采用双共模内回路抑制非隔离光伏并网系统的共模电流的研究

非隔离光伏并网系统中共模电流高频分量的存在会使系统稳定性下降,在低功率运行时,对发电质量影响较大。单共模内回路法对高频分量抑制效果不理想。在构建共模电路等效模型,分析共模电流产生原因的基础上,提出了一种构建双共模内回路抑制共模电流高频分量方法。该方法在保证共模电流满足并网要求的前提下克服了单共模内回路发生高频谐振的缺点,很好地抑制了外部寄生回路共模电流中的高频分量。最后通过仿真和实验证明了所提方法的有效性。

Research of Common-Mode Current Suppression in Non-Isolated PV Grid-Connected System with Double Common-Mode Inner Loops

The existence of high-frequency components in common-mode (CM) current would reduce the stability of non-isolated PV grid-connected system. In low power operation, it has great impacts on the output power quality. The single CM inner loop method in suppressing the high-frequency components was not ideal. Based on the CM equivalent circuit model and the causes of the CM current, a novel double CM inner loops method was proposed to restrain the high-frequency components in CM current. This method not only meets the grid connection demand of CM current, but also overcomes the high frequency resonant problem. Furthermore, the high-frequency components in CM current are substantially reduced. The simulating and experimental results have verified the proposed method.