الفهرس | Only 14 pages are availabe for public view |
Abstract This thesis is aimed at estimating fault location on overhead transmission line using two different approaches. The first approach is based on waves originated at fault location. Faults in power transmission lines usually cause transients that travel at a speed close to the speed of light and propagate along the line as traveling waves. Traveling wave theory is utilized in capturing the travel time of the transients along the line between the fault point and the protective relay. This will help in proposing a fault location technique based on high frequency components of fault current. The resolution time for these components is provided by discrete wavelet transform (DWT). The application of the proposed technique for different fault types is illustrated using simulations obtained by MATLAB Simulink program. The accuracy of the proposed technique for locating the fault is assessed for different fault inception angles and fault resistance values. The second approach for fault location is based on nominal π-model transmission-line representation. It solves the describing differential equation for nominal π-model of line under different types of fault with mutual inductances and mutual capacitances taken into consideration. Sampling of the measured currents and voltages at relay location and using central differences, the current and voltage derivatives can be determined from the measured samples. Using adequate data window for measured current and voltage, the line equation can be solved to determine the line impedance from relay location to fault point and hence ABSTRACT - iii the fault location is defined. Least square error method is used to obtain the best solution from the used data window. The application of the proposed technique for different fault types is illustrated using simulations obtained by ATP/EMTP program. The accuracy of the proposed technique for locating the fault is assessed for different fault inception angles and fault resistance values. The proposed approaches are accurate in assessing the fault location and have the advantages of being independent of the fault resistance and fault inception angles under different fault types. |