Abstract：Grid-interfacing filter that is usually adopted to mitigate switching frequency harmonics introduced by pulse width modulation procedure has a significant influence on inverter system performance, volume and cost. Based on in-depth analysis of harmonic attenuation characteristics of L, LCL and LLCL filters, a unified circuit model of grid-interfacing filter is proposed in this paper. Through topology deduction and performance comparisons of the five-order and the following filters, two new filters, LLCCL1 and LLCCL2 filters, are developed. Mitigations of the high frequency harmonics from the inverter side, suppressions of the high frequency harmonics from the grid side, design methods of filter parameters and passive damping of the resonance peaks are comprehensively investigated and compared among different types of filter structures. Theoretical analysis and simulation results are presented to demonstrate the correctness of the proposed new LLCCL1 and LLCCL2 filters as well as the effectiveness of the addressed deduction methods of filter topologies.
[1] Wang F, Duarte J L, Hendrix M A M, et al. Modeling and analysis of grid harmonic distortion impact of aggregated DG inverters[J]. IEEE Transactions on Power Electronics, 2011, 26(3): 786-797. [2] Castilla M, Miret J, Matas J, et al. Control design guidelines for single-phase grid-connected photovoltaic inverters with damped resonant harmonic compensators [J]. IEEE Transactions on Industrial Electronics, 2009, 56(11): 4492-4501. [3] Liserre M, Teodorescu R, Blaabjerg F. Stability of photovoltaic and wind turbine grid-connected inverters for a large set of grid impedance values[J]. IEEE Transactions on Power Electronics, 2006, 21(1): 263- 272. [4] 王学华, 阮新波, 刘尚伟. 抑制电网背景谐波影响的并网逆变器控制策略[J]. 中国电机工程学报, 2011, 31(6): 7-14. Wang Xuehua, Ruan Xinbo, Liu Shangwei. Control strategy for grid-connected inverter to suppress current distortion effected by background harmonics in grid voltage[J]. Proceedings of the CSEE, 2011, 31(6): 7-14. [5] Gabe I J, Montagner V F, Pinheiro H. Design and implementation of a robust current controller for VSI connected to the grid through an LCL filter[J]. IEEE Transactions on Power Electronics, 2009, 24(6): 1444- 1452. [6] Khajehoddin S A, Ghartemani M K, Jain P K, et al. A control design approach for three-phase grid-connected renewable energy resources[J]. IEEE Transactions on Sustainable Energy, 2011, 2(4): 423-432. [7] Lindgren M, Svensson J. Connecting fast switching voltage-source converters to the grid-harmonic distor- tion and its reduction[C]. Strock Power Tech. Con- ference, Stockholm: IEEE, 1995: 191-195. [8] 王斯然, 吕征宇. LCL型并网逆变器中重复控制方法研究[J]. 中国电机工程学报, 2010, 30(27): 69-75. Wang Siran, Lü Zhengyu. Research on repetitive control method applied to grid-connected inverter with LCL filter[J]. Proceedings of the CSEE, 2010, 30(27): 69-75. [9] 胡雪峰, 龚春英, 陈新, 等. 三相T型滤波并网逆变电源的网侧电流直接控制技术[J]. 电工技术学报, 2012, 27(1): 9-16. Hu Xuefeng, Gong Chunying, Chen Xin, et al. Direct grid current control of the three-phase grid-connected inverter through T filter[J]. Transactions of China Electrotechnical Society, 2012, 27(1): 9-16. [10] Wu W, Blaabjerg F. An LLCL power filter for single- phase grid-tied inverter[J]. IEEE Transactions on Power Electronics, 2012, 27(2): 782-789. [11] Liserre M, Blaabjerg F, Hansen S. Design and control of an LCL filter-based three-phase active rectifier[J]. IEEE Transactions on Industrial Applications, 2005, 41(5): 1281-1291. [12] 刘飞, 查晓明, 段善旭. 三相并网逆变器LCL滤波器的参数设计与研究[J]. 电工技术学报, 2010, 25(3): 110-116. Liu Fei, Zha Xiaoming, Duan Shanxu. Design and research on parameter of LCL filter in three-phase grid-connected inverter[J]. Transactions of China Electrotechnical Society, 2010, 25(3): 110-116. [13] Jalili K, Bernet S. Design of filters of active-front-end two-level voltage-source converters[J]. IEEE Transac- tions on Industrial Electronics, 2009, 56(5): 1674- 1689. [14] Wu Weimin, Huang Min, Sun Yunjie, et al. A composite passive damping method of the LLCL-filter based grid- tied inverter[C]. IEEE International Symposium on Power Electronics for Distributed Generation Systems, Aalborg, 2012: 759-766. [15] Pena-Alzola R, Liserre M, Blaabjerg F, et al. Analysis of the passive damping losses in LCL-filter-based grid converters[J]. IEEE Transactions on Power Electronics, 2013, 28(6): 2642-2646. [16] 张宪平, 李亚西, 许洪华. 新型拓扑滤波器的双馈风电网侧变流器阻尼策略[J]. 中国电机工程学报, 2009, 29(21): 1-7. Zhang Xianping, Li Yaxi, Xu Honghua. Damping strategy of grid-side converter with new topology filter in doubly-fed wind power system[J]. Proceedings of the CSEE, 2009, 29(21): 1-7. [17] 伍小杰, 孙蔚, 戴鹏, 等. 一种虚拟电阻并联电容有源阻尼法[J]. 电工技术学报, 2010, 25(10): 122- 128. Wu Xiaojie, Sun Wei, Dai Peng, et al. An active damping method of virtual resistor[J]. Transactions of China Electrotechnical Society, 2010, 25(10): 122- 128. [18] 王要强, 吴凤江, 孙力, 等. 阻尼损耗最小化的LCL滤波器参数优化设计[J]. 中国电机工程学报, 2010, 30(27): 90-95. Wang Yaoqiang, Wu Fengjiang, Sun Li, et al. Optimized design of LCL filter for minimal damping power loss [J]. Proceedings of the CSEE, 2010, 30(27): 90-95. [19] 许津铭, 谢少军, 肖华锋. LCL滤波器有源阻尼控制机制研究[J]. 中国电机工程学报, 2012, 32(9): 27-33. Xu Jinming, Xie Shaojun, Xiao Huafeng. Research on control mechanism of active damping for LCL filters [J]. Proceedings of the CSEE, 2012, 32(9): 27-33.
2015, Vol. 30 
