Research on a novel series-shunt hybrid active power filter based on fundamental magnetic potential self-balance

In this paper, a novel series-shunt hybrid active power filter based on fundamental magnetic potential self-balance is proposed. It is found that if a LC fundamental series-connected resonance branch is connected in the second side of a zero magnetic flux current converter, the series zero magnetic flux current converter will present low reactance to fundamental and the high impedance to the harmonics. At the same time, the harmonic current waveform can be measured by the testing winding of the zero magnetic flux current converter. The voltage-source PWM converter is controlled as a harmonic voltage source. Where, the voltage-source PWM converter is connected to the passive filters in series through an isolation transformer. As a result, the proposed active power filter really acts a "harmonic isolator", so the harmonic current that flows into the power system will be less. The configuration and working principle of the proposed hybrid active power filter are given out. The validity of the theory and excellent filtering characteristics are verified by the experimental results of a typical harmonic-producing load.