Entropy Weight Health Index method of power transformer condition assessment

Evaluate power transformer's operating status correctly is a key issue to its reliable working and the maintenance policy. The Health Index (HI) represents a practical tool that provides the overall health of the asset, among which reasonably determine the weight of each index is the key to guarantee the quality evaluation. While in the current weight determination process, the method of professor's weighting to define the weight of parameter is generally employed, but in the use of the method, owing to the difference of different professors' experiment or the angle which they view the problem, they will come to different conclusions at one parameter of evaluation, they even make subjective judgment. In this paper, we come up with the entropy weighting method that determines weight by judge-matrix which is made of the index value of all cases, and uses entropy of the parameter to define its entropy weight. This method presents subjective judgment in the weight determination process, and makes the process fairer and more scientific. Entropy Weight Health Index(EWHI) method determines the weight of index according to its relative degree of change that impact on equipment, it can be used to compare health status of different time and to get the succession trend for transformer condition in order to provide basis for condition based maintenance.