Eee Vii Power System Planning [10ee761] Notes

5/19/2018 Eee Vii Power System Planning [10ee761] Notes

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Power System Planning 10EE761

Dept. of EEE, SJBIT Page 1

POWER SYSTEM PLANNING

Subject Code: 10EE761 IA Marks: 25

No. of Lecture Hrs. / Week: 04 Exam Hours: 03Total No. of Lecture Hrs. 52 Exam Marks: 100

PART A

UNIT - 1

Introduction of power planning, National and regional planning, structure of powersystem, planning tools, electricity regulation, Load forecasting, forecasting techniques,

modeling. 8 Hours

UNIT - 2 & 3

Generation planning, Integrated power generation, co-generation / captive power, powerpooling 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 - 4Computer aided planning: Wheeling, environmental effects, green house effect,

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

PART B

UNIT - 5 & 6Power supply reliability, reliability planning, system operation planning, load

management, load prediction, reactive power balance, online power flow studies, stateestimation, computerized management. Power system simulator. 10

Hours

UNIT - 7 & 8Optimal 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 forsolution by programming. 16 Hours

TEXT BOOK:

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


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Table of Contents

Sl.No Chapters Page no

1 Unit 1:Introduction of power planning,

4-12

National and regional planning

structure of power system, planning tools

planning tools,

electricity regulation

Load forecasting

forecasting techniques, modeling.

2 Unit 2&3:Generation planning

13-23

Integrated power generation

co-generation / captive power

power pooling and power trading

transmission & distribution planning

power system economics

power sector finance,f inancial planning

private participation

rural electrification investment

concept of rational tariffs

3 Unit 4:Computer aided planning

24-27Wheeling

environmental effects

green house effect


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technological impacts

insulation co-ordination

reactive compensation

4 Unit 5&6:Power supply reliability

28-32

reliability planning

system operation planning

load management

load prediction

reactive power balance

online power flow studies

state estimation

computerized management

Power system simulator.

5 Unit 7&8:Optimal Power system expansion planning.

33-36

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


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UNIT-1

Introduction to Power System Planning:

Recent cost reductions and the increases in production of solar photovoltaics (PV) are drivingdramatic growth in domestic PV system installations.

Programs such as Solar America Initiative are setting out to make solar energy cost-

competitive with central generation by the year 2015.

As the costs decline, distributed PV becomes an increasingly significant source of power

generation and, at some point, its further growth might be limited by the challenges of its

integration into the power grid.

To prevent these integration challenges from limiting the growth of solar PV installations and

to maximize the overall system benefit, it is necessary to consider solar PV in all areas ofpower system planning, and to evolve the planning practices to better accommodateincreased energy supply from solar PV.

This report reviews the entire power system planning process, including generation,

transmission, and distribution. It discusses how the planning practices are changing toaccommodate variable renewable generation, with a focus on future changes required to

accommodate high penetration levels of solar PV and how to maximize the positive impact of

other technologies such as load control and energy storage. The report also proposes severalareas for future research that will help evolve planning methodologies and enable easier and

more-effective integration of solar PV.

Electricity produced by solar PV currently is not cost-competitive with electricity generated

by central stations, consequently solar PV has limited penetration in grid-connected

applications. As the technology develops and solar PV becomes more competitive, it isexpected that it will start supplying residential and commercial loads at the customers side of

the meter. This area of the power system has the highest cost of electricity, therefore it is

where cost-competitiveness will be achieved first.

Understandably, a sharp increase in the use of any one source of generation is likely to

present integration challenges, but this especially is the case with the distributed solar PV for

the following reasons.

Solar PV is a variable source of generationits power output depends on insolation and it issubject to potentially abrupt changes due to cloud coverage.

Solar PV will evolve as a distributed source of generation first used to offset the connected

load. As the penetration levels increase even further, two options are possible. Energy storage could

be used to ensure that no power is returned to the system, and the power could be sent to other loadsin the system to avoid capital investment for dedicated storage. The second option necessitates

shipping power backwards through a part of the electricity delivery networkthe distribution

systemand backwards power flow is not a design feature of present-day distribution systems.


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The codes and standards that guide the integration of solar PV are focused on simplifying

installations and prescribe grid interconnection requirements that cause minimal interaction with thegrid. When solar PV becomes a significant overall source of generation in the power system, some of

the present interconnection requirements likely will be counterproductive.

National and Regional Planning:1. All issues relating to planning and development of Transmission System in the country are

dealt in the Power System Wing of CEA.

2. This includes evolving long term and short term transmission plans. The network expansion

plans are optimized base on network simulation studies and techno economic analysis.3. This also involves formulation of specific schemes, evolving a phased implementation plan

in consultation with the Central and State transmission utilities and assistance in the processof investment approval for the Central sector schemes, issues pertaining to development of

National Power Grid in the country and issues relating to trans-country power transfer.

4. Transmission planning studies are being conducted to identify evacuation system fromgeneration projects and to strengthen the transmission system in various regions.

5. The studies for long-term perspective plans are also being carried out on All India basis for

establishing inter regional connectivity aimed towards formation of the National PowerSystem.

6. The National Power System is being evolved to facilitate free flow of power across regional

boundaries, to meet the short fall of deficit regions from a surplus region as well as forevacuation of power from project(s) located in one region to the beneficiaries located in

other region(s).

Structure of Power System:


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1. An essential component of power systems is the three-phase ac generator known assynchronous generator or alternator.

2. The source of the mechanical power, commonly known as the prime mover, may behydraulic turbines, steam turbines whose energy comes from the burning of coal, gas

and nuclear fuel, gas turbines, or occasionally internal combustion engines burning oil.

3.

The transformer transfers power with very high efficiency from one level of voltage toanother level. The power transferred to the secondary is almost the same as the primary,

except for losses in the transformer.4. An overhead transmission network transfers electric power from generating units to the

distribution system which ultimately supplies the load.5. High voltage transmission lines are terminated in substations, which are called high-

voltage substations, receiving substations, or primary substations.

6. The distribution system connects the distribution substations to the consumers service-entrance equipment. The primary distribution lines from 4 to 34.5 kV and supply the

load in a well-defined geographical area.7. Industrial loads are composite loads, andinduction motors form a high proportion of

these loads. These composite loads are functions of voltage and frequency and form amajor part of the system load.

Planning Tools:

1. Planning engineers primary requirement is to give power supply to consumers in a

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

2. The criteria and constraints in planning an energy system are reliability, environmental

economics, electricity pricing, financial constraints, society impacts.

3. reliability, environmental, economic and financial constraints can be quantified. Social

effects are evaluated qualitatively.4. The system must be optimal over a period of time from day of operation to the lifetime.

5. Various computer programs are available and are used for fast screening of alternative

plans with respect to technical, environmental and economic constraints.

The available tools for power system planning can be split into:

Simulation tools: these simulate the behavior of the system under certain conditions

and calculate relevant indices. Examples are load flow models, short circuit models,

stability models, etc.

Optimization tools: these minimize or maximize an objective function by choosing

adequate values for decision variables. Examples are optimum power, least cost

expansion planning, generation expansion planning, etc.

Scenario tools: this is a method of 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

automate the management of power system after certain date.
http://electrical-engineering-portal.com/three-phase-induction-motors-operating-principlehttp://electrical-engineering-portal.com/types-of-electrical-power-distribution-systemshttp://electrical-engineering-portal.com/types-of-electrical-power-distribution-systemshttp://electrical-engineering-portal.com/types-of-electrical-power-distribution-systemshttp://electrical-engineering-portal.com/three-phase-induction-motors-operating-principle


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Least Cost Utility Planning:

There are two fundamental problems inherent in traditional planning. The first is thatdemand forecasting 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 inadequately directed at the main constraints facing the sector, namely the seriousshortage of resources.

