Yihui Zheng

A novel traveling-wave-based fault-location algorithm for multi-terminal transmission lines is introduced in this paper. Existing traveling-wave fault-location methods that based on the data measured at line terminals lack reliability and accuracy because time synchronization is needed, which brings error. To solve this problem, the complex structure of multi-terminal power system is divided into several fault identification branches, current at the midpoint of each branched is measured, a novel fault-location algorithm is proposed, and the time synchronization error is eliminated. A line-based device is designed to measure the current at the midpoint of each branch. An accurate value of the traveling wave speed can be obtained by merely applying the data record in one measuring device. Thus, the fault-location accuracy is improved. The system model applied in this article comprises one transmission line and two tapped lines, and the proposed method applies to networks with more terminals. Performance of this method is tested by different cases by PSCAD. The hardware platform has been tested in Sichuan Province, China.

Existing single‐ and double‐terminal travelling‐wave fault‐location approaches have some disadvantages including difficulty in distinguishing the sources of reflect and refract waves, system error in time synchronisation and wave propagation velocity. In this study, a distributed travelling‐wave‐based fault‐location system, which eliminates the time synchronisation and wave propagation velocity error, is introduced. This novel system is consisted of three measurement points, which are located at both ends and the mid‐point of the line. At first, the measurement points, installed at both line ends, record the post‐fault current data for a time interval. The measurement point, located at the mid‐point, records the time tags of the three sequential wavefronts as , and separately including the initial wave and following waves reflected at both the ends. Second, by comparing fault current recorded by the three measurement points, the fault interval can be determined based on current deviation theorem. Finally, travelling‐wave propagation velocity is calculated according to mathematic equation in terms of . Then, the fault point is located without the need of time synchronisation. The simulation and hardware tests match the theoretical analysis well, showing that the proposed location method provides not only high accuracy, but also good reliability.