Abstract: The anti-disturbance ability and dynamic performance are poor in the inverter stage of PET(Power Electronic Transformer)based on traditional VSG(Virtual Synchronous Generator)control. In order to address the problem, a VSG control combined with linear active disturbance rejection control is proposed. A second-order active disturbance rejection controller is added to the active part of the traditional VSG control. State observation and feedback are introduced to the controller to estimate the system error in real time, so that the frequency and power of the inverter can be stably tracked under different operating conditions, while the oscillation phenomenon is weakened. With the improved control strategy, the maximum overshoot is reduced by 54. 5 percent and the frequency fluctuation time is reduced by 0. 22 s, which make the PET inverter stage have stronger dynamic response and steady-state performance. The simulation demonstrates that the control strategy is feasible and effective. It also shows that the improved VSG control strategy accelerates the recovery speed of the PET inverter stage after being disturbed, and has better dynamic performance.

Key words: virtual synchronous generator control, linear active disturbance rejection control, power electronic transformer, power tracking, frequency fluctuation