Impedance modelling and grid integration stability evaluation of three‐phase virtual synchronous generator

Abstract

Abstract Virtual synchronous generator (VSG), which can behave with analogous characteristics as the conventional synchronous generator (SG) and provide voltage and inertia/damping support, is universally regarded as a grid‐friendly interface. Here, the comprehensive sequence‐impedance model of the VSG is developed by using the harmonic linearization method. To improve the accuracy of impedance model, the influences of the reactive power loop (RPL) and mirror frequency effect (MFE) are discussed and evaluated for the first time. Three different impedance models of the VSG (conventional, considering RPL, and considering both MFE and RPL) are derived and compared in detail. Besides, the synchronous frequency resonance (SFR) issue and grid‐interactive oscillation risk of the VSG are also investigated. The results indicate that the VSG may suffer from power oscillation when the integral coefficient of RPL is too large, but has excellent robustness and stability when connected to weak grid. This feature makes it more appealing in weak grid integration. Finally, the validity of the theoretical analysis is verified by simulations and experiments.

Keywords

• Synchronous machines
• Power system control