1. 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 whichthe prices influence the demand growth. Greater attention should be paid to end useefficiency, plant rehabilitation, loss reduction program, etc.

2. Least cost planning (LCUP) is least cost utility planning strategy to provide reliableelectrical services at lowest overall cost with a mix of supply side and demand side

options.3. The LCUP uses various options like end use efficiency, load management, transmission

and distribution options, alternative tariff options, etc.4. This planning process can yield enormous benefits to consumers and society because itaffords acquisition of resources that meet consumer energy service needs that are low in

cost, environmentally friendly.5. LCUP as a planning and regulatory process can greatly reduce the uncertainty and risks

faced by utilities. The logic for least cist planning is shown in the figure below:

6. For an investment to be least cost, the lifetime costs are considered. These include capitalcosts, interest on capital, fuel cost and operation and maintenance costs.


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Fig: flowchart for least cost planning

Electricity Regulation:THE ELECTRICITY REGULATORY COMMISSIONS ACT, 1956

Act to provide for the establishment of a Central Electricity Regulatory Commission andstate Electricity Regulatory Commissions, rationalization of electricity tariff, transparent

policies regarding subsidies, promotion of efficient and environmentally benign policiesand matters connected therewith or incidenta l there to.

Be it enacted by Parliament in the Forty-ninth Year of the republic of India as follows:

STATEMENT OF OBJECTS AND REASONS

India's power sector is beset by problems that impede its capacity to respond to the

rapidly growing demand for energy brought about by economic liberalisation. Despite thestated desire for reform and the initial measures that have been implemented, serious

problems persist.

As the problems of the Power Sector deepen, reform becomes increasingly difficult

underscoring the need to act decisively and without delay. It is essential that theGovernment exit implement significant reforms by focussing on the fundamental issues


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facing the power sector, namely the lack of rational retail tariffs, the high level of cross-subsidies, poor planningand operation, inadequate capacity, the neglect of the consumer,

the limited involvement of private sector skills and resources and the absence of anindependent regulatory authority.

Considering the paramount importance of restructure power sector, Government of Indiaorganised two Conferences of Chie Ministers to discuss the whole gamut of issues in thepower sector and the outcome of these meetings was the adoption of the CommonMinimum National Action Plan for Power (CMNPP).

The CMNPP recognised that the gap between demand and supply of power is widening

and acknowledged that the financial position of State Electricity Boards is fastdeteriorating and the future development in the power sector cannot be sustained withoutviable State Electricity Boards and improvement of their operational performance.

The CMNPP identified creation of regulatory Commission as a step in this direction andspecifically provided for establishment of the Central Electricity Regulatory Commission

(CERC) and State Electricity Regulatory commissions (SERCs). After the finalisation ofthe, national agenda contained in CMNPP, the Ministry of Power assigned the task ofstudying the restructuring needs of the regulatory system to Administrative Staff College

of India (ASCI), Hyderabad. The ASCI report strongly recommended the creation ofindependent Electricity Regulatory Commissions both at the Centre and the States.

To give effect to the aforesaid proposals, the Electricity Regulatory Commissions Bill.

1997 was introduced in the Lok Sabha on 14th August, 1997, However it could not bepassed due to the dissolution of the Eleventh Lok Sabha.

This has resulted in delay in establishing the Regulatory Commissions leading to

confusion and misgivings in various sections about the commitment of the Governmentto the reforms and restructuring of the power sector. Needless to say, this has also slowed

down the flow of public and private investment in power sector.

Since it was considered necessary to ensure the speedy establishment of the RegulatoryCommissions and as Parliament was not in session, the President promulgated the

Electricity Regulatory Commissions Ordinance, 1998 on 25th day of April, 1998.

The salient features of the -said Ordinance are as follows: -(a) It provides for the establishment of a Central Electricity Regulatory Commission at the

Central level and State Electricity Commissions at the State levels-,

(b) The main functions of CERC are: -


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(i) To regulate the tariff of generating companies owned or controlled by the CentralGovernment;

(ii) To regulate inter-State transmission including tariff of the transmission utilities;(iii) To regulate inter-State sale of power;

(iv) To aid and advise the Central Government in the formulation of tariff policy.

(c) The main functions of the SERC, to start with, shall be: -

(i) To determine the tariff for electricity, wholesale, bulk, grid and retail;(ii) To determine the tariff payable for use of the transmission facilities;

(iii) To regulate power purchase the procurement process of the transmission utilities; and(iv) Subsequently, as and when each State Government notifies, other regulatory functions couldalso be assigned to SERCS.

(d) It also aims at improving the financial health of the State Electricity Boards (SEBS) which

are loosing heavily on account of irrational tariffs and lack of budgetary support from the StateGovernments as a result of which, the SEBs have become incapable of even proper maintenance,

leave alone purposive investment. Further, the lack of creditworthiness of SEBs has been adeterrent in attracting investment both from the public and private sectors.

Hence, it is made mandatory for State Commissions to fix tariff in a manner that none of

the consumers or class of consumers shall be charged less than fifty per cent. of theaverage cost of supply, it enables the State Governments to exercise the option of

providing subsidies to weaker sections on condition that the state Governments through asubsidy compensate the SEBS.

As regards the agriculture sector, it provides that if the State Commission considers itnecessary it may allow the consumers in the agricultural sector to be charged less than

fifty per cent, for a maximum period of three years from the date of commencement of

the Ordinance.

It also empowers the State Government to reduce the tariff further but in that case it shall

compensate the SEBs or its successor utility, the different between the tariff fixed by theState Commission and the tariff proposed by the State Government by providing

budgetary allocations.Therefore, it enables the State Governments to fix any tariff foragriculture and other sectors provided it gives subsidy to State Electricity Boards to meetthe loss.

Forecasting Techniques:

Load forecasting is vitally important for the electric industry in the deregulated economy.It has many applications including energy purchasing and generation, load switching, contract

evaluation, and infrastructure development. A large variety of mathematical methods have beendeveloped for load forecasting. In this chapter we discuss various approaches to load forecasting.


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Forecasting Methods

Over the last few decades a number of forecasting methods have been developed. Two of

the thods, so-called end-use and econometric approach are broadly used for medium- andlong-term forecasting. Avariety of methods, which include the so-called similar day

approach,various regression models, time series, neural networks, expert systems,fuzzy

logic, and statistical learning algorithms, are used for short-term forecasting. The development, improvements, and investigation of the appropriate mathematical tools

will lead to the development of more accurate load forecasting techniques.Statisticalapproaches usually require a mathematical model that represents load as function of

different factors such as time, weather, and customer class.

The two important categories of such mathematical models are: additive models and

multiplicative models. They differ in whether the forecast load is the sum (additive) of anumber of components or the product (multiplicative) of a number of factors. For

example, Chen et al. [4] presented an additive model that takes the form of predictingload as the function of four components:

L =Ln +Lw +Ls +Lr,

where L is the total load, Ln represents the normal part of the load,which is a set ofstandardized load shapes for each type of day that has been identified as occurring throughout

the year, Lw represents the weather sensitive part of the load, Ls is a special event componentthat create a substantial deviation from the usual load pattern, and Lr is a completely randomterm, the noise.

