A novel transient power control strategy for inverters in voltage control mode

Inverters in voltage control mode including droop control and virtual synchronous generator (VSG) are promising for interconnecting the renewable energy to the grid, which are both emulating the frequency and voltage regulating functions of synchronous generators through droop method. However, improper transient impact current and reactive power output are observed for inverters in voltage control mode connected to grid in case of symmetrical grid voltage drop. In this paper, transient impact current characteristics are researched when symmetrical grid voltage drop. Furthermore, an effective control strategy is proposed with which proper transient current output and dynamic reactive power support are achieved by designing the constant virtual impedance based on power decoupling and stability, adjusting transient virtual resistance based on impact current decreasing and updating active power reference based on reactive power support. Simulation results verify the effects introduced by the proposed control strategy.