Resilient Distribution System by Microgrids Formation After Natural Disasters

Microgrids with distributed generation (DG) provide a resilient solution in the case of major faults in a distribution system due to natural disasters. This paper proposes a novel distribution system operational approach by forming multiple microgrids energized by DG from the radial distribution system in real-time operations to restore critical loads from the power outage. Specifically, a mixed-integer linear program is formulated to maximize the critical loads to be picked up while satisfying the self-adequacy and operation constraints for the microgrids formation problem by controlling the ON/OFF status of the remotely controlled switch devices and DG. A distributed multiagent coordination scheme is designed via local communications for the global information discovery as inputs of the optimization, which is suitable for autonomous communication requirements after the disastrous event. The formed microgrids can be further utilized for power quality control and can be connected to a larger microgrid before the restoration of the main grids is complete. Numerical results based on modified IEEE distribution test systems validate the effectiveness of our proposed scheme.

I. Introduction

Recent severe power outages caused by natural disasters, such as floods and hurricanes, have highlighted the importance and urgency to improve grid resilience of the U.S. For example, Hurricane Sandy left approximately 7.5 million customers without power across 15 states and Washington, DC, after it hit the eastern shore of the U.S. [1]. A recent Congressional Research Service study estimates the inflation-adjusted cost of weather-related outages at $25 to$70 billion annually in the U.S. [2]. Grid resilience is increasingly critical since the number of outages caused by severe weather is expected to rise as climate change increases the frequency and intensity of hurricanes, blizzards, floods, and other extreme weather events [3]. As the utility grids remain quite vulnerable and exposed to natural disasters, rather than protecting the power grids from storms like Sandy, the power industry has focused on methods of restoring the distribution system quickly after disasters to achieve resilient power grids [1].