A multiplicative model may be of the formL =Ln Fw Fs Fr,

where Ln is the normal (base) load and the correction factors Fw, Fs, and Fr are positivenumbers that can increase or decrease the overall load. These corrections are based on current

weather (Fw), special events (Fs), and random fluctuation (Fr). Factors such as electricitypricing (Fp) and load growth (Fg) can also be included. Rahman [29] presented a rulebased

forecast using a multiplicative model. Weather variables and the base load associated with theweather measures were included in themodel.

Forecasting Modeling

Depends on1. Degree of Accuracy Required

2. 2 Cost of Producing Forecasts3. 3 Forecast Horizon4. 4 Degree of Complexity Required

5. 5 Available Data

Classification of Estimation Methods

1. Time Series Methods

2. Causal Methods3. Judgemental Methods

Time Series Methods: Use historical data as a basis, Underlying patterns are fairly stable.1. Autoregressive Moving Average (ARMA)


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2. Exponential Smoothing3. Extrapolation

4. Linear Prediction5. Trend Estimation

6. Growth Curve

7.

Box-Jenkins Approach

Causal Methods

Belief that some other time series can be useful. Assumption that it is possible to identify theunderlying factors

1. Regression Analysis2. Linear Regression

3. Non-Linear Regression4. Econometrics


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UNIT 2&3

Generation Planning

The electric utility planning process begins with the electricity load-demand forecast. The

demand for electricity initiates actions by utilities to add generation, transmission, or distributioncapacity. Because of the long lead time required to construct new facilities, decisions are often to

be made 2 to 10 years in advance.

A load forecast was developed for the Kingdom and the results are presented in the followingsections covering the study period 2008 to 2023. Load forecasts are developed for all SECoperating areas.

The methodology and the basis of development of demand forecast are highlighted below:

Multiple regression analysis is used to forecast the Energy for the KSA.

Independent variables are chosen to be the population and the Gross Domestic Product (GDP). The dependent variable is the Energy forecast for KSA. The data for the historical and the forecasted GDP has been obtained from the Ministry of

Planning.

The forecast for the total sold energy for the Kingdom was obtained using the regression model.

The total sold energy was then divided between the four operating areas using historical value ofpercentage energy sales for each operating areas. This gives the total sold energy forecast for

each of the operating areas.

Peak Demand is calculated using the equation

Forecasted Peak Demand in Region= Forecasted Energy in Region/8760*Load Factor.

Co-Generation/ Captive Power

Captive power plants are associated with specific industrial complexes, and their output is almost

entirely consumed by that industrial plant. Another term that may sometimes be synonymous is'cogeneration' in which the power plant produces multiple forms of energy (e.g., electric power

and steam), and where both are raw-materials for a related industrial process. Probably the mostclassic example is that of a paper mill. Boilers produce steam. The steam passes through aturbine that spins a generator to produce electricity. Exhaust steam from the turbine is then used

as a source of heat to dry freshly-made paper before is is finally condensed into water and

returned to the boiler. The boiler itself burns the bark that itself cannot be used to make paperand would otherwise be a waste material. In addition, the process of making pulp produces achemical waste called "black liquor' that can also be burned as a fuel in a boiler.

Captive power plants don't necessarily have to be islands that are disconnected from 'the grid'. Infact, it is often the case that the demand of the industrial process exceeds the capacity of the

captive plant, and power must be taken from the grid to make up the difference. Also, there mustbe some provision to 'bootstrap' the integrated process into operation - often this means relying


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on grid power to start-up the plant following an outage. And it is possible that there are timeswhen the captive plant will produce more power than can be consumed in the industrial process,

and rather than throttle back the excess is sold to the grid.TYPES OF COGENERATION SYSTEMS

1. Steam Turbine Cogeneration System

Steam turbines are one of the most versatile and oldest prime mover technologies still in generalproduction. Power generation using steam turbines has been in use for about 100 years, when

they replaced reciprocating steam engines due to their higher efficiencies and lower costs. Thecapacity of steam turbines can range from 50 kW to several hundred MWs for large utility power

plants. Steam turbines are widely used for combined heat and power (CHP) applications.

2. Back Pressure Steam Turbine

A back pressure steam turbine is the simplest configuration. Steam exits the turbine at a pressurehigher or at least equal to the atmospheric pressure, which depends on the needs of the thermal

load. This is why the term back- pressure is used. It is also possible to extract steam fromintermediate stages of the steam turbine, at a pressure and temperature appropriate for the

thermal load. After the exit from the turbine, the steam is fed to the load, where it releases heatand is condensed.

Fig. Back Pressure Steam Turbine

3. Extraction Condensing Steam TurbineIn such a system, steam for the thermal load is obtained by extraction from one or moreintermediate stages at the appropriate pressure and temperature. The remaining steam is

exhausted to the pressure of the condenser, which can be as low as 0.05 bar with acorresponding condensing temperature of about 33C. It is rather improbable that such

low temperature heat finds useful applications. Consequently, it is rejected to theenvironment. In comparison to the back - pressure system, the condensing type turbinehas a higher capital cost and, in general, a lower total efficiency. However, to a certain

extent, it can control the electrical power independent of the thermal load by properregulation of the steam flow rate through the turbine.

4. Gas Turbine Cogeneration System


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Gas turbine systems operate on the thermodynamic cycle known as the Brayton cycle. In aBrayton cycle, atmospheric air is compressed, heated, and then expanded, with the excess of

power produced by the turbine or expander over that consumed by the compressor used forpower generation.

Gas turbine cogeneration systems can produce all or a part of the energy requirement of the site,

and the energy released at high temperature in the exhaust stack can be recovered for variousheating and cooling applications (see Fig 4 below). Though natural gas is most commonly used,

other fuels such as light fuel oil or diesel can also be employed. The typical range of gas turbinesvaries from a fraction of a MW to around 100 MW.

5. Closed-cycle gas turbine cogeneration systems

In the closed-cycle system, the working fluid (usually helium or air) circulates in a closed circuit.It is heated in a heat exchanger before entering the turbine, and it is cooled down after the exit of

the turbine releasing useful heat. Thus, the working fluid remains clean and it does not causecorrosion or erosion. As shown in Fig.5 below.


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6. Reciprocating Engine Cogeneration SystemReciprocating engines are well suited to a variety of distributed generation applications,industrial, commercial, and institutional facilities for power generation and CHP. Reciprocating

engines start quickly, follow load well, have good part-load efficiencies, and generally have highreliabilities. In many cases, multiple reciprocating engine units further increase overall plant

capacity and availability. Reciprocating engines have higher electrical efficiencies than gasturbines of comparable size, and thus lower fuel-related operating costs.

Power Pooling:

Power poolingis used to balance electrical load over a larger network (electrical grid) than a

single utility. It is a mechanism for interchange of power between two and more utilities which


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provide or generate electricity. For exchange of power between two utilities there is an

interchange agreement which is signed by them, but signing up an interchange agreement

between each pair of utilities within a system can be a difficult task where several large utilities

are interconnected. Thus, it is more advantageous to form a power pool with a single agreement

that all join. That agreement provides established terms and conditions for pool members and isgenerally more complex than a bilateral agreement.

In one model, the power pool, formed by the utilities, has a control dispatch office from where

the pool is administered. All the tasks regarding interchange of power and the settlement of

disputes are assigned to the pool administrator.

