Research On The Maximum Power Tracking And Grid-connected Control Of Photovoltaic System Considering Shading

Solar energy has the advantages of cleanness,wide coverage and sustainable utilization,which widely recognized by the international community.However,the current photovoltaic power generation system has problems such as low conversion efficiency and poor quality of photovoltaic power generation.How to use solar energy efficiently and with high quality has become the focus of domestic scholars.Based on the summary of the overseas and domestic research status,this paper proposes a collective intelligence algorithm(DLCI)based on dynamic leader,PI voltage outer loop control and deadbeat inner loop current control technology for maximized power output,output voltage and current meet power quality requirements.The specific research contents are as follows:First of all,the operating principle of photovoltaic cells is systematically described,and the output characteristics of photovoltaic cells at different temperatures and solar irradiation are studied.The results show that there is only one maximum power point(MPP)in different solar irradiation when the temperature is constant.The output characteristics of three photovoltaic cells in series under different temperature and different solar irradiation(shading conditions)are studied.The results show that there is a multi-peak phenomenon in the photovoltaic array under the condition of shading,and there is only one MPP,which is called global maximum power point(GMPP).Secondly,aiming at the multi-peak phenomenon of photovoltaic system under the condition of shading,this paper proposes a new DLCI algorithm.The algorithm combines the search mechanism of five intelligent algorithms,namely GWO,WOA,MFO,ABC and PSO.The collaborative search of each algorithm can significantly improve the global search capability of the DLCI algorithm.It is found that the average volatility and the maximum volatility of one executing guidance strategy after three iterations(k = 3)are the minimum.Therefore,this paper sets the sub-optimizer to implement one guidance strategy after three iterations.Compared to traditional algorithms and heuristic algorithms,under the constant temperature and constant solar irradiation,constant temperature and varying solar irradiation,varying temperature and varying solar irradiation,the tracking efficiency of intelligent MPPT algorithm based on DLCI is increased to 99.79%,99.73% and 99.917%respectively.At the same time,the algorithm also greatly shortens the tracking time and has minimal power fluctuations.Research results show that the DLCI algorithm has the smallest average volatility among all algorithms.In particular,under varying temperature and varying solar irradiation,the average volatility of DLCI is 23.33%,77.78%,76.09%,88.6%,72.16% and 83.33% of the average volatility of INC,PSO,ABC,GWO,MFO and WOA.Therefore,simulation results and data analysis verify the feasibility of DLCI algorithm,which can better achieve global maximum power point tracking(GMPPT)of photovoltaic system.Finally,This article uses MATLAB / SIMULINK simulation software to model the two-stage three-phase photovoltaic grid-connected system,uses LC circuit as the three-phase grid-connected filter,selects SVPWM as the modulation method of the three-phase grid-connected inverter,and uses the double-loop control strategy.Namely,PI control of voltage outer loop and no beat control of current inner loop.Through the MATLAB / SIMULINK simulation verification,it can be seen that when the soalr irradiation changes in 0.2s,the grid current,voltage and corresponding harmonics meet the grid connection requirements,and the simulation verifies the effectiveness and feasibility of the grid connection control strategy.