Research Of On-line Monitoring Partial Discharge System And Spectrogram For HV Transformer

Transformer is an important electrical equipment in power system transmission and transformation operation.Partial discharge of power transformer will cause inner insulation structure aging and continuous deterioration leading to breakdown,which is the key factor affecting the normal operation of transformers.It is closely related to the safe,economical and stable operation of the power network.At present,most of the electrical maintenance units only carry out on-site hand-held detection of transformers in the spring and autumn seasons.On the one hand,due to the low sensitivity of this detection method,large location deviation of the partial discharge power supply and lack of diagnosis capability of the discharge type.The phenomenon of partial discharge with small scale and slight intensity can not be detected predictably.It is difficult to prevent the partial discharge degree from expanding,which can easily lead to the destruction of the whole insulation system and eventually lead to the failure of electrical equipment.On the other hand,It is not convenient for workers to work on the spot in the northern winter.The cold weather conditions put forward higher requirements for both equipment and staff.In order to solve these two problems,Through the design of a transformer partial discharge on-line monitoring system,the insulation hidden trouble can be found in time and the discharge degree can be avoided by using the on-line monitoring method.Therefore,it is of great significance to ensure the normal operation of transformers and to ensure the safe and stable operation of power system and reduce the loss of national production.Based on the theory of transformer partial discharge,this paper summarizes the latest research progress at home and abroad.An on-line monitoring partial discharge system is designed based on the combination of ultrasonic signal and UHF signal.The software and hardware anti-jamming technology is used to overcome the problem of insufficient anti-jamming ability of the traditional hand-held field detector to some extent.After comparing the two positioning methods and studying the characteristics of three partial discharge patterns.The field analysis experiment of partial discharge power source location based on MATLAB genetic algorithm and the field diagnosis experiment of partial discharge type based on analyzing the characteristic of partial discharge phase distribution map are carried out by using this system after comparing the two positioning methods and studying the characteristics of three partial discharge patterns.By comparing the experimental results with the results of transformer dismantling inspection,it is found that the location deviation of the spatial distance difference positioning method based on the characteristics of the monitoring spectrum is very small,and the diagnosis of the discharge type is correct.It is proved that the location method can realize theaccurate location of the local discharge power source,the spectrum of the on-line partial discharge monitoring system is true and accurate,and the diagnosis method of the discharge type is effective.This monitoring system can be applied to the partial discharge monitoring of transformers in engineering field,and it also provides the theoretical basis and technical basis for the maintenance of power transformers.