Design and Operation Analysis of Virtual Synchronous Compensator

To reduce the sensitivity of static synchronous compensator (STATCOM) to power or voltage fluctuation induced by renewable energy generation or grid itself, it can add inertia for reactive compensation. Analogizing the virtual synchronous generator (VSG), a virtual synchronous compensator (VSCOM) is proposed in this article, which adds virtual inertia in reactive power regulation. According to the differences and the respective characteristics of VSG and VSCOM, a proportional-differential (PD) controller is proposed to achieve the fast control of dc-side voltage and cooperates with a series integrator to achieve the stable control of dc voltage. Meanwhile, an integral controller is designed for realizing the inertial control of reactive power. The small-signal model of the proposed VSCOM is built, and the design method of the control parameters is analyzed. Meanwhile, the inertial performance of the proposed VSCOM with different control parameters is analyzed from the unit-step response. In weak grid or multiple parallel devices, the proposed VSCOM is more stable than the typical STATCOM in direct reactive power control mode. Finally, experimental results validate the proposed control strategy and parameter design method.