Research On Photovoltaic Array Power Optimization Strategy Under Complex Shading Conditions

Photovoltaic power generation is considered to be the most promising new energy technology in the world.However,in the actual operation process,the conversion efficiency of photovoltaic power generation is low,which restricts its wide application.In the actual operation process,the photovoltaic array inevitably encounters the problem of shading by the shadow,resulting in a large drop in output power and causing a mismatch.The existing method to solve the mismatch phenomenon is to connect a bypass diode in parallel,but the conduction of the bypass diode may cause the components under normal lighting to be bypassed,resulting in unnecessary power loss.The parallel bypass diode may cause the multi-peak phenomenon,which makes it more difficult to track the maximum power point and exacerbates power loss.How to reduce the power loss of the photovoltaic array is one of the key issues for improving the efficiency of the photovoltaic array.In this paper,in order to improve the power generation efficiency of photovoltaic arrays in the actual operation,we will focus on three aspects:output characteristics,reconstruction strategies,and maximum power point tracking of photovoltaic arrays.Firstly,the paper analyzes the output characteristics of photovoltaic modules and photovoltaic arrays under complex lighting conditions,summarizes the maximum power point distribution of photovoltaic arrays,and presents the local maximum power point current and voltage expressions,and performs simulation verification in Matlab/Simulink simulation tools.Based on the principle of radiation balance,the paper proposed a multi-Knapsack Problem Solving(MKPS)-based photovoltaic array reconstruction strategy.The problem of photovoltaic array reconstruction was attributed to the multi-knapsack problem.A new objective function and boundary conditions were proposed.,And use the advanced artificial fish school algorithm to solve the multi-knapsack problem to improve the algorithm speed and accuracy.Through simulation and verification,the photovoltaic array reconstruction strategy based on multi-knapsack 'problem has effectively improved the output power of the photovoltaic array.The purpose of the principle of radiation balance is to balance the size of the radiation at the topological node and reduce the current limitation caused by partial shadows so that each PV module operates at its maximum operating point.However,the analysis shows that,under certain shadow conditions,exiting the shadow-shadowing component is more conducive to improving the output power of the PV array.So the dissertation optimizes the reconstruction strategy of photovoltaic array based on multi-knapsack problem,and puts forward an improved MKPS photovoltaic array reconstruction strategy.The improved MKPS reconstruction strategy can not only improve the output power of the PV array,but also can roughly determine the maximum power point voltage of the array,greatly simplifying the maximum power point tracking control.Finally,based on the improved MKPS reconstruction strategy,this paper proposes an adaptive PV array maximum power point tracking strategy.The output characteristics of the PV array exhibit single-peak characteristics in the vicinity of the maximum power point.Under complex shadow conditions,the maximum power point range of the PV array can be determined after the reconstruction of the PV array with the improved MKPS reconstruction strategy.This paper uses the fixed voltage method to locate the voltage at the maximum possible power point,and then uses the disturbance observation method to search for the maximum power point in a small range.Through simulation and verification,the adaptive maximum power point tracking strategy combined with the improved MKPS reconstruction strategy can quickly and accurately track the maximum power point under complex lighting and reduce the power loss of the photovoltaic array.