Wideband Harmonic Compensation with a Voltage-Source Hybrid Active Power Filter

In this paper a method for wideband harmonic compensation is presented. The main circuit configuration of the system is shown in Fig. 2. The system compensates the low order harmonics using a simple computational control delay compensation method, while the high order harmonics are filtered with a small passive high pass filter. In the system the whole filtering band of the APF is utilized and the filtering performance is recovered with an HPF when the ability of the APF to filter harmonics effectively is impaired. This way the size of the passive filter can be kept small. First the proposed control system is studied. Then the prototype built and the measurement results at various operating points are presented. The results are compared with other filtering methods. Finally power losses in the hybrid filter system are studied and compared to the losses of the voltage-source shunt APF.