Selective Harmonic Elimination Using Shunt Hybrid Active Power Filters Operating At Different Switching Frequencies

Abstract: Active filtering of electric power has now become a mature technology for harmonic and reactive power compensation in ac networks. This paper proposes a combination of low- and high frequency hybrid active power filter (APF) to operate in parallel for better performance. The individual hybrid Active Power Filter is a series combination of passive filter with the corresponding voltage source inverter. The dc links of both inverters are connected in parallel, and the voltage of this dc link is maintained by the low-frequency inverter (LFI). The low-and high-frequency inverters eliminate lower and higher order harmonics respectively. In addition, it is possible to design the LFI such that it can also compensate the reactive power of the load. The individual passive filter of the hybrid topology is designed to take care of specific order of harmonics that are predominant in the load. In this paper a design for a three phase active power filter use a reduced switch (B4) topology and one cycle control is presented. The B4 topology offers the advantage of reduced cost and bridge losses at the expense of device stress and increased DC-side voltage. This design also provides the advantages associated with one cycle control. The performances of the proposed topology and the controller are examined by MATLAB/SIMULINK-based simulation.

Keywords: Hybrid Active Power Filter (APF), harmonics, passive filter, reduced switch topology.