors into future months would involve considerable judgement as to the future course of the

cyclical and irregular elements and, if these elements were well formulated, would produce

usable forecast of electrical energy demand.

5. Moving average,Here each point of a moving average of a time series is the arithmetic or

weighted average of a number of consecutive points of the series, where the number of data

points is chosen so that the effects of season or irregularity or both are eliminated. A minimum

of two years of past energy consumption is desirable, if seasonal effects are present. Otherwise,

there will be less data. (Of course, more the history, the better.) The moving average must be

specified.

6. Trend projections, This technique fits a trend line to a mathematical equation and then

projects it into the future by means of 'this equation. There are several variations, the slope-

characteristic method, polynomials, logarithms, and so on. Trend analysis is the study of the

behavior of a process in the past and its mathematics modeling so #1at future behavior can be

extrapolated from it. Two general approaches followed for trend analysis are,

(i) The fitting of continuous mathematical functions through actual data to achieve the least overall

error, known as regression analysis; and

(ii) The fitting of a sequence on discontinuous lines or curves to the data.

The second approach in the short term forecasting. A time varying event such as power system

load can be broken down into the following four major components,

(i) Basic trend

(ii) Seasonal variation

(iii) Cyclic variation which includes influences of periods longer than the above and causes the

load pattern to be repeated for two or three years (or even longer cycles)

(iv) Random variations which occur on account of the day-to-day changes are in the case of power

systems, are usually dependent on the time of the week, e.g., weekend, weak day, weather, etc. The

last three variations have a long-term mean of zero as in figures shown in next page.


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Decomposition of typical load growth curve (a) Total process (b) Decomposition

EXAMPLES FOR ABOVE TECHNIQUES

Linear trend.This is a past trend where the increase in consumption from Year to year is more or

less constant. Tabulate the past consumption data and plot it on an arithmetical graph which will

give a straight line. The projection of this line can give a forecast of future demands. But in real

life, such a growth trend is unlikely in the power supply industry. Such a growth trend in the power

industry can be mathematically expressed as Ct = a+bt where, Let

Ct =electricity consumption in any year t , a = consumption for base year t =0 , b = constant

annual increase in energy consumption, t =cardinal number of year t with reference to the base

year, i.e., equal to T - 1 + n, where T is the number of years for which the forecast is required.

a=4GWh, b =0.18GWh, n=5, t=T-1+n, t = 11- 1+5 = 15,

Then,

C15 = 4 + (0.18 x 15)

= 4 + 2.7

= 6.7GWh

Analysis of Time Series. Typical power system load curves can be represented by the equation,

Y=T*C*S*I

Where,

T = long-term trend, C = cyclical trend (often over several years), S = seasonal trend (1 year

cycle), I = irregular movements (noise).

The 'noise' component is due, in part, to temperature effects. A reasonable correlation between

demand and temperature has been found in most power systems. Some time series can be

represented by a sum of these factors, i.e. Y=T+C+S+I.


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CORRELATION OF DEMAND WITH TEMPERATURE

There is a fair amount of correlation the power system demand with temperature. The random

variations left in demand after deseasonalizing and removal of the trend effect are largely due

to temperature variations. There are two portions of the power system load which are

temperature dependent: domestic and commercial loads which increase with cold on account of

the use of heating devices, and with heat which necessitates the use of fans, coolers, air

conditioner etc. resulting in load increase.

The correlation between the seasonal demand and temperature variations is in fact high. e

removal of temperature affects from load readings, however, still leaves cyclic and random

effects. This is because similar weather conditions at different times of the year do not cause

similar human response. Other factors, such as wind and rain seem important, but are hard to

account for, as the repetition of a certain set of exact weather conditions (e.g., cold night, rain)

is unlikely. Typical temperature demand relationship is shown below

7.6 FORECASTING MODELLING

7.6.1 Factors Affecting the Forecasting

There are many factors which influence the prediction of load, and their influence vary from

area to area and from country to country. The impact of any factor on load of a utility needs to be

properly examined before building a forecasting model. The factors found to affect a variety of

utilities' load are time dependent, weather dependent, random, and other.

Time dependent factors

Power systems exhibit a time dependent pattern of electric load demand. At times, these factors

are regular, irregular or random in nature.

Regular pattern is exhibited during the time of day, day of week and week of the year, and

yearly growth.


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Irregular pattern is exhibited on holidays, weekends, special days etc., and load requirements

tend to differ on these days than on other days. Sometimes, load requirements do not follow

any pattern because of weather or other factors.

Electric load requirements tend to depend on work rest style of our set-up as there can be

different possibilities of electric power consumption if people are at home during the day than

if they are away at work. This implies that load patterns are different on weekdays and

weekends, with the

Possibilities of 2-4 groups, namely, weekdays, weekends, and pre and Post-respectively.

An analysis of past data can reveal two or more pattern of load consumption for a week. On the

same lines, load consumption also differs on holidays, special holidays preceding and

following the weekends), and special days of national or social importance which may require

excessive lighting loads etc.

