Abstract：A DC capacitor voltage balance control strategy is proposed, in order to improve waveform quality of the output voltage and output current of cascade STATCOM based on step wave modulation method. This paper analyzed the relation of conduction mode, operating mode and capacitor voltage variation, summarized the four kind of operating regions(A, B, C, D) and numerical relationship between conduction angle and voltage variation in every region. The conduction mode in every region according to capacitor voltage sequencing result in every sampling point is selected, which makes the higher chain voltage, the smaller the voltage rise degree of A and D regions, and makes the higher chain voltage, the bigger the voltage decline degree of B and C regions, so that regulates capacitor voltage toward mean value. The parameters of link conduction angle and modulation ratio do not change in adjustment process. The value and variation of capacitor voltage on two adjacent sampling point are used to judge the operating mode (capacitive, inductive) in order to avoid operating mode judgment inaccuracy that be caused by PLL error. The experimental results verify the feasibility and effectiveness of the proposed control strategy on experimental platform of three-phase eleven-level cascade STATCOM.
杨波, 曾光, 钟彦儒, 周博. 阶梯波调制法链式STATCOM直流电容电压平衡控制[J]. 电工技术学报, 2013, 28(10): 280-287.
Yang Bo, Zeng Guang, Zhong Yanru, Zhou Bo. DC Capacitor Voltage Balance Control Strategy of Cascade STATCOM Based on Step Wave Modulation. Transactions of China Electrotechnical Society, 2013, 28(10): 280-287.
[1] Haque M H. Evaluation of First Swing Stability of a Large Power System With Various FACTS Devices[J]. IEEE Transactions on Power Systems, 2008, 23(3): 1144-1151. [2] de la Villa Jaen A, Acha E, Exposito A G. Voltage source converter modeling for power system state estimation: STATCOM and VSC-HVDC[J]. IEEE Transactions on Power Systems, 2008, 23(4): 1552-1559. [3] Yazdani A, Sepahvand H, Crow M L, et al. Fault detection and mitigation in multilevel converter STATCOMs[J]. IEEE Transactions on Industrial Electronics, 2011, 58(4): 1307-1315. [4] Hatano N, Ise T. Control scheme of cascaded H-bridge STATCOM using zero-sequence voltage and negative-sequence current[J]. IEEE Transactions on Power Delivery, 2010, 25(2): 543-550. [5] Qiang Song, Wenhua Liu. Control of a cascade STATCOM with star configuration under unbalanced conditions[J]. IEEE Transactions on Power Electronics, 2009, 24(1): 45-58. [6] 刘文华, 宋强, 滕乐天, 等．基于集成门极换向晶闸管与链式逆变器的±50Mvar静止同步补偿器[J]．中国电机工程学报, 2008, 28(15): 55-60. Liu Wenhua, Song Qiang, Teng Letian, et al. ±50Mvar STATCOM based on chain circuit converter employing IGCT’s[J]. Proceedings of the CSEE, 2008, 28(15): 55-60. [7] 刘文华, 宋强, 张东江, 等．50MVA STATCOM的链节及其背靠背额定工况运行试验[J]．电工技术学报, 2005, 20(2): 17-22. Liu Wenhua, Song Qiang, Zhang Dongjiang, et al. The link and it’s back-to-back rated operational tests of 50MVA STATCOM[J]. Transactions of China Electrotechnical Society, 2005, 20(2): 17-22. [8] 宫力, 康勇, 陈晶晶, 等．链式STATCOM直流电容电压分布式控制[J]．电工技术学报, 2011, 26(10): 217-223. Gong Li, Kang Yong, Chen Jingjing, et al. DC capacitor voltage distributed control system for cascaded multilevel STATCOM[J]. Transactions of China Electrotechnical Society, 2011, 26(10): 217-223. [9] Akagi H, Inoue S, Yoshii T. Control and performance of a transformerless cascade PWM STATCOM with star configuration[J]. IEEE Transactions on Industry Applications, 2007, 43(4): 1041-1049. [10] Peng F Z, Lai J S, McKeever J W, et al. A multilevel voltage-source inverter with separate DC sources for static var generation[J]. IEEE Transactions on Industry Applications, 1996, 32(5): 1130-1138. [11] Woodhouse M L, Donoghue M W, Osborne M M. Type testing of the GTO valves for a novel STATCOM convertor[C]. AC-DC Power Transmission, 28-30 November 2001 Conference Publication No485, IEE 2001. [12] 刘文华, 宋强, 滕乐天, 等．基于链式逆变器的50MVA静止同步补偿器的直流电压平衡控制[J]．中国电机工程学报, 2004, 24(4): 145-150. Liu Wenhua, Song Qiang, Teng Letian, et al. Balancing control of DC voltage of 50 MVA STATCOM based on cascade multilevel inverters[J]. Proceedings of the CSEE, 2004, 24(4): 145-150. [13] Song Qiang, Liu Wenhua, Yuan Zhichang. Multilevel optimal modulation and dynamic control strategies for STATCOMs using cascaded multilevel inverters [J]. IEEE Transactions on Power Delivery, 2007, 22(3): 1937-1946. [14] Yu Liu, Huang A Q, Wenchao Song, et al. Small-signal model-based control strategy for balancing individual DC capacitor voltages in cascade multilevel inverter-based STATCOM[J]. IEEE Transactions on Industrial Electronics, 2009, 56(6): 2259-2269. [15] Liu Zhao, Liu Bangyin, Duan Shanxu, et al. A novel DC capacitor voltage balance control method for cascade multilevel STATCOM[J]. IEEE Transactions on Power Electronics, 2012, 27(1): 14-27. [16] 刘钊, 刘邦银, 段善旭, 等．链式静止同步补偿器的直流电容电压平衡控制[J]．中国电机工程学报, 2009, 29(30): 7-12. [17] Li Yidan, Wu Bin. A novel DC voltage detection technique in the CHB inverter-based STATCOM [J]. IEEE Transactions on Power Delivery, 2008, 23(3): 1613-1619. [18] Rabinovici R, Baimel D, Tomasik J, et al. Series space vector modulation for multi-level cascaded H-bridge inverters[J]. IET Power Electronics, 2010, 3(6): 843-857. [19] 袁志昌, 宋强, 刘文华．规则采样对载波移相SPWM输出基波相位滞后的影响[J]．电工技术学报, 2010, 25(11): 107-112. Yuan Zhichang, Song Qiang, Liu Wenhua. The effect of regulated sampling on phase delay of phase-shift SPWM output[J]. Transactions of China Electro-technical Society, 2010, 25(11): 107-112. [20] Kang D W, Kim H C, Kim T J, et al. A simple method for acquiring the conducting angle in a multilevel cascaded inverter using step pulse waves[J]. IEE Proceedings-Electric Power Applications, 2005, 152(1): 103-111.
2013, Vol. 28 
