Improved PQ Control Mothod for PV System

Active-reactive power (PQ) control strategy are widely used in the microgrid-connected operation mode, which is an important part of photovoltaic (PV) systems. However, the direct current (DC) voltage of three-phase alternating current/direct current (AC/DC) converter will generate pulsations twice the fundamental frequency when the AC side voltage of hybrid microgrid is unbalanced, which will result in the formation of a large number of 3rd harmonic components and affect the operation of the microgrid seriously. This paper presents an improved PQ control strategy under the premise of analyzing the output characteristic of inverter in an unbalanced condition. In this control strategy, a voltage compensator is introduced in the troditional PQ control for keeping the active-reactive power constant, which realize proportional integration (PI) control and particle swarm optimization (PSO) of the voltage. The experimental result shows that the improved PQ control strategy can suppress the interference and output power fluctuations caused by the voltage imbalance of the power grid effectively, the improved results achieve the stable operation of the local sensitive load. The proposed control strategy is verified feasible through simulation experiments.