Research On The Detection Technology Of Local Arc Under Polluted Conditions On The Optical Fiber Composite Insulator

The research of electric field and temperature field of composite insulator embedded with optical firber is helpful to the application and development of defect optical fiber detection technology of composite insulator.In this paper,the electric field distribution and the radial temperature distribution of composite insulator in the presence of local arc were studied by simulation.Meanwhile,the effectiveness of the temperature measurement used FBGs for detecting the temperature inside the contaminated silicone rubber under the discharge condictions was experimentally studied.Firstly,the two-dimensional geometric model of 10 kV composite insulator embedded with optical fiber was established in the COMSOL multiphysics analysis software,and the electric field simulation was carried out to study the influence of fiber implantation on the electric field distribution of the interface in composite insulator.Simultaneously,a contamination layer was set on the surface of the sheath between the first group of shed belong the composite insulator embedded with optical fiber,and in order to study the influences of pollution layer with different conductivity,the electric field distribution of the interface in composite insulator embedded with optical fiber was studied.The conclusion shows that the implantation of optical fiber does not have significant distortion effect on the electric field strength at the interface of the composite insulator.When optical fiber was embedded in composite insulator,it is necessary to pay attention to the processing of the fiber leading out the sheath side.Since the electric field strength at this side is relatively large,which may easily cause excessive current density and local arcing in operation due to other objective factors.Secondly,on the basis of the above model,the characteristic parameters were found to characterize the thermal properties of the arc,and inputting them as the material parameters of the heat source.Meanwhile,according to the axial temperature distribution of the arc,the heat source boundary conditions were set to simulate the temperature field of composite insulator embedded with optical fiber.The influence of the fiber implantation on the temperature field distribution of the inner interface in the composite insulator was studied.In addition,the influence of the local arc with different location was studied.It is found that the local arc near the shed has a great influence on the inner interface temperature of the insulator.Moveover,the temperature difference between the outer and inner interface of the sheath was characterized by the Fourier function.The conclusion shows that the temperature rise trend of the inner interface of the 10 kV composite insulator implanted with optical fiber is basically the same as that without optical fiber.It means that the implantation of optical fiber does not affect the temperature field of the inner interface in the composite insulator.Finally,according to the structure and size of the rod and sheath of 10 kV composite insulator,a two-layer plate sample was made with embedded FBGs.The temperature calibration tests on the FBGs embedded in the sample and the discharge tests of the contaminated sample were carried out in laboratory.The leakage current and internal temperature were measured,and the arc process of discharges was photographed.A method of detecting the internal temperature distribution under surface polluted discharges by FBGs was investigated.The conclusion shows that The temperature sensing of contaminated discharge on the surface of silicone rubber is realized by the FBG of 3 mm thick interface between silicone rubber and epoxy-GFRP.The FBG implanted on the interface provides an effective detection technology for the study of the discharge process on the contaminated insulating surface.