Fuzzy Synthetic Evaluation of Power Transformer Condition with Variable Weights

Aiming at the deficiency that constant weight is unable to objectively reflect the impact of the deviation of some parameters,a fuzzy synthetic evaluation method with variable weights for condition of power transformers was introduced.Through analyzing the state variables affecting main facts of operation condition,a layered evaluation indices system for transformer condition assessment was built.First,the AHP method was used to determine the constant weight of every indices,then the variable weight model was introduced based on balanced function,in which the constant weights was modified to get the variable weights,according to the deviation of actual data and normal state.Then the fuzzy set theory was applied to determine the membership degree of a single index,and based on the idea of mutli-grade fuzzy evaluation,the condition of every grade was valuated to get the comprehensive status of power transformers.By comparing the fuzzy synthetic evaluation based on constant weights with that based on variable weighs,the example showed that,the condition assessment for power transformers using variable weights based on balanced function is more reasonable and more objective,and the valuation conclusion was also more close to the actual condition of transformer.