Enhancement of Power Decoupling for Virtual Synchronous Generator: A Virtual Inductor and Virtual Capacitor Approach

Abstract

The inertia of a power system decreases with the increasing penetration of renewable energy, and the stability of power systems is facing great challenges. A virtual synchronous generator (VSG) has become one of the effective schemes for the high permeability of distributed generation, due to its similar characteristics to a synchronous generator. However, the coupling of the VSG in the power transmission from the actual power output point to the grid-connected point may lead to a steady-state error and dynamic oscillations, which limits the power output capability of the grid-connected converter and the grid support ability. To solve this problem, first, the power coupling mechanism of VSG is studied. Second, a virtual-inductor and virtual-capacitor control strategy is proposed for power decoupling, which eliminates the power coupling and improves their capability in suppressing the reactive power fluctuation. Finally, simulation and laboratory experimental results verify the effectiveness of the proposed decoupling strategy.