Under-frequency load shedding in isolated multi-microgrids

In this paper, a new under-frequency load shedding (UFLS) scheme is proposed for multi-microgrid (MMG) application. MMG, consists of multiple micro-grids, perhaps with different owners, connected together. Multiple owners make load shedding policies more complex in MMG compared to the policies employed in micro-grids and large power systems. Accordingly, an appropriate UFLS scheme is required, in order to ensure the frequency stability of the MMG, while considering its economic aspects. Therefore, in this paper, an optimization problem has been introduced which minimizes the cost imposed on the owners for mandatory load shedding alongside the cost of MMGs operation after the load shedding procedure. By solving the proposed optimization problem, the optimal locations of loads to be shed are determined. Two optimization algorithms - genetic algorithm (GA) and exchange market algorithm (EMA) - and GAMS software have been used for solving this optimization problem. A new index is introduced in this paper in order to distribute load shedding among MGs based on their total power generation and load demand. Simulation results confirm the efficiency of the proposed methodology. (C) 2021 Elsevier Ltd. All rights reserved.