Simulation Study On Maximum Power Point Tracking Control Of Photovoltaic System Under Partially Shaded Condition

The working environment of photovoltaic(PV) system is becoming increasingly complicated, particularly to the system which is middle-sized or small-scale, the problem of partially shaded condition(PSC) is hard to avoid, it may cause that several extremums could emerge on output voltage and output power curves of PV cell, and traditional maximum power point tracking(MPPT) control methods could be lost in partial extremums, thus, an effective control strategy is needed to solve the MPPT problem under PSC, establishing the simulation platform of PV system with illumination changes is more relevant.This paper aims at establishing simulation platform of MPPT control of PV generation system, and simulation modules of four kinds of control strategies, which are perturb & observe(P & O), self-tuning fuzzy PID, particle swarm optimization (PSO) algorithm and. improved PSO, in Matlab/Simulink. Based on the analysis of PV cell theory, module and output characteristic, the effectiveness and correctness of the module is also verified. In this paper, PV array simulation module under uniform illumination and PSC are established respectively, generation principle and distribution law of power single-peak and several-peak curves are verified and analyzed, PV arrary optimization design is proposed, all of the research contributes to foundation of MPPT strategies theory under PSC.MPPT control is one of the key technologies of PV generation system. In this paper, self-tuning fuzzy PID method is proposed under uniform illumination. Fuzzy control is especially applied to unknown mathematical model and complex nolinear system, PID control can effectively eliminate oscillation phenomenon at working point and this process is easy to realize, thus, these two kinds of methods are combined in this paper, compared to traditional P & O method, results show that the method is about 0.05s more quicker to get into steady-state, and its output power fluctuation range is ±5W less than traditional method averagely, finally let the PV system steadily work at MPP, it has both good dynamic-state and steady-state performance.Under PSC, after knowing the theory, algorithm flow and application of PSO, maximum power tracking theory of PV generation system is combined, an improved PSO. which is applied to theory flow of PV generation system MPPT, is proposed. PV generation system simulation platform under PSC is established, compared to traditional control method, results show that power tracking error rate of the improved PSO can be controlled among 0.29%～0.46% under two-peak and three-peak power curves, while under complex power curve, its error rate is less than 1% and adjust time is less than 0.04s averagely. which shows that this improved PSO has a good tracking performance in the application of MPPT, the problem, which has a low output efficiency of PV array in PSC, is effectively improved.