Protective relay traveling wave fault location

For decades, various versions of the Takagi algorithm have been used by microprocessor-based relays for fault location. This system provides accurate fault location, limited by nonhomogeneous infeed, load flow, fault resistance, and series-compensated or parallel lines. With the emphasis placed on reliability in today´s power system, the need for improved accuracy in fault location has increased. Cases involving transmission lines spanning rivers or large valleys mean that a small error in fault location can force maintenance crews to spend added hours, or days, to find broken insulators or other faulted line components. Traveling wave fault location overcomes the issue of measuring distance using high-frequency fault transients measured from a single line end or both line ends. The complications that have to be overcome include connections to protection current transformers and voltage transformers, filters on incoming circuits to avoid surges and spikes, and processing both power system frequencies (1 Hz to 3 kHz) and traveling wave transient frequencies (10 kHz to 600 kHz) in the same device. This paper discusses the implementation and application aspects of traveling wave fault location in a protective relay. Performance limitations are discussed, as well as system requirements and practical installation considerations.