电压对称跌落下VSG自适应无功补偿控制策略

VSG Adaptive Reactive Power Compensation ControlStrategy under Symmetrical Voltage Sag

虚拟同步机发电机(virtual synchronous generator,VSG)在电网电压对称跌落时逆变器输出电流幅值骤升,并且不能输出无功功率支撑电压。为此,根据无功电流需求推导出VSG在电压故障期间的电压参考指令,在限制电流幅值的同时,使逆变器按照电压跌落深度输出相应的无功功率,实现无功功率的自适应补偿。电压故障结束后VSG由该指令切换成正常工作模式,设计状态跟踪保证无扰切换。仿真结果证明了所提控制策略的有效性。

When the grid voltage drops symmetrically,the output current amplitude of inverter rises sharply and the virtual synchronous generator(VSG)can not output the reactive power support voltage.Therefore,according to the demand of reactive current,the voltage reference command of VSG during voltage failure is deduced,which limits the amplitude of current and makes the inverter output corresponding reactive power according to the voltage sag depth,so as to realize the adaptive compensation of reactive power.After the voltage failure,the VSG is switches to normal working mode by the command,and the designed state tracking ensures undisturbed switching.The simulation results show the effectiveness of the proposed control strategy.