Power Transformer Risk-Based Maintenance by Optimization of Transformer Condition and Transformer Importance

Authors: Kitti Leangkrua

Abstract:

This paper presents a risk-based maintenance strategy of a power transformer in order to optimize operating and maintenance costs. The methodology involves the study and preparation of a database for the collection the technical data and test data of a power transformer. An evaluation of the overall condition of each transformer is performed by a program developed as a result of the measured results; in addition, the calculation of the main equipment separation to the overall condition of the transformer (% HI) and the criteria for evaluating the importance (% ImI) of each location where the transformer is installed. The condition assessment is performed by analysis test data such as electrical test, insulating oil test and visual inspection. The condition of the power transformer will be classified from very poor to very good condition. The importance is evaluated from load criticality, importance of load and failure consequence. The risk matrix is developed for evaluating the risk of each power transformer. The high risk power transformer will be focused firstly. The computerized program is developed for practical use, and the maintenance strategy of a power transformer can be effectively managed.

Keywords: Asset management, risk-based maintenance, power transformer, health index.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1316125

References:

[1] CIGRE working Group A2.34, Guide for Transformer Maintenance, February 2011.
[2] Gradnik M.K., "Physical-chemical oil tests monitoring and diagnostics of oil-filled transformers", Proceedings of 14th international conference on dielectric liquids, 2002
[3] Lundgaard L. E., et al, "Aging of oil-impregnated paper in power transformers", IEEE transactions on power delivery, Vol.19, No.1, 2004
[4] Jayasinghe J.A.S.B., "Investigations on sensitivity of FRA techniques in diagnosis of transformer winding deformations", IEEE international symposium on electrical insulation, 2004
[5] Pleite, J.; Gonzalez, C.; Vazquez, J.; Lazaro, A., "Power transformer core fault diagnosis using frequency response analysis", Proceedings of the 37th North American power symposium, 2005
[6] Drobyshevski, "Assessment of transformer winding mechanical condition by low-voltage impulse method", IEEE PowerTech conference, 2003
[7] Brian Sparling; SMIEEE; Jacques Aubin; “Determination of Health Index for Aging Transformers in View of Substation Asset Optimization”, Proceedings of the 2010 International Conference on Condition Monitoring and Diagnosis, Japan
[8] Muhr M., Sumereder C., "Applying Risk Management for High Voltage Equipment", IEEE International Conference on High Voltage Engineering and Application, China, 2008
[9] Muhr M., "Aging and Degradation, Their Detection and Monitoring & Asset Management", IEEE International Symposium on Electrical Insulating Material, Japan, 2008
[10] J. Schneider, A. Gaul, C. Neumann, J. Hograefer, W.Well ow, M. Schwan, A. Schnettler, Asset Management Techniques, Power Systems Computation Conference, Liege, August 2005.
[11] Cigre Working Group C1.1, Asset Management of Transmission Systems and Associated Cigre Activities, December 2006.