Microcomputer based methodology for distance protection on long UHV transmission lines using symmetrical components

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Date
2010
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Publisher
University of Management and Technology
Abstract
This research work proposes a methodology for the long UHV transmission lines distance protection using microprocessor for fault detection, isolation and auto reclosing processes. For the protection of transmission lines distance relays are used, which depend on a function of impedance between relay location and fault point. In the present era, the development of microprocessors, their extra efficient controlling and computing abilities can be utilized in distance relaying for efficient computing of fault distance on transmission line and the type of fault occurred. The approach that is adopted here is to use sequence components to calculate the distance of fault point. In a normal distance relaying system that uses phasor values of voltage and current as input, six impedance calculating units are required for all ten types of fault that may occur in transmission line. With the advent of symmetrical component analysis tool these six impedance calculating units can be replaced by a single unit which will overall result in a considerable optimized and efficient protection system. Using Symmetrical component theory a single performance equation is developed that will encounter all type of faults on transmission lines. Microprocessor will serve the purpose of computing sequence components, distance of the fault from the relay point and the type of fault. The phasor values of voltage and current is given as an input to the microcomputer that will calculate symmetrical components and resulting sequence impedances. It eventually finds the distance of the fault using performance equation, ratios of voltages in that particular equation and their resulting phase difference. These calculations will lead us to the judgment of the phases involved in fault. ETAP is used for simulation to obtain desired results. Although the formulation described here is independent of hardware yet it provides a complete analytical base for distance protection and is analyzed for different types of fault conditions using simulation tools.
Description
Project Advisor: Abdul Aziz Bhatti
Keywords
UHV Transmission, MS Theses, Symmetrical Components
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