MPPT Control Of PV Generation Under Partial Shading Condition Based On Modified DE Algorithm

While the demand of energy is continuously growing,fossil fuel like coal is exhausted gradually and the environment problem is getting more severe.Under this condition,photovoltaic(PV)generation which makes no pollution or noise attracts a wide spread attention in the field of renewable energy power generation.A key method to increase its efficiency is applying the maximum power point tracking(MPPT)control technology.Differential evolution(DE)is a kind of global intelligent optimization algorithm based on population.It has several merits,such as fast convergent rate,little information dependence of specific problem and simple programming which makes it suitable for solving complex optimization problems.The research object of this paper is the PV generation system,the objective is obtaining maximum power point(MPP)of PV generation systems quickly and accurately under partial shading(PS)condition,and the method is modified DE algorithm.Research results can be summarized as following aspects:(1)Simulation models of PV arrays and DC/DC transform circuit were built in Matlab/Simulink.Then analyzed the output characteristics of PV arrays operating under uniform illumination and PS condition,and pointed out the location of MPP under PS condition was affected by distribution of shadow and illumination intensity.It laid the foundation of designing MPPT algorithm under PS condition.(2)Comparing had been made between several traditional MPPT methods,like constant voltage method,perturbation and observation(P&O)method and incremental conductance(INC)method.The simulation was carried out and the results showed these algorithms' good performance under uniform and failure to obtain MPP under PS condition by itself.(3)Studied the basic principle of DE algorithm,common variants,and affects in performance by parameters selection,etc.A modified DE algorithm was proposed to improve the convergence speed and avoid trapping in local optimal solution.Then the comparison had been made between modified DE algorithm,DE algorithm and particle swarm optimization(PSO)by several benchmark function.And the results showed modified DE algorithm had advantage in convergence speed,precision and the ability to jump out of local optimal solution over other algorithms.(4)With the good performance of modified DE algorithm in multimodal function optimization,this paper made some changes according to the specific problem of MPPT under PS condition.Then the simulation experiment was implemented and the results showed its ability to obtain and track MPP was better than traditional MPPT algorithm.Its good control performance was benefit to improve the PV system's output power and the rate of solar energy utilization.