The formation of power pools provide the following potential advantages:

1. decrease in operating costs

2. saving in reverse capacity requirements

3. help from pool in unit commitment

4.

minimization of costs of maintenance scheduling5. more reliable operation

The formation of a power pool is associated with a number of problems and constraints. These

include:

1.pool agreement may be very complex

2. costs associated with establishing central dispatch office and the needed communication

and computational facilities

3. the opposition of pool members to give up their rights to engage in independent

transactions outside the pool.

4.

the complexity towards dealing with regulatory authorities, if pool operates in more thanone state.

5. the effort by each member of the pool to maximize its savings.

Power pooling is very important for extending energy control over a large area served by

multiple utilities

Power Trading

In economic terms, electricity (both power and energy) is a commodity capable of being bought,

sold and traded. An electricity market is a system for effecting purchases, through bids to buy;

sales, through offers to sell; and short-term trades, generally in the form of financial or obligation

swaps. Bids and offers use supply and demand principles to set the price. Long-term trades are

contracts similar to power purchase agreements and generally considered private bi-lateral

transactions between counterparties.

Wholesale transactions (bids and offers) in electricity are typically cleared and settled by the

market operator or a special-purpose independent entity charged exclusively with that function.

Market operators do not clear trades but often require knowledge of the trade in order to maintain


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generation and load balance. The commodities within an electric market generally consist of two

types: power and energy. Power is the metered net electrical transfer rate at any given moment

and is measured in megawatts (MW). Energy is electricity that flows through a metered point for

a given period and is measured in megawatt hours (MWh).

Markets for energy-related commodities trade net generation output for a number of intervalsusually in increments of 5, 15 and 60 minutes. Markets for power-related commodities required

and managed by (and paid for by) market operators to ensure reliability, are considered ancillary

services and include such names as spinning reserve, non-spinning reserve, operating reserves,

responsive reserve, regulation up, regulation down, and installed capacity.

In addition, for most major operators, there are markets for transmission congestion and

electricity derivatives such as electricity futures and options, which are actively traded. These

markets developed as a result of the restructuring of electric power systems around the world.

This process has often gone on in parallel with the restructuring of natural gas markets.

Transmission and Distribution Planning:

Electricity distribution is the final stage in thedelivery of electricity to end users. A

distribution system's network carries electricity from the transmission system and delivers it to

consumers. Typically, the network would include medium-voltage (2kV to 34.5kV) power lines,

substations and pole-mounted transformers, low-voltage (less than 1 kV) distribution wiring such

as aService Drop and sometimes meters.

The modern distribution system begins as the primary circuit leaves the sub-station and

ends as the secondary service enters the customer's meter socket by way of aservicedrop.Distribution circuits serve many customers.

The voltage used is appropriate for the shorter distance and varies from 2,300 to about

35,000 volts depending on utility standard practice, distance, and load to be served.

Distribution circuits are fed from atransformer located in anelectrical substation, where

the voltage is reduced from the high values used for power transmission.

Conductors for distribution may be carried on overhead pole lines, or in densely

populated areas, buried underground

. Urban and suburban distribution is done with three-phase systems to serve bothresidential, commercial, and industrial loads. Distribution in rural areas may be only

single-phase if it is not economical to install three-phase power for relatively few and

small customers.
http://en.wikipedia.org/wiki/Power_deliveryhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Grid_(electricity)http://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Service_drophttp://en.wikipedia.org/wiki/Electricity_meterhttp://en.wikipedia.org/wiki/Electricity_meterhttp://en.wikipedia.org/wiki/Service_drophttp://en.wikipedia.org/wiki/Service_drophttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Service_drophttp://en.wikipedia.org/wiki/Service_drophttp://en.wikipedia.org/wiki/Electricity_meterhttp://en.wikipedia.org/wiki/Service_drophttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Grid_(electricity)http://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Power_delivery


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Only large consumers are fed directly from distribution voltages; most utility customers

are connected to a transformer, which reduces the distribution voltage to the relatively

low voltage used by lighting and interior wiring systems.

The transformer may be pole-mounted or set on the ground in a protective enclosure. In

rural areas a pole-mount transformer may serve only one customer, but in more built-up

areas multiple customers may be connected.

In very dense city areas, a secondary network may be formed with many transformers

feeding into a common bus at the utilization voltage. Each customer has aservice

drop connection and a meter for billing.

Aground connection to local earth is normally provided for the customer's system as well

as for the equipment owned by the utility. The purpose of connecting the customer's

system to ground is to limit the voltage that may develop if high voltage conductors fall

down onto lower-voltage conductors which are usually mounted lower to the ground, orif a failure occurs within a distribution transformer.

If all conductive objects are bonded to the same earth grounding system, the risk of

electric shock is minimized. However, multiple connections between the utility ground

and customer ground can lead tostray voltage problems; customer piping, swimming

pools or other equipment may develop objectionable voltages. These problems may be

difficult to resolve since they often originate from places other than the customer's

premises.

Distribution network configurations

Distribution networks are typically of two types, radial or interconnected.

A radial network leaves the station and passes through the network area with no normal

connection to any other supply. This is typical of long rural lines with isolated load areas.

An interconnected network is generally found in more urban areas and will have multiple

connections to other points of supply.

These points of connection are normally open but allow various configurations by the

operating utility by closing and opening switches. Operation of these switches may be by

remote control from a control center or by a lineman. The benefit of the interconnectedmodel is that in the event of afault or required maintenance a small area of network can

be isolated and the remainder kept on supply.

Within these networks there may be a mix of overhead line construction utilizing

traditional utility poles and wires and, increasingly, underground construction with cables
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and indoor or cabinet substations. However, underground distribution is significantly

more expensive than overhead construction.

In part to reduce this cost, underground power lines are sometimes co-located with other

utility lines in what are called common utility ducts. Distribution feeders emanating from

a substation are generally controlled by acircuit breaker which will open when a fault is

detected. Automatic circuit reclosers may be installed to further segregate the feeder thus

minimizing the impact of faults.

Long feeders experience voltage drop requiring capacitors or voltage regulators to be

installed.

Characteristics of the supply given to customers are generally mandated bycontract between the

supplier and customer. Variables of the supply include:

AC orDC - Virtually all public electricity supplies are AC today. Users of large amounts ofDC power such as some electric railways, telephone exchanges and industrial processes such

asaluminium smelting usually either operate their own or have adjacent dedicated generating

equipment, or use rectifiers to derive DC from the public AC supply

Nominal voltage, and tolerance (for example, +/- 5 per cent)

Frequency, commonly 50 or 60 Hz, 16.7 Hz and 25 Hz for some railways and, in a few older

industrial and mining locations, 25 Hz.

Phase configuration (single-phase, polyphase including two-phase andthree-phase)

Maximum demand (some energy providers measure as the largest mean power delivered

within a 15 or 30 minute period during a billing period) Load factor, expressed as a ratio of average load to peak load over a period of time. Load

factor indicates the degree of effective utilization of equipment (and capital investment) of

distribution line or system.

