Visualization Research On Temperature Field Distribution In Vacuum Arc Based On Image Processing

With the continuous improvement of power grid voltage level and system capacity in China,people put forward higher requirements for the working performance,reliability and intelligence of high-voltage circuit breaker,the core equipment of power system control and protection.Compared with other dielectric breakers,Vacuum circuit breaker plays a key role in controlling and protecting power systems by virtue of their good insulation properties.A high-temperature arc will be formed during the opening and closing of the contacts of the Vacuum circuit breaker,and the high-temperature arc will have a strong ablation effect on the contacts and the internal space,which seriously reduces the service life of the Vacuum circuit breaker.In order to effectively improve the breaking capacity of the vacuum contact and reduce the ablation of the contact surface by the high-temperature arc,it is necessary to use modern methods to analyze the temperature change throughout the arc combustion process.With the continuous progress of image sensor technology,visualization research is more and more widely used in the field of vacuum arc.Based on this,this paper proposes a visualization method of vacuum arc temperature distribution based on the principle of CCD temperature measurement,and combines digital image processing technology to analyze the combustion process of high-current vacuum arc,which provides a theoretical basis for the research of highcurrent vacuum breaker.In order to realize the research on the temperature distribution of vacuum arc,a set of image acquisition and preprocessing process based on CCD is designed in this paper,including image acquisition,image segmentation,image morphological reconstruction,image noise reduction,image enhancement and other functions;The temperature principle establishes a relationship between the arc temperature and the pixel value of the arc image,integrates the preprocessed arc images at different wavelengths into an arc temperature image,and extracts the arc geometry information based on the arc temperature field distribution.Combined with vacuum arc combustion The temperature distribution changes in the whole process are analyzed for different combustion forms of vacuum arcs,and the causes of concentrated arcs are deeply analyzed by combining factors such as arc current and magnetic field.In order to verify the experimental results of CCD thermometry,this paper is based on the magnetic hydrodynamic model.The steady-state simulation calculation of high-current vacuum arc is carried out,and the influence factors of vacuum contact gap are introduced to conduct further simulation research on the arc.The combustion process of the vacuum arc was divided into five stages: arc initiation stage,stable arc stage,diffusion stage,arc extinction stage and after-arc medium recovery stage based on the temperature field distribution in the vacuum arc combustion process;Statistical analysis of the temperature field found that: during the arc combustion process,the maximum arc temperature does not appear at the peak moment of the arc current,but a delay of nearly 1ms;the axial arc temperature from the cathode to the anode decreases as a whole.The arc radial temperature at the center of the contact gap first rises and then falls,which is in line with the trend of agglomerated vacuum arcs;through the analysis of the arc simulation results,it can be known that the temperature of the vacuum arc under the condition of high current The decreasing trend is basically consistent with the results measured by the optical temperature measurement method;introducing the influencing factors of the contact gap,it is found after simulation research that under the condition of high current,the larger the contact gap of the vacuum switch,the higher the ion temperature in the anode area.The temperature measurement formula derived based on the principle of CCD temperature measurement in this paper is found to be basically consistent with the actual situation after verification.The conclusions obtained can provide a theoretical basis for the optimal design of high-voltage circuit breakers.