A decentralized self-adjusting control strategy for reactive power management in an islanded multi-bus MV microgrid

This paper presents a decentralized self-adjusting reactive power controller for the autonomous operation of a multi-bus medium voltage (MV) microgrid. The main objective of the proposed control strategy of each distributed generation (DG) unit is to compensate the reactive power of its local loads and to share the reactive power of the nonlocal loads among itself and other DG units. The proposed control strategy includes an improved droop controller whose parameters are adjusted according to the reactive power of the local loads. A virtual inductive impedance loop is augmented to the voltage controller to enhance the steady state and transient responses of the proposed reactive power management scheme. The small signal analysis of the proposed method is presented to ensure stability of the system for different reactive power values. The presented strategy considerably enhances the voltage profiles of the microgrid buses as compared with the conventional droop methods. The proposed method does not require any communication link and minimizes the reactive power flow in the MV lines, thus reducing the losses of the overall microgrid. The performance of the proposed control scheme is verified by using digital time-domain simulation studies in the PSCAD/EMTDC software environment.