Power factor of connected load

Earthing systems - TT, TN-S, TN-C-S or TN-C

Prospective short circuit current

Maximum level and frequency of occurrence of transients

Power System Economics:

Power is the rate of flow of energy. Similarly, generating capacity, the ability to produce

power is itself a flow. A megawatt (MW) of capacity is worth little if it lasts only aminute just as a MW of power delivered for only a minute is worth little.
http://en.wikipedia.org/wiki/Common_utility_ducthttp://en.wikipedia.org/w/index.php?title=Distribution_feeders&action=edit&redlink=1http://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Voltage_drophttp://en.wikipedia.org/wiki/Contracthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Railway_electrification_systemhttp://en.wikipedia.org/wiki/Telephone_exchangehttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Two-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Power_factorhttp://en.wikipedia.org/wiki/Earthing_systemhttp://en.wikipedia.org/wiki/Prospective_short_circuit_currenthttp://en.wikipedia.org/wiki/Transient_(electricity)http://en.wikipedia.org/wiki/Transient_(electricity)http://en.wikipedia.org/wiki/Prospective_short_circuit_currenthttp://en.wikipedia.org/wiki/Earthing_systemhttp://en.wikipedia.org/wiki/Power_factorhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Two-phase_electric_powerhttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Telephone_exchangehttp://en.wikipedia.org/wiki/Railway_electrification_systemhttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Contracthttp://en.wikipedia.org/wiki/Voltage_drophttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/w/index.php?title=Distribution_feeders&action=edit&redlink=1http://en.wikipedia.org/wiki/Common_utility_duct


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But a MW of power or capacity that flows for a year is quite valuable. The price of both

power and energy can be measured in $/MWh, and since capacity is a flow like powerand measured in MW, like power, it is priced like power, in $/MWh.

Many find this confusing, but an examination of screening curves shows that this is

traditional (as well as necessary).

Since fixed costs are mainly the cost of capacity they are measured in $/MWh and canbe added to variable costs to find total cost in $/MWh. When generation cost data arepresented, capacity cost is usually stated in $/kW.

This is the cost of the flow of capacity produced by a generator over its lifetime, so thetrue (but unstated) units are $/kW-lifetime. This cost provides useful information but

only for the purpose of finding fixed costs that can be expressed in $/MWh. No otheruseful economic computation can be performed with the overnight cost of capacitygiven in $/kW because they cannot be compared with other costs until levelized.

While the U.S.

Department of Energy sometimes computes these economically useful (levelized) fixed

costs, it never publishes them. Instead it combines them with variable costs and reports

total levelized energy costs.This is the result of a widespread lack of understanding of

the nature of capacity costs. Confusion over units causes too many different units to be

used, and this requires unnecessary and sometimes impossible conversions.

Private Paticpation:

Private participation in 1991 to hasten the increase in generating capacity and to improve the

system efficiency as well. However, although several plants are under construction, till early

1999, eneration had commenced at private plants totalling less than 2,000 MW.

In contrast, some state undertakings have completed their projects even earlier than

scheduled.Independent power producers (IPPs) claim that their progress has been hindered by

problems such as litigation, financial arrangements, and obtaining clearances and fuel supply

agreements. On the other hand, the State Electricity Boards have been burdened by power

purchase agreements (PPAs) that favour the IPPs with such clauses as availability payment

irrespective of plant utilization, tariffs reflecting high capital costs and returns on equity, etc.

The process of inviting private participation in the power sector and the problems experienced

seem to have spurred on the restructuring of the power sector, including the formation of Central

and State Electricity Regulatory Commissions.

However, some important problems have not been addressed. Additions to the generation

capacity without corresponding improvement of the transmission and distribution facilities are

likely to further undermine the system efficiency.


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What is more, issues like the reduction of "commercial losses" appear to have been ignored.Most

importantly, investment in infrastructure has been a state responsibility because the intrinsically

long gestation coupled with the relatively low returns from serving all categories of consumers

have rendered such projects commercially unprofitable. Whether or not private participation can

take on such tasks is to be seen.

Rural Electrification Inves tment:

Rural Electrification Corporation Limited (REC) is a leading public Infrastructure

Finance Company in Indias power sector.

The company finances and promotes rural electrification projects across India, operating

through a network of 13 Project Offices and 5 Zonal Offices, headquartered in New

Delhi. The company provides loans to Central/ State Sector Power Utilities, State

Electricity Boards, Rural Electric Cooperatives, NGOs and Private Power Developers.

REC is a Navratna Companyfunctioning under the purview of the Ministry of Power

Government of India. The company is listed on bothNational Stock Exchange of

India andBombay Stock Exchange.

The company is primarily engaged in providing finance for rural electrification projects

across India and provides loans to Central/ State Sector Power Utilities, State Electricity

Boards, Rural Electric Cooperatives, NGOs and Private Power Developers.

The company sanctions loan as a sole lender or co-lender or in consortium with or

without the status of lead financer. It also provides consultancy, project monitoring andfinancial/ technical appraisal support for projects, also in the role of nodal agency for

Government of India schemes or projects. REC finances all types of Power

Generation projects including Thermal, Hydel, Renewable Energy, etc. without limit on

size or location.

The company aims to increase presence in emerging areas like de-centralised distributed

generation (DDG) projects, and new and renewable energy sources to reach remote and

difficult terrains not connected by power grid network.

In Transmission & Distribution (T&D), REC is primarily engaged in ascertainingfinancial requirements of power utilities in the country in the T&D sector along with

appraising T&D schemes for financing.

REC has financed T&D schemes for system improvement, intensive electrification,

pump-set energisation and APDRP Programme. The company is also actively involved in

physical as well as financial monitoring of T&D schemes.
http://en.wikipedia.org/wiki/Navratnahttp://en.wikipedia.org/wiki/National_Stock_Exchange_of_Indiahttp://en.wikipedia.org/wiki/National_Stock_Exchange_of_Indiahttp://en.wikipedia.org/wiki/Bombay_Stock_Exchangehttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Bombay_Stock_Exchangehttp://en.wikipedia.org/wiki/National_Stock_Exchange_of_Indiahttp://en.wikipedia.org/wiki/National_Stock_Exchange_of_Indiahttp://en.wikipedia.org/wiki/Navratna


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REC also offers loan products for financing Renewable Energy projects. The company

has tied up a line of credit for EUR 100 mn(approximately 6000 mn) with KfWunder

Indo-German Development Cooperation for financingrenewable energypower projects

at concessional rates of interest.

Eligible projects include Solar, Wind, Small Hydro, Biomass Power, and Cogeneration

Power & Hybrid Projects.

Wheeling:

Inelectric power transmission,wheeling is the transportation of electric power

(megawatts or megavolt-amperes) over transmission lines.[1]

Electric power networks are divided into transmission and distribution

networks. Transmission lines move electric power between generating

facilities and substations, usually in or near population centers. From substations, power

is sent to users over a distribution network. A transmission line might move power over a

few miles or hundreds of miles.

An entity that generates power does not have to own power transmission lines: only a

connection to the network or grid. The entity then pays the owner of the transmission line

based on how much power is being moved and how congested the line is.

Some power generating entities join a group which has shared ownership of transmission

lines. These groups may includeinvestor-owned utilities, government agencies, or a

combination of these.

Since prices to move power are based on congestion in transmission line networks,

utilities try to charge customers more to use power during peak usage (demand) periods.

