HVDC and FACTS Controllers: Applications of Static Converters in Power Systems

HVDC and FACTS Controllers: Applications of Static Converters in Power Systems focuses on the technical advances and developments that have taken place in the past ten years or so in the fields of High Voltage DC transmission and Flexible AC transmission systems. These advances (in HVDC transmission and FACTS) have added a new dimension to power transmission capabilities. The book covers a wide variety of topics, some of which are listed below: -Current Source and Voltage Source Converters, -Synchronization Techniques for Power Converters, -Capacitor Commutated Converters, -Active Filters, -Typical Disturbances on HVDC Systems, -Simulation Techniques, -Static Var Compensators based on Chain Link Converters, -Advanced Controllers, -Trends in Modern HVDC. In addition to EHV transmission, HVDC technology has impacted on a number of other areas as well. As an example, a chapter dealing with HVDC Light applications is included providing recent information on both on-shore and off-shore applications of wind farms. Table of Contents Cover HVDC and FACTS Controllers - Applications of Static Converters in Power Systems eISBN: 1402078919 ISBN: 1402078900 Contents Preface Acronyms Chapter 1 Introduction to HVDC Transmission 1.1 INTRODUCTION 1.2 COMPARISON OF AC-DC TRANSMISSION 1.2.1 Evaluation Of Transmission Costs 1.2.2 Evaluation Of Technical Considerations o Stability Limits o Voltage Control o Line Compensation o Problems of AC Interconnection o Ground Impedance o Problems of DC Transmission 1.2.3 Evaluation Of Reliability And Availability Costs 1.2.4 Applications of DC Transmission o Underground or underwater cables o Long distance bulk power transmission o Asynchronous interconnection of ac systems o Stabilization of power flows in integrated power system 1.3 TYPES OF HVDC SYSTEMS 1.3.1 Monopolar Link 1.3.2 Bipolar Link 1.3.3 Homopolar Link 1.4 REFERENCES Chapter 2 Types of Converters 2.1 INTRODUCTION 2.2 CURRENT SOURCE CONVERTERS (CSC) 2.2.1 Case with no overlap period o Relationship between ac and dc current 2.2.2 Case with overlap period less than 60 degrees. 2.3 VOLTAGE SOURCE CONVERTERS (VSC) 2.3.1 Introduction 2.3.2 Control of the DC Capacitor Voltage 2.3.3 VSC with AC Current Control o 2.3.3.1 PWM Pattern Generation Techniques # 1. Periodical Sampling (PS) (Figure 2-14) # 2. Hysteresis Band (HB) (Figure 2-15) # 3. Triangular Carrier (TC) Technique (Figure 2-16) 2.3.4 VSC with AC Voltage Control o 2.3.4.1 PWM with Bipolar Voltage Switching o 2.3.4.2 PWM with Unipolar Voltage Switching 2.4 CLOSING REMARKS 2.5 REFERENCES Chapter 3 Synchronization Techniques for Power Converters 3.1 INTRODUCTION 3.2 REVIEW OF GFUs 3.2.1 Individual Phase Control (IPC) Unit 3.2.2 Equi-Distant Pulse Control (EPC) Unit o 3.2.2.1 Pulse Frequency Control (PFC) Type o 3.2.2.2 Pulse Phase Control (PPC) Type 