Risk-based maintenance for asset management of power transformer: practical experience in Thailand

摘要

Nowadays, the requirement on diminishing operating and maintenance costs is highly concerned for utilitiesrnin competitive electricity market. Power transformer is first focused due to its acquisition costs and failurernconsequences (FCs). Traditional preventive maintenance for power transformer is generally applied. However,rnit is very costly and does not take into account actual transformer condition. Hence, risk-based maintenance isrnintroduced in this paper to facilitate the maintenance works of power transformers. The conditions of powerrntransformers are evaluated from electrical test, insulating oil test and visual inspection by using the rankingrnand weighting techniques. In addition, the Analytic Hierarchy Process (AHP) is proposed to determine the importantrnweighting factor of each transformer component. The three main criteria of the AHP are maintenancerndifficulty, FC and failure history. Moreover, the Weibull distribution techniques are applied to analyze failurerncauses. The computerized web-application program is developed and implemented for practical use in a utilityrnin Thailand. The power transformers installed in 115 kV and 230 kV transmission systems in Thailand arernassessed due to availability and quality of data. From statistical analysis of failure records, the conditions ofrnpower transformer can be divided into three different zones as risk, moderate and healthy zone. The defectiverncomponents in risk zone with higher proportion of failure should be carefully focused. The components andrnoverall condition of the transformers are perceived from the analysis of test results. Subsequently, thernrisk-based maintenance is properly planned according to the actual condition. Therefore, maintenance of powerrntransformer fleet can be effectively managed resulting in higher availability and reliability, lower risk of failurernand lower cost of maintenance. Copyright © 2013 John Wiley & Sons, Ltd.