Research on Harmonic Characteristics and Harmonic Counteraction Problem of EV Charging Station

The development and popularization of electric vehicles (EV) are inseparable from the construction of charging stations, but EV chargers are nonlinear loads, which will bring harmonic pollutions to the power grid. In this case, research on harmonic problems of charging station has practical significance. In this paper, model of a single charger and charging station were established. The variation law of harmonic ratio (HRI), total harmonic distortion (THD) and total demand distortion (TDD) of current with the number of chargers are analyzed under the same charging power or different powers respectively. Then, the mechanism of harmonic counteraction among chargers was analyzed and simulated. The simulation results in this paper showed that: with every charger in the charging station running at the same power, the harmonic current caused by each charger is exactly the same, thus there is no harmonic counteraction; when the operating power of chargers are different, the harmonic amplitude and TDD reduced compared with that under the same power. There exists harmonic counteraction among chargers. In addition., harmonic counteraction is more obvious in higher harmonic orders.