Research On The Structure And Maximum Power Control Of Electrified Highway Photovoltaic Power Generation System

With the increasingly serious energy and environmental problems,new energy,especially solar power generation,has received widespread attention.Our country has a long highway mileage,highway transportation consumes a lot of fossil energy sources.Rearching the electrical highway with photovoltaic power as the core is of positive significance.Improving the efficiency of photovoltaic power generation is the main points of designing photovoltaic electrified highway.In response to unfavorable factors such as poor terrain,excessive dust,susceptibility to shadows,and difficulty in designing the structure of photovoltaic power generation systems on electrified highways,based on the photovoltaic power generation structure and MPPT control as the research focus,this thesis designs a two-stage three-phase photovoltaic power generation grid-connected system.The main work is as follows:Firstly,the characteristics of the centralized photovoltaic power generation structure and distributed photovoltaic power generation structure are analyzed,and the power generation efficiency of the traditional photovoltaic array topology under shadow is evaluated by irradiation equalization.To solve the low efficiency of traditional photovoltaic array in shadows,a photovoltaic electrified highway power generation topology based on static reconstruction is designed.The simulation models of traditional and static reconstructed photovoltaic arrays are built,simulation and calculating the power generation efficiency of different photovoltaic array topological structures.Secondly,for the traditional MPPT algorithm cannot track the peak curve and the classic cuckoo search algorithm has slow late convergence and low tracking accuracy in global MPPT applications.An improved cuckoo search algorithm that introduces reverse learning strategy and adaptive Levy’s flight step is designed,and the performance of the algorithm is tested on the standard test function.On this basis,an MPPT control strategy based on improved cuckoo search algorithm is designed,a photovoltaic maximum power tracking simulation model is built,and the maximum power tracking performance of the algorithm under static and dynamic working conditions is simulated and verified.Finally,the T-type inverter structure and output state were explained,the frequency characteristics and filter performance of LCL filters are analyzed,the parameters of LCL filters are designed,and the resonant peaks of LCL filters are suppressed by passive damping.For the characteristics of the photovoltaic grid-connected input voltage easy fluctuation,a dual closed-loop control strategy with capacitive current and grid-connected current as the internal loop control of the current and the DC side voltage as the outer ring control is designed,and a two-stage threephase photovoltaic grid-connected simulation model is established.The phase of gridconnected current,harmonic content and distortion rate are simulated and calculated,and the performance of the control system is verified.