Solution Manual of Signals and Systems 2nd Edition Haykin.pdf

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In simplelanguage,
the book providesa modernintroduction
to power
systemoperation,controland analysis.
Key Features of the Third
New chaptersadded on
) .PowerSystemSecurity
) StateEstimation
) Powersystemcompensationincluding
svs and FACTS
) Load Forecasting
) VoltageStability
New appendiceson :
> MATLABand SIMULINKdemonstrating
theiruse in problemsolving.
) Realtimecomputercontrolof powersystems.
From the Reviewen.,
The book is verycomprehensive,
wellorganised,up-to-dateand (above
all) lucidand easyto followfor self-study.lt is ampiyillustrated
w1hsolved
examplesfor everyconceptand technique.
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lJ Nagrath
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2. Modern PorroerSYstem
Third Edition

3. About the Authors
D P Kothari is vice chancellor,vIT University,vellore. Earlier,he was
Professor,Centre for Energy Studies,and Depufy Director (Administration)
IndianInstituteof Technology,
Delhi. He hasuiro t."n theHeadof the centre
for Energy Studies(1995-97)andPrincipal(l gg7-g8),Visvesvaraya
Regional
Engineeringcollege, Nagpur.Earlier lflaz-s: and 19g9),he was a visiting
fellow at RMIT, Melbourne, Australia. He obtained his BE, ME and phD
degreesfrom BITS, Pilani. A fellow of the Institution Engineers(India),prof.
Kothari has published/presented
450 papers in national and international
journals/conferences.He has authored/co-authoredmore than 15 books,
including Power system Engineering, Electric Machines, 2/e, power system
Transients, Theory and problems of Electric Machines, 2/e., and. Basic
Electrical Engineering.His researchinterestsinclude power systemcontrol,
optimisation,reliabilityand energyconservation.
I J Nagrath is Adjunct Professor,BITS Pilani and retired as professorof
ElectricalEngineeringand Deputy Directorof Birla Instituteof Technology
and Science,Pilani. He obtainedhis BE in Electrical Engineeringfrom the
university of Rajasthanin 1951and MS from the Unive.rity of Wi"sconsin
in
1956' He has co-authored
severalsuccessful
books which include Electric
Machines 2/e, Power system Engineering, signals and systems and.systems:
Modelling and Analyns. He has also puulistred,"rr.ui researchpapers in
prestigiousnationaland international
journats.
Modern Power System
Analysis
Third Edition
D P Kothari
Vice Chancellor
VIT University
Vellore
Former Director-Incharge, IIT Delhi
Former Principal, VRCE,Nagpur
I J Nagrath
Adjunct Professor, and Former Deputy Director,
Birla Ins1i1y7"of Technologt and Science
Pilani
Tata McGraw Hill Education private Limited
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TataMcGraw-Hill
O 2003,1989,1980,
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Private
I-imited
Sixteenth
reprint2009
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No partof thispublication
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Preface to the Third Edition
Sincethe appearance
of thesecondedition in 1989,the overallenergysituation
has changed considerablyand this has generatedgreat interest in non-
conventionaland renewableenergysources,energyconservationandmanage-
ment,powerreformsandrestructuringanddistributedarrddispersed
generation.
Chaptert has been therefore,enlargedand completelyrewritten. In addition,
the influencesof environmentalconstraintsare alsodiscussed.
The present edition, like the earlier two, is designedfor a two-semester
courseat the undergraduate
level or for first-semesterpost-graduate
study.
Modernpower systemshavegrown largerandspreadover largergeographi-
cal areawith many interconnections
betweenneighbouringsystems.Optimal
planning,operationand control of suchlarge-scale
systemsrequireadvanced
computer-based
techniques
many of which areexplainedin thestudent-oriented
and reader-friendlymannerby meansof numericalexamplesthroughoutthis
book. Electric utility engineers
will also be benefittedby the book as it will
preparethem more adequatelyto facethe new challenges.
The style of writing
is amenable
to self-study.
'Ihe
wide rangeof topicsfacilitates
versarile
selection
of chaptersand sectionsfbr completion in the semester
time frame.
Highlights of this edition are the five new chapters.Chapter13 deals with
power system security. Contingency analysis and sensitivity factors are
described.
An analyticalframeworkis developedto control bulk power systems
in sucha way that securityis enhanced.
Everythingseems
to havea propensity
to fail. Powersystemsareno exception.Powersystemsecuritypracticestry to
control and operatepower systemsin a defensiveposturesothat the effects of
theseinevitable failures areminimized.
Chapter14 is an introductionto the useof stateestimationin electricpower
systems.We have selectedLeast SquaresEstimationto give basic solution.
External system equivalencingand treatmentof bad data are also discussed.
The economics of power transmissionhas always lured the planners to
transmit as much power as possible through existing transmission lines.
Difficulty of acquiring the right of way for new lines (the corridor crisis) has
always motivated the power engineersto develop compensatorysystems.
Therefore,Chapter 15 addresses
compensationin power systems.Both series
and shuntcompensationof linqs havebeenthoroughlydiscussed.
Conceptsof
SVS, STATCOM and FACTS havc-beenbriefly introduced.
Chapter 16 covers the important topic of load forecasting technique.
Knowing load is absolutelyessentialfor solvingany power systemproblem.
Chapter17dealswith theimportantproblemof voltagestability.Mathemati-
cal formulation, analysis, state-of-art, future trends and challenges are
discussed.

5. Wl Preracero rnelhlrd Edrtion
MATLAB andSIMULINK,idealprograms
for powersystem
analysis
are
included
in thisbookasanappendix
alongwith 18solved
examples
illustrating
theirusein solvin tive tem problems.The help rendered
by Shri Sunil Bhat of VNIT, Nagpur in writing this appendixis thankfully
acknowledged.
Tata McGraw-Hill and the authors would like to thank the following
reviewersof this edition: Prof. J.D. Sharma,IIT Roorkee; Prof. S.N. Tiwari,
MNNIT Allahabad;Dr. M.R. Mohan, Anna University, Chennai;Prof. M.K.
Deshmukh,
BITS,Pilani;Dr. H.R. Seedhar,
PEC,Chandigarh;
Prof.P.R.Bijwe
andDr. SanjayRoy, IIT Delhi.
While revising the text, we have had the benefit of valuable advice and
suggestions
from manyprofessors,students
andpractisingengineerswho used
the earlier editions of this book. All theseindividuals have influenced this
edition.We express
our thanksand appreciation
to them.We hopethis support/
response
would continuein the future also.
D P Kors[m
I J Nlcn+rn
Preface to the First
Mathematical
modellingand solutionon digitalcomputers
is theonly practical
approachto systemsanalysisand planning studiesfor a modern day power
system with its large size, complex and integrated nature. The stage has,
therefore,beenreachedwhere an undergraduate
must be trainedin the latest
techniques
of analysisof large-scale
powersystems.
A similarneedalsoexists
in theindustrywherea practisingpowersystemengineeris constantly
facedwith
thechallengeof therapidly advancingfield. This book hasbedndesignedto fulfil
this needby integratingthebasicprinciplesof power systemanalysisillustrated
throughthe simplestsystemstructurewith analysistechniques
for practicalsize
systems.
In this book large-scale
systemanalysisfollows asa naturalextension
of thebasicprinciples.The form andlevelof someof thewell-knowntechniques
are presentedin such a manner that undergraduates
can easily grasp and
appreciatethem.
The book is designedfor a two-semester
courseat the undergraduate
level.
With a judicious choiceof advancedtopics,someinstitutionsmay alsofrnd it
useful for a first coursefor postgraduates.
The readeris expectedto havea prior groundingin circuit theoryandelectrical
machines.He should also have been exposedto Laplace transform, linear
differential equations,optimisation techniquesand a first course in control
theory.Matrix analysisis appliedthroughoutthe book. However,a knowledge
of simple matrix operationswould suffice and these are summarisedin an
appendixfbr quick reference.
The digital computerbeing an indispensable
tool for power systemanalysis,
computationalalgorithmsfor varioussystemstudiessuchasloadflow, fault level
analysis,stability,etc. have beenincludedat appropriateplacesin the book. It
is suggested
that wherecomputerfacilitiesexist,students
shouldbeencouraged
to build computerprogramsfor thesestudiesusing the algorithmsprovided.
Further, the studentscan be asked to pool the various programsfor more
advancedandsophisticated
studies,e.g.optimal scheduling.
An importantnovel
featureof thebook is the inclusionof thelatestandpracticallyusefultopicslike
unit commitment, generationreliability, optimal thermal scheduling,optimal
hydro-thermalschedulingand decoupledload flow in a text which is primarily
meantfor undergraduates.
The introductory chapter contains a discussionon various methods of
electricalenergygenerationandtheir techno-economic
comparison.
A glimpseis
giveninto thefutureof electricalenergy.Thereaderis alsoexposed
to theIndian
power scenariowith facts and figures.
Chapters2 and3 give thetransmission
line parameters
andtheseareincluded
for the sakeof completness
of thetext. Chapter4 on therepresentation
of power
systemcomponents
givesthesteadystatemodelsof thesynchronous
machineand
the circuit modelsof compositepower systemsalong with theper unit method.

6. W
preface ro rhe FrrstEdition
Chapter5 dealswith the performanceof transmissionlines. The load flow
problemis introducedright at this stagethroughthe simpletwo-bussystemand
basicconceptsof watt andvar control areillustrated.A brief treatmentof circle
concept of load flow and line compensation. ABCD constants are generally well
covered in the circuit theory course and are, therefore, relegated to an appendix.
Chapter 6 gives power network modelling and load flow analysis, while
Chapter 7 gives optimal system operation with both approximate and rigorous
treatment.
Chapter 8 deals with load frequency control wherein both conventional and
modern control approaches have been adopted for analysis and design. Voltage
control is briefly discussed.
Chapters 9-l l discuss fault studies (abnormal system operation). The
synchronous machine model for transient studies is heuristically introduced to
the reader.
Chapter l2 emphasisesthe concepts of various types <lf stability in a power
system. In particular the concepts of transient stability is well illustrated through
the equal areacriterion. The classical numerical solution technique of the swing
equation as well as the algorithm for large system stability are advanced.
Every concept and technique presented is well supported through examples
employing mainly a two-bus structure while sometimes three- and four-bus
illustrations wherever necessary have also been used. A large number of
unsolved problems with their answers are included at the end of each chapter.
These have been so selected that apart from providing a drill they help the
reader develop a deeperinsight and illustrate some points beyond what is directly
covered by the text.
The internal organisation of various chapters is flexible and permits the
teacher to adapt them to the particular needs of the class and curriculum. If
desired, some of the advanced level topics could be bypassed without loss of
continuity. The style of writing is specially adaptedto self-study. Exploiting this
fact a teacher will have enough time at his disposal to extend the coverage of
this book to suit his particular syllabus and to include tutorial work on the
numerous examples suggestedin the text.
The authors are indebted to their colleagues at the Birla Institute of
Technology and Science, Pilani and the Indian Institute of Technology, Delhi
for the encouragement and various useful suggestionsthey received from them
while writing this book. They are grateful to the authorities of the Birla lnstitute
of Technology and Science, Pilani and the Indian Institute of Technology, Delhi
for providing facilities necessary for writing the book. The authors welcome
any constructive criticism of the book and will be grateful for any appraisal by
the readers.
I J NlcRArH
D P KorHlnr
A Perspective I
Structureof PowerSystems I0
ConventionalSourcesof Electric Energy I3
RenewableEnergy Sources 25
Energy Storage 28
Growth of Power Systemsin India 29
EnergyConservbtion 3I
Deregulation 33
Distributed and DispersedGeneration 34
EnvironmentalAspectsof Electric Energy Generation 35
PowerSystemEngineersandPower SystemStudies 39
Use of Computersand Microprocessors 39
ProblemsFacing Indian PowerIndustry and its Choices 40
References 43
2. Inductance and Resistanceof Transmission Lines
1.
vn
I
1 . 1
1 . 2
1 . 3
r.4
1.5
1.6
1.7
r.8
1 . 9
1 . 1 0
1 . 1 1
T . I 2
1 . 1 3
2 . 1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2 . l I
2.r2
Introduction 45
Definition of Inductance 45
Flux Linkages of an Isolated
Current-CtrryingConductor 46
Inductanceof a Single-Phase
Two-Wire Line 50
ConductorTypes 5I
Flux Linkages of one Conductorin a Group 53
Inductanceof CompositeConductorLines 54
Inductanceof Three-Phase
Lines 59
Double-CircuitThree-PhaseLines
66
BundledConductors 68
Resistance 70
Skin Effect and Proximity Effect 7I
Problems 72
References 75
45
3. Capacitance of Transmission Lines
3.1 Introduction 76
3.2 Electric Field of a Long StraightConductor 76
Contents
Preface to First Edition
Introduction
76

