Research On Micro-Grid Topology And Control Strategy Of Fast Charging Station Based On Three-level Converter

With the continuous development of the global economy and industry,photovoltaic microgrids and electric vehicles have an increasing impact on the safe and reliable operation of power systems in the context of the energy Internet.The large-scale electric vehicle fast charging station microgrid system studied in this topic can efficiently use clean energy to quickly supply energy to electric vehicle charging stations,and can also adjust and optimize the power quality of the distribution network.This system combines four research hotspots such as photovoltaic power generation,fast charging,large-scale energy storage,and power quality regulation of the distribution network,which are of great significance for the development of microgrids and electric vehicles.Firstly,the system configuration of the micro-grid of a large electric vehicle fast charging station was given,and then the working principle of the key modules of the system was analyzed.The zero-sequence current separation method has been improved.While realizing active power exchange with the distribution network,it performs reactive power compensation,harmonic compensation and unbalance compensation for the distribution network.Using multi-carrier pulse width modulation strategy and double closed-loop control strategy,the center point imbalance problem in the three-level DC/DC converter is solved;then,the three-level DC/DC converter is mathematically modeled and designed Control strategies for photovoltaic power generation,distributed energy storage,fast charging,and grid-connected converter modules.Next,the energy management strategy of the microgrid system of the charging station was analyzed,and the specific energy management strategy suitable for the local area was given based on the time-sharing tariff scheme in Wuhan,Hubei.The architecture and human-computer interaction interface of the energy management system were simply designed.At the end of the article,the simulation model of the microgrid system of the charging station was built using MATLAB / Simulink,and the simulation results of the photovoltaic power generation module,distributed energy storage module,fast charging module and grid-connected converter module were analyzed.The experimental results show that the maximum power point tracking of photovoltaic modules in the microgrid system of the charging station,the neutral point imbalance suppression of the three-level DC / DC converter,the constant current charging of the charging pile,the power quality adjustment of the grid-connected converter,and the active exchange of microgrid and distribution network are effective and correct.