本篇論文提出了一種基於回授零序電壓控制，搭配前饋功率平衡控制之電壓平衡控制策略，及峰值電流限制之低電壓過度策略(LVRT)於一七階層靜態同步補償器(STATCOM)。所有STATCOM的電壓平衡操作都是基於功率潮流分析，可讓所有浮動的直流鏈電壓追隨目標值，不論市電電壓是否在正常或故障的情況下。基於負序電流注入之峰值電流限制控制，可設定最高之峰值電流與命令相同。且在不同類型的電壓驟降情況下，STATCOM要提供虛功率以達到低電壓過度之要求。一種基於開迴路零序電壓控制之故障容忍的控制，被提出來以應對當一些STATCOM之串接模組處於故障之問題。

This thesis presents a voltage balancing control strategy based on feedback zero-sequence voltage control with a feed-forward power balancing control and a low voltage ride-through (LVRT) strategy of peak current limit control for a 7-level STATic synchronous COMpensator (STATCOM). The whole STATCOM voltage balancing operations are based on power flow analysis which can let the whole floating DC buses voltage trace the target value whether the grid voltage is in normal or faulty situation. The peak current limit control based on negative-sequence current injection which can set the highest peak current equals to the command. In different types of voltage sag situation, STATCOM has to support reactive power to meet the LVRT requirements. A fault-tolerant control based on open loop zero-sequence voltage control is proposed to handle the problem while some STATCOM’s cascaded cells are in faulty situation.

Contents
摘要 ....................................................................................... i
Abstract .................................................................................. ii
誌謝 ....................................................................................... iii
Contents .................................................................................. iv
List of Tables ............................................................................ vii
List of Figures ........................................................................... ix
Chapter 1 Introduction .................................................................... 1
1.1 Introduction .......................................................................... 1
1.2 Organization of the thesis ............................................................ 3
Chapter 2 Literature Review ............................................................... 4
2.1 Introduction ...........................................................................4
2.2 Modulation Technique .................................................................. 4
2.3 DC buses Voltage Balancing Control .................................................... 6
2.3.1 Average Power Balancing Control Base Method ......................................... 6
2.3.2 Dr. Akagi’s Zero-Sequence Voltage Control Method .................................... 13
2.4 Bollen’s Seven Types of Three Phase Imbalanced Sags ................................... 19
2.5 Low Voltage Ride-Through Requirement .................................................. 21
2.6 Summary ............................................................................... 22
Chapter 3 Operation Principles ............................................................ 23
3.1 Introduction .......................................................................... 23
3.2 Power Flow Analysis ................................................................... 23
3.2.1 Overall Voltage Balancing Control ................................................... 23
3.2.2 Reactive Power Control .............................................................. 27
3.2.3 Clustered Voltage Balancing Control Based on Negative-Sequence Current Injection .... 28
3.2.4 Three Phase Feed-forward Power Balancing Control..................................... 30
3.2.5 Clustered Voltage Balancing Control Based on Zero-Sequence Voltage Injection......... 31
3.2.6 Individual Voltage Balancing Control ................................................ 34
3.3 Predictive Current Control ............................................................ 36
3.4 Peak Current Limit Control ............................................................ 40
3.5 Fault-tolerant control ................................................................ 45
3.6 Control Block Diagram ................................................................. 50
Chapter 4 Laboratory Test Results ......................................................... 55
4.1 Introduction .......................................................................... 55
4.2 Comparison of Akagi’s ZSVC and Proposed ZSVC .......................................... 56
4.3 Comparison of APBC and Proposed ZSVC .................................................. 73
4.4 Comparison of the Operation With and Without Feed-forward Term ........................ 89
4.5 The Influence of Peak Current Limit Control for Voltage Balancing Operation ........... 99
4.5.1 Imax Is a Constant Value and Idp Is a Adjustable Value during Δ-side Bollen’s B-type, E-type, A-type Sag .................................................................... 99
4.5.2 Idp Is a Constant Value and Imax Is a Adjustable Value during Δ-side Bollen’s B-type, E-type, A-type sag .................................................................... 130
4.6 Fault-tolerant control ................................................................ 159
4.7 Summary ............................................................................... 172
Chapter 5 Conclusion and Future Work ...................................................... 174
5.1 Conclusion ............................................................................ 174
5.2 Future work ........................................................................... 175
Reference ................................................................................. 176

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