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A TECHNIQUE FOR ESTIMATING TRANSMISSION LINE FAULT LOCATIONS FROM DIGITAL IMPEDANCE RELAY MEASUREMENTS

Date

1985-03

Journal Title

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Volume Title

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Type

Degree Level

Masters

Abstract

The usual approach for estimating locations of transmission line shunt faults has been to measure the apparent impedance to the fault from a line terminal and convert the impedance to line length. One factor that adversely affects fault location estimates is the fault resistance that appears to the relay to be an impedance that has both resistive and reactive components if the fault current is supplied from both line terminals. Several methods that estimate transmission line fault locations have been proposed in the past. These methods use fundamental frequency voltages and currents measured at one or both line terminals. The accuracy of the methods that use data from one line terminal depends on the accuracy of the estimates of source impedances and fault current distribution factors. The accuracy of the methods that use data from two line terminals depends on the synchronization of the measurements taken at two line terminals. This thesis presents a technique that estimates the location of a transmission line shunt fault from fundamental frequency voltages and currents measured at the line terminals. The technique uses apparent impedances as seen from the terminals of a transmission line. Line charging is initially neglected and is later taken into consideration. Results from computer simulations of single and multi-phase faults on a 500 kV line inter-connecting two power systems are presented. The results indicate that the proposed method is quite accurate even when fault resistances are numerically comparable to the line impedances. The observations from the two line terminals do not have to be synchronized. Source impedances, distribution factors and pre-fault currents are not needed by the estimation procedure.

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Citation

Degree

Master of Science (M.Sc.)

Department

Electrical Engineering

Program

Advisor

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DOI

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