To improve the reliability of the electric distribution system, National Grid has implemented a ‘home-made’ fault location, isolation & service restoration (FLISR) system. FLISR is a centralized system that communicates with field devices to identify and isolate the location of a fault or “interruption”, before autonomously re-routing power to minimize the impact of the outage. Twenty percent of National Grid’s Massachusetts customers are connected to a distribution feeder with FLISR enabled, and FLISR has had a material impact on customer reliability.

This presentation will address the successes and challenges National Grid has encountered in deploying its home-grown implementation of FLISR and give some examples of successful FLISR operations. A discussion of the technical implementation of FLISR will be included, covering communications and protection equipment, coordination with sub-transmission auto-transfer schemes, coordination between reclosers in alternate feeder configurations, load current validation, load checks to prevent equipment and cable rating violations, load masking by distributed energy resources, safety-interlocks to protect worker safety during feeder maintenance, and scheme simulation testing. In addition, we will discuss the future of FLISR in an ADMS-enabled system, and the potential to integrate FLISR with other wider efforts across National Grid, such as flexible interconnections and distributed energy resource management systems.