Thesis

An expert system approach to on-line fault diagnosis in power system networks

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Awarding institution
  • University of Strathclyde
Date of award
  • 1992
Thesis identifier
  • T7421
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • The increased computing power which has been installed in power system control centres coupled with the introduction of more advanced Supervisory Control And Data Acquisition (SCADA) systems has increased the volume of data presented to system operators. In certain instances, control centre staff have failed to keep track of the interpretation of system conditions following faults. There is a recognised need to provide on-line aids to the interpretation of SCADA system data, such as fault diagnosis systems. This thesis reports on research undertaken to produce a practical fault diagnostic expert system which can cope with real-world problems encountered by power system operators such as protection/switchgear maloperations and missing alarms. The Prolog language was used to represent the knowledge in both logic rules and production rules. In view of the scale of the fault diagnosis problem, hierarchical structures were developed for diagnostic conclusions and the means of diagnosis. Two diagnostic strategies have been developed. Firstly, the “wait-and-see” strategy awaits the appearance of black-out areas and uses the intersection of related relays’ protected areas to locate faults. In contrast, the “hypothesiser” strategy compares activity obtained from qualitative simulations of fault hypotheses with received SCADA alarms. Both strategies rank competing conclusions according to a developed “relative likelihood” measure. Significant portability has been achieved through the incorporation of qualitative modelling knowledge for power and protection system equipment which allows a distinction between the diagnostic knowledge and network knowledge to be maintained. The efficiency of the network tracing used in the expert systems was improved through the co-operative use of a loadflow routine. Both the desire to include maloperations and to contain, to a reasonable level, the number of possible conclusions considered, were found to be contrasting. The evolved hypothesising expert system is presented as a viable solution. Case studies demonstrate the beneficial information provided by the fault diagnosis. They also show the advantages of the ultimate “hypothesiser” over the “wait-and-see” strategy, which include an inherent explanation capability. The level of knowledge in the fault diagnosis conclusions opens up potential for the expert system’s use as the basis of a restoration advisor.
Advisor / supervisor
  • McDonald, J. R. (James Rufus), 1957-
Resource Type
Note
  • Please note page 135 is missing from this thesis.
DOI
EThOS ID
  • uk.bl.ethos.340000
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