D-STATCOM不平衡负载补偿与直流电压控制的研究

Study on Unbalanced Load Compensation and DC Voltage Control for D-STATCOM

配电网中的不平衡负载会造成配电网静止同步补偿器(D-STATCOM)并网连接点电压的不对称,该不对称电压会导致D-STATCOM直流电压2倍频的波动。而D-STATCOM的指令电流检测中通常加入了直流电压控制,直流电压的波动会直接影响指令电流的检测效果。在此基础上,提出一种改进的指令电流检测法,该方法通过对直流电压控制量进行平均值滤波处理,减小直流电压波动对不平衡电流检测的影响。同时,为了抑制DSTATCOM启动时过大的冲击电流,对直流电压采用了分级电压控制,该控制也基本消除了直流升压过程的超调,保护了D-STATCOM设备的安全。仿真和试验结果验证了上述方案的正确性。

A large number of unbalanced load in distribution network may result in voltage asymmetry of common connection point with distribution network static synchronous compensator,which will lead to two times frequency wave of DC voltage in D-STATCOM.Moreover,DC voltage control is usually applied to command current detection in D-STATCOM,so the DC voltage fluctuation will directly affect the command current detection effect.Based in which,the paper proposes an improved command current detection method,using mean filtering of the DC voltage controlled quantity to reduce the impact of the DC voltage fluctuation on the unbalance current detection.Meanwhile,in order to suppress excessive inrush current when the D-STATCOM starts,hierarchical voltage control is used for the DC voltage control,which also basically eliminates DC voltage overshoot and ensures the safety of D-STATCOM devices.Simulation and experimental results verify the correctness of the above strategies.