This paper focuses on the simulation of a fault arc in a closed tank based on the magneto-hydrodynamic(MHD) method,in which a comparative study of three radiation models,including net emission coefficients(NEC),semi-empirical model based on NEC as well as the P1 model,is developed.The pressure rise calculated by the three radiation models are compared to the measured results.Particularly when the semi-empirical model is used,the effect of different boundary temperatures of the re-absorption layer in the semi-empirical model on pressure rise is concentrated on.The results show that the re-absorption effect in the low-temperature region affects radiation transfer of fault arcs evidently,and thus the internal pressure rise.Compared with the NEC model,P1 and the semi-empirical model with 0.7 <α< 0.83 are more suitable to calculate the pressure rise of the fault arc,where is an adjusted parameter involving the boundary temperature of the re-absorption region in the semi-empirical model.
The behavior of fault arc in a high-speed switch(HSS) has been studied theoretically and experimentally.A simplified HSS setup is designed to support this work.A two-dimensional arc model is developed to analyze the characteristics of fault arc based on magnetic-hydrodynamic(MHD) theory.The advantage of such a model is that the thermal transfer coefficient can be determined by depending on the numerical method alone.The influence of net emission coefficients(NEC) radiation model and P1 model on fault arc is analyzed in detail.Results show that NEC model predicts more radiation energy and less pressure rise without the re-absorption effect considered.As a consequence,P1 model is more suitable to calculate the pressure rise caused by fault arc.Finally,the pressure rise during longer arcing time for different arc currents is predicted.
This paper presents a numerical study of the current self-excited oscillations during the opening of high voltage direct current(HVDC) metallic return transfer breaker(MRTB).The switching arc is simulated using the magneto-hydrodynamics(MHD) theory coupled with the electric circuit variation.The simulation is proved accurate in simulating the current oscillation and the commutation process in MRTB by the good agreement between the calculated results and the experimental results,which are obtained on a MRTB prototype designed to break about 5 kA of DC current.Both kinds of the results show that the current oscillation starts at about 16.5 ms and the total arc time is about 24 ms with a commutation capacitor bank of 72 μF and an inductor of 173 μH.With a further analyze on how circuit parameters influence arc current oscillations,this study helps to improve the current interruption capability of MRTB.
LI Yang YANG Fei RONG Mingzhe WU Yi WU Yifei SUN Hao
