A Protection and Operating Scheme Integrated into a Grid-Edge Microgrid

This paper presents a protection and operating scheme integrated into an installed grid-edge microgrid in rural Western Canada. The scheme employs a centralized controller with relays utilizing traditional overcurrent elements in conjunction with voltage and frequency components to yield efficient protection and operation of the microgrid in both grid and islanded modes. The relays are independent and use a single group of settings removing the need to change based on operating topology. The proposed elements are utilized to handle the drastic differences in fault characteristics when transitioning between grid and islanded modes. The proposed scheme is tested in a laboratory environment with an Omicron test set and SEL relays which confirm its efficacy in the context of this microgrid’s application.