COMPUTER-AIDED DESIGN AND PERFORMANCE EVALUATION OF DIGITAL RELAYS
Date
1985-08
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ORCID
Type
Degree Level
Masters
Abstract
During the last several years interest in microprocessor based relays for power system protection has increased considerably. Operating speed and accuracy of these relays are of major concern. A microprocessor based relay has several subsystems, such as, analog input, signal conditioning, digital I/O, digital processor and power supply subsystems.
In digital relays, the accuracy of the acquired data and computed results depend on factors, such as, characteristics of the analog to digital converters, digital processor design and relay software. For studying the influence of these factors on the performance of digital relays, two approaches can be used. One approach would be to design and build a prototype and then test it. This procedure would be expensive if a design has to be changed several times. The second approach would be to develop computer simulations of the digital relays on a main frame computer. This would provide an inexpensive, flexible and interactive approach for assessing relay designs.
This thesis identifies the errors and their sources in digital relays. An interactive technique for simulation of digital relays on a main frame computer is developed. The technique estimates operating speeds of digital relays and examines the accuracy of computed results. The developed
technique uses microprocessor instruction simulators and A/D converter models. Two digital relaying algorithms have been simulated. The results indicate that errors can be unacceptable if improper hardware and software is selected.
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Degree
Master of Science (M.Sc.)
Department
Electrical Engineering