有功无功对三电平中点不平衡的影响

Influence on Active Power and Reactive Power for the Three-level Neutral Point Imbalance

在原有空间矢量中点电位分析的基础上,分析了中点偏移和波动与三电平变流器有功功率和无功功率的关系。将中点电流表达式Park变换到同步旋转的d,q坐标系中,然后分别分析d轴(有功)和q轴(无功)对中点电位的影响。先利用仿真分析得出结论,然后再通过实验验证结论的正确性。实验结果表明,有功功率主要影响中点电位的偏移,无功功率主要影响中点电位的波动。

Based on original space vector PWM neutral-point potential analysis,the relationship among the neutral point shift,fluctuation and the active power and reactive power of three level converter are analysed.The neutral point of the current expression transform from Park transformer to the synchronous rotation of the d,q coordinate sys-tem,then the infection of d axis（active power） and q axis（reactive power） on the neutral point potentials is anal-ysed.Firstly,the conclusion is simulated firstly,then the validity of conclusions is proved by the experiment.The ex-perimental results show that the active power mainly affects the shift of the neutral point potentials,reactive power mainly affects the fluctuations of neutral point potential.