7. fW .contents .
3.3 PotentialDiff'erencebetweentwo Conductors
of a Group of ParallelConductors 77
3.4 Capacitance
of a Two-Wire Line 78
3.5 Capacitanceof a Three-phaseLine
with EquilateralSpacing B0
6.4 Load Flow Problem 196
6.5 Gauss-SeidelMethod 204
6.6 Newton-Raphson
(NR) Method 213
6.7 DecoupledLoad Flow Methods 222
6.9 Controlof Voltage Profile 230
Problems 236
D ^ t - - ^ - - - . ) 2 0
I I Y J E I E T L L C J L J 7
7. Optimal System Operation 242
7.I Introduction 242
1.2 Optimal Operation of Generators
on a Bus Bar 243
7.3 Optimal Unit Commitment (UC) 250
7.4 ReliabilityConsiderations 253
1.5 OptimumGenerationScheduling 259
7.6 Optimal Load Flow Solution 270
7.7 OptimalScheduling
of Hydrothermal
System 276
Problems 284
References 286
8. Automatic Generation and Voltage Control 291'l
8.1 Introduction 290
8.2 Load FrequencyControl (SingleArea Case) 291
8.3 Load FrequencyControland
EconomicDespatchControl 305
Two-Area Load FreqlrencyControl 307
Optimal (Two-Area) Load FrequencyControl 3I0
AutomaticVoltage Control 318
Load FrequencyControl with Generation
RateConstraints(GRCs) 320
SpeedGovernorDead-Bandand Its Effect on AGC 321
Digital LF Controllers 322
DecentralizedControl 323
Prohlents 324
References 325
9. Symmetrical Fault Analysis 327
9.1 Introduction 327
9.2 Transienton a Transmission
Line 328
9.3 ShortCircuit of a Synchronous
Machine
(On No Load) 330
9.4 ShortCircuit of a LoadedSynchronous
Machine 339
9.5 Selectionof Circuit Breakers 344
UnsymmetricalSpacing BI
3.7 Effect of Earth on TransmissionLine capacitance g3
"
o l t - t l - - l a r . ^ / r .
J.o rvleln(Jo or rlvll-, (vloollled) yl
3.9 BundledConductors 92
Problems 93
References 94
4. Representation,of Power System Components
4.1 Introduction g5
4.2 Single-phase
Solutionof Balanced
Three-phase
Networks 95
4.3 One-LineDiagramandImpedanceor
Reactance
Diagram 98
4.4 Per Unit (PU) System 99
4.5 ComplexPower 105
4.6 Synchronous
Machine 108
4.7 Representation
of Loads I2I
Problems 125
References 127
5. Characteristics and Performance of power
Transmission Lines
5.1 Introduction 128
5.2 ShortTransmission
Line 129
5.3 Medium Transmission
Line i37
5.4 The LongTransmission
Line-Rigorous Solution I 39
5.5 Interpretationof the Long Line Equations 143
5.6 FerrantiEffect 150
5.1 TunedPowerLines 151
5.8 The EquivalentCircuit of a Long Line 152
5.9 PowerFlow througha Transmission
Line I58
5.10 Methods
ol'Volrage
Control 173
Problems 180
References 183
6. Load Flow Studies
6.1 lntrotluction 184
6.2 NetworkModelFormulation I85
95
128
8.4
8.5
8.6
8.7
8 . 8
8.9
8 . 1 0
t84

8. rffi#q confenfs
I
9.6
'
Algorithm for ShortCircuit Studies 349
9.7 Zsus Formulation 355
Problems 363
References 368
Symmetrical Com
10.1 Introduction 369
10.2 SymmetricalComponentTransformation370
10.3 PhaseShift in Star-DeltaTransformers 377
10.4 Sequence
Impedances
of TransmissionLines 379
10.5 Sequence
Impedances
and Sequence
Network
of PowerSystern 381
10.6 Sequence
Impedances
and Networksof
Synchronous
Machine 381
10.7 Sequence
Impedances
of TransmissionLines 385
10.8 Sequence
Impedances
andNetworks
of Transformers 386
10.9 Constructionof Sequence
Networksof
a Power System 389
Problems 393
References 396
ll. Unsymmetrical Fault Analysis
11.1 Introduction 397
11.2 SymmetricalComponentAnalysis of
UnsymmetricalFaults398
, 11.3 SingleLine-To-Ground
(LG) Fault 3gg
11.4 Line-To-Line(LL) Fault 402
11.5 Double Line-To-Ground
(LLG) Fault 404
11.6 Open Conductor
Faults 414
11.1 Bus Impedance
Matrix Method For Analysis
of Unsymmetrical
ShuntFaults 416
Problems 427
References 432
12. Power System Stability
12.1 Introduction 433
12.2 Dynamicsof a Synchronous
12.3 Power Angle Equation 440
12.4 Node Elimination Technique
I2.5 SimpleSystems 451
12.6 Steady StateStability 454
12.7 Transient Stability 459
I2.8 Fq'-ralArea Criterion 461
Machine 435
444
12.10MultimachineStabilitv 487
Problems 506
References 508
13. Power System Security
13.1 Introduction 510
13.2 SystemStateClassification 512
13.3 SecurityAnalysis 512
13.4 Contingency
Analysis 516
13.5 SensitivityFactors 520
13.6 Power SystemVoltage Stability 524
References 529
14. An Introduction to state Estimation of Power systems 531
l4.l Introduction 531
I4.2 Least SquaresEstimation: The Basic
Solution 532
14.3 StaticStateEstimationof Power
Systems 538
I4.4 Tracking StateEstimation of Power Systems 544
14.5 SomeComputational
Considerations 544
14.6 External SystemEquivalencing 545
I4.7 Treatmentof Bad Dara 546
14.8 Network observability andPseudo-Measurementss49
14.9 Application of Power SystemStateEstimation 550
Problems 552
References 5.13
397
433
550
15. Compensation in Power Systems
15.1 Introduction 556
15.2 LoadingCapability 557
15.3 LoadCompensation 557
15.4 Line Compensation 558
15.5 SeriesCompensation 559
15.6 ShuntCornpensators 562
I5.7 ComparisonbetweenSTATCOM and SVC 565
15.8 FlexibleAC Transmission
Systems
(FACTS) 566
15.9 Principleand Operationof Converrers 567
15.10FactsControllers 569
References 574

9. 16. Load Forecasting Technique
16.1 Introduction 575
16.2 Forecasting
Methodology 577
timationof Averageand Trend Terms 577
Estimationof PeriodicComponents 581
Estimationof y.,(ft):Time SeriesApproach 582
Estimationof Stochastic
Component:
Kalman Filtering Approach 583
Long-TermLoadPredictions
Using
EconometricModels 587
ReactiveLoad Forecast 587
References 589
Voltage Stability
11.1 Introduction 591
17.2 Comparisonof Angle and Voltage Stability 592
17.3 ReactivePowerFlow and Voltage Collapse 593
11.4 MathematicalFormulationof
Voltage StabilityProblem 593
11.5 Voltage StabilityAnalysis 597
17.6 Preventionof VoltageCollapse 600
ll.1 State-of-the-Art,FutureTrends and Challenses 601
References 603
Appendix A: Introduction to Vector and Matrix Algebra
Appendix B: Generalized Circuit Constants
Appendix C: Triangular Factorization and Optimal Ordering
Appendix D: Elements of Power System Jacobian Matrix
Appendix E: Kuhn-Tucker Theorem
Appendix F: Real-time Computer Control of power Systems
Appendix G: Introduction to MATLAB and SIMULINK
Answers to Problems
Index
I.T A PERSPECTIVE
Electric energy is an essentialingredient for the industrial and all-round
development
of any country.It is a covetedform of energy,because
it canbe
generated
centrallyin bulk and transmittedeconomically
over long distances.
Further,it can be adaptedeasily and efficiently to domesticand industrial
applications,particularly for lighting purposesand rnechanicalwork*, e.g.
drives.The per capitaconsumptionof electricalenergyis a reliableindicator
of a country'sstateof development-figuresfor 2006 are615 kwh for India
and 5600 kWh for UK and 15000kwh for USA.
Conventionally,electricenergyis obtainedby conversion
fiom fossil fuels
(coal,oil, naturalgas),andnuclearandhydrosources.
Heatenergyreleased
by
burningfossilfuelsor by fissionof nuclearmaterialis convertedto electricity
by first converting
heatenergyto the mechanical
form througha thermocycle
and then convertingmechanicalenergy throughgenerators
to the electrical
form. Thermocycleis basicallya low efficiencyprocess-highestefficiencies
for modernlargesizeplantsrangeup to 40o/o,
while smallerplantsmay have
considerably lower efficiencies. The earth has fixed non-replenishablere-
sourcesof fossil fuels and nuclear materials,with certain countries over-
endowedby natureandothersdeficient.Hydro energy,thoughreplenishable,is
alsolimited in termsof power.The world's increasingpowerrequirementscan
only be partially met by hydro sources.Furthermore,ecologicaland biological
factorsplacea stringentlimit on the useof hydro sources
for power production.
(The USA has already developed around 50Voof its hydro potential and
hardlyany furtherexpansionis plannedbecause
of ecological
considerations.)
x Electricity is a very inefficient agentfor heatingpurposes,
becauseit is generatedby
the low efficiency thermocyclefrom heat energy. Electricity is used for heating
purposesfor only very specialapplications, say an electric furnace.
16.4
1 6 . 5
16.6
16.7
r6.8
17. 591
605
617
623
629
632
634
640

10. Introduction
with the ever increasingper capitaenergyconsumptionand exponentially
_______--^D v^,vt6J vurrJLurlp[rult iltlu gxpongnlla
rising population, technologists already r* the end of the earth,s nc
s non-
llfenislable
fuel reso.urces*.
-The
oil crisis of the 1970shas dramatically
intensepollution in their programmes of energy
generatingstations are more easily amenableto
centralizedone-point measurescan be adopted.
development.Bulk power
control of pollution since
drawnattentionto this fact.In fact,we canno lon
tor generationof electricity. In terms of bulk electric energy generation,a
distinct shift is taking placeacrossthe world in favour of coalLJin particular
*varying estimatcs
havebccnput forthfor rescrvcs
ol'oil, gasandcoalancllissionable
rnaterials'At the projectedconsumptionrates,oil and gasesare not expectedto last
much beyond50 years;severalcountrieswill face seriousshortagesof coal after 2200
A'D' while fissionable materials may carry us well beyond the middle of the next
century. Theseestimates,however, cannot be regardedas highly dependable.
Cufiailment of enerry consumption
The energyconsumptionof most developcdcorrntries
has alreaclyreachecl
a
level, which this planetcannotafford. Thereis, in fact, a needto find waysand
meansof reducingthis level. The developingcountries,on theotherhand,have
to intensifytheireffortsto raisetheir level of energyproductionto providebasic
amenities to their teeming millions. of course,-in doing ,o th"y need to
constantly draw upon the experiencesof the developedcountries and guard
againstobsolete
technology.
rntensification of effofts to develop alternative sources of
enerw including unconventional sources like solan tidal
energy, etc.
Distant hopesarepitchedon fusion energybut the scientific and technological
advanceshave a long way to go in this regard.Fusion when harnessed
could
provide an inexhaustiblesourceof energy.A break-throughin the conversion
from solar to electric energy could pr*io" anotheranswer to the world,s
steeplyrising energyneeds.
Recyclingr of nuclear wastes
Fastbreederreactortechnologyis expectedto providethe answerfor extending
nuclear energyresourcesto last much longer.
D evelopm ent an d applicati on of an ttpollu tion techn ologries
In this regard, the developing countries already have the example of the
developed countries whereby they can avoid going through the phasesof
consumption
on a worldwidebasis.This figureis expected
to rise asoil supply
for industrial usesbecomesmore stringent.Transportation
can be expectedto
go electric in a big way in the long run, when non-conventionalenergy
resourcesare we[ developedor a breakthroughin fusion is achieved.
To understandsomeof the problems that the power industry faces let us
briefly review some of the characteristic featuresof generationand transmis-
sion.Electricity, unlike water and gas,cannotbe storedeconomically (except
in very small quantities-in batteries),andthe electricutility can exerciselittle
control over the load (power demand) at any time. The power system must,
therefore,be capableof matching the output from generatorsto the demandat
anytime at a specified
voltageandfrequency.
Thedifficultyencountered
in this
taskcan be imagined from the fact that load variationsover a day comprises
three components-a steady component known as base load; a varying
componentwhosedaily patterndependsuponthetime of day; weather,season,
a popularfestival, etc.;anda purely randomly varying componentof relatively
small amplitude. Figure 1.1showsa typical daily load curve.The characteris-
tics of a daily load curve on a grossbasisare indicatedby peak load and the
time of its occurrenceand load factor defined as
averageload = lessthan unity
maximum (peak)load
Fig. 1.1 Typicaldailyloadcurve
The average load determines the energy consumption over the day, while
the peak load along with considerations of standby capacity determines plant
capacity for meeting the load.
100
B
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c
o
tr
6 6 0
:o
E
l + o
x
o

