Frequency Control of a Bidirectional Interlinking Converter in an Islanded Hybrid AC/DC Microgrid

Abstract

This paper proposes a bidirectional virtual inertial control (BVIC) strategy for an islanded hybrid AC/DC microgrid (MG) including two renewable-energy power-generation systems and an energy-storage system (ESS). The studied hybrid AC/DC MG consists of a wind farm, a PV farm, a bidirectional DC-DC converter, and a bidirectional interlinking converter (BIC). The vanadium redox flow battery (VRFB)-based ESS is connected to the DC MG through a bidirectional DC-DC converter, while the DC MG is connected to the AC MG through the BIC. On the basis of the virtual synchronous generator, this paper uses the BVIC strategy based on BIC to achieve power distribution between the DC and AC MGs, suppress the deviations of both DC-link voltage and frequency of the AC side, and compare the differences for the studied system with and without the BVIC. The steady-state frequency-domain analysis of the studied system under different operating conditions is performed. Both dynamic and transient time-domain simulations of the studied system under various disturbance conditions are also carried out.