An Adaptive Adjustment Algorithm for Electrothermal Simulation of Surge Arrester

In this paper, we propose an adaptive adjustment algorithm to solve transient nonlinear finite element models for arresters with coupled temperature and electro-quasistatic fields quickly and accurately. Due to slow temperature changes, it can be considered that the electrical quasi-static field is in a stable state within ΔTsteady. Hence, there is no need for transient solutions of the quasi-static field at every moment. We determine ΔTsteady which is dynamically changing based on the change rate of conductivity of ZnO varistor. The results indicate that as the injected energy increases, power losses might exceed the heat flow dissipation due to the negative temperature coefficient of resistivity of the ZnO varistor, leading to arrester thermal runaway.