A practical approach to harmonic compensation in power systems-series connection of passive and active filters

A combined system consisting of a passive filter and a small-rated active filter that are connected in series is discussed as a method of overcoming power system harmonic interferences caused by harmonic-producing loads such as diode or thyristor converters and cycloconverters. The system features filtering characteristics independent of the source impedance, parallel and series resonance between the source and the passive filter that is dumped by the active filter, and a required rating of the active filter which is much smaller than that of a conventional active filter. Experimental results obtained from a prototype model are shown to verify the developed theory.<>