Dynamic performance analysis of paralleled virtual synchronous generators under grid-connected and islanded mode

Abstract

With increasing penetration of the intermittent and fluctuating renewable energy resources, control strategy of inverters in microgrid is important. Therefore, due to lack of inertia in power electronic converters, virtual synchronous generator control is proposed to introduce backup inertia and improve dynamic performance of frequency. Researches recently have proposed different methods on control of single virtual synchronous generator and the performance is investigated. However, characteristics of paralleled virtual synchronous generators in microgrids are not sufficiently studied. In this paper, a simplified transfer function model of paralleled virtual synchronous generators is constructed and verified in simulation, which is used to study microgrids with multiple virtual synchronous generators in both grid-connected mode and islanded mode. Frequency, phase and power response of ac bus and virtual synchronous generators are investigated. Influences of inertia and grid-side inductance are analyzed in detail, which shows dynamic characteristics of paralleled virtual synchronous generators and provides some practical advices on VSG design in microgrids.