The Impact Of Electric Vehicle Charging On The Distribution Network And Control Strategies

As environmental issues become more and more concerned at home and abroad,energy saving and environmental protection become the new theme of various industries.Due to the characteristics of energy saving and environmental protection of electric vehicles,they have been developed rapidly in recent years with strong support from the policy,however,the charging behavior of electric vehicles has brought many adverse effects to the distribution network.On the one hand,EVs are charged in a disorderly manner,and when the charging time coincides with the peak period of the distribution network,it will challenge the upper limit of the wave peak and cause impact to the distribution network;on the other hand,as the charging piles of EVs contain a large number of non-linear components,they will generate a large amount of harmonic current when charging,which will affect the power quality.Therefore,the following research is conducted in this thesis to investigate the impact of EV charging on the distribution network load and the harmonic suppression strategy.For the impact of EV charging on the distribution network load,this thesis predicts the EV charging load and analyzes the time-sharing tariff to guide the EV charging in a staggered manner.For different types of EVs,the charging load prediction models of electric cabs,electric buses and private EVs are established respectively,considering their average daily driving distance,battery load status and user behavior characteristics.The Monte Carlo method is used to simulate and analyze the three charging load prediction models respectively,and the charging load distribution curves of different types of electric vehicles under the disorderly charging method of charging after use;the charging load distribution curves of private electric vehicles under the orderly charging method of time-of-use tariff are obtained.Taking the charging behavior of private EVs in a district in Beijing as an example,the impact on the distribution network load under different charging methods is studied.The results show that under the disordered charging mode,the private EV charging load overlaps with the peak period,resulting in a 1.73% increase in the peak load;under the ordered charging mode,the private EV charging load overlaps with the trough period,resulting in a 0.89% increase in the trough load.For the harmonic control strategy part,the active power filter(APF)based on proportional-integral(PI)control is used to compensate the EV charging harmonic current.For its large overshoot and poor robustness,this thesis proposes an improved algorithm to improve the harmonic suppression effect by introducing a control system combining particle swarm algorithm(PSO)and fuzzy PI control.By improving the weight value of PSO algorithm,the effect and speed of PSO convergence are improved.Simulation experiments show that the improved particle swarm(IPSO)optimized fuzzy PI control APF reduces the charging harmonic distortion rate of 7k W EV by 22.68%and reduces the charging harmonic distortion rate of 60 k W EV by 21.64%.