Abstract:Under unbalanced conditions, the three-phase four-leg inverter parallel system not only can output balanced three-phase voltage waveforms, but also can expand the capacity of the system. Compared with the traditional three-leg inverter parallel system, the three-phase four-leg inverter parallel system need to control the positive, negative and zero sequence current, so the control of three-phase four-leg inverter parallel system is more complex. In this paper, the distribution of the sequence current in parallel operation of three-phase four-leg inverter is analyzed. In order to make the inverter output of positive, negative and zero sequence current to distribute according to the parallel inverter capacity. This paper puts forward a new control method that the positive sequence current uses a droop control, negative sequence current and the fourth leg current use virtual impedance method respectively control the positive sequence current, negative sequence current and zero sequence current distribution of the inverter output, and the front three leg and the fourth leg of the three-phase four-leg inverter control independently. Finally, the output voltage is balanced at the same time the output current and the output power of the parallel system are distributed according to the capacity of the parallel inverter under unbalanced conditions, and the circulation of the system is reduced. The correctness of the method is verified by simulation and experiment.
闫朝阳, 白鹤, 张喆, 李建霞. 不平衡工况下基于虚拟阻抗法的并联三相四桥臂逆变器的桥臂控制[J]. 电工技术学报, 2017, 32(23): 207-219.
Yan Zhaoyang, Bai He, Zhang Zhe, Li Jianxia. Leg Control of Parallel Three-Phase Four-Leg Inverter Based on Virtual Impedance Method under Unbalanced Conditions. Transactions of China Electrotechnical Society, 2017, 32(23): 207-219.
[1] Zhong Qingchang. Robust droop controller for accurate proportional load sharing among inverters operated in parallel[J]. IEEE Transactions on Industrial Electronics, 2013, 60(4): 1281-1290. [2] Xu Zhuang, Li Rui, Zhu Hui, et al. Control of parallel multiple converters for direct-drive permanentmagent wind power generation systems[J]. IEEE Transactions on Power Electronics, 2012, 27(3): 1259-1270. [3] 林燎源, 林钊, 刘伟, 等. 基于阻性下垂的逆变器无线并联均流控制[J]. 电工技术学报, 2016, 31(8): 43-50. Lin Liaoyuan, Lin Zhao, Liu Wei, et al. Wireless current sharing scheme for parallel operation of inverters using resistive output impedance [J]. Transactions of China Electrotechnical Society, 2016, 31(8): 43-50. [4] 吕志鹏, 苏剑, 李蕊, 等. 不同功率等级微源逆变器并联控制新方法[J]. 电工技术学报, 2013, 28(7): 192-198. Lü Zhipeng, Su Jian, Li Rui, et al. New power control strategy on paralleled micro-Source inverters with different power levels[J]. Transactions of China Electrotechnical Society, 2013, 28(7): 192-198. [5] 陈宏志, 王旭, 刘建昌. 基于虚拟电阻匹配模式的逆变器并联方案[J]. 中国电机工程学报, 2012, 32(6): 24-32. Chen Hongzhi, Wang Xu, Liu Jianchang. Current sharing method for parallel inverters based impedance matching mode[J]. Proceedings of the CSEE, 2012, 32(6): 24-32. [6] 阮新波, 严仰光. 四桥臂三相逆变器的控制策略[J]. 电工技术学报, 2000, 15(1): 61-64. Ruan Xinbo, Yan Yangguang. The control strategy for three-phase inverter with four bridge legs[J]. Transactions of China Electrotechnical Society, 2000, 15(1): 61-64. [7] 陈轶涵, 任磊, 邓翔, 等. 一种基于3次谐波注入的并联三相四桥臂逆变器均流控制策略[J]. 电工技术学报, 2016, 31(4): 104-113. Chen Yihan, Ren Lei, Deng Xiang, et al. Current sharing control method for parallel three phase four leg inverter based on third harmonic injection[J]. Transactions of China Electrotechnical Society, 2016, 31(4): 104-113. [8] Rivera M, Yaramasu V, Llor A. Digital predictive current control of a three-phase four-leg inverter[J]. IEEE Transactions on Industrial Electronics, 2013, 60(11): 4903-4912. [9] 孙驰, 马伟明, 鲁军勇. 三相逆变器输出电压不平衡的产生机理分析与其矫正[J]. 中国电机工程学报, 2006, 26(21): 57-64. Sun Chi, Ma Weiming, Lu Junyong. Analysis of the unsymmetrical output voltages distortion mechanism of three-phase inverter and its corrections[J]. Proceedings of the CSEE, 2006, 26(21): 57-64. [10] Vechiu I, Curea O, Camblong H. Transient operation of a four-leg inverter for autonomous applications with unbalanced load[J]. IEEE Transactions on Power Electronics, 2010, 25(2): 399-407. [11] 刘秀翀, 张化光, 陈宏志. 四桥臂逆变器中第四桥臂的控制策略[J]. 中国电机工程学报, 2007, 27(33): 87-92. Liu Xiuchong, Zhang Huaguang, Chen Hongzhi. Control strategy of fourth leg in four-leg inverter[J]. Transactions of China Electrotechnical Society, 2007, 27(33): 87-92. [12] Marwali M N, Jin-Woo J, Keyhani A. Control of distributed generation systems-part II: load sharing control[J]. IEEE Transactions on Power Electronics, 2004, 19(6): 1551-1561. [13] Prodanovic M, Green T C. High-quality power generation through distributed control of a power park microgrid[J]. IEEE Transactions on Industrial Electronics, 2006, 53(5): 1471-1482. [14] Cheng P T, Chen C A, Lee T L, et al. A cooperative imbalance compensation method for distributed-generation interface converters [J]. IEEE Transactions on Industrial Electronics, 2009, 45(2): 805-815. [15] 周啸, 金新民, 唐芬, 等. 微电网孤岛工况下基于四桥臂变流器的不平衡负载分配策略[J]. 电工技术学报, 2015, 30(12): 76-86. Zhou Xiao, Jin Xinmin, Tang Fen, et al. Four-leg converter based unbalanced load sharing method in islanding microgrid[J]. Transactions of China Electrotechnical Society, 2015, 30(12): 76-86. [16] Wang Xianwei, Zhuo Fang, Li Jing, et al. Modeling and control of dual-stage high-power multifunctional PV system in d-q-0 coordinate[J]. IEEE Transactions on Industrial Electronics, 2013, 64(4): 1556-1570. [17] 陈轶涵, 沈茜, 任磊, 等. 基于虚拟阻抗分析的并联三相四桥臂逆变器环流抑制[J]. 电工技术学报, 2016, 31(8): 51-62. Chen Yihan, Shen Qian, Ren Lei, et al. Output impedance analysis for circulating current minimization of paralleled three phase four leg inverter [J]. Transactions of China Electrotechnical Society, 2016, 31(8): 51-62. [18] 林金燕, 王正仕, 陈辉明, 等. 一种高性能三相四桥臂逆变器控制器的设计[J]. 中国电机工程学报, 2007, 27(22): 101-105. Lin Jinyan, Wang Zhengshi, Chen Huiming, et al. High performance controller design for three-phase four-leg inverters[J]. Proceedings of the CSEE, 2007, 27(22): 101-105.