This is accomplished by installing time-of-use meters to recover wheeling costs.
http://en.wikipedia.org/wiki/KfWhttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Wheeling_(electric_power_transmission)#cite_note-1http://en.wikipedia.org/wiki/Wheeling_(electric_power_transmission)#cite_note-1http://en.wikipedia.org/wiki/Transmission_linehttp://en.wikipedia.org/wiki/Power_stationhttp://en.wikipedia.org/wiki/Power_stationhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Electricity_distributionhttp://en.wikipedia.org/wiki/Electrical_utilityhttp://en.wikipedia.org/wiki/Electrical_utilityhttp://en.wikipedia.org/wiki/Electricity_distributionhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Power_stationhttp://en.wikipedia.org/wiki/Power_stationhttp://en.wikipedia.org/wiki/Transmission_linehttp://en.wikipedia.org/wiki/Wheeling_(electric_power_transmission)#cite_note-1http://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/KfW


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UNIT 4:

Computer aided Planning:

With the increasing complexity of electrical power systems, the need for accurate toolsfor their design, planning and operation become a necessity. Investigations are made on the

appropriate design tools for analyzing complicated energy system configurations under different

contingencies in order to cope with the challenges. Education and training using these tools

requires familiarization with software and hardware employed in this process. Studies shows that

the new delivery modes using the full advantage of digital computers in a multi-media

environment will improve the efficiency of instruction, and understanding of complex problems.

Environmental impact:

The environmental impact of electricity generation is significant because modern society

uses large amounts of electrical power. This power is normally generatedatpower

plants that convert some other kind of energy into electrical power. Each system has

advantages and disadvantages, but many of them pose environmental concerns.

The amount of water usage is often of great concern for electricity generating systems as

populations increase and droughts become a concern. Still, according to theU.S.

Geological Survey, thermoelectric power generation accounts for only 3.3 percent of net

freshwater consumption with over 80 percent going to irrigation. Likely future trends in

water consumption are covered here. General numbers for fresh water usage of different

power sources are shown below.

Steam-cycle plants (nuclear, coal, NG, solar thermal) require a great deal of water for

cooling, to remove the heat at the steam condensors. The amount of water needed relative

to plant output will be reduced with increasingboiler temperatures. Coal- and gas-fired

boilers can produce high steam temperatures and so are more efficient, and require less

cooling water relative to output. Nuclear boilers are limited in steam temperature by

material constraints, and solar is limited by concentration of the energy source.

Thermal cycle plants near the ocean have the option of usingseawater. Such a site willnot have cooling towers and will be much less limited by environmental concerns of the

discharge temperature since dumping heat will have very little effect on water

temperatures. This will also not deplete the water available for other uses. Nuclear power

in Japan for instance, uses no cooling towers at all because all plants are located on the

coast. If dry cooling systems are used, significant water from the water table will not be
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used. Other, more novel, cooling solutions exist, such as sewage cooling at the Palo

Verde Nuclear Generating Station.

Most electricity today is generated by burning fossil fuels and producing steamwhich is

then used to drive a steam turbinethat, in turn, drives an electrical generator.Such

systems allow electricity to be generated where it is needed, since fossil fuels can readily

be transported. They also take advantage of a large infrastructure designed to support

consumer automobiles.

The world's supply of fossil fuels is large, but finite. Exhaustion of low-cost fossil fuels

will have significant consequences for energy sources as well as for the manufacture

ofplastics and many other things. Various estimates have been calculated for exactly

when it will be exhausted (seePeak oil). New sources of fossil fuels keep being

discovered, although the rate of discovery is slowing while the difficulty of extraction

simultaneously increases.

Nuclear power plants do not burn fossil fuels and so do not directly emit carbon dioxide;

because of the high energy yield of nuclear fuels, the carbon dioxide emitted during

mining, enrichment, fabrication and transport of fuel is small when compared with the

carbon dioxide emitted by fossil fuels of similar energy yield.

A large nuclear power plant may reject waste heat to a natural body of water; this can

result in undesirable increase of the water temperature with adverse effect on aquatic life.

Green House Effect:

The greenhouse effect is a process by which thermal radiation from a planetary surface is

absorbed by atmosphericgreenhouse gases, and is re-radiated in all directions. Since part of this

re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the

average surface temperature above what it would be in the absence of the gases.

Solar radiation at the frequencies of visible light largely passes through the atmosphere to warm

the planetary surface, which then emits this energy at the lower frequencies of infraredthermal

radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of

the energy to the surface and lower atmosphere. The mechanism is named after the effect of solar

radiation passing through glass and warming a greenhouse, but the way it retains heat is

fundamentally different as a greenhouse works by reducing airflow, isolating the warm air inside

the structure so that heat is not lost by convection.
http://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_Stationhttp://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_Stationhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Peak_oilhttp://en.wikipedia.org/wiki/Greenhouse_gashttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Greenhousehttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Greenhousehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Greenhouse_gashttp://en.wikipedia.org/wiki/Peak_oilhttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_Stationhttp://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_Station


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Insulation Co-ordination:

The term Insulation Co-ordination was originally introduced to arrange the insulation

levels of the several components in the transmission system in such a manner that an

insulation failure, if it did occur, would be confined to the place on the system where itwould result in the least damage, be the least expensive to repair, and cause the least

disturbance to the continuity of the supply. The present usage of the term is broader.

Insulation co-ordination now comprises the selection of the electric strength of equipment

in relation to the voltages which can appear on the system for which the equipment is

intended. The overall aim is to reduce to an economically and operationally acceptable

level the cost and disturbance caused by insulation failure and resulting system outages.

To keep interruptions to a minimum, the insulation of the various parts of the system

must be so graded that flashovers only occur at intended points. With increasing system

voltage, the need to reduce the amount of insulation in the system, by proper co-

ordination of the insulating levels become more critical.

Reactive compensation:

Except in a very few special situations, electrical energy is generated, transmitted,

distributed, and utilized as alternating current (AC). However,alternating currenthas

several distinct disadvantages. One of these is the necessity of reactive power that

needs to be supplied along with active power.

Reactive power can be leading or lagging.While it is the active power that contributes

to the energy consumed, or transmitted, reactive power does not contribute to the

energy. Reactive power is an inherent part of the total power.

Reactive power is either generated or consumed in almost every component of the

system, generation, transmission, and distribution and eventually by the loads. The

impedance of a branch of a circuit in an AC system consists of two components,

resistance and reactance.

Reactance can be either inductive or capacitive, which contribute to reactive power in

the circuit.Most of the loads are inductive, and must be supplied with lagging reactive

power.

It is economical to supply this reactive power closer to the load in the distribution

system.Reactive power compensation in power systems can be either shunt or series.
http://electrical-engineering-portal.com/ac-vs-dchttp://electrical-engineering-portal.com/how-reactive-power-is-helpful-to-maintain-a-system-healthyhttp://electrical-engineering-portal.com/resources/knowledge/electrical-formulas/reactancehttp://electrical-engineering-portal.com/resources/knowledge/electrical-formulas/reactancehttp://electrical-engineering-portal.com/how-reactive-power-is-helpful-to-maintain-a-system-healthyhttp://electrical-engineering-portal.com/ac-vs-dc


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Shunt Capacitors:

Shunt capacitors are employed at substation level for the following reasons:

Reducing power losses

Compensating the load lagging power factor with the bus connected shunt capacitor bank

improves the power factor and reduces current flow through the transmission lines,

transformers, generators, etc. This will reduce power losses (I2R losses) in this equipment.

Increased utilization of equipment

Shunt compensation with capacitor banks reduces kVA loading of lines, transformers, and

generators, which means with compensation they can be used for delivering more power

without overloading the equipment. Reactive power compensation in a power system is of two

typesshunt and series. Shunt compensation can be installed near the load, in a distribution

substation, along the distribution feeder, or in a transmission substation.

Voltage regulation

The main reason that shunt capacitors are installed at substations is to control the voltage

within required levels. Load varies over the day, with very low load from midnight toearly

morning and peak values occurring in the evening between 4 PM and 7 PM. Shape of the load

curve also varies from weekday to weekend, with weekend load typically low.

