Research On Power Electronic Transformer In Distribution Network Considering The Access Of Electric Vehicles

Compared with traditional transformers,power electronic transformer(PET)can guarantee high quality power supply and facilitate the access of new energy,which is in line with the development of future power grid.PET is expected to be gradually applied to the distribution network in the future.With the rapid development of economy,the power load is increasing rapidly,and the load types are constantly changing.The shortage of power supply is becoming more and more serious during the peak period of electricity consumption,which challenges the reliability and quality of power supply.In recent years,with the rapid development of electric vehicles(EVs)in China.It is very important to provide an efficient and fast charging method for electric vehicles.And electric vehicles used as energy storage device has become one of the methods to solve the shortage of electric energy in the peak period and ensure the reliability of the power supply.Giving a full use of electric vehicles is also very important.The combination of PET and electric vehicles can achieve electric vehicles charging and discharging,power supply reliability and power quality,which has important research significance.Firstly,a new type of PET topology suitable for medium and high voltage distribution network is proposed.The proposed topology adopts the topology of four stage,and the input level and isolation level still use the existing topology.The feature of the proposed topology is that the output stage is composed of inverter module,switchable power module and energy storage module.The PET input level,isolation level topology and control strategy are briefly analyzed.The working principles and control strategies of each link of output stage are mainly analyzed,and a filter parameter design scheme is proposed for this topology.Then a capacity configuration scheme for the proposed topology is proposed.This method is based on Monte Carlo to predict the EV fast charging load.Based on the prediction curve,considering the relationship between the EV fast charging and the basic AC load,the capacity of the switchable power module,the inverter module and the energy storage module are configured.Finally,the overall design and simulation of the proposed topology are carried out.According to the main performance index of the system,the main parameters of each link of PET are designed.And a simulation module of the proposed topology is built in PSCAD simulation environment.Simulations of steady running and switching power module working mode switching process and the input voltage level interruption are carried out.The simulation results verified the realization of the basic functions of the proposed topology and the feasibility of the control strategy.