Harmonic Analysis In EV Charging Station And The Simulating Research On EV Charging-discharging System

With the development of the society, energy and environment problems get more and more attention; Because of less pollution and low consumption, electric vehicles will play an important role in solving the energy shortage and environmental degradation problems. However, due to the presence of nonlinear devices, large amounts of harmonic will be generated during the charging process of electric vehicles, if the harmonic is not properly handled, it may do great harm to the utility grid. It is important to analyze the characteristic of harmonics generated during charging process, then corresponding harmonic suppress method can be adopted, which make the power grid more safety. Electric vehicles can be used as the storage battery of the power grid, charging from the grid at valley hours discharging at peak hours, make the peak load shifting, considering the complexity of the experimental system, the simulation model of charging-discharging system and its control strategy was established in software usually. Therefore, establish the simulation model of the charging-discharging system and its control strategy has important practical significance.In this paper, at first the simulation model of the EV charger and the EV charging station are built, the characteristic of harmonic generated during the charging process is analyzed, which help us determine whether harmonic suppress method should be adopted. Then, several harmonic control strategies are given, passive filters are added to the model of the electric charging station, and the filtering result is fine. At last, the simulation model of the charging-discharging system and its control strategy are established. To the charging process, a dual-channel closed-loop control strategy with current-inner-loop and voltage-outer-loop is adopted, which makes the DC-side voltage remain steady and the system will run in unit factor; to the discharging process, the PQ control strategy is adopted, a soft ware Phase locked loop is established making the ev battery connected to the power grid.