Shunt Reactive Power Compensation

Since most loads are inductive and consume lagging reactive power, the compensation

required is usually supplied by leading reactive power. Shunt compensation of reactive power

can be employed either at load level, substation level, or at transmission level.

It can be capacitive (leading) or inductive (lagging) reactive power, although in mostcases compensation is capacitive. The most common form of leading reactive power

compensation is by connecting shunt capacitors to the line.

As the load varies, voltage at the substation bus and at the load bus varies. Since the

load power factor is always lagging, a shunt connected capacitor bank at the substation

can raise voltage when the load is high. The shunt capacitor banks can be permanently

connected to the bus (fixed capacitor bank) or can be switched as needed. Switching

can be based on time, if load variation is predictable, or can be based on voltage, power

factor, or line current.


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UNIT 5&6

Power Supply Reliability:

The term reliability is broad in meaning. In general, reliability designates

the ability of a system to perform its assigned function, where past experience helps toform advance estimates of future performance.

Reliability can be measured through the mathematical concept ofprobability by identifying the probability of successful performance with the degree of

reliability. Generally, a device or system is said to perform satisfactorily if it does not failduring the time of service. On the other hand, a broad range of devices are expected toundergo failures, be repaired and then returned to service during their entire useful life.

In this case a more appropriate measure of reliability is the availability of

the device, which is defined as follows:

The indices used in reliability evaluation are probabilistic and,

consequently, they do not provide exact predictions. They state averages of past eventsand chances of future ones by means of most frequent values and long-run averages. Thisinformation should be complemented with other economic and policy considerations for

decision-making in planning, design and operation. The function of an electric powersystem is to provide electricity to its customers efficiently and with a reasonable

assurance of continuity and quality.

The task of achieving economic efficiency is assigned to system operators

or competitive markets, depending on the type of industry structure adopted. On the otherhand, the quality of the service is evaluated by the extent to which the supply of

electricity is available to customers at a usable voltage and frequency. The reliability ofpower supply is, therefore, related to the probability of providing customers withcontinuous service and with a voltage and frequency within prescribed ranges around the

nominal values.

Load management:

Load management, also known as demand side management (DSM), is the process

ofbalancing the supply of electricity on the network with the electrical load by adjustingor controlling the load rather than the power station output.

This can be achieved by direct intervention of the utility in real time, by the use offrequency sensitive relays triggering circuit breakers (ripple control), by time clocks, orby using special tariffs to influence consumer behavior.

Load management allows utilities to reduce demand for electricity during peak usagetimes, which can, in turn, reduce costs by eliminating the need forpeaking power plants.

In addition, peaking power plants also often require hours to bring on-line, presentingchallenges should a plant go off-line unexpectedly.
http://en.wikipedia.org/wiki/Load_balancing_(electrical_power)http://en.wikipedia.org/wiki/Peaking_power_planthttp://en.wikipedia.org/wiki/Peaking_power_planthttp://en.wikipedia.org/wiki/Load_balancing_(electrical_power)


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Load management can also help reduce harmful emissions, since peaking plants or

backup generators are often dirtier and less efficient than base load power plants. Newload-management technologies are constantly under development both by privateindustry and public entities.

Load Prediction:

Electric load forecasting is the process used to forecast future electric load, given

historical load and weather information and current and forecasted weather information. In the

past few decades, several models have been developed to forecast electric load more

accurately. Load forecasting can be divided into three major categories:

Long-term electric load forecasting, used to supply electric utility company

management with prediction of future needs for expansion, equipment

purchases, or staff hiring

Medium-term forecasting, used for the purpose of scheduling fuel supplies andunit maintenance

Short-term forecasting, used to supply necessary information for the system

management of day-to-day operations and unit commitment.

Reactive Power balance:

The balance for the reactive power in a whole- or a part of a system is the next:

QE+QI=QF+QH, where:

QE is the amount of the reactive power from the power plants QI is the balance of the

imported reactive power flows (incoming is the positive) QF is the amount of the substationsreactive power consumptions QH is the amount of the system elements reactive power

consumptions (wires, cables, transformers, reactors, static compensators, etc.). The reactive

power flows from the capacitors and overexcited generators called reactive power production,

the under excited generators and inductances reactive power called reactive power

consumption. The reactive power is positive, if the current is delaying to the voltage, while the

active power is positive compared to the power flows on an arbitrary system element S=P+jQ.

These principles considers to the high/middle voltage level systems, but there is no reason to

not to use in micro/smart grid systems as well.

Online power flow studies:

Inpower engineering, the power-flow study, also known as load-flow study, is an

important tool involving numerical analysis applied to a power system. A power-flow study

usually uses simplified notation such as aone-line diagram andper-unit system, and focuses on

various forms of AC power (i.e.: voltages, voltage angles, real power and reactive power). It

analyzes the power systems in normal steady-state operation. A number of software

implementations of power-flow studies exist.
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Many software implementations perform other types of analysis, such asshort-

circuit fault analysis, stability studies (transient & steady-state), unit commitment

andeconomic dispatch.In particular, some programs use linear programming to find

the optimal power flow, the conditions which give the lowest cost per kilowatt

hour delivered.

Power-flow or load-flow studies are important for planning future expansion of power

systems as well as in determining the best operation of existing systems. The principal

information obtained from the power-flow study is the magnitude and phase angle of the

voltage at eachbus,and the real and reactive power flowing in each line.

Commercial power systems are usually too large to allow for hand solution of the power

flow. Special purposenetwork analyzers were built between 1929 and the early 1960s to

provide laboratory models of power systems; large-scale digital computers replaced the

analog methods.

Newton-Raphson method is the most widely accepted load flow solution algorithm.

However LU factorization remains a computationally challenging task to meet the real-

time needs of the power system.

The application of very fast multifrontal direct linear solvers for solving the linear system

sub-problem of power system real-time load flow analysis by utilizing the state-of-the-art

algorithms for ordering and preprocessing.

Additionally the unsymmetric multifrontal method for LU factorization and highly

optimized Intel Math Kernel Library BLAS has been used. Two state-of-the-art

multifrontal algorithms for unsymmetric matrices namely UMFPACK V5.2.0 and

sequential MUMPS 4.8.3 (Multifrontal Massively Parallel Solver) are customized for

the AC power system Newton-Raphson based load flow analysis.

The multifrontal solvers are compared against the state-of-the-art sparse Gaussian

Elimination based HSL sparse solver MA48. This study evaluates the performance of

above multifrontal solvers in terms of number of factors, computational time, number of

floating-point operations and memory, in the context of load flow solution on nine

systems including very large real power systems.

The results of the performance evaluation are reported. The proposed method achieves

significant reduction in computational time.
http://en.wikipedia.org/wiki/Short-circuithttp://en.wikipedia.org/wiki/Short-circuithttp://en.wikipedia.org/wiki/Economic_dispatchhttp://en.wikipedia.org/wiki/Linear_programminghttp://en.wikipedia.org/wiki/Kilowatt_hourhttp://en.wikipedia.org/wiki/Kilowatt_hourhttp://en.wikipedia.org/wiki/Busbarhttp://en.wikipedia.org/wiki/Network_analyzer_(AC_power)http://en.wikipedia.org/wiki/Network_analyzer_(AC_power)http://en.wikipedia.org/wiki/Busbarhttp://en.wikipedia.org/wiki/Kilowatt_hourhttp://en.wikipedia.org/wiki/Kilowatt_hourhttp://en.wikipedia.org/wiki/Linear_programminghttp://en.wikipedia.org/wiki/Economic_dispatchhttp://en.wikipedia.org/wiki/Short-circuithttp://en.wikipedia.org/wiki/Short-circuit


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State Estimation:

State estimators allow the calculation of these variables of interest with high confidence

despite measurements that are corrupted by noise measurements that may be missing or grossly

Inaccurate.

