| Power transformer is an important power system equipment. Its operation status directly affect the safe operation of the power system.Hence,diagnosing the transformer fault effectively and judging the status of transformer accurately have great significance.Resonable condition assessment on power transformer is the premise of condition-based maintenance.Details about the running condition and the pretest maintenance are all indispensable.Accurate evaluation of the states of the transformer,based on virious messages,plays a vital role in guiding the transformer maintenance and improving the operation reliability of power system.Evaluating the transformer has an important influence on implementing the maintenance plan and reducing the costs.Firstly,this paper introduces some methods on evaluation of the states of the transformer.Then,after understanding the common indexes and basic characteristics of the transformer, the state index system of 220kV power transformer is established.Besides,the method of calculating the weight of common index is studied,including:the subjective weight method(the analytic hierarchy process)and the objective weight method(the entropy weight method).Considering the advantages of the subjective and objective weight method, this paper adopts the subjective and objective weight value as the power transformer evaluation index weight. According to the different dimension of the state index of power transformer.the method of normalization need to be studied.In addition,the evaluation method of the power transformer condition index,extension method,is studied,and the method is improved. Finally,take the 220kV power transformer data as an example.The state of the transformer is evaluated by the analytic hierarchy process, entropy weight method and the improved extension method.The example analysis proves that the model is reasonable and effective in the evaluation of the running states of the transformer. |
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