Control of three-phase power filter with direct calculation of load current´s active fundamental harmonic

Supply network pollution, produced by nonlinear loads, can be reduced in many different ways. This paper presents a solution, where a three-phase parallel active filter is used. The filter, that generates reactive power required by load, is controlled by microprocessor, which calculates the active fundamental harmonic of load current for all three phases and consequently determines the filter current. Several approaches of synchronization to the network are discussed and the obtained results are presented.