Seven-level active power conditioner for a renewable power generation system

A seven-level active power conditioner (SLAPC) used to inject the real power of the clean power source into the grid is proposed in this study. This SLAPC is composed of a four-level DC-DC power converter and a full-bridge inverter. The four-level DC-DC power converter converts the output voltage of the clean power source into a four-level pulse voltage. The full-bridge inverter is switched at low frequency and synchronised with the utility voltage and the output voltage of SLAPC is a seven-level AC voltage. Accordingly, the switching power loss, harmonic distortion and electromagnetic interference caused by the switching operation of power electronic switches are reduced because of the four-level in the DC side and the seven-level in the AC side of the full-bridge inverter. In addition, the proposed SLAPC acts as an active power filter that filters out the harmonic current of the load, so the utility current of the proposed SLAPC is a sinusoidal current and in phase with the utility voltage. A hardware prototype is developed to verify the performance of the proposed SLAPC. The experimental results show that the performance of the proposed SLAPC is as expected.