Analysis of Cascading Operations for Adjacent Line Faults
Cascading operations can be challenge to analyze. Prior to utilizing digital fault recorder for disturbance analysis, it was very difficult to analyze a complicated cascading operation due to lack of time aligned fault records on both analog and digital data. Two 115kV line fault events occurred on the same line within 1 second at National Grid, which cascaded and resulted in unexpected operations of a 345/115kV transformer and three adjacent 115kV line breakers, interrupting services to customers and impacting system reliability - a major concern for the Regional Transmission Operator ISO New England and National Grid. The protection system shall isolate faults and minimize customer outages. This paper examines a cascading operation during two 115kV line faults. Fault records of digital fault recorders were utilized to determine what happened. The fault records captured by fault and Sequence of Events recording equipment provided valuable information which gave an insight into the nature of this disturbance. The analog and digital data of fault records facilitate an efficient investigation and accurate analysis of these events.