An Analytic Fault-Location Expression for Three-Ended Transmission Networks Capable of Avoiding Synchronization-Angle Estimation Mismatch

This article presents a distinctive and reliable fault location approach tailored for three-ended transmission lines using voltage and current phasors acquired from intelligent electronic devices (IEDs) based digital relays installed individually at each end, without data synchronization functions. By integrating analytic methodologies with state-of-the-art synchronization algorithms and an imaginary-part observation method, an exclusive faulty branch index and a fault location index are designed to pinpoint closed-form faulty line branch and fault position solutions. Crucially, the unsynchronized phasor measurements among three ends can be simultaneously eliminated from the proposed noniterative calculation process. Not only is the proposed method unaffected by synchronization-angle estimation mismatch, but it also avoids problems such as multiple or approximate solutions, fault-path and source impedance assumptions, numerical divergence, and fault-type selections. The proposed method has been deployed in the fault location platform of Taiwan Power Company (Taipower) since early 2024. Importantly, both simulations and field empirical testing conducted on Taipower's actual fault events have validated the feasibility and effectiveness of the suggested ideas in power industry applications, showcasing its potential impact to enhance fault location accuracy and reliability in real-world operational environments.