# New Algorithms for Locating Faults in Series Capacitive Compensated Transmission Lines

## Degree

Doctor of Philosophy

## Program

Electrical and Computer Engineering

## Supervisor

Sidhu, Tarlochan S.

## Abstract

The precise location of the fault in a series capacitive compensated transmission line (SCCTL) plays an integral part in limiting the maintenance time following its tripping due to the occurrence of a permanent fault. Since, an SCCTL acts as a huge corridor of power, its outage will result in huge monetary losses which are directly proportion to the time it remains out of service. In worst case scenario, the tripping of an SCCTL might lead to the cascaded tripping of the parallel transmission lines due to overloading. Therefore, the need for an accurate and robust fault location algorithm for the SCCTLs becomes critical. Consequently, the focus of this thesis is to develop new fault location algorithms for the SCCTLs.

First of all, the concept of fault location in conventional transmission lines and its application to SCCTLs has been explained. The mathematical analysis of impedance-based fault location algorithms for SCCTLs which are the most widely used fault location algorithms for SCCTLs, is performed. The mathematical analysis enables a deeper look into the strengths and deficiencies of the existing algorithms. After the identification of the innate limitations of the existing fault location algorithms, three new impedance-based fault location algorithms have been proposed with the aim of maximum utilization of the available measurements to improve the accuracy of the fault location results in SCCTLs. The proposed impedance-based algorithms are then tested for various fault scenarios using simulations carried out in Matlab, and PSCAD. The comparative analysis of the proposed algorithms with the existing algorithms is also performed.

The interest in traveling wave-based fault location algorithms has been renewed lately due to the availability of commercial relays capable of sampling in the range of 1 MHz. Therefore, the traveling wave theory which forms the basis of traveling wave-based fault location algorithms is discussed. The mathematical analysis of reflection, and transmission of the traveling waves from various points of discontinuity in an SCCTL has been performed which enables the understanding of the shortcomings of the existing fault location algorithms. Thereafter, a new single-ended traveling wave-based fault location algorithm has been proposed in this thesis. The performance of the proposed algorithm has been verified through the simulations carried out in PSCAD.

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