A phase A fundamental positive sequence voltage selected unit based on LPF substitutes for the original ip-iq PLL to ensure exact voltage of A phase is selected even in case of imbalance three phase voltage.

• 并采用一种新颖的基于低通滤波的A相正序电压提取单元来代替原始的ip-iq检测法的PLL锁相环,在三相电压畸变情况下仍可以正确提取A相正序电压,以精确检测出谐波和无功电流。