11. mterconnection,rgreajly
aidsinjackinguFtn,a factorsater in&viJJp i of the.station
.staff.
excess
Powerof a plantaudngtight"toaa
periodsis evacuated
throughlong i
Tariff structures
maybesuchasto influence
theloadcurveandto improve
distance
highvoltage
transmissionlo"r,*hl"
"
h"""itr;;;pj;;,:;";# |
s"j:9.fi",.:''
I
.Ahighloadfactorhelpsindrawngmoreenergy*'nu,'u"n,n,.u*I',i
uvrl,; ur (xawrrg more energy lrom a given installation. I
Asindividuar
road
centris
have
rJiro*n
"r,#u","'.i.,ii,
;;;ilnffi | Tt:"9:"lT:f:,_Tj_.:llT:11,:::."1:,1.j:ij:::.,j:j:*T:j
generalhavea time dJveniry,which when;61il ;&;';;"irili,jij I
o:rynd..o_ltheunitsproduced
andtherefore
onth€tuelcharges
andthewages
power.
'"*-- Prur rwervcs
] Tariff should consider the pf (power factor) of the load of the consumer.
If it is low, it takes more current for the same kWs and hence Z and D
Diversity Factor i i;;;;.i." and distribution) losses are conespondinglyincreased.The
rhisisdenned
as
the
sum
ofindividual
maximum
demands
on
the
consumers,i ::m:r,:_".*'Ji:[1t z%""l,i""irT3H::Tgl""rii:'J],f;fi:_'J""1tr
divided
by
,r,"
**i-u--i;#"#UH:ffiTTfi,1"ff":"il:ffi:I :#:*'::i,:"ff"Hf,.j,f.',.d1:$:"*Yil'.:fff:fii*,:.;iff;
::::*1":i""1".:1t:i1;ft;,"
,."'.::"'?;
;3:":ffii"T,"-jT,ffiH:
i tr;'3f:l
;xl#1rJ,ffi?,1?Til'jl[,"ff"tJ'trJ;
ili"tH
i:s,?"
i:"::19'c,.r"d
transmission
prant.
rf authedemands
"r-"
;;" ,;"'11'f,;: i
-:,':T":.-"::i,"":"^::::":--":J
_ ;;ff; ;;"";;'--
-- *
i.e.
unitv
divenitv
ru"to',
tr,"'iotJ
;;';";;;il.;;;;;;ilTffi? i lil m
tharee,lfe
::"T:l:_^,:Tl it1:Y_T^:*
more.Luckily,rhefactoris muchhighertrranunity,
"il*t,
f-;;#; I
tlil a pf penaltyclausemaybe imposed
on the consumer.
loads. , (iiD the consumermay be askedto use shuntcapacitorsfor improving the
A high diversity factor could be obtained bv; I po*er factor of his installations.
1' Giving incentivesto farmers and/or someindustriesto useelectricity in
the night or lighr load periods.
uru ruEirr ur UBI|L roao pefloos.
2 using daylight saving as in many other counfies. Llg4"
1'1
L------
3' staggering the offrce timings
A factory to be set up is to have a fixed load of 760 kw gt 0.8 pt. The
4' Having different time zones in the country like USA, Australia, etc. L electricrty board offeri to supplJ,energy at the following alb;ate rates:
5' Having two-part tariff in which consumer has to pay an amount (a) Lv supply at Rs 32ftvA max demand/annum + 10 paise/tWh
dependent on the maximum demand he makes, plus u
"h.g;
fo.
"u"t
(b) HV supply at Rs 30/kvA max demand/annum + l0 paise/kwh.
unit of energyconsumed.sometimesconsumerii chargedo? tt" u"si, i rne lrv switchgearcosts Rs 60/kvA and swirchgearlossesat full load
of kVA demandinstead of kW to penalize to"O. of to'* lo*", tin"tor. I amount to 5qa- Intercst depreciation chargesibr the snitchgear arc l29o of the
other factors used frequently are:
plant capacity foctor
enuy 3re: capital cost. If the factory is to work for 48 hours/week, determine the more
e.conomical tariff.
- Actual energyproduced 7@
m a x i m u m p o s s i b l e e ' m s o f u t i o n M a x i m u m d e m a n d = 0 3 = 9 5 0 k v A
@ased
on instarelptant capaciiyy
-
Loss in switchgear= 5%
_ Average demand 950
Installedcapacity .. InPut dematrd= j- = 1000 kvA
Plant usef(tctor
I
"ost
of switchgear
= 60 x 1000= Rs 60,000
_ _ --_ Actualenergyproduced
(kWh)
-. . -,:- -- ' Annualcharges
on degeciation
= 0.12x 60,000= Rs 7,200
plantcapacity
(kw) x Time(inhours)th" plunrh^ b;i" il;;ti""
Annual fixed chargesdue to maximum demandcorrespondingto tariff (b)
Tariffs
= 30 x 1.000
= Rs30,000
The cost of electricpoweris normally givenby the expression(a + Dx kW Annual running chargesdueto kwh consumed
+ c x kWh) per annum,where4 is a rixea clarge f_ ,f," oiifif,'ina"p".a"* = 1000x 0.8x 48 x 52 x 0.10
of the power output;b depends
on themaximumdemandon tir" syrie- ano i
= Rs 1.99.680

12. t
Total charges/annum
= Rs 2,36,gg0
Max. demandcorresponding
to tariff(a) j 950 kVA
Annual running chargesfor kWh consumed
= 9 5 0 x 0 . 8 x 4 8 x 5 2 x 0 . 1 0
= Rs t,89,696
Total= Rs 2,20,096
Therefore, tariff (a) is economical.
B
0 Hours afoo
Fig. 1.2 Loadduration
curve
Annual cost of thermarplant = 300(5,00,000
- p) + 0.r3(zrg x r07_ n)
Total cost C = 600p + 0.038 + 300(5,00,000
_ p)
+ 0.t3(219 x 107
_ E)
For minimum cost, 4Q- = 0
dP
A region has a maximum demandof 500 MW at a road factor of 50vo.The
Ioad duration curve can be assumedto be a triangle. The utility hasto meet
this load by settingup a generatingsystem,which is partly hydro and partry
thermal. The costsare as under:
Hydro plant: Rs 600 per kw per annumand operatingexpenses
at 3p
per kWh.
Thermal plant: Rs 300 per kw per annumandoperatingexpenses
at r3p
Determine
the
:ffily:f
hydroprT!, rheenergy
generated
annually
by
each, and overall generation
cost per kWh.
Solution
Total energy generated
per year = 500 x 1000 x 0.5 x g760
- 219 x 10' kwh
Figure 1.2 shows the load duration
curve.Sinceoperatingcostof hydroplant
is low, the baseload would be supplied
from the hydro plant and peak load from
the thermal plant.
Ler the hydro capacity be p kW and
the energy generaredby hydro plant E
kWh/year.
Thermal capacity= (5,00,000_ p) kW
Thermal energy = (2lg x107_ E) kwh
Annual cost of hydro plant
= 6 0 0 P + 0 . 0 3 E
I
500,000
- P
Introduction WI
I
.'.600+0.03
or
l"'
4E-too-o.r3dE
= o
dP dP
dE=3m dP
d E = d P x t
From triangles ADF and ABC,
5,00,000-P_ 3000
5,00,000 8760
P = 328,say330MW
Capacityof thermalplant= 170MW
Energy generatedby thermal plant = 170x3000x1000
= 255 x106kwh
Energy generatedby hydro plant = 1935x i06 kwh
Total annual cost= Rs 340.20 x 106/year
overall
generation
cost
=
###P
x100
= 15.53paise/kWh
l 5
0.50=
installed
capacity
Installed
capacity
= += 30 MW
0.5
A generatingstationhasa maximum demandof 25 MW, a loadfactor of 6OVo,
a plant capacity factor of 5OVo,and a plant use factor of 72Vo.Find (a) the
daily energy produced, (b) 'the
reservecapacity of the plant, and (c) the
maximum energy that could be produceddaily if the plant, while running as
per schedule,
were fully loaded.
Solution
Load factor = average
demand
maximumdemand
0.60=
average
demand
25
Average demand= 15 MW
average
demand
Plant capacity factor =
;#;;..0".,,,

13. Reservecapacityof the plant = instalredcapacity- maximum demand
= 3 0 - 2 5 = 5 M W
Daily energyproduced
= flver&g€
demand
x 24 = 15x 24
=360MWh
Energycorresponding
to installed
capacity
perday
= 2 4 x 3 0 _ 7 2 0 M W h
axlmum energy t be produced
_ actualenergyproducedin a day
plant usefactor
= :9 = 5ooMWh/day
0.72
From a load durationcurve, the folrowing data are obtained:
Maximum demandon the sysremis 20 Mw. The load suppliedby the two
unitsis 14 MW and 10 MW. Unit No. 1 (baseunit) works for l00Voof the
time, and Unit No. 2 (peakload unit) only for 45vo of the time. The energy
generatedbyunit
I is 1x 108units,andthatbyunit
zis7.5 x 106units.Find
theload factor,plant capacityfactor and plant usefactor of eachunit, and the
load factor of the total plant.
Solution
Annual load factor for Unit 1 = 1 x 1 0 8 x 1 0 0
:81.54Vo
14,000
x 8760
The maximumdemand
on Unit 2 is 6 MW.
Annual load factorfor Unit 2 = 7.5x106
x100 = 14.27Vo
6000
x 8760
Loadfactorof Unit 2 for the time it takestheload
7 . 5 x 1 0 6 x 1 0 0
6000x0.45x8760
= 3I.7I7o
Since no reserveis available at Unit No. 1, its capacity factor is the
sameas the load factor,i.e. 81.54vo.
Also sinceunit I has beenrunning
throughoutthe year, the plant use factor equalsthe plant capacityfactor
i.e.81.54Vo.
Annual plant capacityf'actorof Unit z = lPgx
100
loxg76oxloo
= 8'567o
7 . 5 x 1 0 6 x 1 0 0
Introduction N
I
The annualload factor of the total plant = 1.075x10Ex100
= 6135%o
20,000
x 8760
CommentsThe various plant factors, the capacity of baseand peak load
units can thus be found out from the load duration curve. The load factor of
than that of the base load unit, and thus the
cosf of power generation from the peak load unit is much higher than that
from the baseload unit.
i;;;";-l
' - ' - . - - * - "
i
There are threeconsumersof electricity having different load requirementsat
different times.Consumer t has a maximum demandof 5 kW at 6 p.m. and
a demandof 3 kW at 7 p.m. and a daily load factor of 20Vo.Consumer2 has
a maximum demandof 5 kW at 11 a.m.' a load of 2 kW at 7 p'm' and an
averageload of 1200 w. consumer 3 has an averageload of I kw and his
maximum demandis 3 kW at 7 p.m. Determine:(a) the diversityfactor, (b)
the load factor and averageload of eachconsumer,and (c) the averageload
and load factor of the combinedload.
Solution
(a) ConsumerI M D 5 K W
a t 6 p m
M D 5 K W
at 11 am
M D 3 K W
a t T p m
Maximum demandof the systemis 8 kW at 7 p'm'
sum of the individual maximum dernands
= 5 + 5 + 3 = 13 kw
DiversitYfactor = 13/8= 7.625
Consumer2
Consumer3
3 k w
a t T p m
2 k w
a t T p m
LF
ZOVo
Averageload
12kW
Average load
1 k w
(b) ConsumerI Averageload 0'2 x 5 = I
Consumer
2 Averageload 1.2kW,
Consumer3 Averageload I kW,
(c) Combinedaverageload = I + l'2 +
kW, LF= 20Vo
L F =
l ' 2 * 1 0 0 0 - 2 4 V o
5
I
LF=
5x
100-33.3Vo
l = i . 2 k W
Combinedload factor
Load Forecasting
As power plant planning andconstructionrequirea gestationperiodof four to
eight yearsor evenlonger for the presentday superpower stations,
energy anrl
load demandfnrecastingplaysa crucialrole in power systemstudies.
= + x 1 0 0
= 4 0 V o
Plant use factor of Unit 2 =
10x0.45x8760x100
= 19.027o

