Study on Dielectric Property Test and Image Computer Recognition of UHVDC Bushing

Abstract

This paper briefly describes the diagnosis methods of bushing insulation, and focuses on the research status of dielectric response measurement methods. By studying the design method of bushing, the basic insulation structure parameters of 10kV model bushing are designed, and the basic steps of how to trial produce bushing under laboratory conditions are explained. The temperature control platform and dielectric response test platform for 10kV AC epoxy resin impregnated dry bushing are built. The dielectric spectra of dry bushing and epoxy resin sample are measured respectively. Comparing the experimental results of dry bushing and epoxy resin sample, it is found that the dielectric constant and dielectric loss tangent of bushing are much larger than those of epoxy resin sample, because the epoxy resin will shrink when curing during manufacturing, And the sample sleeve used for measurement may be damp during storage; The experimental data are fitted by the model of superposition of three HN functions to verify the effectiveness of the model, and the characteristic parameters such as DC conductivity are extracted. It is found that its dependence on temperature basically conforms to Arrhenius formula. On this basis, build a thermal aging test platform for epoxy resin samples, carry out the accelerated thermal aging test at 115 °C, measure the dielectric spectrum of samples with different aging time with the dielectric response test system, compare the dielectric spectrum under different aging time, and analyze the reasons for the differences. The experimental results show that the dielectric constant will rise with the increase of aging time, The dielectric loss tangent will not change much. Combined with the image database information, insulation distance information and typical main equipment casing E-field distribution information, the operation state parameters are effectively obtained, and the intelligent algorithm is applied to automatically evaluate the operation state.