Stochastic Energy Management of Microgrids During Unscheduled Islanding Period

This paper deals with energy management of microgrids during unscheduled islanding events, initiated by disturbances in the main grid. In these situations, the main challenge is uncertainty about duration of disconnection from the main grid. In order to tackle this issue, a stochastic framework is proposed for optimal scheduling of microgrid resources over this period. The presented framework addresses the prevailing uncertainties of islanding duration as well as prediction errors of demand and renewable power generation. According to this framework, the probability distribution of islanding duration needs to be estimated, instead of predicting its exact value. The objective is to minimize the expected value of operation cost over the estimated islanding interval, while restricting the load loss risk imposed by uncertain parameters within an acceptable level. Moreover, the impact of microgrid scheduling on the subsequent grid-connected operation is considered via a simple method. The associated stochastic optimization problem is formulated as a mixed integer linear programming model. The developed framework is implemented on a test microgrid and various case studies are presented to demonstrate its effectiveness.