Power control strategy in islanded microgrids based on VF and PQ theory using droop control of inverters

A microgrid (MG) as a main component of the smart grid integrates Distributed Generation System (DGS) to supply power of local loads. In other words, MG is a unit of integration of the DGs and loads which can operate either connected to or isolated from the main grid. Coordinated control of DGs in MGs is one of the technical difficulties. In this paper, a typical MG consisting of three DGs which are considered inverter interfaced is proposed. In this network, Voltage Source Inverters (VSIs) can be operated in active-reactive power (PQ) mode, active power-voltage (PV) mode and voltage-frequency mode (VF). The MG operation is influenced by the control strategy selection highly. So in this study, two typical control schemes (PQ and VF) of the VSIs are overall expounded and active/reactive power required network is distributed between VSIs properly. In this control strategy, the power regulation for all of the VSIs should meet the total demand of MG so that the power of PQ-DGs operates at maximum power point (MPP) and the VF-DGs units share the remained power according to the droop control strategy. Simulation results are shown to validate the proposed control strategy.