The impact of these holidays and special days on load demand would depend on the extent of

public participation, impact on industrial activity, and state-level celebrations requiring

excessive lighting load. There are seasonal variations in hourly or daily load, due to change in

daylight hours, change in heating to cooling load or vice-versa, typicality of load pattern of

some months etc. From the past data (typically 2-5 years), periods in a year can be divided into

time-scales (hourly, daily etc.) which exhibit an established load curve and others with a

comparatively variable load curve.

Weather Dependent Factors

Weather is one of the principal causes of load variations as it affects domestic load, public

lighting, commercial loads etc. Therefore, it is essential to choose relevant weather variables

and model their influence on power consumption. Principal weather variables found to affect

the power consumption include temperature, cloud cover, visibility, and precipitation.

The first two factors affect the domestic/office (e.g., heating, cooling) loads, whereas the others

affect lighting loads as they affect daylight illumination.

Average temperature is considered to be the most significant dependent factor that influences

load variations. However, temperature and load are not linearly related, and variations in

temperature in one temperature range may not have any effect on the load, whereas in other

temperature ranges and/or other seasons a 1C change can change load demand by over one per

cent. This non-linear relation is further complicated by the influence of humidity and by the

effects of extended periods of extreme heat or cold spell.


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Random Factors

There are random phenomena which affect load consumption and can cause large errors in

load forecast.

It is difficult to accurately model their actual impact on load demand. These include school

holidays, factory strikes, and influence of popular TV programmes.

Influence of these Phenomena can be studied .if past data on these occurrences are available.

Other Factors

Other factors that influence the load demand include,

(i) Effects of DSEs (Distributed generating devices).

(ii) Effects of rate tariff (time-of-day pricing, change in industrial tariffs).

(iii) Change over to winter time or summer time.

Impact of these factors in past data should be identified. The model should be selected based

on these factors and other considerations, and should be fitted to the data. Before use, the model

should be checked to discover possible lack of fit or any inadequacy, and necessary correction

should be applied as required.

7.6.3Forecasting Models

Regression Model.

This functionally relates load to other economic, competitive or weather variables and

estimates an equation using the least squares technique. Relationships are primarily analyzed

statistically, although any relationship should be selected for testing on a rational ground.

Regression analysis involves the necessity of using judgment along with statistical analysis

whenever forecasting takes place.

Regression of time series data is a common occurrence in utilities where tracking important

measures of performance on a weekly, monthly, or quarterly basis is conducted. As

autocorrelation is a common problem in such studies, an understanding of this condition and

its cure becomes vital if the results of such analyses are to be valid in the decision-making

process.

Econometric Model.

An econometric model is a system of interdependent regression equations that describes energy

sales. The parameters of the regression equations are usually estimate simultaneously. As a rule,

these models are relatively expensive to develop. However, due to the system of equations inherent

in such models, they will better express the casualties involved than an ordinary regression

equation and hence, will predict turning-points more accurately.


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Strategic Forecasting.

Strategic forecasting is becoming increasingly important and involves the explicit examination

of the factors and issues affecting future growth, It recognizes the impact that policy decisions

can have on future loads.

This requires details of consumer operations, their current and potentili1' demand for

electricity, their competitiveness in the market place and their options with respect to

production processes,

Switching alternatives, energy conservation technologies, etc.

In the industrial sector, this implies combining elements of the econometric approach with the

technology detail found in end use/process models. Strategic models must be capable of doing

more than merely forecasting future requirements. They must be able to provide planners with

additional information to help shape the future demand.

Mathematical Modelling-Simulation

In modelling, the total load is considered to be the sum total of various components due to

various factors.

These factors need to be measured and interrelated with load requirements. Thus, this

technique requires individual modelling of each load type, and identifying their

interrelationship to arrive at future load requirements.

This is mathematical modelling. Mathematics is a language that allows us to represent physical

problems in a form that a computer can understand.

The strength of a method lies in the accuracy of the results it gives. Errors in predicted loads

are found mainly in peak periods, transitional phase (from peak to off peak and vice-versa),

and on weekends and special days.

In extrapolation, future load is treated as an extension of the past and the load curve based on

past data is suitably adjusted to reflect growth trend. Thus, this technique involves the detection

of trends in the past data for various parameters, fitting a trend curve-which could be a straight

line, a parabola, exponential or a polynomial of other orders or a mix of the above-and finding

coefficients of these curves as given below,

Straight line Y=a+bx

Parabola Y=a + bx+ cx2

S. curve Y=a + bx +cx2+dx

3

Exponential Y=becx

Modified exponential Y =a + becx

Logistics Y =1 / (a + becx

)Where Y is a variable to be fitted,x is time in assigned frame (in day, week, year etc.), and a, b

,c, d are coefficients be calculated. Extrapolation could be deterministic or probabilistic, with the


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accuracy of results quantified using statistics (i.e., standard deviation, variance etc.) in the letter

case.

The mathematical models for domestic, commercial and other sectors have been determined by

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