An optimal current control strategy for a three-phase grid-connected photovoltaic system using Particle Swarm Optimization

A robust current control strategy for PV (photovoltaic) grid-connected systems is required for reliable use of solar energy as an abundant and clean renewable energy. This paper presents real time optimization parameters of the current control strategy for a 3-phase photovoltaic grid-connected Voltage Source Inverter (VSI) system. The proposed controller scheme is implemented based on a synchronous reference frame; the Phase-Locked Loop (PLL) is used as grid phase detector. Particle Swarm Optimization (PSO) algorithm is an intelligent searching algorithm that is used to implement the real time self-tuning method for the current control parameters. Two conventional PI controllers are used and feed-forward compensation is applied with the inner inverter current control loop to achieve fast dynamic response. The main aim of this work is to achieve high dynamic response for the inverter output current with acceptable harmonics level in steady-state condition all of which is required for power quality improvement. The results show that the proposed strategy provides an excellent dynamic response within real time optimization.