Electric And Thermal Field Simulation On ±160kV HVDC XLPE Insulation Cable Terminal

With the development of the HVDC transmission technology, DC cable system has been widely concerned as the important carrier of power transmission. DC cable terminal is the important component of cable system. When installation is needed to strip the shielding layer at the end of cable where the intensity of electric field is distorted, the probability of failure is higher than other place. At the same time, the existence of a variety of mediums and layers, conductivity characteristic differences between materials and the presence of space charge make it more difficult to design the electric field of cable terminal. therefore, the study on the fundamental principles of temperature field and electric field is very important.The paper presented the calculation model of HVDC cable terminals and the simulation method for steady temperature field distribution, and analyzed the influence of conductor current and the surface temperature of terminals. A calculation method of current-carrying capacity of HVDC cable terminals was provided on the basis of the temperature field. An iterative and a non-iterative method were compared with the deviation of non-iterative method was analyzed in this paper. At the same time, a thermal-electric coupled field calculation of HVDC cable terminal was provided in the paper. Within the scope of normal current-carrying and there was no damage in inner insulation of cable terminal, the influence of leakage current on thermal field can be ignored through the consideration of heat product in insulation which influenced thermal field or not. Based on the electric potential and electric field simulation of HVDC cable terminal, distribution rules on electric field of different current carrying were got and electric field concentrated of several locations were analyzed mainly.On the basis of the thermal-electric coupling analysis, the paper provided a kind of scheme that optical fiber embedded in cable terminal. Through the simulation analysis of temperature and electric field data on main positions of cable terminal which embedding optical fiber proved that embedding scheme did not affect the original temperature and electric field distribution of cable terminal. At the same time, the paper provided a method to achieve a temperature measurement system of optical fiber through the monitoring of carrying current of the core and temperature of main positions measured by optical fiber which corresponding to get some important parameters of thermal and electric field such as the highest temperature of the core, the maximum temperature gradient of XLPE insulation and the maximum field strength of stress core. This temperature measurement system controlled the change of temperature and electric field through temperature measurement of optical fiber. The results of this paper provide references for insulation layers and temperature rise design for HVDC cable terminals and it provides a theory method to achieve on-line monitoring of temperature and electric field.