14. ffiil,ftffi| Modern
powerSyslem
nnatysis
I
This necessitates
long rangeforecasting.
while sophisticated
methodsexist in literature[5, 16, 28], the simple extrapolation
quite adequatefor long rangeforecasting.since weatherhas a
influence on residentialthan the industrial component,it may
prepareforecast in constituentparts to obtain total. Both power
uru ractorsrnvolved re ng an involved
processrequiring experienceand high analytical ability.
Yearly forecastsare basedon previous year's loading for the period under
considerationupdatedby factors such as generalload increases,major loads
and weathertrends.
In short-termload forecasting,hour-by-hour predictionsare made for the
decadeof the 21stcenturyit would be nparing2,00,000Mw-a stupendous
task indeed.This, in turn, would requirea correspondingdevelopmeniin coal
resources.
T.2 STRUCTURE OF POWER SYSTEMS
Generating
stations,
transmission
linesandthedistributionsystemsarethemain
components
of an electricpower system.Generatingstationsand a distribution
systemareconnected
throughtransmission
lines,which alsoconnectone power
* 38Voof the total power
of electricityin India was
less than 200 billion kWh
required in India is for industrial consumption.Generation
around 530 billion kWh in 2000-2001 A.D. compared to
in 1986-87.
system(gtid,area)to another.A distributionsystemconnects
all the
a particularareato the transmission
lines.
For economical
andtechnological
reasons
(which will bediscussed
probabilistic
technique is
much more
be better to
and energy
loads in
in detail
electricallyconnected
areasor regionalgrids (also calledpower pools).Each
areaor regionalgrid operatestechnicallyand economicallyindependently,but
theseare eventuallyinterconnected*to form a national grid (which may even
form an internationalgrid) so thateachareais contractuallytied to other areas
in respectto certaingenerationand scheduling
features.India is now heading
for a nationalgrid.
The siting of hydro stationsis determinedby the natural water power
sources.
The choiceof sitefor coalfired thermalstationsis moreflexible. The
following two alternativesare possible.
l. power starions
may be built closeto coaltnines(calledpit headstations)
and electric energy is evacuatedover transmissionlines to the load
centres.
Z. power stationsmay be built close to the load ceutresand coal is
transportedto them from the mines by rail road'
In practice,however,power stationsitingwill dependuponmanyfactors-
technical, economical and environmental.As it is considerablycheaper to
transport bulk electric energy over extra high voltage (EHV) transmission
lines than to transportequivalentquantitiesof coal over rail roqd,the recent
trends in India (as well as abroad)is to build super (large) thermal power
stations near coal mines. Bulk power can be transmitted to fairly long
distancesover transmissionlines of 4001765
kV and above.However, the
country'scoalresources
are locatedmainly in the eastern
belt and somecoal
fired stationswill continueto be sitedin distantwesternandsouthern
regions.
As nuclearstationsare not constrained
by the problemsof fuel transport
and air pollution, a greater flexibility exists in their siting, so that these
stationsarelocatedcloseto loadcentres
while avoidinghigh densitypollution
areasto reducethe risks, howeverremote,of radioactivityleakage.
*Interconnectionhas the economic advantageof reducing the reservegeneration
capacityin eacharea.Under conditionsof suddenincreasein loador lossof generation
in one area,it is immediately possibleto borrow power from adjoininginterconnected
areas.Interconnection
causeslargercurrentsto flow on transmission
linesunderfaulty
condition with a consequent increase in capacity of circuit breakers. Also, the
centres.It providescapacity savingsby seasonal
exchangeof power betweenareas
having opposingwinter and summer requirements.It permits capacity savings from
time zonesandrandom diversity. It facilitatestransmissionof off-peak power. It also
gives the flexibility to meet unexpectedemergencyloads'
lntroduction

15. In India, asof now, abou
t 75voof electricpower usedis generated
in thermal
plants(includingnuclear).23vofrommostly hydro stationsandZvo.comefrom
:^:yft.s
and.others.
coal is thefuerfor mostof thesream
plants,therest
substation,
wherethereductionis to a rangeof 33 to 132kV, depending
on the
transmissionline voltage.Someindustriesmay require power at thesevoltage
level.
The nextstepdownin voltageis at the distributionsubstation.
Normally, two
distribution voltagelevels are employed:
l. The primary or feedervoltage(11 kV)
2. The secondaryor consumervoltage (440 V three phase/230V single
phase).
The distribution system, fed from the distribution transformer stations,
suppliespower to ttre domesticor industrialand commercialconsumers.
Thus, the power system operatesat various voltage levels separatedby
transformer.Figure 1.3 depictsschematicallythe structureof a power system.
Though the distribution system design,planning and operation are subjects
of great importance,we are compelled,for reasonsof space,to excludethem
from the scopeof this book.
1.3 CONVENTIONAL SOURCES OF ELECTRIC ENERGY
Thermal (coal, oil, nuclear) and hydro generationsare the main conventional
sources of electric energy. The necessityto conserve fosqil fuels has forced
scientists and technologistsacross the world to search for unconventional
sourcesof electric energy. Someof the sourcesbeing explored are solar, wind
and tidal sources.The conventionalandsomeof the unconventionalsourcesand
techniquesof energygenerationarebriefly surveyedherewith a stresson future
trends, particularly with referenceto the Indian electric energy scenario-
Ttrermal Power Stations-Steam/Gas-based
The heatreleasedduring the combustionof coal, oil or gasis usedin a boiler
to raise steam.In India heat generationis mostly coal basedexceptin small
sizes, becauseof limited indigenous production of oil. Therefore, we shall
discussonly coal-fired boilers for raising steamto be used in a turbine for
electric generation.
The chemical energy stored in coal is transformed into electric energy in
thermal power plants.The heat releasedby the combustionof coal produces
steamin a boiler at high pressureandtemperature,which whenpassedthrough
a steamturbine gives off someof its internal energyasmechanicalenergy. The
axial-flow type of turbine is normally usedwith severalcylinders on the same
shaft. The steamturbine actsasa prime mover and drives theelectric generator
(alternator). A simple schematicdiagram of a coal fired thermalplant is shown
in Fig. 1.4.
The efficiency of the overall conversionprocessis poor and its maximum
value is about4OVo
because
of thehigh heatlossesin the combustiongasesand
a O Generating
stations
.qi-aji, '-qff-9-a,
at 11kV- 25kv
Tielinesto
othersystems
Large
consumers
Small
consumers
Fig. 1.3 schematic diagram depicting power system structure
Transmission
level
(220kv - 765 kV)

16. E r t ^ - r ^ - - h - . - ^ - ^
and the large quantity of heatrejectedto the condenserwhich has to be given
off in cooling towers or into a streamlake in the caseof direct condenser
cooling' The steam power stationoperateson the Rankinecycle, modified to
vv'yvrDrwrr ur r'.lr. r.u Inecnanlcal energy) can be increased by
using steam at the highest possible pressure and temperature. with steam
Ah Step-up
uE transformer
10-30kv /
turbinesof this size, additionalincreasein efficiency is obtainedby reheating
the steam after it has been partially expanded by an ext;;; i"ui"r. rn"
reheatedsteamis then returnedto the turbine where it is expandedthrough the
final statesof bleedins.
To take advantageof the principle of economy of scale(which applies to
units of all sizes),the presenttrendis to go in foilarger sizesof units. Larger
units can be installed at much lower cost per kilowatt. Th"y are also cheaper
to opcrate because of higher efficiency. Th"y require io*", labour and
maintenanceexpenditure.According to chaman Kashkari [3] there may be a
savingof ashigh as l|vo in capitalcostper kilowatt by going up from a 100
to 250 MW unit size and an additional saving in fuel cost of ubout gvo per
kwh. Since larger units consumeless fuer pJr kwh, they produce ress air,
thermaland wastepollution, and this is a significant advantage
in our concern
for environment' The only trouble in the cai of a large unit is the tremendous
shock to the system when outageof such a large capacityunit occurs. This
shock can be tolerateclso long as this unit sizeloes not exceed r}vo of the
on-line capacity of a large grid.
rntroduction Effi
perhaps increase unit sizes to several GWs which would result in better
generatingeconomy.
Air and thermal pollution is always presentin a coal fired steamplant. The
COz,SOX, etc.) are emitted via the exhaustgasesandthermal pollution is due
to the rejected heat transferredfrom the condenserto cooling water. Cooling
towers are used in situations where the stream/lake cannot withstand the
thermal burdenwithout excessivetemperaturerise.The problem of air pollution
can be minimized through scrubbers and elecmo-staticprecipitators and by
resortingto minimum emission dispatch [32] and Clean Air Act has already
beenpassedin Indian Parliament.
Fluidized-bed Boiler
The main problem with coal in India is its high ashcontent(up to 4OVo
max).
To solve this, Jtuidized bed combustiontechnologyis being developedand
perfected.The fluidized-bedboiler is undergoingextensivedevelopmentandis
being preferreddue to its lower pollutant level and better efficiency. Direct
ignition of pulverizedcoal is being introducedbut initial oil firing supportis
needed.
Cogeneration
Considering the tremendousamount of wasteheat generatedin tlbrmal power
generation,it is advisableto save fuel by the simultaneousgenerationof
electricity and steam(or hot water) for industrial use or spaceheating. Now
called cogeneration,such systemshave long beencommon, here and abroad.
Currently, thereis renewedinterestin thesebecauseof the overall increasein
energy efficiencieswhich are claimed to be as high as 65Vo.
Cogeneration of steam and power is highly energy efficient and is
particularlysuitablefor chemicals,paper,textiles,food,fertilizer andpetroleum
refining industries.Thus theseindustriescansolveenergyshortageproblem in
a big way. Further,they will not haveto dependon thegrid power which is not
so reliable. Of coursethey can sell the extra power to the governmentfor use
in deficient areas.They may aiso seil power to the neighbouringindustries,a
conceptcalled wheelingPower.
As on 3I.12.2000,total co-generationpotentialin India is 19,500MW
-and
actual achievementis 273 MW as per MNES (Ministry of Non-Conventional
Energy Sources,Governmentof India) Annual Report200H1.
There are two possible ways of cogenerationof heat and electricity: (i)
Topping cycle, (ii) Bottoming cycle. In the topping cycle, fuel is burnt to
produce electrical or mechanicalpower and the wasteheat from the power
generationprovidestheprocessheat.In thebottomingcycle,fuel first produces
processheat and the waste heat from the process6s
is then used to produce
power.
Stack
Coolirrgtower
-Condenser
mill
Burner
Preheated
air Forced
draft fan
Flg. 1.4 schematic
diagram
of a coarfiredsteamprant
In India, in 1970s the first 500 Mw superthermalunit had been
commissioned at Trombay. Bharat Heavy Electricals Limited (BHEL) has
producedseveralturbogenerator
setsof 500 MW capacity.Today;smaximum
generator unit size is (nearly 1200 Mw) limited by the permissiblecurrent
cjensitiesused in rotor and stator windines. Efforts are on to develoo srDer.

