Evaluation of insulation state based on the combination of analytical hierarchy process and TOPSIS

The insulation state evaluation of transformer oil paper is a complex problem with multiple features. In this paper, an improved analytical hierarchy process and technique for order preference by similarity to ideal solution (AHP-TOPSIS) method of insulation state evaluation model with positive and negative reference points is proposed. First, the response voltage method (RVM) is utilized to extract the related features of the insulation state of oil paper. The hierarchical structure of the insulation state evaluation of the transformer oil paper is formulated. Secondly, the analytic hierarchy process is applied to determine the weight coefficients based on the characteristic quantity of the expert experience. Then, the state is divided into the fine insulation and the serious aging degradation. These two factors are adopted as references to assess the transformer. In this way, a decision matrix can be constructed, which is normalized and combined with the weight. The positive and negative reference points of this paper are positive and negative ideal solutions. Finally, the close degree of the transformer and the positive reference point are calculated. The insulation state of transformer is evaluated according to the interval of proximity. The application example proves the accuracy of the improved AHP-TOPSIS method in the insulation state evaluation of the transformer. Compared with the traditional TOPSIS method, the insulation state of the transformer oil paper can be evaluated more accurately. © 2018, Science Press. All right reserved.