Calculation and Analysis of Very Fast Transient Over-voltage Characteristic on the Condition of Dynamic Arcing Model

In the process of simulation calculation of very fast transient over-voltage(VFTO),establishing an accurate high-frequency arc model is a key factor to improve the accuracy of VFTO.A dynamic arcing model was presented based on the segmental arcing model.In the pre-breakdown stage,hyperbolic time-varying resistance was used in the model to consider the impact of breakdown delay time on VFTO waveform;in the extinction phase,a complete Mayr model was established to describe the dynamic physical processes of arc.Moreover,taking the 1 100 kV station as an example,this paper calculated the amplitude,the frequency and the gradient of VFTO in gas insulated substation(GIS) on the condition of two arcing models,and discussed the influence of breakdown delay time on VFTO waveform.It is found that VFTO has higher magnitude,higher frequency and higher gradient under the dynamic arcing model;breakdown delay time affects the initial rise time and amplitude of VFTO.By comparing VFTO simulation results with the measured data,it is found that the dynamic arcing model is the further improvement of the segmental arcing model and has great significance for improving the accuracy of the simulation calculation of VFTO.