Objectives:

To provide a view of real-time power system conditions

Real-time data primarily come from SCADA SE supplements SCADA data: filter, fill,

smooth.

To provide a consistent representation for power system security analysis

On-line dispatcher power flow

Contingency Analysis

Load Frequency Control

To provide diagnostics for modeling & maintenance

Computerized management:

Research shows that personal computers (PC) are not being actively used during the vastmajority of the time that they are kept on. It is estimated that an average PC is in use 4 hourseach work day and idle for another 5.5 hours. It's also estimated that some 30-40 percent of theUS's work PCs are left running at night and on weekends.

Office equipment is the fastest growing electricity load in the commercial

sector. Computer systems are believed to account for 10 percent or more of commercialelectricity consumption already. Since computer systems generate waste heat, they also increase

the amount of electricity necessary to cool office spaces.

For the Medical Center, we estimate the savings from PC power management to behundreds of thousands of dollars annually, even without factoring in increased office cooling

costs. Considerable savings are also possible from easing wear-and-tear on the computersthemselves.

Power System Simulator:

Power system simulation models are a class of computer simulationprograms that focus on the

operation of electrical power systems. These computer programs are used in a wide range of

planning and operational situations including:

1. Long-term generation and transmission expansion planning

2. Short-term operational simulations

3. Market analysis (e.g. price forecasting)
http://en.wikipedia.org/wiki/Computer_simulationhttp://en.wikipedia.org/wiki/Computer_simulation


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These programs typically make use of mathematical optimizationtechniques such linear

programming, quadratic programming, and mixed integer programming.

Key elements of power systems that are modeled include:

1.

Load flow (power flow study)2. Short circuit

3. Transient stability

4. Optimal dispatch of generating units (unit commitment)

5. Transmission (optimal power flow)
http://en.wikipedia.org/wiki/Mathematical_optimizationhttp://en.wikipedia.org/wiki/Linear_programminghttp://en.wikipedia.org/wiki/Linear_programminghttp://en.wikipedia.org/wiki/Quadratic_programminghttp://en.wikipedia.org/wiki/Mixed_integer_programminghttp://en.wikipedia.org/wiki/Power_flow_studyhttp://en.wikipedia.org/wiki/Power_flow_studyhttp://en.wikipedia.org/wiki/Mixed_integer_programminghttp://en.wikipedia.org/wiki/Quadratic_programminghttp://en.wikipedia.org/wiki/Linear_programminghttp://en.wikipedia.org/wiki/Linear_programminghttp://en.wikipedia.org/wiki/Mathematical_optimization


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UNIT 7&8:

Optimal Power System Expansion Planning:

Optimization Techniques:

In everyday life, all of us are confronted with some decision makings. Normally, we try to decide

or the best. If someone is to buy a commodity, he or she tries to buy the best quality, yet with theeast cost. These types of decision makings are categorized as optimization problems in which theaim is to find the optimum solutions; where the optimum may be either the least or the most.

Most of the operational and planning problems consist of the following three major steps

Definition Modeling Solution algorithm

Decision variables are the independent variables; the decision maker has to determine their

optimum values and based on those, other variables (dependent) can be determined. For instance,in an optimum generation scheduling problem, the active power generations of power plants maybe the decision variables. The dependent variables can be the total fuel consumption, system

losses, etc. which can be calculated upon determining the decision variables. In a capacitorallocation problem, the locations and the sizing of the capacitor banks are the decision variables,

whereas the dependent variables may be bus voltages, system losses, etc. MathematicalAlgorithms.

A mathematical optimization technique formulates the problem in a mathematicalrepresentation; as given by (2.2) through (2.4). Provided the objective function and/or the

constraints are nonlinear, the resulting problem is designated as Non Linear optimizationProblem (NLP). A special case of NLP is quadratic programming in which the objective functionis a quadratic function of x. If both the objective functions and the constraints are linear

functions of x, the problem is designated as a Linear Programming (LP) problem. Othercategories may also be identified based on the nature of the variables. For instance, if x is ofinteger type, the problem is denoted by Integer Programming (IP). Mixed types such as

MILP(Mixed Integer Linear Programming) may also exist in which while the variables may beboth real and integer, the problem is also of LP type. For mathematical based formulations, some

algorithms have, so far, been developed; based on them some commercial software have alsobeen generated. In the following subsections, we briefly review these algorithms. We should,however, note that generally speaking, a mathematical algorithm may suffer from numerical

problems and may be quite complex in implementation. However, its convergence may beguaranteed but finding the global optimum solution may only be guaranteed for some types such

as LP. There is no definite and fixed classification of mathematical algorithms. Here, we are notgoing to discuss them in details. Instead, we are going to introduce some topics which are ofmore interest in this book and may be applicable to power system planning issues.1 Some topics,

such as game theory, which are of more interest for other power system issues (such as marketanalysis of power ystems), are not addressed here.


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Calculus Method:These types of methods are the traditional way of seeking optimum points. These are applicable

to continuous and differentiable functions of both objective and constraints terms. They makeuse of differential calculus in locating the optimum points. Based on the basic differential

calculus developed for finding the optimum points of C(x) , the method of Lagrange Multipliers

has been developed in finding the optimum points; where equality constraints may also apply. Ifinequality constraints (2.4) are also applicable, still the basic method may be used; however, the

so called Kuhn-Tucker conditions should be observed. The solution is not so straightforward inthat case.

Linear Programming (LP) Method:As already noted, LP is an optimization method in which both the objective function and the

constraints are linear functions of the decision variables. This type of problem was firstrecognized in the 1930s by the economists in developing methods for the optimal allocation of

resources. Noting the fact that Any LP problem can be stated as a minimization problem; due to the fact that, as already

described, maximizing C(x) is equivalent to minimizing (-C(x)). The problem can be stated in aform known as canonical. Then, a solution known as the simplex method, first devised in 1940s,may be used to solve the problem. Using the simplex method normally requires a large amount

of computer storage and time. The so called revised simplex method is a revised method inwhich less computational time and storage space are required. Still another topic of interest in LPproblems is the duality theory. In fact, associated with every LP problem, a so called dual

problem may be formulated. In many cases, the solution of an LP problem may be more easilyobtained from the dual problem. If the LP problem has a special structure, a so called

decomposition principle may be employed to solve the problem in which less computer storageis required.

Non Linear Programming (NLP) Method:We noted earlier that if the objective function and/or the constraints are nonlinear functions of

the decision variables, the resulting optimization problem is called NLP. Before proceedingfurther on NLP problems, we should note that most practical problems are of constrained type inwhich some constraint functions should be satisfied. As for constrained problems, however,

some algorithms work on the principle of transforming the problem into a unconstrained case,we initially review some existing algorithms on solving unconstrained problems. The solution

methods for unconstrained problems may be generally classified as direct search (or non-gradient) methods and descent (or gradient) methods. The former methods do not use the partialderivatives of the objective function and are suitable for simple problems involving a relatively

small number of variables. The latter methods require the evaluations of the first and possibly,

the higher order derivatives of the objective function. As a result,

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Eee Vii Power System Planning [10ee761] Notes

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