台電配電系統傳統上以偵測單相電壓為有載分接頭變壓器之電壓調整參考，由於配電系統的不平衡將造成不同三相電壓，進而使有載分接頭變壓器電壓調節失當。本文利用DSP同時搭配小波轉換理論濾除雜訊，精確地計算出正序電壓，並以正序電壓為有載分接頭變壓器之電壓調整值，避免有載分接頭變壓器電壓調節失當造成電力用戶端偏高或偏低之電壓。本文採用Simulink release 13程式模擬一五個匯流排的不平衡配電系統，比較傳統以單相電壓為參考基準及以正序電壓為參考基準之電腦模擬分析，比較兩種做法下範例配電系統各匯流排之電壓。
藉由模擬分析結果得知以正序電壓為有載分接頭變壓器之電壓調整值可避免傳統以單相電壓偵測為三相有載分接頭變壓器電壓調整值之電壓調節失當，造成用戶用電端過高或過低之電壓，且由於電壓調動範圍較小分接頭所需移動之位置較少，使得有載分接頭切換器使用壽命增長，故有載分接頭變壓器以正序電壓為參考電壓基準調節是較佳的選擇。

Generally the on-load tap-changer transformers of Taiwan Power Company’s conventional power distribution system only detect and gather the low-voltage side single-phase voltage for reference values. Because the unbalance of distribution system will cause the different three phase voltage that will make the on-load tap-changer transformers inappropriate adjustment of the voltage. The thesis is using DSP collocated wavelet transformation filtering the noise, then calculated the positive voltage accurately as the reference voltage of three-phase voltage transformer to avoid the voltage at the end points of the consumer feeder is too high or too low. The thesis adopts Simulink release 13 to simulate a five bus distribution system. The results of simulation are the comparison between the distribution system voltages that the reference voltages of on-load tap-changer transformer is adopted the single phase voltage and the reference voltages of on-load tap-changer transformer is adopted the positive sequence voltage.
According to the results of simulation, using the positive sequence voltage as the reference value of the on-load tap-changer transformer can avoid the inappropriate adjustment of the voltage that was used the single phase as the reference value and the lifetime of tap-changer increase because of the less position shift. Therefore using the positive sequence voltage as the reference value of the on-load tap-changer transformer is the better choice.

CONTENTS
Page
ABSTRACT (in Chinese) I
ABSTRACT (in English) II
ACKNOWLEDGMENT III
CONTENTS IV
LIST OF FIGURES VII
LIST OF TABLES X
CHAPTER 1 INTRODUCTION 1
1.1 Background 1
1.2 The Action of the Research Way 3
1.3 The Outlines of Chapter 4
CHAPTER 2 THREE-PHASE ON LOAD TAP CHANGER TRANSFORMER 6
2.1 Introduction 6
2.2 The Control Systems of On-Load Tap-Changer Transformer and Mathematical Model 7
2.1.1 The measuring element 9
2.1.2 Time-delay element 10
2.1.3 Motor Drive-Unit and Tap-Changer Mechanism 11
2.1.4 On-load tap-changer transformer 12
2.1.5 Measuring transformer 13
2.1.6 Line-drop compensator 14
2.3 Auto-Voltage Regulator (AVR) 15
2.4 The Arrangement of Three-phase On-Load Tap-Changer and
the Notes 22
2.4.1 Inspection 23
2.4.2 Overhaul 24
2.4.3 Contact replacement 24
CHAPTER 3 VOLTAGE UNBALANCE FACTOR AND POSITIVE SEQUENCE VOLTAGE 25
3.1 The Influence of Three-Phase Voltage Unbalance 25
3.1.1 Impacts on manufactures due to voltage unbalance 25
3.1.2 Impact on consumers due to voltage unbalance 26
3.1.3 Impacts on power company due to voltage unbalance 27
3.2 The Definitions of Voltage Unbalance Factor 29
3.3 Regulation of Voltage Unbalance 29
3.4 The Positive Sequence Voltage 30
3.5 The Conventional Getting of Positive Sequence Voltage 32
3.6 The DSP Framework and Processing 35
3.6.1 The code composer studio (CCS) 42
3.6.2 The DSP program processing 43
CHAPTER 4 THE SIMULATION OF THREE-PHASE VOLTAGE UNBALANCE DISTRIBUTION SYSTEM AND USING DSP CALCULATED POSITIVE SEQUENCE VOLTAGE 45
4.1 Introduction 45
4.2 The Parameter of Simulate System 46
4.2.1 The transmission line 46
4.2.2 The three-phase transformer 47
4.2.3 The load 48
4.3 The Simulation of Three-Phase On-Load Tap Changer Transformer Regulating the Voltage of Distribution System by Using Different Reference Voltage 49
4.4 Using Wavelet Transformation to Filter the Noise 54
4.4.1 The wavelet transformation 54
4.4.2 The noise 56
4.4.3 The processing of de-noising 56
4.5 Using DSP Filters the Noise and Calculates the Positive Sequence Voltage 59
CHAPTER 5 CONCLUSION 62
APPENDIX A THE EQUIVALENT CIRCUIT OF OLTC TRANSFORMER 64
APPENDIX B CHARACTERISTICS OF ALUMINUM CABLE STEEL REINFORCED 67
APPENDIX C OLTC TRANSFORMER 68
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