Assessment And Maintenance Of UHV Transformer Based On Set Pair Analysis And Comprehensive Health Index

With the rapid construction of UHV substations and the formation of a ring network with UHV grid as the main grid,the grid voltage level is getting higher and higher.The capacity and quantity of grid equipment are increasing.The operating state of the electrical equipment is related to the safe and stable operation of the UHV grid.State evaluation,life prediction and fault diagnosis for UHV transformers have gradually become the focus of research.This paper focuses on the UHV transformer state assessment method based on set pair analysis theory and comprehensive health index research,in order to more scientifically guide the development of maintenance strategy.In view of the special structural characteristics of UHV transformers,it is confirmed that the state evaluation of UHV transformers focuses on the evaluation of the insulation state of UHV transformers.The relationship between the dielectric response characteristics of oil-paper insulation and the insulation aging state was studied.It was found that the dielectric response test at different frequencies can be fitted to reflect the aging condition of the insulation.For this reason,an evaluation system for the insulation state of UHV transformers based on the dielectric response of insulating cardboard and other conventional test parameters was built.The traditional analytic hierarchy process is improved by evaluating the expert's variable weight.The set pair analysis intelligent algorithm is used to improve the correlation degree of each state quantity in the state evaluation system.Based on the case study,the calculation method of insulation state evaluation of UHV transformer based on set pair analysis theory is given.The insulation state evaluation result of the UHV transformer is quantified to obtain the insulation health index of the UHV transformer.The operating environment,operating period,maintenance status of the ultra-high transformer and the influence of the operation status of each accessory on the state of the UHV transformer are fully considered.The comprehensive health index of the transformer is used to accurately evaluate the operating state of the UHV transformer.According to the final comprehensive evaluation results of the UHV transformer,the corresponding maintenance strategy is formulated to make the state overhaul more scientific and efficient.