3.3 GFUs DESIGN AND ANALYSIS 3.3.1 Conventional GFU 3.3.2 DQO GFU 3.3.3 Comparison 3.4 TESTS ON GFUs 3.4.1 Loss of Synchronization Voltage 3.4.2 Harmonic Distortion Test 3.5 EMTP SIMULATION OF A TEST SYSTEM 3.5.1 Start-up Of System Model 3.5.2 10% Step Change In Current Order 3.5.3 Single Phase Fault 3.5.4 DC Line Fault 3.6 CONCLUSIONS 3.7 ACKNOWLEDGEMENT 3.8 REFERENCES Chapter 4 HVDC Controls 4.1 HISTORICAL BACKGROUND 4.2 FUNCTIONS OF HVDC CONTROLS Limit the maximum dc current. Maintain a maximum dc voltage for transmission. Minimize reactive power consumption. Other features. 4.3 CONTROL BASICS FOR A TWO-TERMINAL DC LINK 4.4 CURRENT MARGIN CONTROL METHOD 4.4.1 Rectifier mode of operation 4.4.2 Inverter Mode of operation o At the rectifier: o At the inverter: 4.5 CURRENT CONTROL AT THE RECTIFIER 4.6 INVERTER EXTINCTION ANGLE CONTROL 4.6.1 Measurement of Gamma Approach 1 [5] 4.6.2 Prediction of Gamma Approach 2 [7] 4.7 HIERARCHY OF CONTROLS 4.7.1 Bipole Controller (Figure 4-14) 4.7.2 Pole Controller (Figure 4-15) 4.7.3 Valve Group (VG) Controller (Figure 4-16) 4.8 ACTION BY CONTROLS AFTER A DISTURBANCE 4.9 REFERENCES Chapter 5 Forced Commutated HVDC Converters 5.1 INTRODUCTION 5.2 COMMUTATION TECHNIQUES FOR HVDC CONVERTERS 5.2.1 Definition Of Commutation o 5.2.1.1 Definition of Terms 5.2.2 Line (or Natural) Commutation o 5.2.2.1 Limitations of Line Commutation 5.2.3 Circuit Commutation 5.2.4 Series Capacitor Circuit o 5.2.4.1 Parallel Capacitor Circuit 5.2.5 Self-Commutation o 5.2.5.1 Current Source Converter (CSC) 5.2.6 Voltage Source Converters (VSCs) o 5.2.6.1 Comparison of Current and Voltage Source Converters 5.2.7 Regions Of Converter Operation o 5.2.7.1 With Circuit Commutated Devices o 5.2.7.2 With Self-Commutated Devices 5.3 EXAMPLES OF FC CONVERTERS FOR HVDC TRANSMISSION 5.3.1 Circuit-Commutated Converters o 5.3.1.1 Series Capacitor Circuits o 5.3.1.2 Parallel Capacitor Circuits o 5.3.1.3 DC Line Side Commutated Circuits 5.3.2 Self-Commutated Converters o 5.3.2.1 Current Source Converter Circuit o 5.3.2.2 Voltage Source Converter Circuit 5.4 REFERENCES Chapter 6 Capacitor Commutated Converters for HVDC Systems 6.1 CAPACITOR COMMUTATED CONVERTERS 6.1.1 Reactive Power Management 6.1.2 Thyristor Valve Modules 6.2 CONTROLLED SERIES CAPACITOR CONVERTER (CSCC) 6.3 COMPARISON OF CCC AND CSCC 6.3.1 Steady State Performance o A. Extinction Angle Characteristics: o B. Maximum Available Power: o C. Converter Valve Voltage Stress: o D. Harmonics and Filtering: 6.3.2 Transient Performance o A. Load Rejection Over-voltages: o B. Three Phase AC Bus Fault: o C. Single Phase Remote AC Fault: o D. Valve Short Circuit Over-current: 6.4 GARABI INTERCONNECTION BETWEEN ARGENTINA BRAZIL 6.4.1 Valve Stresses 6.4.2 AC Switchyard 6.4.3 AC Filters 6.4.4 Thyristor Valves Modules 6.4.5 Modular Design Benefits 6.5 CLOSING REMARKS 6.6 ACKNOWLEDGEMENT 6.7 REFERENCES Chapter 