Thursday, October 21, 2010

Operation and Control in Power Systems

Operation and Control in Power Systems

Prof. P. S. R. MURTY

B.Sc. (Engg.) (Hans.) ME.,

Dr. - lng (Berlin), F.I.E. (India)

Life Member - ISTE

(Formerly Principal O.U. College of Engineering &

Dean, Faculty of Engineering, O.U. Hyderabad)

2008

421 Pages

ISBN: 978-81-7800-181-0

Contents

1 Introduction

2 Load Flow Analysis

2.1 Bus Classification ............................................................................................... 9

2.2 Modelling for Load Flow Studies ...................................................................... 10

2.3 Gauses - Seidel Iterative Method ...................................................................... 13

2.4 Newton - Raphson Method .............................................................................. 16

2.4.1 Rectangular Coordinates Method ..................................................... 17

2.4.2 The Polar Coordinates Method ........................................................ 19

2.5 Sparsity of Network Admittance Matrices ........................................................ 22

2.6 Triangular Decompostion .................................................................................. 23

2.7 Optimal Ordering ............................................................................................... 25

2.8 Decoupled Methods ........................................................................................... 27

(xiI) Contents

2.9 Fast Decoupled Methods ............................................................................•...... 27

2.10 Load Flow Solution Using Z Bus ...................................................................... 29

2.10.1 Bus Impedance Formation ............................ ~ .................................. 29

2.10.2 Addition of a Line to the Reference Bus .......................................... 29

2.10.3 Addition ofaRadial Line and New Bus ........................................... 30

2.10.4 Addition of a Loop Closing Two Existing Buses in the System ...... 30

2.10.5 Gauss - Seidel Method Using Z-bus for Load Flow Solution ......... 31

2.11 Load Flow Solution with Static Load Model .................................................... 32

2.12 Comparision of Various Methods for Power Flow Solution ............................. 33

Questions ............................................................. ................ .......... .......... ........ 71

Problems ......................... ................... .... ..... ................................... ................. 72

3 Economic Operation of Power Systems

3.1 Characteristics of Steam Plants ........................................................................ 86

3.2 Input Output Curves ......................................................................................... 87

3.3 The Incremental Heat Rate Characteristic ........................................................ 88

3.4 The Incremental Fuel Cost Characteristic ........................................................ 88

3.5 Heat Rate Characteristic .................................................................................... 89

3.6 Incremental Production Cost Characteristics ................................................... 89

3.7 Characteristics of Hydro Plants ........................................................................ 90

3.8 Incremental Water Rate Characteristics ............................................................ 91

3.9 Incremental Production Cost Characteristic ..................................................... 92

3.10 Generating Costs at Thermal Plants .................................................................. 93

3.11 Analytical Form for Input-Output Characteristics of Thermal Units ................ 93

3.12 Constraints in Operation .................................................................................... 94

3.13 Plant Scheduling Methods ................................................................................. 96

3.14 Merit Order Method .......................................................................................... 97

3.15 Equal Incremental Cost Method: Transmission Losses Neglected .................. 97

3.16 Transmission Loss Formula - B. Coefficients .................................................. 99

3.17 Active Power Scheduling ................................................................................. 103

3.18 Penalty Factor .................................................................................................. 106

3.19 Evaluation ofl for Computation ....................................................................... 107

(xfu) Contents

3.20 Hydro Electric Plant Models ............................................................................ 119

3.21 Pumped Storage Plant ...................................................................................... 120

3.22 Hydro Thermal Scheduling .............................................................................. 120

3.23 Energy Scheduling Method .............................................................................. 121

3.24 Short Term Hydro Thermal Scheduling ........................................................... 125

3.24.1 Method of Lagrange Multipliers (losses neglected) ........................ 125

3.24.2 Lagrange Multipliers Method Transmission Losses Considered .... 126

3.24.3 Short Term Hydro Thermal Scheduling using

B-Coefficients for Transmission losses .......................................... 127

Questions ........................................................................................................ 151

Problems ........................................................................................................ 152

4 Optimal Load Flow

4.1 Reactive Power Control for Loss Minimization ............................................... 155

4.2 Gradient Method for Optimal Load Flow ......................................................... 156

4.3 Non - Linear Programming .............................................................................. 157

4.4 Lagrange Function for Optimal Load Flow ..................................................... 158

4.5 Computational Procedures ................................................................ _ ............. 159

4.6 Conditions for Optimal Load Flow ................................................................... 159

4.7 Implementation of optimal conditions .............................................................. 161

Questions ........................................................................................................ 168