17. -
Coal-fired plants share environmental problems with some other types of
fossil-fuel plants; these include "acid rain" and the ,,greenhouse,,
effect.
Gas Turbines
With increasing availability of natural gas
uangladesh)primemoversbasedon gas turbineshave been developedon the
lines similar to those used in aircraft. Gas combustion generateshigh
temperatures and pressures, so that the efficiency of the las turbine is
comparable to that of steamturbine. Additional advantageis that exhaustgas
from the turbine still has sufficient heat content, which is used to raise steam
to run a conventional steam turbine coupled to a generator. This is called
combined-cyclegas-turbine(CCGT) plant. The schernaticdiagramof such a
plant is drawn in Fig. 1.5.
Steam
Fig.1.5 CCGTpowerstation
CCGT plant has a fast start of 2-3 min for the gas turbine and about
20 minutes for the steam turbine. Local storage tanks Jr gur
"ui-u"
ured in
caseof gas supply intemrption. The unit can take up to ITVooverload for short
periodsof time to take care of any emergency.
CCGT unit produces55voof CO2producedby a coal/oil-firedplant. Units
arenow available for a fully automatedoperation for 24h or to meet the peak
demands.
In Delhi (India) a CCGT unit6f 34Mw is installed at Indraprasthapower
Station.
There are culrently many installationsusing gas turbinesin the world with
100Mw generators.A 6 x 30 MW gas turbine station has alreadybeenput
up in Delhi. A gasturbine unit can alsobe usedas synchrono.r,.ornp"nsator
to help maintain flat voltage profile in the system.
H
I
The oldest and cheapestmethod of power generationis that of utilizing the
potential energy of water. The energy is obtainedalmost free of nrnning cost
and is completely pollution free. Of course, it involves high capital cost
requires a long gestation period of about five to eight years as compared to
four to six yearsfor steamplants. Hydroelectricstationsare designed,mostly,
as multipurpose projects such as river flood control, storageof irrigation and
drinking water, and navigation. A simple block diagram of a hydro plant is
given in Fig. 1.6. The vertical difference betweenthe upper reservoir and tail
race is called the head.
Surgechamber
Headworks
Spillway
Valve house
Reservoir
Penstock
Powerhouse
Tailrace
pond
Fig. 1.6 A typical layout for a storagetype hydro plant
Hydro plants are of different types suchas run-of-river (use of water as it
comes), pondage (medium head) type, and reservoir (high head) type. The
reservoir type plants are the ones which are employed for bulk power
generation.Often, cascaded
plants are alsoconstructed,
i.e., on the sa.me
water
stream where the dischargeof one plant becomesthe inflow of a downs6eam
plant.
The utilization of energy in tidal flows in channetshas long been the
subject of researeh;Ttrsteehnical and economicdifficulties still prevail. Some
of the major sites under investigation are: Bhavnagar,Navalakhi (Kutch),
Diamond Harbour and Ganga Sagar. The basin in Kandala (Gujrat) has been
estimated to have a capacity of 600 MW. There are of course intense siting
problems of the basin. Total potential is around 9000 IvftV out of which 900
MW is being planned.
A tidal power station has been constructedon the
northern France where the tidal height rangeis 9.2 m
estimatedto be 18.000m3/sec.
Different types of turbines such as Pelton.Francis and Kaplan are used for
storage,pondageand run-of-river plants,respectively.
Hydroelectricplantsare
La Rance estuary in
and the tidal flow is
Generator

18. W - Modern
powersystem
Anarvsis
t -
p = g p W H W
where
W = dischargem3ls through turbine
p = densiry1000kg/m3
11= head(m)
8 = 9.81mlsz
Problemspeculiarto hydro plant which inhibit expansionare:
1. Silting-reportedly Bhakra deadstoragehas silted fully in 30 years
2. Seepage
3. Ecologicaldamageto region
4. Displacement
of humanhabitationfrom areasbehindthe dam which will
fill up and becomea lake.
5. Thesecannotprovidebaseload, mustbeusedfor peak.shaving
andenergy
savingin coordinationwith thermalplants.
India alsohasa tremendous
potential(5000MW) of having largenumberof
micro (< 1 Mw), mini (< 1-5 Mw), and,small (< 15 Mw) Mrl plants in
Himalayan region, Himachal, up, uttaranchal and JK which must be fully
exploitedto generate
cheapandcleanpowerfor villages situatedfar awayfrom
the grid power*. At present500 MW capacityis und"r construction.
In areaswheresufficienthydro generationis not available,peakloadmay be
handled by meansof pumped storage.This consistsof un ,rpp". and lower
reservoirs and reversibleturbine-generatorsets,which cun ulio be used as
motor-pump sets.The upperreservoir hasenoughstoragefor about six hours
of full load generation.Sucha plant actsasa conventionalhydro plant during
the peak load period, when production costsare the highest.The iurbines are
drivenby water from theupperreservoirin theusualmanner.During the light
load period, water in the lower reservoiris pumped back into the ipper one
so as to be ready for use in the next cycle of the peak ioad p.rioo. rn"
generatorsin this period changeto synchronousmotor action and drive the
turbineswhich now work aspumps.The electricpower is suppliedto the sets
from the general power network or adjoining thermal plant. The overall
efficiency of the sets is normarly as high ut 60-7oEo. The pumped srorage
scheme,in fact, is analogousto the chargingand dischargingor u battery.It
has the added advantagethat the synchronousmachin", tu1 be used as
synchronouscondensersfor vAR compensationof the power network, if
required.In-a way, from the point of view of the thermal sectorof the system,
* Existing capacity (small hydro) is 1341 MW as on June 200I. Total estimated
potentialis 15000MW.
daily load demandcurve.
Someof the existingpumpedstorageplantsare I100 MW Srisailemin Ap
and 80 MW at Bhira in Maharashtra.
Nuclear Power Stations
With the end of coalreservesin sight in the not too distantfuture, the immediate
practicalalternativesourceof large scaleelectricenergygenerationis nuclear
energy.In fact, the developedcountrieshave alreadyswitchedover in a big way
to the use of nuclear energy for power generation.In India, at present,this
sourceaccountsfor only 3Voof the total power generation
with nuclearstations
at Tarapur (Maharashtra),Kota (Rajasthan),Kalpakkam(Tamil Nadu), Narora
(UP) and Kakrapar (Gujarat). Several other nuclear power plants will be
commissioned
by 20I2.In future,it is likely thatmoreandmorepower will be
generatedusing this important resource(it is plannedto raise nuclear power
generationto 10,000MW by rhe year 2010).
When Uranium-235is bombardedwith neutrons,fissionreactiontakesplace
releasingneutronsandheatenergy.Theseneutronsthenparticipatein the chain
reactionof fissioning more atoms of 235U.
In order that the freshly released
neutronsbe able to fission theuranium atoms,their speeds
must be ieducedto
a critical value- Therefore,for the reaction to be sustained,
nuclear fuel rods
mustbe embeddedin neutronspeedreducingagents(like graphite,hqavywater,
etc.) called moderators.Forreaction control, rods madeof n'eutron-absorbing
material (boron-steel)are usedwhich, when insertedinto the reactor vessel,
control the amount of neutron flux thereby controlling the rate of reaction.
However,this ratecanbe controlledoniy within a narrowrange.The schemadc,
diagramof a nuclearpowerplant is shown in Fig. 1.7.Theheit releasedby the
'uclear reaction is transported
to a heat exchangervia primary coolant (coz,
water,etc.). Steamis then generated
in the heatexchanger,
which is usedin a
conventionalmannerto generateelectric energyby meansof a steamturbine.
Varioustypes of reactorsare being usedin practicefor powerplant pu{poses,
viz., advancedgas reactor (AGR), boiling water reactor (BwR), und h"uuy
water moderatedreactor.etc.
Waterintake
Control
rods
Fuelrods_

19. W
ModernPo*", systemAn"tysis
CANDU reactor-Natural uranium(in cixideform), pressurized
heavywater
moderated-is adopted in India. Its schematic diagram is shown in Fig.
1 . 8 .
Containment
Fig. 1.8 CANDUreactor-pressurized
heavywaterrnoderated-adopted
in
India
The associated
merits and problemsof nuclear power plants as compared
to conventionalthermal plants are mentionedbelow.
Merits
1. A nuclearpower plant is totally free of air pollution.
2. It requireslinle fuel in termsof volume and weight, andthereforeposes.
no transportation
problems and may be sited, independentlyof nuclear
iiiriociucrion -
require that they be normally located away from populatedareas.
Demerits
Nuclear reactors produce radioactive fuel waste, the disposal
poses serious environmentalhazards.
The rate of nuclearreactioncan be lowered only by a small margin, so
that the load on a nuclear power plant can only be permitted to be
marginally reducedbelow its full load value. Nuclear power stations
must, therefore, be realiably connectedto a power network, as tripping
of the lines connectingthe station can be quite seriousand may required
shutting down of the reactor with all its consequences.
Because of relatively high capital cost as against running cost, the
nuclear plant should operate continuously as the base load station.
Wherever possible, it is preferable to support such a station with a
pumped storageschemementionedearlier.
The greatestdangerin a fission reactoris in the caseof loss of coolant
in an accident.Even with the control rods fully loweredquickly called
scrarn operation, the fission does continueand its after-heatmay cause
vaporizing and dispersalof radioactivematerial.
The world uraniumresourcesare quite limited, and at the presentrate may
not last much beyond 50 years.However, thereis a redeemingfeqture.During
the fission of 235U,some of the neutrons are absorbedby lhe more abundant
uraniumisotope
238U
lenricheduraniumcontainsonly about3Voof 23sUwhile
most of its is 238U)converting it to plutonium ("nU), which in itself is a
fissionablematerial andcanbe extractedfrom the reactorfuel wasteby a fuel
reprocessingplant. Plutonium would then be used in the next generation
reactors (fast breeder reactors-FBRs), thereby considerablyextending the
life of nuclearfuels. The FBR technologyis being intenselydevelopedas it
will extend the availability of nuclear fuels at predicted rates of energy
consumptionto severalcenturies.
Figure 1.9 shows the schematicdiagramof an FBR. It is essentialthat for
breeding operation, conversionratio (fissile material generated/fissilematerial
consumed) has to be more than unity. This is achieved by fast moving
neutronsso that no moderatoris needed.The neutronsdo slow down a little
through collisions with structural and fuel elements.The energydensitylkg of
fuel is very high and so the core is small. It is therefore necessarythat the
coolant should possessgood thermal propertiesand hence liquid sodium is
used.The fuel for an FBR consistsof 20Voplutonium phts8Vouranium oxide.
The coolant, liquid sodium, .ldavesthe reactor at 650"C at atmospheric
pressure.The heat so transportedis led to a secondarysodiumcircuit which
transfers it to a heat exchangerto generatesteam at 540'C.
2.
3.
4.

20. t Modprn pnrrrar errolam Anal.,^l^
_ r r t y y v r r . r v r r v r v y g l g t t l n t t d t v s t s
with a breeder reactor the release of plutonium, an extremely toxic
material, would make the environmentalconsiderationsmost stringent.
An experimentalfast breedertestreacror(FBTR) (40 MW) has
-been
built
at Kalpakkam
alongside
a nucrear
powerplant.FBR technology
i,
"*f..l"J
conventionalthermal plants.
- Core
Coolant
Containment
Fig. 1.9 Fastbreeder
reactor
(FBR)
An important advantageof FBR technologyis that it can alsouse thorium
(as fertile material) which gets convertedto t33U
which is fissionable.This
holds great promisefor India as we have one of the world's largestdeposits
of thoriym-about 450000tons in form of sanddunesin Keralu unaalong the
Gopalpfur
Chatrapurcoastof Orissa.We havemerely 1 per cent of the world's
suitedfor India,with poorqualitycoal,inadequare
hydropotentiaiilentiful
reserves
of uranium(70,000tons)andthorium,andmanyyearsof nuclear
engineeringexperience.The presentcost of nuclear
wlm coal-ttred power plant, can be further reduced by standardisingpl4nt
designandshifting from heavy wate,r
reactorto light waterreactortechnology.
Typical power densities1MWm3) in fission reactorcores are: gas cooled
0.53,high temperaturegascooled 7.75, heavywarer 1g.0,boiling iut., Zg.O,
pressurizedwater 54.75, fast breederreactor 760.0.
Fusion
Energy is producedin this processby the combination of two light nuclei to
form a single heavier one under sustainedconditions of exiemely high
temperatures
(in millions of degreecentigrade).Fusion is futuristic. Genera-
tion of electricity via fusion would solve the long-tenn energyneedsof the
world with minimum environmental problems. A .o--"i.iul reactor is
expectedby 2010 AD. Consideringradioactivewastes,the impact of fusion
reactorswould be much less than the fission reactors.
In caseof successin fusion technologysometimein the distantfuture or a
breakthroughin the pollution-free solarenergy,FBRs would becomeobsolete.
However, there is an intense need today to develop FBR technology as an
insuranceagainstfailure to deveropthesetwo technologies.
In the past few years, serious doubts have been raised.about the safety
claims of nuclearpower plants.Therehavebeenasmany as 150neardisaster
nuclear accidents from the Three-mile accident in USA to the recent
Chernobyl accidentin the former USSR.There is a fear.that all this may pur
the nuclearenergydevelopmentin reversegear.If this happenstherecould be
serious energy crisis in the third world countries which have pitched their
hopeson nuclearenergy to meet their burgeoningenergyneeds.France(with
78Voof its power requirementfrom nuclearsources)and Canadaarepossibly
the two countrieswith a fairty cleanrecordof nucleargeneration.India needs
to watch carefully their design, constructionand operatingstrategiesas it is
committed to go in a big way for nuclear generation and hopes to achieve a
capacity of 10,000MW by z0ro AD. As p.erIndian nuclear scientists,our
heavywater-based
plants aremost safe.But we must adoptmore conservative
strategies
in design,constructionand operationof nuclearplants.
World scientistshave to adoptof differentreactionsafetystrategy-may be
to discover additives to automaticallyinhibit feaction beyond cr;ii"at rather
than by mechanicallyinsertedcontrol rods which havepossibilitiesof several
primary failure events.
Magnetohydrodynamic (MHD) Generation
In thermal generation of electric energy, the heat released by the fuel is
converted to rotational mechanical energy by means of a thermocvcle. The

