Damping Techniques of Harmonic Resonances in Power Distribution Systems

Harmonic resonances may damage equipments and interrupt electric power customers services. Shutdowns may affect seriously harmonic resonant frequencies and may initiate new resonances in distribution power systems. This paper proposes various techniques for damping harmonic resonances in power systems[1-4]. A series reactor should be connected in series with the shunt power factor correction capacitor, damping resistance across inductor terminals of LC passive filter, increasing the short circuit system power, derating the harmonic generating equipment, and by using hybrid active filters. The hybrid active filters consists of active filter connected in shunt with passive filter. The active filter is characterized by detecting the harmonic current flowing into the passive filter. It is controlled in such a way as to behave as resistor by adjusting certain gain. It is proved that this significantly improves damping of the harmonic resonances, compared with the passive filter when used alone[5-7].