Research on the Construction and Optimization of Thermal Stability Mechanism Model of Isolator

The thermal stability of isolator is a key issue for the safe operation of power system, and its overheating fault directly affects the reliability of power supply. In order to overcome the shortcomings of traditional thermal analysis models in the prediction of dynamic thermal behavior and extreme conditions, an electrical-thermal-mechanical multi-field coupling mechanism model was constructed to reveal the interaction mechanism between the dynamic characteristics of contact resistance, Joule heat generation and the degradation of material thermal properties. By introducing the Hertz contact theory and the hierarchical modeling strategy, the three-dimensional thermal-electrical coupled equations and the thermal network model are established, and the nonlinear characterization of the temperature rise in the contact area is realized. Experimental verification shows that the temperature prediction error of the model is controlled within 4. 5% and 3. 8% under steady and transient conditions, respectively. Based on the parameter sensitivity analysis, the contact pressure optimization (280 N), W-shaped contact finger structure and double contact parallel design are proposed, which can reduce the contact peak temperature by 19. 3% and the temperature rise rate by 18. 5%. The error between experiment and simulation of the optimized prototype is further reduced to 3.7%, which confirms the effectiveness of the model in guiding the structure design and thermal stability improvement of the isolator.