21. ry
Modern
Power
System
Anatysis
mechanicalenergy is then used to rotate the electric generator.Thus two
stagesof energy conversion are involved in which the heat to mechanical
energy conversionhas inherently low efficiency. Also, the rotating machine
has its associated
lossesand maintenance
problems.In MHD technology,
cornbustionof fuel without the needfor mechanicalmoving parts.
In a MHD generator,electricallyconductinggasat a very high temperature
is passed in a strong magneticfleld, thereby generatingelectricity. High
temperature is needed to iontze the gas, so that it has good eiectrical
conductivity.The conductinggasis obtainedby burning a fuel and injecting
a seeding materials such as potassium carbonate in the products of
combustion. The principle of MHD power generationis illustrated in Fig.
1.10.Abotrt 50Vo
efficiency canbe achievedif the MHD generatoris operated
in tandem with a conventionalsteamplant.
Gas flow
at 2,500'C
Strongmagnetic
field
Fig.1.10 Theprinciple
of MHDpower
generation
Though the technologicalfeasibility of MHD generationhas beenestab-
lished,its economicf'easibilityis yct to be demonstrated.
lndia had starteda
researchand developmentproject in collaborationwith the former USSR to
install a pilot MHD plant basedon coal and generating2 MW power. In
Russia,a 25 MW MHD plant which usesnatural gas as fuel had been in
operation for someyears.In fact with the developmentof CCGT (combined
cycle gas turbine) plant, MHD developmenthas been put on the shelf.
Geothermal Power Plants
In a geothermalpower plant, heat deep inside the earth act as a source of
power. There has been someuseof geothermalenergyin the form of steam
coming from undergroundin the USA, Italy, New Zealand,Mexico, Japan,
Philippines and some other countries.In India, feasibility studies of 1 MW
station at Puggy valley in Ladakh is being carried out. Another geothermal
field has beenlocatedat Chumantang.
There area numberof hot springsin
India, but the total exploitableenergypotentialseemsto be very little.
Ttre presentinstalled geothermalplant capacity in the world is about 500
MW and the totalestimatedcapacityis immenseprovidedheatgenerated
in the
Introduction w
I
volcanic regionscan be utilized. Sincethepressureand temperatures
are low,
the efficiencyis even lessthan the conventional
fossil fuelledplants,but the
capital costsareless and the fuel is availablefree of cost.
I.4 RENEWABLE ENERGY SOURCES
To protectenvironmentand for sustainable
development,
the importanceof
renewableenergysourcescannotbe overemphasized.
It is an established
and
acceptedtact thatrenewableand non-conventional
forms of energywill play
an increasinglyimportant role in the future as they are cleanerand easier to
useand environmentally
benign and areboundto becomeeconomicallymore
viable with increased
use.
Becauseof the limited availability of coal, there is considerable
interna-
tional effort into the developmentof alternative/new/non-conventionaUrenew-
able/cleansourcesof energy. Most of the new sources(someof them in fact
have been known and used for centuries now!) are nothing but the
manifestationof solar energy, e.g., wind, seawaves, oceanthermalenergy
conversion(OTEC) etc. In this section,we shall discussthe possibilitiesand
potentialitiesof various methods of using solar energy.
Wind Power
Winds are essentiallycreatedby the solarheatingof the atmosphere.
Several
attemptshave beenmade since 1940 to use wind to generateelectric energy
and developmentis still going on. However, technoeconomicfeasibility has
yet to be satisfactorily
established.
Wind as a power sourceis attractivebecause
it is plentiful,inexhaustible
and non-polluting.Fnrther, it does not impose extra heat burden on the
environment.Unlbrtunately,it is non-steadyand undependable.
Control
equipmenthasbeendevised to startthe wind power plant wheneverthe wind
speedreaches30 kmftr. Methods have alsobeenfound to generate
constant
frequencypowerwith varying wind speeds
and consequently
varyingspeeds
of wind mill propellers. Wind power may prove practical for small power
needsin isolatedsites.But for maximum flexibility, it shouldbe used in
conjunctionwith other methodsof power generationto ensurecontinuity.
For wind power generation,there are three types of operations:
1. Small, 0.5-10 kW for isolatedsinglepremises
2. Medium, 10-100 kW for comrnunities i
3. Large, 1.5MW for connectionto the grid.
The theoreticalpower in a wind streamis given by
P = 0.5 pAV3W
densityof air (1201g/m' at NTP)
meanair velocity (m/s) and
p =
V _
where
A = sweptarea(rn").

22. 2. Rural grid systems
arelikely to be 'weak,
in theseareas.since
retatrvelylow voitagesupplies(e.g.33 kV).
3. There are alwaysperiods without wind.
In India, wind power plants have been installed in Gujarat, orissa,
Maharashtra
and Tamil Nadu, where wind blows at speedsof 30 kmftr during
summer'On the whole, the wind power potential of India has been estimated
to be substantialand is around 45000 Mw. The installed capacity as on
Dec. 2000 is 1267 Mw, the bulk of which is in Tamil Nadu- (60%). The
conespondingworld figure is 14000 Mw, rhe bulk of which is in Europe
(7UVo).
Solar Energy
The average incident solar energy received on earth's surface is about
600 W/rn2 but the actual value varies considerably.
It has the advantageof
beingfree of cost,non-exhaustible
andcompletelypollution-free.On theother
hand,it has severalcrrawbacks-energydensitypei unit areais very row, it is
available for only a part of the day, and cl,oud
y and,hazy atmospheric
conditions greatly reduce the energy received. Therefore, harnessing solar
energyfor electricitygeneration,
challengingtechnological
problemsexist,the
mostimportant being that of the collection and concentrationof solar energy
and its conversionto the electricalform through efficient and comparatively
economical
means.
Totalsolarenergy
potential
in Indiais 5 x lOlskwh/yr.Up ro 31.t2.2000.
462000solarcookers,55 x10am2solarthermai systemcollector area,47 MW
of SPV power, 270 community lights, 278000 solar lanterns(PV domestic
lighting units),640 TV (solar),39000PV streetlights and3370 warerpumps
MW of grid connectedsolar power plants were in operation. As per one
estimate[36], solarpower will overtakewind in 2040andwould becomethe
world's overall largest source of electricity by 2050.
Direct Conversion to Electricity (Photovoltaic Generation)
This technologyconvertssolarenergyto theelectricalform by meansof silicon
wafer photoelectriccells known as"Solar Cells". Their theoreticalefficiency is
about25Vobut the practical valueis only about I5Vo.But that doesnot matter
as solar energy is basically free of cost. The chief problem is the cost and
maintenance
of solarcells.With the likelihoodof a breakthrough
in the large
scaleproductionof cheap solar cells with amorphoussilicon, this technology
may competewith conventionalmethodsof electricity generation,particularly
as conventional
fuels becomescarce.
Solar energy could, at the most, supplementup to 5-r0vo of the total
energydemand.It hasbeenestimated
that to produce1012
kwh per year, the
necessary
cellswould occupyabout0.l%oof US landareaasagainsthighways
which occupy 1.57o(in I975) assumingI07o efficiency anda daily insolation
of 4 kWh/m'. .
In all solarthermalschentes,
storage
is necessary
because
of the fluctuating
natureof sun's energy.This is equallytrue with many otherunconventional
sourcesas well as sourceslike wind. Fluctuatingsources
with fluctuating
loads complicatestill further the electricitysupply.
Wave Energy
The energyconientof seawavesis very high. In India, with severalhundreds
of kilometersof coastline, a vastsourceof energyis available.
The power in
the wave is proportionalto the squareof the anrplitudeand to the period of
the motion.Therefore,rhelong period(- 10 s), largeamplitude(- 2m) waves
are of considerable interest for power generaticln, with energy fluxes
commonly averagingbetween50 and 70 kW/m width of oncomingwave.
Though the engineeringproblemsassociated
with wave-powerare formidable,
the amountof energythat can be harnessed
is largeanddevelopment
work is
in progress
(alsoseethe sectionon HydroelectricPowerGeneration,
page17).
Sea wave power estimatedpoterrtialis 20000 MW.
Ocean Thermal Energy Conversion (OTEC)
The ocean is the world's largest solar coilector. Temperaturedifference of
2O"Cbetween,varrn,
solar absorbingsurfacewater and cooler 'bottorn'
water
At present,two technologiesare being developedfor conversion of solar
energyto the electricalform.-'Inone technology,collectorswith concentrators
areemployedto achievetemperatures
high enough(700'C) to operatea heat
engrneat reasonableefficiency to generateelectricity. However, there are
considerableengineeringdifficulties in building a singletracking bowi with a
diarneter
exceeding30 m to generate
perhaps200 kw. The schemeinvolves
largeand intricate structuresinvoiving
lug" capital outlay and as of today is
f'ar from being competitive with
"otru"titional
Jlectricity generation.
The solar power tower [15] generates
steamfor electricityprocluction.
]'here is a 10 MW installationof such a tower by the SouthernCalifornia
EdisonCo' in USA using 1818planernirrors,each
i m x 7 m reflectingdirect
racliation
to thc raisecl
boiler.
Electricity may be generated
from a Solar pond by using a special .low
temperature'
heatenginecoupledto an electricgenerator.
A solarpond at Ein
Borekin Israelprocluces
a steady150 kW fiorn 0.74 hectare
at a busbarcost
of about$ O.tO/kwh.
Solarpower potentialis unlimited,however,total capacityof about 2000
MW is being planned.
Introduction

