An investigation study of transmission line fault location using travelling wave

Abstract

The project report proposes that travelling wave will produced different location when the reflected wave is interpreted differently by the devices in the system. The security of Sarawak Grid depends very much on the availability of the transmission network. It is, therefore, important that any transmission line fault can be located speedily and accurately to minimize the down-time or repeated tripping. Currently, Sarawak Energy Berhad (SEB) is using Traveling Wave Fault Location System (TWS) to identify correct transmission line fault location. For a single-ended travelling wave fault location, the identification on the reflected wave is the core of getting precise location of the fault. Due to the polarity of the travelling wave reflected from the fault point or from the remote-end bus is affected by the bus configuration at both ends of the faulted line, it is difficult to identify whether the travelling wave is reflected from the fault point or the remote-end bus using the polarity of single modal travelling wave. A previous study only proposes method of locating by simulating the fault in a controlled environment. There are two types of traveling wave analysis techniques are proposed in the project report. The modelling of the simplified electrical network will be done using MATLAB Simulink where four types of fault; 3-phase fault, 2-phase fault, 2 phase-to-ground faults and single-phase fault will be simulated in the network. Analysis of the travelling wave waveforms are done after the signal processing of the faulted current waveform are carried out. Analysis of the travelling wave waveforms show that effects of variables such as fault inception angle, fault resistance, line distance and weak-end will produce a fault location which is not accurate. The data analyzed with the methods proposed in the project report found that the results reflect the finding in the simplified electrical network modelling. The simulation shows that the fault impedance has a minor effect (less than 5% error margin) on the traveling wave waveform and amplitude. However, the fault inception angle (less than 5°) can be a cause for the TWS fault location equipment to mis-operate and not capture the event.