Fast Selective Harmonic Detection and Compensation by Three Phase Cascaded Delayed Signal Cancellation with Shunt APF Circuit

Abstract

Fast and accurate selective harmonic detection has crucial value for many power system harmonic compensation systems.  The system can be flexibly configured to eliminate or attenuate fundamental harmonic and various background harmonics then detect targeted harmonic's magnitude, phase angle and frequency by PLL. That detected harmonic will be compensated by shunt active power filter circuit. The overall harmonic detection methods are known to have a few drawbacks, such as higher total harmonic distortion, long delay time, sensitivity to grid frequency variation, difficulty to achieve zero study state error and higher total harmonics distortion. In order to overcome these drawbacks, this paper proposes a selective harmonic detection system based on the three phase cascaded delayed signal cancellation with shunt active power filter circuit. It also features very short transient and excellent adaptability under small and considerable frequency variations. Finally this paper provides guidance on how to detect the targeted harmonic's magnitude phase angle and frequency. Also this paper compares the total harmonics distortion in overall harmonics detection method and selective harmonics detection method.