The Harmonic Characteristic And Suppression Of EV Charging Station

With the increase of energy crisis and environment pollution problems, the EV technology which obtains positive support of our government becomes the important direction of development of auto technology. So EV charging station as the supporting facilities also get rapid development. However, the charging machine which is nonlinear equipment produces the harmonic current so that the scale of the construction of charging station would cause serious pollution to the power grid. So it is necessary to study the harmonic characteristic and corresponding method of harmonic suppression for the EV charging station.The main content of the paper include the harmonic characteristic of EV charging station, the relationship between factors influencing the harmonic characteristic and the size, the phase of harmonic current was studied. At last, the paper puts forward the optimal method of harmonic suppression for the large-scale construction of EV charging station through the comparison between12-pulse rectifier, active power filter and PWM rectifier. And the specific content was as follow:Firstly, the influence of harmonic current on the equipment and power grid was explained. And on the basis of theoretical analysis, the principle of different type charging machine and corresponding harmonic characteristic were studied. Secondly, according to the theory of charging machine, the charging machine model was built though the PSCAD simulation software. The validity of the model was proved by measured data. The charging station model was built on the basis of charging machine model. And this model can control the factors including the number of chargers, the input time of chargers, the voltage and current of charging battery, initial capacity of charging battery and so on. At last, a method of studying harmonic characteristics of charging stations under different operation conditions was put forward. Furthermore, based the charging station model, the relationship between factors influencing the harmonic characteristic and the size, the phase of harmonic current was studied. According to the conclusion, some advices of the operation and composition of charging station were put forward. For example, the method that the EV is charged by more than one charger in parallel way should be avoided; the method that chargers are input in concentrated moment should be avoided. Lastly, according to the common method of harmonic suppression and that adopted in practice, three methods that were6-pulse rectifier with APF,12-pulse rectifier, PWM rectifiers were compared from some aspects including harmonic content, power factor, working performance and economy. As a result, the method of harmonic suppression for large-scale construction of EV charging station was put forward, that was the active power filter with LC filter will be the common method for the harmonic suppression of EV charging station in the future.