Research On Insulation And Thermal Diffusion Characteristics Of 10kV Cable Accessories

Due to the different structural sizes of cable accessories manufactured by different manufacturers,their electrical characteristics differ greatly.The performance evaluation of the insulation characteristics and thermal diffusion characteristics of different cable accessories can effectively provide reference value for the selection of cable accessories.At present,there is no suitable evaluation method to evaluate the insulation characteristics and thermal diffusion characteristics of cable accessories from different manufacturers.Relevant key parameters can be obtained by conducting partial discharge test and temperature rise test.The insulation characteristics and thermal diffusion characteristics of cable accessories can be evaluated by comparing the key parameters of different samples,so that the most suitable cable accessories can be selected in different occasions.Therefore,it has important engineering application value to evaluate the thermal diffusion characteristics and insulation characteristics of different manufacturers.Firstly,a mathematical analysis method as the evaluation method in this thesis was introduced,which called analytic hierarchy process(AHP).The steps of AHP to normalize data,established judgment matrix and weight matrix were expounded.The solution method of positive and negative ideal solution were also introduced.the method had been determined which obtaining the performance ranking of evaluation object indices by calculating the size of relative fitness.Secondly,the 10kV cable joints and T-type terminals from nine different manufacturers at home and abroad have been selected as the research objects.The insulation performance of the cable joints and T-type terminals have been studied.The electric field strength distribution in the cable accessories have been simulated.The influence of metal particles on electric field distribution in cable accessories have been studied.It is found that under the same size of the particle,the presence of metal particles increased the maximal electric field strength in the cable joint by about 12 times.The field strength in the T-type terminal increased by about 5 times.A partial discharge test platform for cable accessories was built.Based on the partial discharge test,five key parameters which are initial discharge voltage,discharge quantity,discharge times,discharge energy and average current are designted.The insulation performance of cable accessories was evaluated based on the AHP,and the rank of the insulation performance of nine test samples has been obtained.Finally,the thermal diffusion characteristics of the cable joints and T-type terminals were studied,and the temperature distribution of the cable accessories was simulated.It has been found that the surface temperature of the cable section is higher than the surface temperature of the joint section.Under the same ambient tempertature,the maximum temperature of the former is 55.05℃,and the latter is 42.85℃,and the surface temperature of the joint from the end to the middle is increasing.The maximum surface temperature of T-type terminal appears at the corner,which is 63.3℃.The temperature rise test platform of cable accessories was built.Based on the temperature rise test,two key parameters which named temperature rise rate and current sensitivity of temperature rise rate are proposed.The thermal diffusion characteristics of cable accessories were evaluated based on the AHP,and the rank of the insulation performance of nine test samples has been obtained.