Multi‐loop virtual synchronous generator control of inverter‐based DGs under microgrid dynamics

Abstract

The increasing penetration of small-scale renewable power sources into the passive distribution networks brings direct deteriorated impacts on operation of microgrids due to the lack of inertia and damping property, e.g. unexpected voltage rise, increased fault level. To this end, this study presents a novel virtual synchronous generator (VSG) based multi-loop control solution aiming to efficiently manage the embedded inverter-based renewable distributed generators (DGs) in a plug-and-play fashion. With such multi-loop control structure, the virtual flux oriented control is adopted to avoid the harmonic interference and guarantee accurate control of vector orientation process in the U / I closed-loop feedback based vector control. The VSG based control is able to obtain timely current response and carry out static error free tracking control of output voltage. The pre-synchronising control aligned to the outer loop to ensure smooth transition from island to grid-connected mode is also studied. The proposed control solution is assessed through a set of simulation experiments in a microgrid for both island and grid-connected scenarios, and the numerical result confirms its technical benefits.