分散式電力系統之不平衡電壓補償方法｜國立清華大學博碩士論文庫

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研究生：	陳建安 Chien-An Chen
論文名稱：	分散式電力系統之不平衡電壓補償方法 An Unbalance Voltage Compensation method for the Distributed Generation System
指導教授：	鄭博泰 Po-Tai Cheng 鍾太郎 Tai-Lang Jong
口試委員:
學位類別：	碩士 Master
系所名稱：	電機資訊學院 - 電機工程學系 Department of Electrical Engineering
論文出版年：	2007
畢業學年度：	95
語文別：	英文
論文頁數：	81
中文關鍵詞：	分散式發電系統、不平衡負載、下降控制器、反流器
外文關鍵詞：	distributed generation system, unbalanced load, droop controller, inverter
相關次數：	點閱：2 下載：0
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近年來由於再生能源等小型發電源的普及，而這些小型發電源連結成分散式發電系統的型態已成為一種新興的趨勢。在分散式發電系統中，為了解決各分散式發電系統間電力潮流分配的問題，實功率-頻率與虛功率-電壓振幅下降控制器已被應用在電力系統與小型發電源作為介面的反流器中。然而，當系統中有不平衡負載，前述的功率分配控制器無法有效率的分配不平衡的電流。儘管已有相關的研究針對不平衡負載作電壓，然而不平衡電流的分配問題仍無法獲得解決。
因此這此論文中提出一個負序虛功率-負序導納的下降控制器，此控制器能使反流器產生負序導納，並根據各個反流器所輸出的負序功率來調整其導納，以達到在不需通訊的情況下，自動分配不平衡電流以及抑制不平衡電壓的功能。此控制器能順利的與實功率、虛功率分配下降整合運作分配實功、虛功、負序虛功。使得分散式電力系統在不平衡負載的情況下，在系統中各反流器間仍能依據其額定，自動的分配其輸出能量。
為了驗證所提出的控制器，相關的硬體實驗與模擬將會在此論文中架設並近一步的分析討論。

As regeneration sources become more and more popular, distributed generation (DG) system which integrates these small power sources has become a trend for future power system. In DG system, to balance power flow from each microsource, the power-frequency droop and reactive power-voltage droop controllers are applied in converters which interface the microsources. However, when the system is connected with imbalanced load, the droop controllers can not equally distribute the unbalanced current. Previous studies about line imbalance can maintain symmetrical line voltages under load imbalance, yet the distribution of the unbalanced current is not addressed in these literatures. Consequently, the unbalanced workload distribution among converters is still a problem to be solved.
To approach this problem, a droop controller is proposed to share the unbalanced current in DG system. In this controller, a negative sequence conductance G is introduced in each converter, and the conductance command will be determined by the negative sequence reactive power Q— of each converter. Through the droop control of the conductance, the unbalanced current will be shared among converters without communication, and also the implementation of the conductance will reduce the unbalanced voltage level. The proposed controller can be seamlessly combined with P-f droop and Q-v droop controllers to share the power, reactive power and negative sequence reactive power between converters. Therefore, an automatically energy distribution proportional to the capacity of each converter can thus be achieved in the distributed generation system under imbalanced loading.
To realize the control method, hardware test and simulation of DG system will be constructed and analyzed in the thesis.

LIST OF FIGURES    3
LIST OF TABLES    5
Chapter 1 Introduction    6
2 Unbalanced Phenomenon    7
3 Solution of unbalanced phenomenon    8
4 Proposed Negative Sequence Controller in DGS    8
5 Power and Reactive Power Droop Controllers in DGS    9
6 Summary    10
7 Organization of the thesis    10
Chapter 2 Literature Review    12
1 introduction    12
2 SRF 2-PI voltage controller    12
3 SRF PI controller on positive sequence component    15
4 Negative sequence current compensation    16
5 G-S droop in DGS     20
6 Summary    21
Chapter 3 Operation Principle of Unbalanced Compensation DGU    22
1 Introduction    22
2 Unbalance analysis    23
3 Control block diagram    25
4 Q—-G droop    27
4.1 negative sequence reactive power Q—      28
4.2 Q— calculation in controller    30
4.3 Q—-G droop analysis    32
5 P-F & Q-V droop    34
6 Voltage and current controller    36
7 Summary    37
Chapter 4 Simulation Results    38
1 Introduction    38
2 Configuration of Simulation Circuit    39
3 Voltage imbalance under open loop controller    41
4 Comparison conventional controller (P-f and Q-v droop) without and with Q—-G droop    42
4.1 Positive sequence parts (P,Q) result and analysis    43
4.2 negative sequence parts (Q-, V ) results and analysis    44
4.3 Output currents results and analysis with Q—-G droop controller    46
4.4 Summary of the section    47
5 Comparison with constant G control and the Q—-G droop    48
5.1 negative sequence parts (Q- ,G ,V) results and analysis    48
5.2 Summary of the section    50
6 DGUs of different capacity    50
4.4 Summary of the section    54
7 Summary    54
Chapter 5 Experimental Results    56
1 Introduction    56
2 Hardware and controller configuration    56
3 Grid connected mode    59
4 Islanding mode    62
4.1 DGUs of the same capacity    63
4.2 DGUs of the different capacity    65
4.3 Summary of islanding mode    67
5 Summary    68
Chapter 6 Conclusion and Future Work    69
1 Conclusion    69
2 Future Work    70
References    71
Appendix A    75
A.1 The laboratory test bench : inverter 1    75
A.2 The laboratory test bench : inverter 2    78
Appendix B    79
B.1 Three phase diode bridge datasheet    79
B-2 IGBT datasheet    80
Appendix C    81
C-1 Protection block circuit    81

                                

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