基于全通滤波器的虚拟同步发电机低电压穿越控制策略

Low-voltage ride-through control strategy of virtual synchronous generator based on all-pass filter

传统的虚拟同步发电机(VSG)不具备低电压穿越能力,在电网电压跌落时难以保持其同步性,造成电流越限及设备脱网,为此提出一种基于全通滤波器(APF)的VSG低电压穿越控制方法。结合APF的工作原理提出在电网电压故障时如何获取准确的频率、相位信息。在此基础上设计了VSG低电压穿越的具体方法,利用阻尼转矩保证转子运动的稳定性,同时增加电网电压偏差反馈防止有功功率指令的突变及释放无功电流,使得VSG在电压跌落时保持了同步性且保证了输出电流的平稳过渡,实现了VSG在不同故障下的低电压穿越。

Traditional VSG(Virtual Synchronous Generator) may lose its synchronism under the voltage dip, resulting in the over-limit current and equipment outage. To solve these problems, a VSG LVRT (Low-Voltage Ride-Through) control method based on APF(All-Pass Filter) is proposed. How to obtain accurate frequency and phase information in the case of voltage fault is proposed according to the principle of APF. On this basis, a definite VSG LVRT control scheme is established. To ensure the synchronism of VSG and smooth the output current under the voltage dip, the proposed approach utilizes the damping torque to stabilize the rotor motion, and further introduces a voltage deviation feedback to prevent the active power command mutation and release the reactive current. Consequently, the VSG LVRT under different grid faults is realized.