Decentralized model predictive hierarchical control strategy for islanded AC microgrids

Abstract

This paper presents decentralized Model Predictive Control (MPC) based hierarchical control scheme with both primary and secondary level for an islanded AC microgrid to address power quality and unequal power sharing problems. The control scheme consists of an inner control loop, primary control and secondary control. Finite Control Set-Model Predictive Control (FCS-MPC) is incorporated in the inner loop to track the reference voltage and fix the capacitor voltage in each Distributed Generator (DG) unit. Primary control comprises of virtual impedance loop and droop control to control power flow and power sharing among DG systems. Moreover, state space predictor based secondary control is proposed for regulating frequency of the microgrid and node voltage to their nominal values in islanded operation. Furthermore, the performance of the proposed control method is analyzed with the static model of dynamic loads and validated with conventional control scheme under mismatched feeder impedance.