A protection scheme using ultra-fast circuit breakers for wildfire mitigation and reliability improvement for rural distribution

Abstract

The advent of ultra-fast (half-cycle), compact, remote controllable and cost effective circuit breakers suitable for deployment on rural lateral lines provides opportunities for new approaches to protecting these lines. This paper will present a novel scheme that provides significant benefit to operators of rural overhead MV distribution networks in terms of reliability improvement and minimizing the risk of electrical faults causing ignition of wild fires. Firstly, the key criteria for reliability optimization and mitigation of electrical faults causing ignition of fires are presented. An assessment of the performance of a number of typical lateral line protection schemes is conducted. All traditional approaches have a number of deficiencies, primarily related to preventing wild fires. New ultra-fast circuit breaker technology is introduced that enables a new approach to the optimal protection of rural lateral lines. A novel protection scheme is presented and is shown to represent the optimal solution for both reliability performance and prevention of electrical faults causing wild fire ignition on extreme weather days. For fault levels typical on rural lateral lines, when switched off in less than a half cycle, there is inadequate energy in the arc to cause fire ignition. This alternate protection mode can be remotely commanded over SCADA to allow rapid network response to extreme weather. An example is presented to clarify the expected performance.