Study on stress distribution of distribution network arresters under complex operating conditions based on electro-thermal-mechanical coupling

Zinc oxide arresters are the main devices for preventing lightning strike faults in distribution network lines. In the actual operation process, the operating conditions of arresters are complex and diverse. When subjected to various unbalanced forces caused by factors such as non-vertical installation methods, wind force and horizontal tensile force, the thermal stress superimposed by lightning impulse is an important cause of aging and failure of arresters. Considering the influence of various unbalanced forces and multiple lightning strikes, based on the principle of multi-field coupling of electricity, heat and force, a simulation model for calculating the operating parameters of arresters was established. The internal distribution of electricity, heat and force of the entire 10kV arrester under different working conditions was analyzed. The calculation results show that multiple lightning strikes increase the stress at the interface of zinc oxide resistance sheets inside the arrester by about 15% compared with a single lightning strike. Under the combined action of unbalanced force and lightning strike, the stress at the interface of zinc oxide resistance sheets increases by about 25% compared with the sum of the stresses when unbalanced force and lightning strike act separately. The mutual coupling of thermal stress and mechanical stress The phenomenon of nonlinear stress enhancement occurred. The research results provide a reference for analyzing the fault causes of surge arresters under complex operating conditions from the perspective of stress.