On-line Temperature Monitoring Technology Of Defective Dry-type Air-core Reactor Envelope

Dry-type air-core reactor has been extensively applied to the compensating of reactive energy in electric power system.,improving power transmission quality and limiting over-voltage.Because of the manufacturing process deviation and the damage in the process of transportation and installation,some reactors have the defects of more turns and few turns of coils and broken strands.Due to the existence of turns deviation and broken strand fault,the overall loss of dry-type air-core reactor and current and other electrical parameters change in a small amount,the use of electrical parameters to troubleshoot the effect is not good,this paper attempts to temperature,a nonelectrical parameters to test whether there are defects.The 66 kV defective dry-type air-core reactor is used as the research object,and the temperature field calculation principle is used to solve the reactor envelope loss and calculate the heat source intensity according to the envelope volume parameter.A three-dimensional flow field-temperature field model consistent with the actual reactor dimensions is established,and the temperature field of the defective dry-type air-core is obtained by simulation using ANSYS software.Statistics on the change of temperature rise and temperature field distribution of dry-type air-core reactor under different defects to provide alarm temperature basis for online monitoring system.According to the theory of electromagnetic field,the magnetic field distribution of the dry-type air-core reactor is calculated,ANSYS software is used to simulate and analyze the magnetic field distribution characteristics of the reactor,and analyze the method to reduce eddy current loss of metal parts in the online monitoring system.Design a dot matrix infrared temperature measurement online monitoring system,the temperature measurement module collects the temperature rise data of each envelope and sends it to the host computer through the wireless communication module,according to the defective envelope simulation temperature criterion,the host computer issues a timely warning.Due to the complex high-voltage strong magnetic environment of the reactor itself,independent power supply and metal shielding are designed for the online monitoring system.The results show that the temperature rise of the envelope changes when there are turn deviations and broken strands defects.When the number of broken strands and the number of turn deviations increase,the temperature rise change increases,and the temperature rise change at the top of the envelope is larger compared to the bottom,which is more suitable for the monitoring point of the online monitoring system.The magnetic field distribution inside the reactor is symmetrical,and the magnetic induction strength is stronger along the radial direction as it approaches the envelope,and the magnetic induction strength is maximum at the axial center and decreases along the two ends.The thickness of the metal shield in the online monitoring system has the greatest influence on the eddy current loss,and the eddy current loss value of the shield is proportional to the primary side of its height and the third side of its width.By reducing the thickness and width of the shield,the choice of low resistivity materials is a more effective measure to reduce eddy current loss.Online temperature monitoring system based on wireless communication can carry out good signal transmission in the high-voltage strong magnetic environment of the reactor,the design of the independent power supply can reduce the difficulty of the system power supply,the system metal shielding can avoid the interference of the system components by the electric field,and the temperature rise and eddy current loss of the metal shield within the permissible limits.The online monitoring system maintains high measurement accuracy and solves the problem of temperature monitoring of defective reactors to a certain extent,which has certain engineering application value.