Research On Output Characteristics And MPPT Of PV Array In Partial Shadow

The problem of environment pollution and resource depletion caused by traditional fossil energy makes the new technology such as photovoltaic play an increasingly important role in the energy structure.As an important technology of photovoltaic power generation system,PV array maximum power tracking technology has been a research hot spot.However,when the PV array is under the condition of partial shadow,its output characteristic curve will have multiple power extreme points,so the traditional maximum power tracking technology could be easily trapped in local optimal value and result in waste of electricity.Therefore,the study of photovoltaic array output characteristic and maximum power tracking under partial shadow is of great significance.This article first elaborated the research background and significance of photovoltaic power generation.The principle of traditional maximum power tracking technology was introduced in detail,as well as the advantages and disadvantages.The research status about MPPT technology at home and abroad was also analyzed.Then,the physical characteristics,work ing principle and mathematical model of photovoltaic cells were analyzed,and working principle of the power converter was introduced.In the MATLAB/Simulink,the simulation model of photovoltaic cell components of the unit was established.Considering working temperature difference of battery caused by different light intensity,par tial improvement strategies of simulation model were put forward,and rationality was verified.Afterwards,in view of the shadow caused by the cumulus cloud in actual working environment,the simulations about different size of the PV array under the condition of complex shadow were carried out.According to output characteristic of photovoltaic array under partially shaded condition,the maximum number and distribution law of extreme points were studied in detail.The reason why power extreme points of the PV array appear and disappear was analyzed.Last,the basic characteristic,principle and design process of the conventional particle swarm optimization(PSO)algorithm were studied.The problem of slow convergence speed and some particles easily trapped in local optimal solution considered,this paper put forward an improved chaotic PSO algorithm,namely a combination of the chaos algorithm and PSO algorithm,which was applied to maximum power tracking study under partial shadow condition.Therefore the maximum power tracking strategy based on the improved chaotic PSO algorithm was accomplished.Case studies of curve simulation about output characteristics of photovoltaic array under the condition of various shadows by MATLAB programming show that compared with the conventional PSO algorithm,this method can make particles jump out of local extreme points,accurately and quickly find global maximum points,and the output of the PV array voltage remain in the maximum power point voltage.The above studies prove the superiority and effectiveness of the algorithm,and efficiency of the photovoltaic system is greatly improved.