一种提高三相VSR直流母线电压控制能力的方法

Enhancement of DC voltage control for three-phase VSR

在三相VSR系统中,当直流母线电压跌落较大时会导致交流侧电压饱和,从而引起交流侧电流畸变和系统的动态响应变差。针对该问题,通过分析三相VSR直流侧电压对交流侧电流的影响以及交流侧矢量关系,提出从电网吸收或向其注入一定无功功率的方法。同时给出了给定无功电流的选取方法。实验结果表明,当直流母线电压跌落并导致变换器交流侧电压饱和时,所提方法可使交流侧电压降低到线性调制区域,降低了交流侧电流的畸变率,改善了系统的动态响应。

In three-phase VSR system,the decline of DC-bus voltage may lead to the saturation of AC-side voltage,resulting in AC-side current distortion and system dynamic response degradation,for which,a method to absorb or inject the reactive power from or into the power grid is proposed.The AC-side vector relationship of three-phase VSR and the influence of its DC-bus voltage on AC-side current are analyzed and the method to select the reference reactive current is given.Experimental results show that,when DC-bus voltage declines and AC-side voltage is saturated,the AC-side voltage is decreased into the linear modulation region by the proposed method,which reduces the distortion of AC-side current and improves the dynamic response of system.