Research On Running State Evaluation And Remnant Life Of Power Transformer

Power transformer is the key equipment for the power transmission in the power system.Its running state is directly related to the reliable and safety of the power system.With the change of the maintenance model of power equipment from regular maintenance to condition based maintenance,to assess the running state and remnant life of the transformer through the condition information of the power transformer has practical significance for the development to the condition based maintenance.This paper starts with the mass evaluation indexes that affect the running state of the power transformer.According to the difference of the insulation state of transformer between the evaluation indexes,the multi layer insulation condition evaluation system of power transformer is established.Some experts are invited to use the improved fuzzy analytic hierarchy process(AHP)and the grey relational grade to determine the weights of the indexes.The accuracy of weight results are improved by iterative computation.By calculating the grey correlation between experts,the subjectivity of AHP in determining the judgment matrix is effectively reduced.According to the fuzzy classification,the running state of power transformer are classified into different grades.With the membership function,the evaluation indexes are quantized,adopting the improved evidence theory to fuse the quantitative indexes.The improvement of evidence theory on the one hand changes the evidence composition rules;on the other hand,according to the idea of deteriorating variable weights correcting the evidence body to make the deteriorated evidence body is assigned more weight.The result shows that the evaluation model is effective.Based on the theory of health index,the remnant life assessment model of power transformer is established.The assessment model divides the remnant life factors of transformers into three categories.The assessment model of operation condition,insulation condition and accessories and maintenance records are respectively established,then quantify the assessment results as the health index.By calculating the average hot spot temperature in the steady state of the transformer,the aging factor in the model is corrected.Finally,according to the health index of the transformer obtain the life evaluation results based on the deduction of the health index formula.Taking MATLAB as the software platform,the remnant life assessment GUI interface of power transformer is established.The feasibility of the model is proved by an example.