Detecting and close-loop control methods for selective-harmonic-compensation active power filter

This paper presents a selective harmonic detecting method and a new close-loop control algorithm for selective-harmonic-compensation active power filters (SHC-APF). The SHC-APF consists of a selective detection unit, DC voltage control and current control loops. Selective harmonic detection unit detects precisely the selected harmonic currents instead of all harmonics produced by distorting loads. At the same time, the unit adds a preceding compensatory angle in order to compensate the infection of delays caused by the digital controller and voltage-source inverter (VSI). The algorithms for the closed-loop control are discussed. Simulations for the harmonic detection and control loop response are implemented and the results confirm the theoretical analysis.