Research Papers - Department of Electrical and Electronic Engineering

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Author: search.filters.author.Hettiwatte, S. NSubject: search.filters.subject.Power Transformer

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    Missing measurement estimation of power transformers using a GRNN
    (IEEE, 2017-11-19) Islam, M. D. M; Hettiwatte, S. N; Lee, G
    Many industrial devices are monitored by measuring several attributes at a time. For electrical power transformers their condition can be monitored by measuring electrical characteristics such as frequency response and dissolved gas concentrations in insulating oil. These vectors can be processed to indicate the health of a transformer and predict its probability of failure. One weakness of this approach is that missing measurements render the vector incomplete and unusable. A solution is to estimate missing measurements using a General Regression Neural Network on the assumption that they are correlated with other measurements. If these missing values are completed, the entire vector of measurements can be used as an input to a pattern classifier. To test this approach, known values were deliberately omitted allowing an estimate to be compared with actual values. Tests show the method is able to accurately estimate missing values based on a finite set of complete observations.
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    Incipient fault diagnosis in power transformers by clustering and adapted KNN
    (IEEE, 2016-09-25) Islam, M. D. M; Lee, G; Hettiwatte, S. N
    Dissolved Gas Analysis (DGA) is one of the proven methods for incipient fault diagnosis in power transformers. In this paper, a novel DGA method is proposed based on a clustering and cumulative voting technique to resolve the conflicts that take place in the Duval Triangles, Rogers' Ratios and IEC Ratios Method. Clustering technique groups the highly similar faults into a cluster and makes a virtual boundary between dissimilar data. The k-Nearest Neighbor (KNN) algorithm is used for indexing the three nearest neighbors from an unknown transformer data point and allows them to vote for single or multiple faults categories. The cumulative votes have been used to identify a transformer fault category. Performances of the proposed method have been compared with different established methods. The experimental classifications with both published and utility provided data show that the proposed method can significantly improve the incipient fault diagnosis accuracy in power transformers.