7 Static Compensators: STATCOM Based On Chain-link Converters 7.1 INTRODUCTION 7.1.1 Static Var Compensator (SVC) 7.2 THE CHAIN LINK CONVERTER 7.2.1 Chain Link Ratings 7.2.2 Losses 7.3 ADVANTAGES OF CHAIN CIRCUIT STATCOM 7.4 DESIGN FOR PRODUCTION 7.5 ACKNOWLEDGEMENTS 7.6 REFERENCES Chapter 8 HVDC Systems Using Voltage Source Converters 8.1 INTRODUCTION 8.2 BASIC ELEMENTS OF HVDC USING VSCs 8.2.1 Voltage Source Converters 8.2.2 The XLPE Cables o 8.2.2.1 Comparing AC-DC Cables 8.3 VOLTAGE SOURCE CONVERTER 8.3.1 Operating Principles Of A VSC o 8.3.1.1 Design Of Control Systems 8.3.2 Design Considerations o 8.3.2.1 Steady State Characteristics [3] 8.4 APPLICATIONS 8.4.1 In Environmentally Sensitive Locations, i.e. City Centres 8.4.2 Infeeds Of Small Scale Renewable 8.4.3 Power From Wind Farms 8.4.4 Increasing Capacity on existing RoW o Converting ac to dc o Adding capacity with dc cables o Control of power flow 8.4.5 Improved Reliability Of City Centres 8.5 TJAEREBORG WINDPOWER PROJECT IN DENMARK 8.5.1 Description Of The Project 8.5.2 Main Data o Converter o DC Cable 8.5.3 Operational Regime Of The Voltage Source Converter 8.5.4 Power Quality 8.5.5 Control System 8.5.6 DC Cable 8.5.7 Building 8.5.8 Performed Tests On Site 8.5.9 Advantages 8.6 POWER SUPPLY TO REMOTE LOCATIONS (i.e. ISLANDS) 8.6.1 The Gotland Island System 8.7 ASYNCHRONOUS INTER-CONNECTIONS 8.7.1 Directlink Project New South Wales And Queensland 8.7.2 Main System Components 8.7.3 Control System 8.8 CONCLUDING REMARKS 8.9 ACKNOWLEDGEMENT 8.10 REFERENCES Chapter 9 Active Filters 9.1 INTRODUCTION 9.2 DC FILTERS 9.3 AC FILTERS 9.3.1 Test System 9.3.2 Control Philosophy o 9.3.2.1 Block 1: Derivation of Component # (A) Compute Peak Bus Voltage. This sub-block is used to derive the peak # (B) Compute Instantaneous Load Power. The instantaneous load power # (C) Compute (peak) Load Current Reference. The sensed average load o 9.3.2.2 Block 2: Derivation of Component o 9.3.2.3 Block 3: Derivation of Switching Signals for AF, 9.3.3 Test Results o 9.3.3.1 Steady State Performance of the AF (Figure 9-3) o 9.3.3.2 Transient Performance of the AF 9.4 CONCLUDING REMARKS 9.5 ACKNOWLEDGEMENT 9.6 REFERENCES Chapter 10 Typical Disturbances in HVDC Systems 10.1 INTRODUCTION 10.2 CIGRE BENCHMARK MODEL FOR HVDC CONTROL STUDIES 10.3 DETAILS OF CONTROL SYSTEMS USED 10.3.1 Rectifier Control Unit 10.3.2 Inverter Control Unit 10.4 RESULTS 10.4.1 Controller Optimization Tests o 10.4.1.1 10% Step Change In Rectifier Current Reference o 10.4.1.2 5% Step Change In Inverter Current Reference o 10.4.1.3 2.5° Step Change In Inverter Gamma Reference 10.4.2 Mode Shift 10.4.3 Single-phase, 1-cycle Fault At The Inverter (Single Commutation Failure) 10.4.4 Single-phase 5-cycle Fault At The Inverter (Multiple Commutation Failures) 10.4.5 3-Phase 5-cycle Fault At The Inverter 10.4.6 1-phase 5-cycle Fault At The Rectifier 10.4.7 