Dynamic load shedding for an islanded microgrid with limited generation resources

Abstract

When an extreme weather event strikes a distribution system, the utility power may not be available for days or even weeks. As a result, a microgrid in the affected area will be operated in the islanded mode during that period. To continuously serve critical load with available generation resources, which are usually limited, load shedding actions can be performed to gradually disconnect load with low priority. This study proposes a method to obtain the dynamic load shedding strategy for an islanded microgrid with limited generation resources. First, dynamic load shedding is formulated as a stochastic optimisation problem, where the uncertainties induced by intermittent energy sources and load are incorporated. The objective is to maximise the economic performance of the microgrid. Limits on the generation resources and operational constraints are considered. Then, a model based on Markov decision process (MDP) is developed for the problem. A solution method for the MDP model is proposed to obtain the optimal load shedding strategy. Finally, numerical simulations are performed to validate the effectiveness of the proposed method. Impacts of available generation resources, uncertainties of wind power prediction, and load shedding time period on the load shedding strategy are discussed.