Improving Safety and Reliability On High-Voltage Lines With Broken-Conductor Detection: A Utility’s Perspective

This paper provides real-world examples to demonstrate how broken conductor detection (BCD) can complement and improve traditional shunt fault protection schemes. The paper also analyzes three particular real-world events—two from the Great River Energy (GRE) system and one from the Bonneville Power Administration (BPA) system. Each event started with a broken conductor and evolved to include a line-to-ground (LG) shunt fault on one side of the conductor break. One event resulted in a breaker failure operation caused by a slow breaker, which led to a more impactful outage. In all three events, the shunt faults introduced concerns with ground protection sensitivity, specifically regarding the ability to detect the shunt fault from the terminal on the opposite side of the break. Complementing the existing shunt fault protection schemes with BCD would have mitigated several concerns in these events.

A conductor break starts as a series fault before, in many cases, evolving to include an LG shunt fault on one or both sides of the break. The series fault duration is almost always long enough to measure the waveform characteristics of a series fault event, even in a falling conductor scenario. Detecting and isolating the broken conductor in the series fault state results in a safer power system with improved reliability by minimizing the risk of wildfire, the stress on equipment, and the impacts of outages. This paper presents an enhanced BCD method and, through event analysis, demonstrates its response to the broken conductor events. In addition, the provided discussion demonstrates the benefits of applying BCD techniques concurrently to shore up dependability gaps in traditional detection schemes during this simultaneous fault.