A novel active power filter applied to high voltage distribution systems

A novel active power filter based on linear transformer harmonic current compensation is proposed for high voltage power distribution systems application. In the active power filter, the primary of the transformer is in parallel with the harmonic-producing loads, the secondary of the transformer is connected with PWM voltage source inverters that produce harmonic compensation current. The harmonic current of the primary is detected and tracked by the inverters with a fixed compensation coefficient. When satisfied the harmonic current compensation condition, the linear transformer can really exhibit nearly zero impedance to harmonic current and excitation impedance to fundamental current, thus lead harmonic current flow into the linear transformer circuit. The principle of operation of the proposed active power filter is discussed in detail. Simulated waveforms and experimental results obtained from a prototype are presented to verify the effectiveness of the active power filter