23. ffiffi| Modem
Pow'er
system
Anatysis
can occlrr.This can providea continuallyreplenished
storeof thermal
which is in principle availablefbr conversion to other energy forms.
refers to the conversionof someof this thermal energyinto work and
lntroduction
solar.The most widely usedstoragebatteryis the lead acid battery.invented
by Plantein 1860.Sodiuttt-sulphur
battery(200 Wh/kg) and othercolrbina-
tions of materialsarea-lso
being developed
to get more outputandstorageper
unit weisht.
Fuel Cells
A fuel cellconverts
chemicalenerryof a fuel into electricity
clirectly,
with no
intermediatecotnbustioncycle. In the fuel cell, hyclrogen
is suppliedto the
negativeelectrodeand oxygen (or air) to the positive.Hydrogenand oxygen
are combined to give water and electricity. The porous electrodesallow
hydrogenions to pass.The main reason';rhyfuel cells arenot in wide useis
their cost (> $ 2000/kW). Global electricity generatingcapacityfrom full cells
will grow fromjust 75 Mw in 2001ro 15000MW bv 2010.US. Germanvand
Japanmay take lead for this.
Hydrogen Energy Systems
Hydrogen can be used as a medium for energy transmissionand storage.
Electrolysis
is a well-established
commercial
process
yieldingpurehydrogen.
Ht can be convertedvery efficientlybackto electi'icityby rneans
of fuel ceils.
Also the useof hydrogena.s
fuel for aircraftandautomcbilescouldencourase
its large scaleproduction,storageand distriburion.
1"6 GROWTH OF POWER SYSTEII{S IN INDIA
India is fairly rich in naturalresources
like coal and lignite; while sorneoil
reserveshavebeendiscoveredso far. intenseexplorationis beingundertakeri
in vitriousregitlnsof thc country.Indiahas immensewaterpowerl.csources
alsoof whichonly around25To
havesofarbeenutiliseci,
i.e.,oniy25000t,IW
hasso far beencommissioned
up to theend of 9th plan.As per a recentreport
of tlreCEA (CcntlalFlectricit,v
Authority),thetotalpotentialof h1,dro
power
is 84,040Iv{Wat ('L't%
loadfactor.As regardsnuclearpower,Indiais cleflcient
in uranium,but hasrich deposits
of thorir-im
rvhichcanbe utilisedat a future
clatc in l'astbrccclorrci.tctor.s.
Since indepcndcncc,
thc coulltry has nnde
tremendous
progress
in thedevelopment
of electricenergyandtodayit hasthe
largestsystemamongthe developingcountries.
When lndia attainedindependence,
the installeclcapacitywas as low as
1400MW in the early stagesof the growth of power system,themajor portion
of generationwas through thermal stations,but due to economicalreasons.
hydro development
receivedattentionin areaslike Kerala,Tamil Nadu. Uttar
Pradeshand Punjab.
In the beginningof the First Five Year Plan (1951-56),the rotalinstalled
capacitywasaround2300MV/ (560MW hydro, 1004MW thermal,149 MW
through oil stations and 587 MW throughnon-utilities).For transportingthis
energy
OTEC
thence
50,000Mw.
A proposedplant usingseaiemperaturedifferencewould be situated25 km
castol'Mianii (USA), wherethe temperature
clil'l'eronce
is 17.5"C.
Biofuels
The material of plants and animals is called biomass, which may be
transformed by chemical and biological processesto produce intermediate
biofuels sttch as methanegas, ethanol liquid or charcoal solid. Biomass is
burnt to provide heat for cooking, comfort heat (spaceheat), crop drying,
tactory processes
andraisingsteamfor electricity productionand transport.In
India potential
I'ttlbio-Energy
is 17000MW andthatfbr agricultunrl
wirstcis
about 6000 MW. There are about 2000 community biogasplants and tamily
size biogas plants are 3.1 x 106.Total biomasspower harnessedso far is
222 MW.
Renewableenergyprogrammes
are specially designedto meet the growing
energy needs in the rural areas for prornoting decentralizedand hybrid
dcvelopment
st.las to stemgrowing migrationof rural populationto urban
areasin searchof betterliving conditions.It would bethroughthis integration
of energy conservationefforts with renewableenergyprogrammesthat India
would be able to achievea smoothtransition from fossil fuel economy to
sustainablerenewableenergybasedeconomy and bring "Energy for ali" for
ec;uitable
and environrnental
friendlysustainable
development.
1.5 ENERGY STORAGE
'l'here
is a lol ol problenrin storingclectricityin largc quantities.Enclgy
wliich can be convertedinto electricitycan be storedin a number of ways.
Storageof any natureis lrowever
very costly arrcl
its cconomicsmust be
worked out properly. Variousoptions availableare: pLrmped
storage,c:onl-
pressedair, heat,hydrogengas,secondary
batteries,
flywheelsand supercon-
ductingcoils.
As already mentioned, gas turbines are normally used for meeting peak
loads but are very expensive.A significant amount of storage capable of
instantancous
usewould be betterway of meetingsuchpeakloads,and so far
the most importantway is to havea pumpedstorage
plantasdiscussed
earlier.
Other methodsare discuss-ed
below very briefly.
Secondary Batteries
Large scalebattery useis almostruled out and they will be used for battery
powered vehiclesand local fluctuating energy sourcessuchas wind mills or

24. power to the load
were constructed.
centres,transmissionlines of up to 110
HE
Introduction
FI
regions of the country with projectedenergyrequirementandpeakload in the
year 2011-12 [19]'
io ororrcrt crcncreri At the
During the Fourth Five Plan,India startedgeneratingnuclearpower'
Tarapur iuclear Plant 2 x 210 MW units were comrnissionedin April-May
. This stationusestwo boiling water reactorsof American design.By
commissionedbY 2012.
The growth of generatingcapacityso
2012 A.D. are given in Table 1'1'
far and future projection for 2011-
Tabte1.1 Growthof Installed
capacityin lndia(ln MW)
Year Hydrtt Nuclear Thermal DieseI Total
Northern region
308528
(49674)
.,.
MW* 9
Western
region
299075
(46825)
1970-7t
1978-79
1984-85
2000-01
398
=2700 MW
renewable
r4704
28640
42240
101630
6383
l 1378
t4271
25141
420
890
1095
2720
7503
t6372
27074
71060
'./
Fig. 1.11 Mapof Indiashowing
fiveregional
projected
energyrequirement
in
MkWhandparkloadin MW for year2011-12'
The emphasisduringtheSecondPlan (1956-61) wason the developmentof
basic ancl heavy inclustries
and thus there was a need to step up power
generation.The total installedcapacitywhich wasaround3420MW at the end
of tn" First Five year Planbecame5700 MW at the end of the SecondFive
year plan. The introductionof 230kv transmission
voltagecame up in Tarnil
Pattern of utlization of electrical energy in 1997-98 was: Domestic
{O.6go,commercial
6.917o,inigation 30.54Vo,
industry35'22Vo
and othersis
6.657o.It is expectedto remainmore or lesssamein 2004-05'
To be self-sufficient in power' BHEL has plants spreadout all over the
countryancltheseturn out an entirerangeof powerequipment,
viz' turbo sets'
hydro sets,turbinesfor nuclearplants,tiigft pi".ture boilers,power transform-
-
ers, switch gears,etc. Each plant specializes
in a rangeof equipment'BHEL's
first 500 MW turbo-generatorwas cornmissionedat singrauli' Today BIIEL
is consideredone of the major power plant equipment manufacturersin the
world.
T.7 ENERGY CONSERVATION
Energyconservation
is the cheapest
new sourceof energy'we shouldresort
to variousconservationmeasures
suchascogeneration(discussed
earlier),and

25. lu
,r32 I Modernpower SvstemAnalvsis
useenergy efficient motorsto avoid wasteful electricuses.We can achieve
considerable
electricalpower savingsby reducingunnecessary
high lighting
levels,oversizedmotors,etc.A 9 W cornpactfluorescent
lamp (CFL) may be
used insteadof 40 w fluorescenttube or 60 w lamp, all having the same
Load Management
As mentionedearlierby various
'load management'schemes.It is possibleto
shift demanrlaway frorn peak hours (SectionI .1.). A more direct method
would be the control of the load either throughrnodified tariff structurethat
encourage
schedules
or direct electrical control of appliancein the form of remotetimer
controlled on/off switches with the least inconvenience io the customer.
Various systems for load rnanagementare describedin Ref. [27]. Ripple
control has been tried in Europe. Remote kWh meter reading by carrier
sysremsis being tried. Most of the potential for load control lies in the
domestic sector. Power companies are now planning the introduction of
system-wideload managementschemes.
1.8 DEREGULATION
For over onehundredyears,the electricpowerindustryworldwide operatedas
a regulatedindustry.In any areatherewas only one company oI government
agency(mostly state-owned)that produced,transmitted,distributed and sold
electricpower and services.Deregulationas a conceptcame in early 1990s.It
broughtin changesdesigneci
to enc<.rutage
competition.
Restructuringinvolves disassemblyof the power industry and reassembly
into anotherform or functional organisation.Privatisation startedsale by a
governmentof its state-owned
electricutility assets,
and operatingeconomy,
to private companies.In somecases,deregulationwas driven by privatization
needs.The state wants to sell its electric utility investment and changethe
rules (deregulation)to make the electric industry more palatablefor potential
investors,thus raising the price it could expectfrom the sale.Open accessrs
nothing but a common way for a govenlmentto encouragecompetitionin the
electric industry and tackle monopoly.The consumeris assuredof good
quality power supply at competitive price.
The structurefor deregulationis evolved in terms of Genco (Generation
Company),Transco(Transrnission
Company)and ISO (Independent
System
Operator).It is expectedthat the optimal bidding will help Gencoto maximize
its payoffs. The consumersare given choice to buy energy from different retail
energy supplierswho in turn buy the energyfrom Genco in a power market.
(independentpower producer, IPP).
The restructuringof the electricity supplyindustrythat norrnally accompa-
nies the introduction of competiiion providesa fertile ground for the growth
of embeddedgeneration,i.e. generationthat is connectedto the distribut-icn
systemratherthan to the transmission
systetn.
The earliestreforms in power industrieswereinitiated in Chile. They were
followed by England, the USA, etc. Now India is also implementing the
restructuring.
Lot of research
is needed
to clearlyunderstand
thepower system
operation under deregulation. The focus of, researchis now shifting towards
a year.Everyoneshouldbe madeawarethroughprint or electronicmediahow
consumptionlevelscanbereducedwithout any essential
lowering of comfort.
Raterestructuringcanhaveincentivesin this regard.Thereis no conscious-
nesson energyaccountability
yet etndno senseof urgencyas in developed
countries.
Transmissionand distributionlossesshoulclnot exceed2OVo.
This can be
achievedby employing series/shunt
compensation,power factor improvement
methods, static var compensators,HVDC option and FACTS (flexible ac
technology) devices/controllers.
Gas turbirre combined with steam turbine is ernployed for peak load
shaving. This is more efficient than normal steam turbine and has a quick
automated starl and shut doivn. It improves the load factor of the steam
staflon.
Energy storage can play an important role where there is time or rate
mismatchbetweensupplyand demandof energy.This hasbeen discussed
in
Section 1.5.Pumpedstorage(hyclro)schemehas beenconsiclered
in Section
1 . 3 .
Industry
In India where most areashave large number of sunny days hot water for
bath arrdkitchen by solarwaterheatersis becomingcommonfor commercial
buildings,hotelsevenhospitals.
In India where vastregionsaredeficient in electricsupply and,aresubjected
to long hours of power sheddingmostly random,the useof small diesel/petrol
generators
and invertersare very conmon in commercialand domesticuse.
Theseare highly wastefulenergydevices.By properplannedmaintelance the
downtime of existing large stationscan be cut down. Plant utilization factors
of existingplants mustbe improved.Maintenance
must be on schedulerather
than an elner-qency.
Maintenancemanpower training shouldbe placed on war
footing. These actionswill also improve the load factor of most power
stations,which would indirectly contributeto energyconservation.
lntroduction

26. W Modernpo*", Syster Anulyri,
finding the optimal bidding methodswhich take into accountlocal optimal
dispatch,revenueadequacyand marketuncertainties.
India has now enactedthe ElectricityRegulatoryComrnission'sAct, 1998
and the Electricity (Laws) AmendmentAct, 1998.Theselaws enablesetting
uo of
State Electricity RegulatoryComrnissions(SERC) at sratelevel.
'fhe
main
purposeof CERC is to promoteefficiency, economy and competitionin bulk
electricity supply. orissa, Haryana,Andhra Pradesh,etc. have startedthe
processof restructuringthe power sectorin their respectivestates.
1.9 DISTRIBUTED AND DISPERSED GENERATION
DistributedGeneration
(DG) entailsusinglnanysrnallgenerators
of 2-50 MW
output,installedat variousstrategic
pointsthroughout
the area,so that each
providespower to a small numberof consumers
nearby.Thesemay be solar,
mini/micro hydel or wind turbine units, highly efficient gas turbines,small
combincdcycle plitnts,sinccthcsearo the rnostccon<lnrical
choiccs.
Dispersedgenerationreferesto useof still smaller generatingunits, of less
than 500 kW output and often sizedto serveindividual homesor businesses.
Micro gasturbines,fuel cells,diesel,and small wind and solarPV senerators
make up this category.
Dispersedgenerationhasbeenusedfor clecades
as an emergencybackup
power source.Most of theseunitsare usedonly fbr reliability reinfbrcement.
Now-a-daysinvertersare being increasinglyused in domesticsectoras an
emergency
supplyduring blackouts.
The distributed/dispersed
generatorscan be stand alone/autonomous
or
grid connecteddependingupon the requirement.
At the time of writing this (200i) therestill is and will probablyalwaysbe
some economy of scale f-avouringlarge generators.But the margin of
economydecreased
considerably
in last 10 years[23]. Even if thepoweritself
ctlstsa bit rtttlrcthitnccn(r'al
station
powcr,thereis no nccd<tftransrnission
lines, and perhapsa reducedneedfbr distribution equipmentas well. Another
maior advantageof dispersedgene.ration
is its modularity, porlability and
relocatability.
Dispersed
generators
alsoincludetwo new typesof tbssilfuel
units-fuel cells and microgasturbines.
The main challengetoday is to upgradethe existing technologies
and to
proniotedeveloprnent,
demonstration,
scalingup and cornmercialization
of
new and emerging technologiesfor widespreadadaptation.In the rural sector
main thrust areasare biomassbriquetting,biomass-based
cogeneration,
etc. In
solar PV (Photovoltaic),large size solar cells/modulesbasedon crystalline
siliconthin films needto bedeveloped.
Solarcellsefficiencyis to beimproved
to 15%o
to be of useat commercial
level.Otherareasaredeveloprnent
of high
eificiency inverters.Urban andindustrialwastesare usedfor variousenergy
applications
including power generationwhich was around 17 Mw in 2002.
Introduction
Therearealready32 million improvedchulhas.
If growingenergyneedsin the
rural areasare met by decentralised
and hybrid ener-qy
systems(distributed/
dispersed
generation),
this can stem growing migrationof rural populationto
urbanareasin searchof betterliving conditions.Thus, India will be able to
able-energy based econolny iind bring "Energy for all" for equitable,
environment-friendly,
and sustainabie
development.
1.10 ENVIRONMENT/L ASPECTS OF ELECTRIC ENER,GY
GENERATION
As far as environmental
andhealthrisks involvedin nuclearplantsof various
kinds are concerned,
thesehave already'been
discussed
in Section1.3. The
problerns
relatedto largelrydroplantshavealsobeendwelleduponin Section
1.3.Therefore,we shallnow focus our attentionon fossil fuel plant including
gas-based
plants.
Conversion of clne lornr ol' energy or anotherto electrical tortn has
unwantedsideeffectsand the pollutantsgenerated
in the processhaveto be
disposed off. Pollutants know no geographical boundary, as result the
pollution issuehas becomea nightmarishproblemand strong nationaland
international pressuregroupshave sprung up and they are having a definite
impacton thedevelopment
of energyresources.
Governmental
awareness
has
creatednumerouslegislationat nationalandinternational
levels,w[ich power
engineers
haveto be fully conversantwith in practiceof their professionand
survey and planning of large power projects.Lengthy, time consuming
procedures
at governrnent
level,PIL (publicinterestlitigation)and demonstra-
tive protestshave delayedseveralprojectsin severalcountries.This has led
to favouringof small-size
projectsand redevelopment
of existingsites.But
with the increasinggap in electricdernandandproduction,our countryhasto
move forward fbr severallarge thermal,hydro and nuclearpower projects.
Entphasis
is lrcinglaidon cor]scrviltiort
issucs.
curtuiltnent
of transntissittn
losses, theft, subsidizedpower supplies and above all on sustainable
devektpnrenlwittr uppntpriata technolog-)'
whercverfeasible. It has to be
particularly assuredthat no irreversible damageis causedto environment
which wouid affect the living conditions of thefuturegenerations.Irreversible
damages
like ozonelayerholesandglobal warmingcaused
by increase
in CO2
in the atmosphere
are alreadyshowing up.
Atmospheric Pollution
We shall treathere only pollutrorras causedby thermalplants usingcoal as
feedstock. Certain issuesconcerning this have already been highlighted in
Section 1.3. The fossil fuel based generatingplantsfonn the backboneof
power generation in our country and also giobally as other options (like
nuclear and even hydro) have even strongerhazardsassociatedwith them.

