A Hybrid Method for Fault Location in EHV Multi-Terminal Circuits

Protection of Extra High Voltage (EHV) multi-terminal circuits in power systems is complicated due to non-availability of measurements at the tap points. Locating a fault in such circuits is an important task for post-fault repairs or identification of weak spots in the system. This paper presents a new fault location scheme for an EHV multiterminal circuit. The proposed method utilizes synchronized voltages and currents of three phases from all the ends of the circuit. Both transient high frequency and fundamental frequency components of the fault signals are used to detect and locate the fault. While the Wavelet Transform is used to extract the features for fault detection and section identification, a Discrete Fourier Transform (DFT) based approach is applied to estimate phasors for exactly locating fault with in the faulted section. The scheme is tested on a simulated system for various types of faults, fault locations, inception angles and fault resistances. Results indicate that the scheme is reliable, fast and accurate. KeywordsPower System protection, Fault Location, Multi-terminal Circuits.