Problems ........................................................................................................ 169

5 Unit Commitment

5.1 Cost Function Formulation .............................................................................. 171

5.2 Constraints for Plant Commitment Schedules ................................................. 173

5.3 Priority - List Method ...................................................................................... ·174

5.4 Dynamic Programming .................................................................................... t:z5

5.5 Unit Commitment by Dynamic Programming ................................................. 177

Questions ........................................................................................................ 180

Problems ........................................................................................................ 180

Contents

6 Load Frequency Control

6.1 Speed Governing Mechanism .......................................................................... 183

6.2 Speed Governor ................................................................................................ 183

6.3 Steady State Speed Regulation ......................................................................... 185

6.4 Adjustment of Governor Characteristics ......................................................... 185

6.5 Transfer Function of Speed Control Mechanism ............................................ 186

6.6 Transfer Function of a Power System ............................................................ 188

6.7 Transfer Function of the Speed Governor ....................................................... 190

6.8 Governing of Hydro Units ................................................................................ 191

6.9 Penstock Turbine Model .................................................................................. 193

6.10 Modal for a Steam Vessel ................................................................................ 196

6.11 Steam Turbine Model ...................................................................................... 197

6.12 Reheat Type Steam Turbine Model .................................................................. 198

6.13 Single Control Area ........................................................................................... 199

6.14 The basics of Load Frequency Control ........................................................... 200

6.15 Flat Frequency Control .................................................................................... 201

6.16 Real Power Balance for Load Changes ............................................................ 202

6.17 Transfer Function of a Single Area System ..................................................... 203

6.18 Analysis of Single Area System ........................................................................ 205

6.19 Dynamic Response of Load Frequency Control Loop .................................... 208

6.20 Control Strategy ............................................................................................... 209

6.21 PID Controllers ................................................................................................ 212

6.22 The optimal Control Problem ........................................................................... 222

6.23 The Linear Regulator Problem ......................................................................... 222

6.24 Matrix Riccati Equation .................................................................................... 224

6.25 Application of Modern Control Theory ............................................................ 224

6.26 Optimal Load Frequency Control - Single Area System .................................. 225

Contents

6.27 Optimal Control for Tandem Compound Single Reheat Turbine -

Generator System ............................................................................................. 229

6.28 Optimal Control of Hydro Speed Governing System ....................................... 232

6.29 A Review of Optimal Control ........................................................................... 235

6.30 Load Frequency Control with Restrictions on the Rate of

Power Generation '" .................... : ..................................................................... 236

6.31 Load Frequency Control using Output Feedback ............................................ 237

6.32 Load frequency Control and Economic Dispatch ............................................ 238

Questions ....................................................................................................... "39

Problems ........................................................................................................ 240

7 Control of Interconnected Systems

7. 1 Interconnected Operation ................................................................................. 241

7.2 Flat Frequency Control of Interconnected Stations ......................................... 241

7.3 Flat Tie-Line and Flat Frequency Control ........................................................ 244

7.4 Tie-Line Bias Control ........................................................................................ 247

7.5 Complete Tie-Line Bias Control ....................................................................... 250

7.6 Two Area System - Tie-Line Power Model ..................................................... 253

7.7 Block Diagram for Two Area System .............................................................. 254

7.8 Analysis of Two Area System .......................................................................... 255

7.9 Dynamic Response ........................................................................................... 257

7.10 Tie-Line Bias Control- Implementation ........................................................... 266

7.11 The Effect of Bias Factor on System Regulation ............................................ 267

7.12 Scope for Supplementary Control .................................................................... 269

7.13 State Variable Model for a Three Area System ................................................. 269

7.14 State Variable Model for a Two Area System ................................................... 274

7.15 State Variable Model for a Single Area System ................................................ 275

7.16 Model Reduction and Decentralised Control .................................................. ,284

Questions ........................................................................................................ 287

Problems ........................................................................................................ 288

