Research On State Evaluation Of 220kV Power Transformer Based On Extension Matter-element Theory

As the key equipment of power transmission and distribution,the running state of power transformer plays a vital role in the safe and stable operation of power network.Therefore,strengthening transformer status assessment and maintenance is an important measure to ensure the safe and stable operation of power supply network.Based on the summary of the current status of power transformer monitoring and assessment technology,this paper proposes a transformer condition assessment model based on the extension matter-element theory.It is expected to provide more effective transformer maintenance strategies based on reliable and accurate state assessment and provide early warning for preventive maintenance.The specific content mainly includes the following aspects:First,establish a scientific,comprehensive and effective evaluation index system.The composition of transformer is more complex,there are many indicators to characterize the working state of transformer,some indicators have high correlation,and the monitoring technology of individual indicators is not mature.In view of the large number of transformer status evaluation indicators and the difficulty of monitoring,according to the relevant national standards of transformer maintenance and the daily maintenance experience of transformer,the coefficient of variation method is used to screen out some of the insensitive indicators to reduce the index redundancy,and then cluster analysis is used to analyze the correlation among indicators and select a reasonable clustering coefficient.The operational factors of indicator monitoring are fully considered,and independent indicator variables are selected to achieve effective simplification of the indicator system,and a transformer operation status evaluation indicator system with 8 evaluation indicators is constructed.Secondly,the weights of each evaluation index in the transformer state evaluation model are determined.On the basis of constructing the evaluation index system,questionnaires about the importance of each index were distributed to the personnel engaged in transformer operation and maintenance for a long time.The subjective weights were determined by using the improved analytic hierarchy process(AHP)and the investigation results.Then,through the weight method of CRITIC,the objective weight is determined by fully considering the degree of the indicator’s distinction to the evaluation status.On the basis of subjective and objective weights,a function with the goal of minimization of deviation is constructed based on game theory.By solving the function,the coefficients of subjective and objective weights are determined,and finally the combined weights are obtained,so as to accurately quantify the correlation between each index and transformer state.Furthermore,the transformer state evaluation model is constructed.The extension matter-element theory proposed by Professor CAI Wen in 1983 is adopted to construct the matter-element to be evaluated of transformer state on the basis of scientific evaluation indexes.The classical domain and node domain of transformer matter-element are determined according to DL/T596-2021 Preventive Test Procedures for Power Equipment,and the operation state of transformer is obtained by constructing correlation function and calculating correlation degree.Finally,the comprehensive evaluation model established in this paper is applied to the state evaluation of a transformer,and the result of the example analysis verifies the feasibility of the evaluation model,the scientificity of the evaluation index system and the rationality of the combination of weights.