Risk management model of 69 kV power transformer bushing in Metropolitan substation

This paper presents diagnosis techniques to assess the risk of power transformer bushing rating of 69 kV in Metropolitan substation by means of condition evaluation and importance evaluation. Tan delta test with available data is conducted for condition evaluation of the transformer bushing, while the selected criteria with updated network data is utilized for importance evaluation of the power transformer fleet. Score and weighting techniques are used for the transformer risk assessment. To achieve the proper bushing maintenance, the indices of both assessment of the transformer are plotted in the risk model. Consequently, the maintenance action can be accomplished by nine separated maintenance zones with color indicators such as corrective maintenance, time-based maintenance, condition-based maintenance, and online monitoring. In the analysis, 30 power transformers with rating of 69/24 kV are selected for planning the maintenance action of the 69 kV bushing in Metropolitan substation. Finally, the reduced transformer risk and improved reliability in the system can be achieved with decreased maintenance costs.