近年來，綠能產業透過國家政策的積極推動，不斷提升其在市場上之地位，其中太陽能光伏系統已在業界中受到廣泛運用。由於太陽能光伏系統經常應用於中、高壓層級，因此電力轉換器中之元件需承受較大之電壓應力，利用星型串聯橋式轉換器架構來確保開關元件的應力範圍，也因此該電路架構被廣泛應用於此系統上。然而隨著串聯模組的增加，將導致控制器之迴授訊號大量增加且使模組訊號間之通訊複雜度提升，也因此大幅提升系統實踐之難度。本篇論文提出一種分散式之控制策略來減少迴授訊息量藉此解決上述之問題，同時考慮到法規在低電壓過渡(LVRT)期間所要求的條件。透過實際機台測試及模擬結果驗證此控制策略在減少通訊量及市電驟降情形下之平衡能力。

In recent years, many renewable energy systems (RESs) have been installed in the power system due to the government policies, and photovoltaic (PV) devices play an important role in RESs. Since these RESs are usually installed at medium voltage level, the modular multilevel cascaded converter with the configuration of single-star bridge cells (MMCC-SSBC) has drawn an interest in PV system. Connecting the cells in series can assure a low voltage stress of each device. As the cascaded numbers increase, the significant numbers of feedback signals, such as DC bus voltage and IGBT’s gate signal, enhance the control complexity, and hence normal operation in each cell should be confirmed in order to prevent unstable system. This thesis proposes a distributed control strategy to reduce amount of sensors, and low voltage ride through (LVRT) is also taken into consideration. The laboratory test results and simulation results are given to verify the effcetiveness of the proposed method.

目錄...........................................................IV
圖目錄.........................................................VI
表目錄.........................................................XI
第一章、緒論....................................................1
1.1、研究背景與動機.............................................1
1.2、論文內容概述...............................................3
第二章、文獻回顧................................................4
2.1、簡介.......................................................4
2.2、相位移之單極性正弦脈波寬度調變.............................4
2.3、平均功率潮流分析 (Power Flow Analysis).....................6
2.4、實驗室提出之平均功率平衡法-零序電壓注入(APB-ZVI)..........13
2.5、預測電流控制..............................................19
2.6、單相鎖相..................................................22
第三章、操作原理...............................................24
3.1、簡介......................................................24
3.2、分散式控制策略應用於單相系統..............................26
3.3、分散式控制策略應用於三相系統..............................32
3.3.1、分散式控制策略之三相鎖相................................32
3.3.2、分散式控制策略之整體電流命令............................33
3.3.3、分散式控制策略之預測電流控制............................36
3.3.4、分散式控制策略之簇功率控制..............................38
3.3.5、分散式控制策略之獨立電壓控制............................44
3.4、電壓調變分析..............................................47
3.4.1、負載變動之電壓調變......................................47
3.4.2、低電壓過渡之電壓調變....................................57
第四章、理論模擬數據...........................................64
4.1、簡介......................................................64
4.2、平衡狀態操作..............................................66
4.3、負載變動操作..............................................68
4.3.1、獨立電壓控制模塊切換半載................................68
4.3.2、整體電流控制模塊切換半載................................72
4.3.3、獨立及整體控制模塊切換半載(同相)........................75
4.3.4、獨立及整體控制模塊切換半載(非同相)......................78
4.4、低電壓過渡操作............................................81
4.4.1、單相驟降30%.............................................82
4.4.2、雙相驟降30%.............................................85
4.4.3、三相驟降30%.............................................88
第五章、機台實驗結果...........................................91
5.1、簡介......................................................91
5.2、三相平衡負載操作波形圖....................................94
5.3、三相不平衡負載波形圖......................................96
5.3.1、獨立直流鏈電壓控制模塊輕載切換..........................96
5.3.2、整體電流控制模塊輕載切換................................99
5.4、低電壓過渡波形圖.........................................102
第六章、結論與未來展望........................................105
6.1、結論.....................................................105
6.2、未來展望.................................................106

[ 1 ]
H. Akagi, "Classification, Terminology, and Application of the Modular Multilevel Cascade Converter (MMCC)," in IEEE Transactions on Power Electronics, vol. 26, no. 11, pp. 3119-3130, Nov. 2011.

