City Research Online

Abstract

The problems associated with detection and clearing of faults on overhead distribution systems, particularly in interconnected networks, are still of great concern. Most utilities employ reclosing relays with circuit breakers to handle transient faults. Permanent faults, however, require a location of the faulty line section, isolation and possibly rescheduling of the network, before normal power delivery may be resumed.

This work is mainly concerned with the design of a new directional fault locator, suitable for use on overhead power distribution systems operating typically at llkV. It is possible to design a protective scheme based upon a variety of operating principles, but the operating principle of the new equipment and the scheme developed are based upon detection of fault generated noise. In the past, schemes based upon this operating principle have relied on use of a communication link to locate a fault. However, the new scheme developed in this work does not require the presence of such a communication link.

The electronics that interface with the new equipment enable it to determine the direction of a fault, i.e, distinguish between upstream and downstream faults. The means by which directional fault finding is achieved are fully discussed. Moreover, with further signal processing of fault generated signals, the usefulness of the new scheme has been extended and, in addition to being directional, it is also capable of locating the faulty line section of an overhead distribution system, i.e, distinguish between in-zone and out-of-zone faults.

The effect of fault resistance, fault inception angle, fault position, source capacity and the effect of type of fault on the performance of the new equipment have been studied and relevant simulation results are presented. Finally the behaviour of a number of new directional fault locators on a radial overhead system has been evaluated using the Electromagnetic Transients Program, EMTP.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments:	School of Science & Technology > Engineering > Electrical & Electronic Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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