The influence of virtual synchronous generators on low frequency oscillations

Abstract

By simulating the operating dynamics of synchronous generators (SGs), the use of virtual synchronous generators (VSG) can help overcome inverter-based generators' shortcomings of low inertia and minimal damping for grid-forming applications. VSGs' stability is very important for its solar and wind electricity applications. Currently, the related research mostly focuses on VSGs and their application to microgrids. There has been little research to explore how VSGs effect low frequency oscillations in power transmission systems. This paper describes a small-signal model of a VSG-SG interconnected system, which is suitable for studying low frequency oscillations damping in a power transmission grid. Based on the model, the effects of VSGs on low frequency oscillations are compared with the effects of SG to reveal the mechanism of how VSGs influence the damping characteristic. The influence of each VSG control loop on oscillations is also analyzed in the paper. Then, the low frequency oscillation risks with different types of VSGs are described. Finally, experiments on a real-time laboratory (RT-LAB) platform were conducted to verify the small-signal analysis results.