Publications (6)5.16 Total impact
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Article: Expert system for the assessment of power transformer insulation condition based on type-2 fuzzy logic systems.
Expert Syst. Appl. 01/2011; 38:8119-8127. -
Article: Expert system for the assessment of power transformer insulation condition based on type-2 fuzzy logic systems
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ABSTRACT: An efficient expert system for the power transformer condition assessment is presented in this paper. Through the application of Duval’s triangle and the method of the gas ratios a first assessment of the transformer condition is obtained in the form of a dissolved gas analysis (DGA) diagnosis according IEC 60599. As a second step, a knowledge mining procedure is performed, by conducting surveys whose results are fed into a first Type-2 Fuzzy Logic System (T2-FLS), in order to initially evaluate the condition of the equipment taking only the results of dissolved gas analysis into account. The output of this first T2-FLS is used as the input of a second T2-FLS, which additionally weighs up the condition of the paper-oil system. The output of this last T2-FLS is given in terms of words easily understandable by the maintenance personnel. The proposed assessing methodology has been validated for several cases of transformers in service.Expert Systems with Applications 01/2011; · 2.20 Impact Factor -
Article: Fuzzy Risk Index for Power Transformer Failures due to External Short-circuits
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ABSTRACT: A novel methodology to assess the risk of power transformer failures caused by external faults, such as short-circuit, taking the paper insulation condition into account, is presented. The risk index is obtained by contrasting the insulation paper condition with the probability that the transformer withstands the short-circuit current flowing along the winding during an external fault. In order to assess the risk, this probability and the value of the degree of polymerization of the insulating paper are regarded as inputs of a type-2 fuzzy logic system (T2-FLS), which computes the fuzzy risk level. A Monte Carlo simulation has been used to find the survival function of the currents flowing through the transformer winding during a single-phase or a three-phase short-circuit. The Roy Billinton Test System and a real power system have been used to test the results.Electric Power Systems Research 01/2009; 79(4):539–549. · 1.48 Impact Factor -
Article: A new class of flat-top windows for exposure assessment in magnetic field measurements.
Signal Processing. 01/2007; 87:2151-2164. -
Article: Fuzzy risk index for power transformer failures due to external short-circuits
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ABSTRACT: A novel methodology to assess the risk of power transformer failures caused by external faults, such as short-circuit, taking the paper insulation condition into account, is presented. The risk index is obtained by contrasting the insulation paper condition with the probability that the transformer withstands the short-circuit current flowing along the winding during an external fault. In order to assess the risk, this probability and the value of the degree of polymerization of the insulating paper are regarded as inputs of a type-2 fuzzy logic system (T2-FLS), which computes the fuzzy risk level. A Monte Carlo simulation has been used to find the survival function of the currents flowing through the transformer winding during a single-phase or a three-phase short-circuit. The Roy Billinton Test System and a real power system have been used to test the results.Electric Power Systems Research. -
Article: Corona loss characteristics of contaminated conductors in fair weather
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ABSTRACT: In the present work, the results of a laboratory measurement project of corona losses on contaminated conductors in fair weather are presented. The measurements carried out furnish new information, which is not available in the literature. The research work performed in the past has dealt with corona losses under rain and snow, and some semiempirical formulae have been proposed, which do not approach adequately the corona losses in the case of contamination in fair weather. A calculation formula for the case of contaminated conductors in fair weather has been proposed in this work on the basis of the performed research, and the corresponding fitting coefficients have been calculated. An appropriate mathematical tool for the predetermination of corona losses is hence available for this case.Electric Power Systems Research 59(1):21-29. · 1.48 Impact Factor
