Generating Method of Three-Phase Voltage Sag in EV Charging System Performance Testing

摘要

In order to analyze the impact between Electric Vehicle (EV) charging system and grid influence. In this paper, a method of three-phase voltage sag generating based on DQ transformation is proposed. With the 'Back to Back' linked two PWM voltage-source converters, normal and fault state of infinite grid is simulated. Aiming at seven typical voltage sag faults (including all the voltage sag types in symmetric, asymmetric excluding zero-sequence and asymmetric contain zero-sequence circumstances), compound operation is completed in synchronous rotational axes (dqO) under symmetrical component method applied. Especially, abc-dqO transform is amended for asymmetric contain zero-sequence voltage sag situation. So the space vector pulse width modulation (SVPWM) control signal is generated. Three-phase voltage sag generated with this method could satisfy the phase relationship and amplitude relationship of the inter-phase automatically. As a result, common connection point (PCC) fault voltage could be accurately generated. And the full scope of the depth of voltage sag adjustable and fault duration of any settings are realized. Simulation and experiment results show that this method is the rationality and feasibility.