Research On Microgrid Distributed Photovoltaic Power Supply Three-level DC-DC Converter

In recent years,photovoltaic microgrids have received increasing attention in the research of renewable power sources because they can fully facilitate the large-scale access of distributed power and renewable energy.However,there are many problems in the field of DC-DC converters in photovoltaic microgrid systems that are worth exploring.Based on this,this paper optimizes the half-bridge three-level DC-DC topology to make it suitable for large-scale microgrid distributed power supply.The optimized DC-DC converter can output stable high-voltage direct current to realize fast charging of the energy storage terminal and DC load.It also includes the maximum power point tracking technology under partial shadow.In order to achieve these goals,the article focuses on solving the problem of midpoint voltage fluctuation at the output of a three-level DC-DC converter and the algorithm of maximum power point tracking under partial shading.The optimized DC-DC converter is small in size,high in power density,and more diversified in functions,so that the efficiency of the entire microgrid is improved and the functions are more comprehensive.In order to solve the problem of unbalanced voltage output in the three-level DC-DC converter,the topology and working principle of the optimized three-level DC-DC converter are introduced in detail first,and then the imbalance is analyzed.The reason for this is to select a phase-spaced multi-carrier pulse-width modulation strategy by comparing and studying the midpoint potentials during the balance and the six unbalanced cases.Next,the article discusses the differences in the maximum power point tracking algorithm between shadowless shadowing and shaded shadowing,and then selects the particle swarm algorithm to solve the maximum power point tracking algorithm under shadow obscuration.problem.The optimized topological structure and suitable modulation strategy make the inverter only need to use voltage and current double closed-loop control to achieve good midpoint voltage suppression.Finally,the main circuit device parameters and control circuit of the converter were calculated and designed with the system of 10 kW photovoltaic battery,output voltage 500 V,current 20 A and output 1200 V.Through simulation modeling,the effectiveness of modulation strategy,maximum power point tracking and control method is verified.The simulation results show that the topology can achieve DC boost and suppress the midpoint voltage fluctuation.It can be demonstrated that the modulation strategy studied in this paper,the tracking of the maximum power point under partial shadow occlusion,the control method,and the design of the hardware part are all effective and feasible.