Numerical simulation of streamer discharge with different electrode shapes in C4F7N

In recent years, the environmentally friendly gas, C4F7N, has been recognized as a potential SF6 alternative gas due to its excellent insulation. To study the streamer discharge characteristics of different electrode shapes in C4F7N, a fluid model was established by COMSOL, and simulations were performed. Streamer discharge as a function of varying electrode shapes was analyzed, and the variation law of electric field intensity and photon flux was obtained, which serves as a theoretical basis for optical detection and reliable diagnosis of partial discharge. Simulation results demonstrate that under the same discharge conditions, the electric field inhomogeneity of the needle-plane model, rod-plane model, and ball-plane model decreased successively and the breakdown difficulty increased. With the increase in the applied voltage, the peak electric field intensity of the streamer head was found to increase, whereas an increase in the electrode spacing was found to decrease this property. The change in photon flux was found to be similar to the change in the electric field intensity.