Research On Characteristics Of Insulation And Airflow Field Of 40.5kV SF₆ Interrupter

With the capacity of State Grid increasing,a large number of reactive-load compensation equipment need to be equipped,especially the increase of shunt capacitor banks,which correspondingly increases the demand for reactive power compensation circuit breaker.Therefore,it is particularly important to develop SF₆ circuit breakers with superior breaking performance and capacitor-switching capability.On this basis,the characteristics of the electric field,cold state and hot state of the 40.5kV SF₆ arc extinguishing chamber are studied in depth by simulation and experimental methods.Firstly,The finite element method was used to calculate the three-dimensional electric field of the interrupter.The structure of auxiliary nozzle was adjusted to compare the electric field distribution in the three key positions of short arcing,medium arcing and opening in the interrupter.The electric-field strengths of sample pints along the shield,and contacts were compared and analyzed in this dissertation.The research shows that the electric field of arc contact is more uniform if the structure was no auxiliary nozzle.Then,Due to the mutual influence between the airflow and the arc in the breaking process of the circuit breaker,it was necessary to simulate the airflow field in the interrupter.The factors like gas physical properties,grid slipping,and valve movement and nozzle ablation characteristics increase the difficulty of airflow field simulation.In this paper,the sliding mesh model,valve movement model and the nozzle ablation model were established,and the physical parameters of gas were introduced into the control equations,cold and hot airflow field characteristics of the interrupter were studied.The gas flow phenomenon in the interrupter during the cold airflow field was described,and the pressure change of interrupter were analyzed by changing the structure of auxiliary nozzle.The temperature,pressure,ablation vapor dynamic changes and the stress and motion characteristics of the valve during the breaking process were also analyzed.The research shows that the breaking current of self-extinguishing SF₆ interrupter can be up to 31.5kA.Finally,The simulation analysis is based on theoretical and empirical assumptions,which cannot fully reflect the actual operating status of the product.Therefore,experiments are an indispensable part in product development.In this paper,capacity experiment and back-to-back capacitor bank experiment were conducted on the prototype.The comparison and analysis of the experiment results and simulations results verified the correctness and effectiveness of the simulation model.