Research On The Method Of Power Transformer Condition Evaluation

Power transformer as an important electric equipment,its safe operation is the basis to ensure the security and stability of pwer system.Once the transformer failure,not only will cause huge economic losses,but also have a huge impact on society.Therefore,through the condition evaluation of transfomer to found the change of conditon and safety problems,not only can provide help for condition maintenance,but also ensure the stable operation of power system.Aiming to solve the problems of various indicators and complex system structure in transformer evaluation system,we proposed the hierarchy grey relation analysis which is based on fault type to establish the key indicator system of transformer.According to the guide for transformer conditon,the fault set and initial indicator set are selected Then the grey relational analysis is proposed to get the comprehensive correlation degree,so as to design the dynamic method for screening the key indicator.Finally the support degree is introduced to check the rationality of the reserved indicators and the key indicator system is formed.According to the characteristics of the indicator system,we evaluate transformer condition layer by layer.Aiming at the fault layer,a single condition evaluation method for transformer based on fixed weight grey clustering is proposed.Firstly,the association rules is introduced to determine the fixed weight of key indicators which can avoid the interference of subjective factors.And then the triangle whiten function based on core point is design.Finally,the single condition of transformer is obtained by using the grey clustering.In the stage of comprehensive evaluation,the fuzzy comprehensive evaluation of transformer based on fuzzy variable weight is proposed.According to the evaluation valuse of the fault and fixed weight of key indicator,the variable weight coefficient of each fault type is calculated by using variable weight theory.The application of the variable is helpful to solve the problem that it may not reflect the true condition of the transformer under the fixed weight.Finally,the comprehensive evaluation result is obtained by fuzzy evaluation method.Using the method which proposed in this paper to evaluate the condition of 220 kV transformer,the evaluation results show that the proposed method can objectively and accurately evaluate transformer comprehensive condition,and can determine the fault type by the single state,and provide help for condition maintenance.