27. f f i f f i | r r ^ r ^ - - n ^ . . . ^ - ^ . , - r - - a - - r . - - ,
w_ tviouern
row-eruystemAnaiysts
Also it shouldbe understood
that pollutionin large citieslike Delhi is caused
more by vehicrtlartraffic and their emission.In Delhi of courseInderprastha
andBadarpurpower stationscontributetheir sharein certainareas.
Problematic pollutants in emissionof coal-basedgeneratingplants are.
lntroduction
Oxides of Carhon (CO, COt)
CO is a very toxicpollutantbut it getsconverted
to CO'.,
in theopenatmosphere
(if available) surroundingthe plant. On theotherhandCO2hasbeenidentified
developingcountries.
Ifydrocarbons
During the oxidation processin cornbustioncharnbercertain light weight
hydrocarbon may be formed. Tire compounds are a major source of
photochemicalreactionthat adds to depleti,rnof ozone layer.
Particulates (fIY ash)
Dust content is particularly high in the Indian coal. Particulatescome out of
the stack in the form of fly ash.It comprisesfine particlesof carbon,ashand
other inert materials.In high concentrations,thesecausepoor visibility and
respiratorydiseases.
Concentrationof pollutantscan be reducedby dispersalover a wider area
by use of high stacks.Precipitators canbeusedto removeparticlesasthe flue
gasesrise up the stack.If in the stacka verticalwire is strungin the middle
and charged to a high negative potential, it emits electrons.These electrons
arecapturedby the gasmoleculestherebybecomingnegativeions. Theseions
acceleratetowards the walls, get neutralizedon hitting the'walls and the
particlesdrop down thewalls. Precipitatorshavehigh efficiency up to 99Vofor
large particles,but they have poor performancefor particlesof size less than
0.1 pm in diameter.The efficiency of precipitators
is high with reasonable
sulphurcontentin flue gasesbut dropsfor'low sulphurcontentcoals;99Vofor
37o sulphur and 83Vofor 0.5Vosulphur.
Fabric filters in form of bag lnuses have also been employed and are
located before the flue gasesenter the stack.
Thermal Pollution
Steam fronr low-pressureturbine has to be liquefied in a condenser and
reduced to lowest possible temperatureto maximize the thermodynamic
efficiency. The bestefficiencyof steam-cycle
practicallyachievable
is about
4Vo.It meansthat60Vo
of theheatin steamatthecycleendmustberemoved'
This is achievedby following two methods'
1. Once throughcirculationthrough condenser
cooling tubesof seaor river
water whereavailable.This raisesthetemperature
of water in thesetwo
sourcesand threatenssea and river life aroundin sea and downstream
in river. ThesE,are serious environmentalobjections and many times
cannot be overruled ard also theremay be legislation againstit.
2. Cooling tov,ersCool water is circulatedrottnd the condensertube to
remove heat from the exhaust steam in order to condenseit. The
a
a
o
a
2
NO.r,nitrogenoxides
CO
coz
. Certainhydrocarbons
o Particulates
Though the accountthat follows will be general,it needsto be mentioned
herethat Indian coal has comparativelylow sulphur content but a very high
ashcontent which in some coals may be as high as 53Vo.
A brief accountof various pollutants,their likely impact and methods of
abatements
are presentedas follows.
Oxides of Sulphur (SOr)
Most of the sulphur present in the fossil fuel is oxidized to SO2 in the
combustion
chamberbefore being emittedby the chimney.In atmosphere
it
getsfurther oxidized to HrSOo and metallic sulphateswhich are the major
sourceof concernasthesecan causeacid rain, impaired visibility, damageto
buildings and vegetation. Sulphate concenffationsof 9 -10 LElm3 of air
aggravate
asthma,lung and heart disease.
It may also be noted that although
sulphurdoesnot accumulatein air, it does so in soil.
Sulphuremissioncan be controlledby:
o IJse of fuel with less than IVo sulphur;generallynot a feasiblesolution.
o LJseof chemical reaction to remove sulphur in the form of sulphuric
acid, from combustionproductsby lirnestonescrubbersor fluidized bed
combustion.
. Removingsulphurfrom the coal by gasificationor floatationprocesses.
It has been noticed that the byproduct sulphur could off-set the cost of
sulphurrecovery plant.
Oxides of Nitrogen (NO*)
Of theseNOz,nitrogenoxides,is a majorconcernas a pollutant.
It is soluble
in water and so has adverseaff'ecton humanhealth as it entersthe lungs on
inhaling and combining with moisture converts to nitrous and nitric acids,
which danngethelungs.At ievelsof 25-100partsper million NO, cancause
acutebronchitis and pneumonia.
Emissionof NO_,
can be controlledby fitting advanced
technologyburners
which can assuremore completecombustion,
therebyreducingtheseoxides
from being emitted.Thesecan also beremovedfrom the combustionproducts
by absorptionprocessby certainsolventsgoing on to the stock.

28. Gfrfud
ffi-ffii Mociern
PowerSysteqAnaiysis
I
circulatingwater getshot in the process.
tt is pumpedto cooling tower
and is sprayedthrough nozzlesinto a rising volume of air. Someof the
waterevaporates
providingcooling.The latentheatof wateris 2 x 106
J/kg andcoolingcan occurfast,But this hasthe disaclvantage
of raising
unoestraoteJ
tevels ln thc sulrftlundlng
areas.
coursethe waterevaporated
must be macleup in the systemby adcting
fresh waterfrom the source.
Closed coolingtowerswhere condenr;ate
flows throughtubcsanclair is
blown in thesetubesavoidsthe humidityproblembut at a very high cost.In
India only v,et towersare being used.
Electromagnetic Radiation from Overhead Lines
Biological effectsof electromagnetic
radiationfrom power lines and even
cablesin closeproximity of buildings have recently attractedattentionand
have alsocausedsomeconcern.Powerfrequency(50 or 60 Hz) andeventheir
harmonics are not consideredharmful. Investigationscarried out in certain
advanced countrieshave so far proved inconclusive.The electrical and
electronicsengineers,
while being awareof this controversy,must know that
many otherenvironmentalagentsaremoving aroundthat cancausefar greater
harm to humanhealththan does electromagnetic
radiation.
As a pieceof information it may be quotedthat directly underan overhead
line of 400 kV, the electricfield strengthis 11000V/m and magnericflux
density (dependingon current) may be as much as 40 ptT. Electric field
strengthin the rangeof 10000-15000 v/m is consideredsafe.
Visual and Audible Impacts
These environmentalproblems are causedby the following factors.
l. Right of way acquiresland underneath.
Not a seriousproblernin India
at present.Could be a problem in future.
2. Lines converging
at a largesubstation
mar the beautyof the lanclscape
around.Underground
cablesas alternativeare too expensivea proposi-
tion exceptin congestecl
city areas.
3' Radio interference
(RI) has to be takeninto accountand counteredbv
varlous means.
4. Phenomenon
of corona (a sort of electric dischargearoundthe high
tensionline) producesa hissingnoisewhich is aucliblewhenhabitation
is in close proximity. At the to'wersgreat attention must be paid to
tightness of joints, avoidanceof sharp edgesand use of earth screen
shieldingto lirnit audible noiseto acceptable
levels.
5' Workers inside a power plant are subjectedto various kinds of noise
(particularlynear the turbines)and vibration of floor. To reducethis
uoise to tolerable level foundations and vibration filters have to be
designedproperlyand simulation studiescarried out. The worker nlust
be given regularmedical examinations
and soundmedical advice.
sffi
lntrcCuction EEF
T.TT POWER SYSTEMENGINEERSAND POWER
SYSTEM STUDIES
The power systemengineerof the first decadeof the twenty-first century has
abreastof the recentscientific advancesand the latesttechniques.On the
planning side, he or she has to make decisionson how much electricity to
generate-where, when, and by using what fuel. He has to be involved in
constructiontasksof greatmagnitudebothin generation
andtransmission.
He
hasto solve the problemsof planning and coordinatedoperationof a vast and
complex power network, so as to achieve a high degreeof economy and
reliability. In a country like India, he has to additionallyface the perennial
problem of power shortages
and to evolve strategies
for energyconservation
and load management.
For planningtheoperation,
improvementandexpansion
of a power system,
a power systemengineerneedsload flow studies,short circuit studies,and
stabilitystudies.He hasto know the principlesof economicload despatchand
load frequency control. All theseproblemsare dealt with in the next few
chapters after some basic concepts in the theory of transmissionlines are
discussed.The solutionsto these problemsand the enormouscontribution
madeby digital cornputers
to solvethe planningand operational
problemsof
power systemsis also investigated.
I.I2 USE OF COMPUTERS AND MICR.OPROCESSOiTS
Jlhefirst rnethos
lirl solvingvariouspowcrsystemproblenis
wereAC andDC
network analysers
developed
in early 1930s.AC analysers
wereusedfor load
florv and stabilitystudieswhereasDC werepreferredfor short-circuitstudies.
AnaloguecompLrters
were developed
in 1940sand wereusedin conjunc-
tion with AC networkanalyserto solvevariousproblemsfor off--linestudies.
In 1950s many analoguedevices were developedto control the on-line
tunctions such as genelationr--ontrol,
Ii'equencyand tie-line controt.
The 1950salsosaw the adventof digital computerswhich were first used
to solve a.load flow problem in 1956.Power systemstudiesby computers
gave greaterflexibility, accuracy,speedand economy.Till 1970s,therewas
a widespreaduseof computersin systemanalysis.With the entry of micro-
processors
in the arena,now, besidesmain framecompLlters,
mini, micro and
personalcomputersareall increasinglybeingusedto carryout variouspower
systern studies and solve power system problems for off-line and on-line
applications.
Off-line applications include research,routine evaluation of system
performanceand dataassimilationand retrieval.It is mainly usedfor planning
and arralysing some new aspectsof the system. On-line and real time
applicationsinclude data-loggingand the monitoring of the system state.