750kV Transformer Health Condition Evaluation

With the rapid development of China's economy and the continuous expansion of power grid scale,750 kV power grid system were developed by the national power industry to meet the characteristics of long-distance transmission of northwest power grid and to cut the losses of transmission process,Just a few years,750 kV power grid has gradually become The main power grid in northwest China.750 kV transformer is the core equipment in the process of power transmission and transformation in the west.The safe and stable operation of the northwest power grid and regional substation will be directly affected by its health condition.Therefore,the correct evaluation of the health about 750 kV transformer can effectively reduce the cost of the system in the process of maintenance,and improve power supply reliability.First,in this thesis,the health condition evaluation index of transformer is established by studying the aging mechanism of 750 kV transformer.Based on the requirement of 750 kV transformer health condition evaluation and practical operability,the scientific and reasonable evaluation index is selected.Second,It uses the order relationship analysis method to calculate the subjective weight of the indicators,so that qualitative indicators and quantitative indicators combined.And the entropy method in the objective analysis method is combined to optimize the weight of each evaluation index,so that the comprehensive weight can be more reasonable and more accurate to reflect the relative importance of each state quantity in the evaluation.The weighted gray target theory is introduced,and the health condition of the transformer is obtained by combining the state classification strategy,and the method is verified by an example.Finally,As a single evaluation method can only consider some factors,it can not solve all the problems of transformer health condition evaluation,and it has some limitations.Therefore,the formula of calculating the health index of electric power equipment is deduced,and the formula of residual life and probability of failure are obtained.The health condition evaluation model of 750 kV transformer is established,and the parameters which affect the comprehensive health index of transformer are taken as the evaluation index.It combines the weighted grey target theory to evaluate the health status of the transformer.The health index,residual life and failure probability of transformer can be verified by examples.The evaluation results are compared with the actual situation to verify the feasibility of the evaluation method.It provides a theoretical basis for condition based maintenance.