Abstract：Instability phenomenon exists in practical applications of the direct output current control for LCL interfaced grid-connected inverters. In order to clarify its nature, the system control linear model is developed, and the characteristic equations are deduced. Based on the Routh-Hurwitz stability criterion, a significant conclusion is reached that instability is unavoidable whatever P, PI or PID control is used. A straightforward solution is to put resistors in series with the LCL filter so as to increase the phase margin and improve the system stability. The relationship between resistances, control parameters and stability margins is analyzed and quantified precisely. Finally, the influence of nonlinear factors such as the switching and over modulation saturation on the validity of conclusions is discussed.
郭小强, 邬伟扬, 顾和荣, 王立乔, 赵清林. 并网逆变器LCL接口直接输出电流控制建模及稳定性分析[J]. 电工技术学报, 2010, 25(3): 102-109.
Guo Xiaoqiang, Wu Weiyang, Gu Herong, Wang Liqiao, Zhao Qinglin. Modelling and Stability Analysis of Direct Output Current Control for LCL Interfaced Grid-Connected Inverters. Transactions of China Electrotechnical Society, 2010, 25(3): 102-109.
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2010, Vol. 25 
