基于功角与电流灵活调控的VSG故障穿越方法研究

Study on Fault Ride-through Method of VSG Based on Power Angle and Current Flexible Regulation

电网发生故障时,虚拟同步发电机(virtual synchronous generator,VSG)的运行稳定性受到影响,且无法抑制短路过电流,影响其对电网的支撑能力。保证在电网故障下VSG能够继续为微电网提供电压频率支撑是提高电网稳定性的重要方法。针对该问题,该文充分利用VSG灵活可控的优势,提出一种基于暂态功角与电流灵活调控的VSG故障穿越方法。所提方法能够抑制故障期间VSG输出电压与电网电压之间的相位偏移,在保证VSG在故障期间的暂态功角稳定性的同时可以兼顾对短路电流的控制,有效防止VSG短路过电流。通过分析,给出暂态控制策略原理与具体控制流程。仿真与实验结果证明所提VSG暂态控制策略的正确性和有效性。

Virtual synchronous generator(VSG)cannot suppress the fault current in the case of symmetric short-circuit fault of the grid,and the stability of VSG is threatened,which will affect its ability to support the grid.Therefore,it is an important mean to improve the stability of the grid by ensuring the VSG to continue to provide voltage and frequency support for the microgrid in the case of grid failure.On this basis,taking full advantage of the flexible and controllable VSG,a fault-ride through method of VSG based on power angle and current flexible regulation was proposed.This strategy can ensure the transient power angle stability of VSG by suppressing the phase deviation between the VSG output voltage and the grid voltage during the fault.Besides,it can prevent the VSG from overcurrent effectively.Through analysis,the principle and control flow of transient stability and fault current suppression are given.Finally,simulation and experiment results show that the proposed VSG transient control strategy is correct and effective.