Proposed Risk Model of Maintenance Management for Power Transformer in Transmission System

Abstract

Risk on acquisition and maintenance costs of electrical equipments, in particular power transformer, has been faced by electric utilities so that proper maintenance strategies for reducing the risk with acceptable reliability to the system are concerned. Risk model, developed by combining transformer condition and network characteristic with applied scoring and weighting approach, is proposed. Diagnostic tests such as electrical and oil tests are utilized for condition assessment, while operating characteristics of the transformer are used for network assessment. In addition, the developed risk model with higher priority on the transformer network respect to the transformer condition with 70%-30% weighting, provides recommended maintenance zones that are categorized by risk levels of the transformer. The risk level of the transformer is calculated by means of trigonometry technique. The transformer with high risk is maintained first for its maintenance task. The test results and the network characteristic data of the transformers rating of 115/22 kV and 230/115 kV are selected and collected for supporting the proposed risk model. Subsequently, maintenance actions of the obtained risky transformers are subsequently planned suitably to improve reliability and stability of the transmission system.