(XVl) Contents

8 Voltage and Reactive Power Control

8.1 Impedance and Reactive Power ....................................................................... 289

8.2 System Voltage and Reactive Power ................................................................ 293

8.3 Reactive Power Generation by Synchronous Machines .................................. 294

8.4 Effect of Excitation Control ............................................................................. 295

8.5 Voltage Regulation and Power Transfer ........................................................... 296

8.6 Exciter and Voltage Regulator .......................................................................... 297

8.7 Block Schematic of Excitation Control ............................................................ 299

8.8 Static Excitation System .................................................................................. 300

8.9 Brushless Excitation Scheme ........................................................................... 301

8.10 Automatic Voltage Regulators for Alternators .................................................. 302

8.11 Analysis of Generator Voltage Control ............................................................. 303

8.12 Steady State Performance Evaluation .............................................................. 306

8.13 Dynamic Response of Voltage Regulation Control ........................................... 306

8.14 Stability Compensation for Voltage Control ..................................................... 307

8.15 Stabilizing Transformer .................................................................................... 307

8.16 Voltage Regulators ............................................................................................ 309

8.17 ieee Type 1 Excitation System ......................................................................... 310

8.18 Power System Stabilizer .................................................................................. 313

8.19 Reactive Power Generation by Turbo Generator ............................................. 314

8.20 Synchronous Compensators ............................................................................ 314

8.21 Reactors 315

8.22 Capacitors315

8.23 Tap---Changing Transformers ........................................................................... 316

8.24 Tap-Staggering Method ................................................................................... 317

8.25 Voltage Regulation and Short Circuit Capacity ................................................. 318

8.26 Loading Capability of a Line ............................................................................. 320

8.27 Compensation in Power Systems ..................................................................... 320

(xviI) Contents

8.28 Load Compensation .......................................................................................... 321

8.29 Static Compensators ........................................................................................ 328

8.30 Steady State Perfonnance of Static var compensators ................................... 331

8.31 Overvoltages on Sudden Loss of Load ............................................................ 334

8.32 Voltage Dips ...................................................................................................... 335

8.33 Subsynchronous Resonance ............................................................................ 337

Questions ........................................................................................................ 343

Problems ........................................................................................................ 344

9 Introduction to Advanced Topics

9.1 Facts Controllers .............................................................................................. 346

9.1.1 Series Controllers ............................................................................ 346

9.1.2 Shunt Controller .............................................................................. 347

9.1.3 Series - Series Controllers .............................................................. 347

9.1.4 Series - Shunt Controllers .............................................................. 348

9.1.5 Power Flow Control ...................................................................... 348

9.1.6 Static Var Compensator(SVC) ........................................................ 349

9.1.7 Unified Power Flow Controller ....................................................... 349

9.1.8 Advantages due to FACTS devices ................................................. 349

9.2 Voltage Stability ................................................................................................ 350

9.3 Power Quality ................................................................................................... 352

9.3.1 Power Quality Index ....................................................................... 353

9.3.2 Voltage Sags .................................................................................... 353

9.3.3 Rectifier Loads ................................................................................ 355

9.3.4 Flicker ............................................................................................. 355

9.3.5 Power Acceptability or Voltage Tolerance ....................................... 356

9.3.6 Solutions to Power Quality.problem ............................................... 356

9.4 Data Base for Control ....................................................................................... 357

9.5 State Estimation ................................................................................................ 358

9.6 Power System Security .................................................................................... 360

(xviii) Contents

9.7 Steady State Security Assessment ................................................................... 361

9.8 Application to Outage Studies .......................................................................... 362

9.9 Pattern Recognition Methods ........................................................................... 363

9.10 Power System Control Centres ........................................................................ 365

9.11 Level Decomposition in Power Systems ......................................................... 367

9.12 NetworkAutomation ........................................................................................ 368

9.13 LoadPrediction ................................................................................................. 369

9.14 Load Prediction using Matereological Data ...................................................... 371

9.15 Spetral Expansion Method ................................................................................ 376

9.16 Prediction by Scaling a Standard Load .......................................................... 377

9.17 Short - Term Load Forecasting Using Exponential Smoothing ....................... 378

9.18 Peak Power Demand Prediction ....................................................................... 378

9.19 State Estimation in Load Forecasting ............................................................... 379

9.20 Generating Capacity Reliability and Outage Probabilities ................................. 380

Questions ........................................................................................................ 386

Objective Questions .......................................................................... 387

Answers to Objective Questions ...................................................... 400

References ......................................................................................... 401

Index ................................................................................................. 407


Link

http://ifile.it/5ucngmf/8178001810.pdf

http://ifile.it/ptxe4qz/Operation%20and%20Control%20in%20Power%20Systems.pdf

http://mediafire.com/?2le0i49k7oekd1e

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