Research on Electric Field and Temperature Distribution under Insulation Deterioration of UHV Arrester

With the initial construction of UHV AC network backbone, higher requirements are put forward for the insulation coordination of substation equipment. UHV ac zinc oxide arrester is an important over-voltage protection equipment in substation, its stable operation directly affects the reliability and security of UHV power grid. The continuous power loss caused by the lightning arrester under the action of power frequency voltage for a long time will lead to the thermal stress concentration of the resistor chip, which will eventually lead to the aging of the lightning arrester, and the uneven distribution of potential and temperature of the resistor chip or its own structure will accelerate the deterioration process, seriously affecting the stability of the entire power system. In this paper, a 3D simulation model of thermoelectric coupling of UHV AC lightning arrester was established based on the finite element principle, and the rationality of the model was verified by fiber-current method. Then, the electric field and temperature distribution of lightning arrester under the condition of insulation aging and damp were simulated and analyzed using the model. The results show that: When the lightning arrester is aging or damp affected, its potential and field strength are not evenly distributed, both of which show the law of decreasing the value of the degraded node and increasing the normal node. Different from the law of electric field distribution, when the UHV lightning arrester is damp affected, the temperature rise of the damp node will be significantly higher than that of the normal node. The temperature rise of the aging segment is significantly lower than that of the normal segment, and the temperature change of the internal resistance column is more sensitive than that of the surface. The conclusion can provide the basis for the accurate evaluation of the lightning arrester operation state and the accurate diagnosis of potential faults in non-ideal environment, so as to ensure the safe and stable operation of power grid.