Enhancing Resilience in Islanded Microgrids with PV-Battery using Bi-level MILP Optimization

Over the last decades, a substantially increasing number of extreme weather events have happened due to climate change and global warming. Under this environment, islanded power systems that are usually weakly connected to the main grid, face unprecedented challenges in keeping power supply to critical loads during extreme weather events. To cope with the rising risk of isolation from the main grid during extreme weather events, there is a need to transform weakly connected islanded power systems into flexible microgrids with renewable generation and battery energy storage systems (BESS). Traditionally, the capacity of energy storage is determined by minimizing investment and operational costs or aiming to alleviate the impacts of intermittent renewable energies. Without considering the expected duration of power outage during isolated operation, these approaches are not enough for building a resilient island power system. In this paper, a two-level MILP BESS sizing model is proposed to transform a island power system into a flexible and resilient microgrid, aiming to maximize the critical load supplied in required duration, also to minimize the total cost at the same time. The seasonal PV power output profile and load profile are derived from the operation records of Orcas Power & Light Coorperative(OPALCO) and utilized in model validation and case studies. The sensitivity analysis between BESS sizing and PV integration capacity indicates that the consistency between PV profile and load demand profile has a great impact on how PV capacity may influence BESS sizing. Further, the resilience improvement brought about by the installation of BESS is quantified through a set of resilience metrics.