3-phase 5-cycle Fault At The Rectifier 10.4.8 DC Line Fault At The Rectifier Side 10.4.9 DC Line Fault At The Inverter Side 10.5 CLOSING REMARKS 10.6 ACKNOWLEDGEMENT 10.7 REFERENCES Chapter 11 Advanced Controllers 11.1 INTRODUCTION 11.2 APPLICATION OF AN ADVANCED VDCL UNIT 11.2.1 Introduction 11.2.2 Fuzzy Inference 11.2.3 Structure of RBF NN 11.2.4 Methodology 11.2.5 HVDC System Considered For The Study o 11.2.5.1 HVDC system o 11.2.5.2 Control system representation 11.2.6 Results And Discussions o 11.2.6.1 Case 1 Starting-up Of DC System o 11.2.6.2 Case 2 Reduction Of DC Voltage o 11.2.6.3 Case 3 Recovery From Fault o 11.2.6.4 Case 4 Current Reference Tracking 11.3 CONCLUSIONS 11.4 ACKNOWLEDGEMENT 11.5 REFERENCES Chapter 12 Measurement/Monitoring Aspects 12.1 INTRODUCTION 12.2 MONITORING OF SIGNALS 12.3 PROTECTION AGAINST OVER-CURRENTS Current Extinction (CE) Commutation Failure (CF) or misfire Short Circuits internal or dc line 12.4 PROTECTION AGAINST OVER-VOLTAGES 12.5 ACKNOWLEDGEMENT 12.6 REFERENCES Chapter 13 Case Studies Of AC-DC System Interactions 13.1 INTRODUCTION 13.2 AC-DC SYSTEM INTER-ACTIONS 13.2.1 System Aspects 13.2.2 DC Controller Aspects 13.3 MULTI-TERMINAL HVDC SYSTEMS [1,2,3] 13.3.1 Remote 3 Phase Fault At Rectifier 1 13.3.2 Commutation Failure At The Small Inverter 2 13.4 HARMONIC INTER-ACTIONS AT CHANDRAPUR HVDC STATION [6] 13.5 CONCLUSIONS 13.6 ACKNOWLEDGEMENT 13.7 REFERENCES Chapter 14 Simulators For Analyzes Of Power System Phenomena 14.1 INTRODUCTION 14.2 THE IREQ HYBRID SIMULATOR [4-7] 14.2.1 Modelling Techniques 14.3 OFF-LINE DIGITAL SIMULATION PACKAGES 14.3.1 EMTP 14.3.2 EMTDC/PSCAD o Network Components o Control Blocks o Power Electronics o Meters o 14.3.2.1 PSCAD Graphical User Interface (GUI) 14.4 REAL-TIME DIGITAL SIMULATORS 14.4.1 Methodology 14.4.2 Hardware Considerations 14.4.3 Software Considerations 14.4.4 Graphical User Interface (GUI) 14.4.5 Validation Of Real-time Digital Simulators 14.4.6 Hardware Implementations 14.5 PRESENT AND FUTURE TRENDS 14.6 ACKNOWLEDGEMENT 14.7 REFERENCES Chapter 15 Modern HVDC State Of The Art 15.1 INTRODUCTION 15.2 PAST DECADE VERSION Valves: Typical of the state-of-the-art valves during this period was the Converter Transformers: These were three 1-phase winding trans- AC Filters: These were mainly of the conventional, passive double- DC Filters: These were of the passive type with either air or oil cooled DC Controls: These were mainly digital, but with some analog parts 15.3 PRESENT DECADE VERSION 15.3.1 Thyristor Valves 15.3.2 Self-commutated Valves 15.3.3 Active Filters o 15.3.3.1 AC Side Of The Converter o 15.3.3.2 DC Side Of The Converter 15.3.4 Tunable AC Filters 15.3.5 AC-DC Measurements 15.3.6 Digital Signal Processor (DSP) Controllers 15.3.7 Compact Station Design 15.3.8 Deep Hole Ground Electrode 15.4 CONCLUDING REMARKS 15.5 ACKNOWLEDGEMENTS 15.6 REFERENCES Index About the Author