Patent ID: 7906872
Filing Date: 2011-03-15
Classification: H02M,H03H

Abstract:
1. A dynamic harmonic filter for an AC power system comprising at least one voltage source and at least one load, the harmonic filter comprising a current sensing or voltage injection transformer connected in series with the voltage source and the load with one end of the primary of the current sensing or voltage injection transformer connected to the voltage source and the other end of the primary of the current sensing or voltage injection transformer connected to the load, a current injection or voltage sensing transformer connected in parallel with the voltage source with one end of the primary of the current injection or voltage sensing transformer connected to the point of common coupling between the voltage source and the primary of the current sensing or voltage injection transformer and the other end of the primary of the current injection or voltage sensing transformer earthed, the net transformation ratio between the two transformers being unity and a parallel resonant LC circuit tuned to the fundamental frequency of the power system, one end of the secondary of the current injection or voltage sensing transformer being connected to one junction of the parallel resonant LC circuit and the other end of the secondary of the current injection or voltage sensing transformer being connected to the other junction of the parallel resonant LC circuit through the secondary of the current sensing or voltage injection transformer.