[ 2 ]
L. M. Tolbert and F. Z. Peng, "Multilevel converters as a utility interface for renewable energy systems," Power Engineering Society Summer Meeting, 2000. IEEE, Seattle, WA, 2000, pp. 1271-1274 vol. 2.

[ 3 ]
H. Akagi, S. Inoue and T. Yoshii, "Control and Performance of a Transformerless Cascade PWM STATCOM With Star Configuration," in IEEE Transactions on Industry Applications, vol. 43, no. 4, pp. 1041-1049, July-aug. 2007.

[ 4 ]
L. Maharjan, S. Inoue and H. Akagi, "A Transformerless Energy Storage System Based on a Cascade Multilevel PWM Converter With Star Configuration," in IEEE Transactions on Industry Applications, vol. 44, no. 5, pp. 1621-1630, Sept.-Oct. 2008.

[ 5 ]
Yiqiao Liang and C. O. Nwankpa, "A new type of STATCOM based on cascading voltage-source inverters with phase-shifted unipolar SPWM," in IEEE Transactions on Industry Applications, vol. 35, no. 5, pp. 1118-1123, Sep/Oct 1999.

[ 6 ]
Hyosung Kim and H. Akagi, "The instantaneous power theory on the rotating p-q-r reference frames," Power Electronics and Drive Systems, 1999. PEDS '99. Proceedings of the IEEE 1999 International Conference on, 1999, pp. 422-427 vol.1.

[ 7 ]
Akagi, Hirofumi, Edson Hirokazu Watanabe, and Mauricio Aredes. Instantaneous power theory and applications to power conditioning. Vol. 31. John Wiley & Sons, 2007.

[ 8 ]
C. T. Lee, H. C. Chen, C. W. Wang, P. H. Wu, C. H. Yang and P. T. Cheng, "A flexible DC voltage balancing control based on the power flow management for star-connected cascaded H-bridge converter," 2014 IEEE Energy Conversion Congress and Exposition (ECCE), Pittsburgh, PA, 2014, pp. 3922-3929.

[ 9 ]
C. T. Lee, H. C. Chen, C. W. Wang, P. H. Wu, C. H. Yang and P. T. Cheng, "Zero-sequence voltage injection for DC capacitor voltage balancing control of the star-connected cascaded H-bridge PWM converter under unbalanced grid," 2014 IEEE Energy Conversion Congress and Exposition (ECCE), Pittsburgh, PA, 2014, pp. 4670-4676.

[ 10 ]
H. C. Chen, S. Y. Tsai, P. H. Wu, W. L. Huang and P. T. Cheng, "Managed DC voltage utilization technique for the renewable energy source based on the star-connected cascaded H-bridges converter," 2015 IEEE Energy Conversion Congress and Exposition (ECCE), Montreal, QC, 2015, pp. 3726-3733.

[ 11 ]
e. behrouzian; M. Bongiorno, "Investigation of Negative-Sequence Injection Capability of Cascaded H-Bridge Converters in Star and Delta Configuration," in IEEE Transactions on Power Electronics , vol.PP, no.99, pp.1-1

[ 12 ]
T. M. Rowan and R. J. Kerkman, "A New Synchronous Current Regulator and an Analysis of Current-Regulated PWM Inverters," in IEEE Transactions on Industry Applications, vol. IA-22, no. 4, pp. 678-690, July 1986.

[ 13 ]
L. N. Amuda, B. J. Cardoso Filho, S. M. Silva, S. R. Silva and A. S. A. C. Diniz, "Wide bandwidth single and three-phase PLL structures for grid-tied PV systems," Photovoltaic Specialists Conference, 2000. Conference Record of the Twenty-Eighth IEEE, Anchorage, AK, 2000, pp. 1660-1663.

[ 14 ]
C. T. Lee, C. W. Hsu and P. T. Cheng, "A Low-Voltage Ride-Through Technique for Grid-Connected Converters of Distributed Energy Resources," in IEEE Transactions on Industry Applications, vol. 47, no. 4, pp. 1821-1832, July-Aug. 2011.

[ 15 ]
B. Xiao, L. Hang, J. Mei, C. Riley, L. M. Tolbert and B. Ozpineci, "Modular Cascaded H-Bridge Multilevel PV Inverter With Distributed MPPT for Grid-Connected Applications," in IEEE Transactions on Industry Applications, vol. 51, no. 2, pp. 1722-1731, March-April 2015.