Virtual synchronous generator and its comparison to droop control in microgrids

Abstract

A microgrid allows the flexible integration of distributed generators, loads and energy storages, into the distribution system with standalone and grid connected modes of operation. Droop control is a popular control scheme to ensure proper load sharing in a microgrid with more than one distributed generator. Most of the renewable energy based distributed generators are connected to the utility grid through power electronic converters and they do not have the inherent mechanical inertia which synchronous generators possess. This could cause some stability issues for a microgrid during standalone operation. The virtual synchronous generator control concept is based on the emulation of inertial characteristics by a power electronic converter in a microgrid with the support of electrical energy storage. Using virtual synchronous generator approach, it is possible to control the active power flow through a power electronic converter like a synchronous generator. Although droop control and virtual synchronous generator control are different control strategies, equivalence is established between these two methods based on some assumptions and the same is validated using simulations.