Improved Particle Swarm Optimization (PSO)-based MPPT Method for PV String under Partially Shading and Uniform Irradiance Condition

This paper introduces an improved particle swarm optimization (PSO) method to track the global peak (GP) under partially shading condition (PSC) and uniform irradiance condition (UIC). In this method, the initial position of particles (i.e. the converter duty cycle in this paper) can be determined by a strategy, not random. When the photovoltaic (PV) string operates under PSC, the initial particles can ensure that the corresponding operating points work in the vicinity of the peaks. And under UIC, the initial position is close to the GP duty cycle by using the characteristic of DC-DC converter. Thus, the improved PSO maximum power point tracking (MPPT) method can reach the GP fast. In Matlab/Simulink, the comparisons between the proposed method and other methods, including conventional incremental conductance (INC) and PSO method, are made under various schemes.