Harmonic current suppression for three phase PV generation system under unbalanced grid voltage

The ride-through operation of photovoltaic (PV) generation under unbalanced grid voltage will produce apparent harmonic current. This paper studies on power control of PV under unbalanced voltage, and has analyzed the total harmonic distortion (THD) and each order of the harmonics in the inverter currents. Then the analytic formulas of power fluctuation, current THD and each order of current harmonic of the PV inverter are derived, and two algorithms of the adjustment coefficients of PV power control are proposed. The control strategy model of current harmonic suppression under unbalanced grid voltage is built. The feasibility of this method is verified by the simulation result produced by PSCAD/EMTDC.