A new optimal under-voltage load shedding scheme for voltage collapse prevention in a multi-microgrid system

Abstract

In this paper, a new optimal under-voltage load shedding (UVLS) method is presented to maintain voltage stability of a multi-microgrid (MMG) system. Great benefits are gained by exploiting MMGs, indicating the integration of microgrids (MGs) and distributed energy sources (DERs), at both medium voltage (MV) and low voltage (LV) levels. Advanced strategies should be employed in order to guarantee stability of a MMG. This paper, for the first time, presents an optimal UVLS scheme for the MMGs which considers voltage stability margin, minimum amount of load shedding and minimum operation cost of the system in the objective function, simultaneously. In addition, application of demand response programs (DRPs) and MGs/loads priorities have been addressed in the proposed method. The optimal load shedding problem is solved using hybrid discrete continuous exchange market algorithm (HDCEMA) with regard to system stability, voltage magnitudes and other related constraints. The proposed method is tested on a 55-bus MMG system consisting of 5 MGs with distributed and renewable energy sources. In order to compare results with previous methods, two UVLS schemes and two optimization algorithms in the literature are implemented on the simulated MMG system. Simulation results confirm the effective performance of the proposed method.