Research On Mppt Control Of PV System Under Uneven Illumination

Photovoltaic power as the current most promising green renewable energy become more and more attention by people, maximum power point tracking control is a key technology in photovoltaic system. However, the PV system always be affected by the situation of uneven illumination in reality, under uneven illumination, the traditional maximum power point tracking algorithm may appear mistake, therefore, research on maximum power point tracking control of photovoltaic system under uneven illumination have more significance.Under uneven lighting conditions, if photovoltaic array has overtopped temperature, there would be the phenomena named hot spot effect and the system output power will be reduced, while photovoltaic arrays P-V curves show multi peak characteristics, which lead to traditional MPPT algorithm easily appear mistakes, therefore, in order to make the PV array output maximum power and improve the efficiency, research on the MPPT control algorithm under the condition of uneven illumination is very important to track maximum power point in real time.In order to monitor the state of the PV array under uneven illumination,thesis design of photovoltaic data acquisition system based on ZigBee, then analyzes the working principle and the physical characteristics of photovoltaic cells, establish photovoltaic cell simulation model in MATLAB/Simulink.Analysis the generating mechanism and solutions of the hot spot effect, then explain multi peak characteristics of P-V curves under uneven illumination and give the mathematical models, compare and analysis the advantages and disadvantages of existing MPPT method. Taking into account the weaknesses of the particle swarm optimization algorithm in MPPT control, present an improved PSO algorithm with extended rollback, Then test the performance of algorithm by numerical test, the results show that the PSO with extended rollback are better than the standard PSO in optimization accuracy and convergence rate.Concern the advantages of the algorithm in multi peak search, suitable for the MPPT control under uneven illumination, build the PSO algorithm with extended rollback MPPT simulation model in MATLAB/Simulink, the results show that the algorithm can accurately track the maximum power point under uneven illumination. Then build the whole simulation control system for the entire PV system, the results show that the method can realize the global optimization under uneven illumination, the maximum power point can be found accurately and quickly and has good stability, it is proved feasible and effective, this will effectively improve the efficiency of the photovoltaic system under uneven illumination.