Direct power control of reduced switch active filters

Nonlinear and time variant loads generate harmonic currents in power systems. Active filters (AF) are used to reduce the amplitude of these currents or omit them. Different control strategies have been presented for AF that among them the p-q theory is more popular. In this paper direct power control (DPC) method is used to implement the p-q theory. Active and reactive power of load and AF are measured and command values are calculated to compensate the load reactive power and just the oscillating part of load active power. The used converter is a reduced switch AF and has two switches less than a conventional full bridge AF, so this leads to less cost, complexity and loss. The simulation results show the excellent performance of this structure with zero source reactive power and a dc active power.