Preface to the First Edition xxi

1 Introduction 1

1.1 Risk in Power Systems 1

1.2 Basic Concepts of Power System Risk Assessment 4

1.3 Outline of the Book 9

2 Outage Models of System Components 15

2.1 Introduction 15

2.2 Models of Independent Outages 16

2.3 Models of Dependent Outages 31

2.4 Conclusions 42

3 Parameter Estimation in Outage Models 45

3.1 Introduction 45

3.2 Point Estimation on Mean and Variance of Failure Data 46

3.3 Interval Estimation on Mean and Variance of Failure Data 49

3.4 Estimating Failure Frequency of Individual Components 54

3.5 Estimating Probability from a Binomial Distribution 56

3.6 Experimental Distribution of Failure Data and Its Test 57

3.7 Estimating Parameters in Aging Failure Models 60

3.8 Conclusions 70

4 Elements of Risk Evaluation Methods 73

4.1 Introduction 73

4.2 Methods for Simple Systems 74

4.3 Methods for Complex Systems 84

4.4 Correlation Models in Risk Evaluation 91

4.5 Conclusions 102

5 Risk Evaluation Techniques for Power Systems 105

5.1 Introduction 105

5.2 Techniques Used in Generation-Demand Systems 106

5.3 Techniques Used in Radial Distribution Systems 114

5.4 Techniques Used in Substation Configurations 118

5.5 Techniques Used in Composite Generation and Transmission Systems 129

5.6 Conclusions 141

6 Application of Risk Evaluation to Transmission Development Planning 143

6.1 Introduction 143

6.2 Concept of Probabilistic Planning 144

6.3 Risk Evaluation Approach 146

6.4 Example 1: Selecting the Lowest-Cost Planning Alternative 149

6.5 Example 2: Applying Different Planning Criteria 158

6.6 Conclusions 167

7 Application of Risk Evaluation to Transmission Operation Planning 169

7.1 Introduction 169

7.2 Concept of Risk Evaluation in Operation Planning 170

7.3 Risk Evaluation Method 173

7.4 Example 1: Determining the Lowest-Risk Operation Mode 175

7.5 Example 2: A Simple Case by Hand Calculation 181

7.6 Conclusions 188

8 Application of Risk Evaluation to Generation Source Planning 191

8.1 Introduction 191

8.2 Procedure of Reliability Planning 192

8.3 Simulation of Generation and Risk Costs 193

8.4 Example 1: Selecting Location and Size of Cogenerators 196

8.5 Example 2: Making a Decision to Retire a Local Generation Plant 205

8.6 Conclusions 210

9 Application of Risk Evaluation to Selecting Substation Configurations 211

9.1 Introduction 211

9.2 Load Curtailment Model 212

9.3 Risk Evaluation Approach 215

9.4 Example 1: Selecting Substation Configuration 217

9.5 Example 2: Evaluating Effects of Substation Configuration Changes 223

9.6 Example 3: Selecting Transmission Line Arrangement Associated with Substations 229

9.7 Conclusions 233

10 Application of Risk Evaluation to Renewable Energy Systems 235

10.1 Introduction 235

10.2 Risk Evaluation of Wind Turbine Power Converter System (WTPCS)  237

10.3 Risk Evaluation of Photovoltaic Power Systems 251

10.4 Conclusions 272

11 Application of Risk Evaluation to Composite Systems with Renewable Sources 275

11.1 Introduction 275

11.2 Risk Assessment of a Composite System with Wind Farms and Solar Power Stations 276

11.3 Determination of Transfer Capability Required by Wind Generation 296

11.4 Conclusions 310

12 Risk Evaluation of Wide Area Measurement and Control System 313

12.1 Introduction 313

12.2 Hierarchical Structure and Failure Analysis of WAMCS 314

12.3 Risk Evaluation of Phasor Measurement Units 317

12.4 Risk Evaluation of Regional Communication Networks in WAMCS 325

12.5 Risk Evaluation of Backbone Network in WAMCS 335

12.6 Numerical Results 343

12.7 Conclusions 349

13 Reliability-Centered Maintenance 351

13.1 Introduction 351

13.2 Basic Tasks in RCM 352

13.3 Example 1: Transmission Maintenance Scheduling 355

13.4 Example 2: Workforce Planning in Maintenance 360

13.5 Example 3: A Simple Case Performed by Hand Calculations 363

13.6 Conclusions 367

14 Probabilistic Spare-Equipment Analysis 369

14.1 Introduction 369

14.2 Spare-Equipment Analysis Based on Reliability Criteria 370

14.3 Spare-Equipment Analysis Using the Probabilistic Cost Method 373

14.4 Example 1: Determining Number and Timing of Spare Transformers 376

14.5 Example 2: Determining Redundancy Level of 500 kV Reactors 381

14.6 Conclusions 387

15 Asset Management Based on Condition Monitoring and Risk Evaluation 389

15.1 Introduction 389

15.2 Maintenance Strategy of Overhead Lines 390

15.3 Replacement Strategy for Aged Transformers 402

15.4 Conclusions 414

16 Reliability-Based Transmission-Service Pricing 417

16.1 Introduction 417

16.2 Basic Concept 418

16.3 Calculation Methods 422

16.4 Rate Design 424

16.5 Application Example 425

16.6 Conclusions 430

17 Voltage Instability Risk Assessment and Its Application to System Planning 431

17.1 Introduction 431

17.2 Method of Assessing Voltage Instability Risk 432

17.3 Tracing and Locating Voltage Instability Risk for Planning Alternatives 447

17.4 Case Studies 448

17.5 Conclusions 456

18 Probabilistic Transient Stability Assessment 459

18.1 Introduction 459

18.2 Probabilistic Modeling and Simulation Methods 460

18.3 Procedure 464

18.4 Examples 465

18.5 Conclusions 475

Appendix A Basic Probability Concepts 477

A.1 Probability Calculation Rules 477

A.2 Random Variable and Its Distribution 478

A.3 Important Distributions in Risk Evaluation 479

A.4 Numerical Characteristics 483

A.5 Nonparametric Kernel Density Estimator 485

Appendix B Elements of Monte Carlo Simulation 489

B.1 General Concept 489

B.2 Random Number Generators 490

B.3 Inverse Transform Method of Generating Random Variates  491

B.4 Important Random Variates in Risk Evaluation 492

Appendix C Power Flow Models 497

C.1 AC Power Flow Models 497

C.2 DC Power Flow Models 499

Appendix D Optimization Algorithms 503

D.1 Simplex Methods for Linear Programming 503

D.2 Interior Point Method for Nonlinear Programming 506

Appendix E Three Probability Distribution Tables 511

References 515

Further Reading 523

Index 525