Phasors for Measurement and Control (Power Systems)

This book is focused on the development of Phasor Measurement Units (PMUs) as a tool to analyse and control power systems. The book develops a nonlinear system-wide approach to control using PMU signals and provides numerous examples of different power systems to demonstrate the robustness of the approach in comparison to heuristic optimization. Some of the applicable controls include: · Excitation systems; · Wind power; · Static VAR compensators;· High evoltage DC; and · Inverter dynamics. For the operation of transmission and distribution systems, the book explains the dynamics of power systems and explores how well-established tools such as energy-based control and Kalman filters can address many of the existing and developing issues in their operation. By providing a thorough guide to PMUs, this book enables readers to fully understand the potential benefits their implementation can bring. Preface Acknowledgements Contents 1 Phasor Measurements for Identification and Control 1.1 How a Phasor Measurement Unit Works 1.2 Outline References 2 Load Modelling 2.1 Load 2.2 Overall Load Model 2.3 Measurement Approaches 2.3.1 Tap Changer 2.4 Load Modelling 2.4.1 Traditional Load Modelling 2.4.2 Inadequacy of the Traditional Model 2.4.3 Closed-Loop Feedback Load Modelling 2.5 Example 2.6 Motor Loads 2.7 Real Loads 2.8 Application References 3 Identification of Power System Dynamics 3.1 Identification of Dynamics 3.1.1 Identification with White Input 3.1.2 Power System Dynamics-Forming Parameter Estimates 3.1.3 State Estimation 3.1.4 Forming Areas for Aggregation 3.2 Aggregation of Power System Areas 3.2.1 Introduction 3.2.2 Aggregation Process Based on Generator Coherency 3.2.3 Simulation on Test Systems 3.2.4 Summary of Aggregation Process 3.3 Aggregation for Machines Without Clear Delineation of Areas 3.3.1 Mathematics of Aggregation Where Modes Are Spread 3.3.2 Example of Aggregation with Poorly Separated Areas 3.3.3 Uniform 2D Mesh 3.3.4 Process of Aggregation 3.4 HVDC Control Based on Kinetic Energies 3.4.1 Control of 2D Aggregated Systems 3.4.2 Non Uniform Impedance Set for Linear Connection of Generators 3.4.3 Control Case 3.4.4 DC Link to Island 3.5 Load Estimation 3.6 Estimation of Criticality of a Disturbance 3.6.1 Summary of Model Reduction with Imprecise Definition of Areas 3.7 Introduction to Identification from Ambient Noise 3.7.1 Identification from White Noise 3.7.2 Frequency Domain Fit to the Spectrum 3.7.3 Prony or Extended Prony Fit to the Time Domain Data 3.7.4 Autocorrelation Analysis 3.7.5 Pole Fitting Results 3.7.6 Effect of Damping Term 3.8 Identifying Forced Oscillations 3.8.1 Forced Oscillations 3.9 Application References 4 Direct Control of Power System Dynamics 4.1 Wide Area Control Approach 4.1.1 Application Considerations 4.1.2 Controls Acting Behind a Delay 4.2 First Swing Stability of Critical Links 4.2.1 Control Law Based on Remote Measurements 4.2.2 Results 4.3 Nonlinear Dynamic State Estimation of the Reduced System 4.3.1 Robustness to System Dynamic Loads 4.3.2 Transfer Capacity Improvement 4.3.3 Robustness to Time Delays in Controls 4.3.4 Time Delay Compensation in Kalman Filter 4.3.5 Proposed Non-linear Delay Compensation Algorithm 4.3.6 Implementation and Testing of Algorithm 4.3.7 Results 4.3.8 Discussion 4.3.9 Summary 4.4 Application References 5 Indirect Control of Power System Dynamics 5.1 The Need of Wide Area Damping Control: Inverse Filtering 5.2 Wide Area Damping Controllers 5.3 Comparison Between SVCs and Excitation Systems 5.3.1 Excitation System 5.4 Inverse Filtering 5.5 Controller 5.5.1 Controller Design Steps 5.6 Example 5.7 Summary 5.8 Applications References 6 Inverters Operating in Power System in Weak Grids 6.1 Introduction 6.2 Simple Model of Ideal Current Source and Quadrature Voltage Locking 6.3 Estimator Based Controllers of Inverters in Weak Grids (Switch Averaged) 6.4 Case 1: Model with Unknown 50 Hz Phase and Angle of Terminal Volts 6.5 Case 2 Broadcast of Reference Angle 6.6 Case 3 Projecting to Vs Using Inverter Current 6.7 Offset the Current Reference with Respect to Inferred Source 6.8 Kalman Filter Based PLL 6.9 LQR/Kalman Control in Switching Inverter 6.9.1 Notes 6.10 Extreme Case of Step Impedance 6.11 Summary of Performance of Inverters 6.12 Wide Area Control of Power Systems with Inverters and Synchronous Generators 6.13 Hierarchy of Control Efforts 6.14 Control Design 6.15 Inverters to Add Damping by Reducing Output When Velocity in the Area Is High 6.16 Discussion 6.17 Summary of Inverter Synchronization 6.18 Distributed Versus Lumped Battery Compensators 6.18.1 Introduction to Distributed Controllers 6.18.2 Battery Controller 6.18.3 Case 1 Line of Generators 6.18.4 Case 2 Interconnected Generators 6.18.5 Summary of Lumped Vs Distributed Batteries 6.19 Distributed Control by Batteries with a Spread of Delays 6.20 Applications References 7 Travelling Waves 7.1 Electromechanical Wave Propagation 7.2 Attenuation of Electromechanical Waves Using SVC 7.3 Frequency Range and Modal Analysis 7.3.1 Forward Wave Analysis 7.4 Test Systems and Simulations 7.5 Artificial Test Systems 7.6 IEEE Benchmark System (Simplified Australian System) 7.7 Summary of Travelling Waves 7.8 Applications References 8 Identification of Dynamics of Inverters and Loads in Power Systems 8.1 Summary of Inverter Identification 8.2 Identification of Load Dynamics Using PMUs and SVCs 8.3 Load Adaptive Wide-Area Controlled SVCs 8.4 Implementation of Adaptive Wide-Area Controller 8.5 Identification of a Set of Thevenin Impedances from Residential PV Inverters 8.5.1 Example of Identification of Thevenin Impedance in Distribution 8.6 Applications of Thevenin Identification References 9 Phasors for Distribution 9.1 Introduction 9.2 Distribution State Estimation 9.3 Forecast Aided Complex State Estimator 9.3.1 Augmented Complex Kalman Filter 9.3.2 Implementation 9.3.3 Weighted Least Squares (WLS) Formulation 9.3.4 Network Layers 9.3.5 Scalar Measurements 9.4 Results 9.5 Summary of Distribution State Estimation 9.5.1 Contribution of Distribution Loads and Batteries to System Stability While Assisting Local Constraints 9.5.2 Voltage Controllers 9.5.3 Centralized Control of Real Power 9.5.4 Load Modulation Only 9.5.5 Battery and Load Modulation 9.5.6 Using Local Angle Measurement 9.6 Applications References 10 Conclusions Index