Modified Maximum Power Point tracking (MPPT) of grid-connected PV system under partial shading conditions

PV systems essentially depend on insolation and temperature; but partial shading phenomenon defects characteristics of PV systems significantly. Unlike under ideal condition that PV system has only one maxima, it has several locals under partial shading (with only one global maxima). Conventional Maximum Power Point Trackers (MPPTs) easily fail to track real optimum point and are trapped at locals. It loses considerable energy of PV system. To overcome this problem and draw maximum possible energy from PV system, this paper proposes a Maximum Power Point tracking technique based on Differential Evolution (DE) which is capable of finding global MPP under partial shading conditions. The performance of proposed algorithm is verified by means of simulation in MATLAB/Simulink and is well compared with conventional MPPT. The proposed MPPT is applied to a grid-connected PV system in conjunction with DC-DC boost converter and DC-AC inverter. The simulation results validate that presented MPPT is able to track global MPP under partial shading condition accurately, fast and with zero oscillation.