Study on the compensation delay and its countermeasure of active power filter

The effect of compensation delay, which is caused by compensation reference calculation and current control, on the performance of active power filter (APF) is analyzed. It can be seen that the compensation of high order harmonics is degraded seriously by even small time delay. The reason causing time delay is analyzed in case of digital control and digital-analog hybrid control. Then the current control method without compensation error is figured out. On this basis, a simple and effective phase compensation method is presented to compensate the time delay caused by compensation reference calculation and current control. Moreover, a simple predictor is implemented to improve the dynamic performance of APF, which essentially does not increase the complexity of calculation. Finally, testing results on an experimental shunt APF are presented to validate the proposed method.