High Temperature Insulation Design of Capacitive Wall Bushing for High-temperature Solid Electrical Heat Storage Devices

Abstract

The temperature resistance and voltage level of the wall bushing are the key factors restricting the increase of the heat storage capacity of the solid electrical heat storage device. Therefore, by studying the electrical insulation and heat insulation principles of the wall bushing of the solid electrical heat storage device, a new type of capacitive solid electric heat storage device wall bushing suitable for 66∼500 kV high voltage and 800 °C high temperature was designed, and its internal insulation parameter calculation method considering the influence of high temperature was proposed. The analysis of the bushing through the multi-physics coupling field of temperature field, force field and electric field shows that high temperature deformation does not affect the electrical insulation of the capacitor core. However, in order to reduce the pressure of the outer insulation layer of the bushing, a deformation margin of 3% of the radius of the ground electrode plate still needs to be left. The change of relative dielectric constant will enhance the field strength at the edge of the capacitor core plate and deteriorate the electric field distribution of the bushing. Therefore, when calculating the internal insulation, it is necessary to set a partial discharge calculation margin of 1.4 times and the ratio of the length of the internal and external steps of the capacitor core furnace to 86%. As the voltage level increases, the effect of high temperature on the electric field distribution of the bushing becomes weaker.