Publication: Design of fault locators for transmission lines using matlab simulation
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Date
2012-06-01
Authors
Ho, Chee Wai
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Abstract
Transmission and distribution lines experiences faults due to storms, lightning, snow, freezing rain, insulation breakdown and, short circuits caused by birds and other external objects. In most cases, electrical faults manifest in mechanical damage, which must be repaired before returning to service. When the fault is at the transmission line, a precise fault locator must be able to detect the fault so the maintenance team can reach and fix the problem quickly. A good fault locator may help to remove the fault quickly, save cost, improve in system reliability and decrease in economic damages. Transmission line faults can be categorized to Balanced threephased, Single Line to Ground, Double Line to Ground, and Line to Line Faults. When the unbalanced faults occur, we need to consider the symmetrically balanced positive-sequence and negative-sequence set, and also a single-phased zero-sequence set parameters. Impedance-based fault location methods are the most commonly used in practice for reason of simplicity and low building cost. In this report, three methods of single terminal impedance-based fault location techniques are analyzed to compare their efficiency. The above four categories are considered in this project. Beside fault location to determine the length on the transmission line, a fault locator for fault buses is developed because fault bus is also a problem to the power system. A MATLAB program for each category/case is developed and the program can be used to calculate the error on the transmission line using all the information given including line impedance, voltage source, current source, and fault current in magnitude and degree. Fault location can be further improved into medium and long transmission line and more buses in the power transmission networks.