Research On Precise Solution Of Electric Field And Inversion Of Arc Characteristics To Vacuum Circuit Breaker

As the security guard of power system at all levels of generation,transmission,distribution and utilization,switch apparatus play important role in controlling and protecting the reliability and stability of the system.In particular,with the improvement of voltage grade,breaking capacity and technical parameters,higher requirements are put forward for the dynamic and static insulation characteristics,dielectric medium characteristics and operation characteristics of switch apparatus in the service cycle.Vacuum circuit breakers are the main products in medium and high voltage switch apparatus.Numerical analysis of the dynamic evolution behavior of electric field,magnetic field and arc plasma is one of the effective ways to study the electrical,magnetic and thermal comprehensive performance of the circuit breaker.In the operating process of mechanical circuit breaker,there exist many parameters such as electricity,magnetism,heat and material interaction in space and time in the arc extinguishing chamber.Arc plasma inevitably occurs between the switch breaks.The coupling effect of the above factors directly affects the insulation,medium recovery and breaking performance of the circuit breaker.The methods such as combining modeling and analysis based on the physical mathematical model,combining autonomous design of precise numerical solution and experiment research,areeffective in quantitative analysis and research on the operation performance of circuit breaker.Aiming at high precision numerical simulation of electromagnetic field and autonomous design of precise solution,an improved finite element method based on region decomposition strategy and adaptive forward subdivision is proposed.A ripple model is proposed to improve the quality of the subdivision element,which is based on the dynamic generation scheme with the minimum inner angle maximized as the constraint condition.A strategy combining controllable uniform field discretization and controllable gradient discretization in boundary domain is adopted.Platform in C++language environment has been designed independently based on the field numerical analysis,using SQL Server database to store model data and field numerical simulation calculation.A fine solution and a visualization software platform for describing the temporal and spatial distribution of electromagnetic field are developed independently in circuit breakers by using Open GL library function.A complete solution of solution and fine electromagnetic field simulation of swtich gear with multiple dielectric and thin layer floating electrode is proposed.Based on the solution of electric field and magnetic field differential equations,a fine solution algorithm for the improved finite element based on cubic Hermite interpolation function has been designed.In order to ensure high order finite element with fine efficiency and precision,the interrupter of medium-voltage vacuum circuit breaker with thin-layer floating electrode is taken as the object of study,and a parallel fine solution algorithm based on virtual homogeneous boundary region method and multi-threading technology has been improved.The Hermite method,Lagrange method and ANSYS software package are used to calculate and compare the electric field of typical models with analytical solutions,and the relative error of the solution relative to the analytical solution has been obtained.The comparison analysis shows that the calculation accuracy of Hermite method is nearly 290%higher than that of Lagrange method,and 150%higher than that of ANSYS software package.The multi-threaded parallel finite element method has effectively solved the problem of engineering analysis of insulation characteristics and precise field solution of vacuum circuit breakers.In comparison with commercial software and carrying out fields numerical simulation of typical case,it is verified that the unit quality and calculation accuracy can be improved without affecting the calculation efficiency.4?9 threads parallel Hermite algorithm are used to solve the electric field problem of circuit breaker.Compared with the non-parallel Hermite algorithm,the computational efficiency hasbeen improved by 30%?40%.Based on the numerical analysis of vacuum circuit breaker in the arc extinguishing chamber,the improved finite element analysis platform,which adopt adaptive pre-processing,solution and visualization of spatial-temporal field distribution,makes the solution of the unbounded field of multi-media and thin-layer floating electrodes in parallel come true.In order to describe the dynamic variation of arc plasma in the interrupting process of arc extinguishing chamber for the vacuum circuit breaker,a high-speed camera is used to capture and analyze the arc dynamic behavior during the arcing,and extinguishing process of40.5k V/2500A/31.5k A vacuum circuit breaker with direct experimental conditions in Liaoning High Voltage Apparatus Quality Test Co.Ltd,High Voltage Apparatus Quality test Center of Machinery Industry,based on the self-built arc analysis system of vacuum circuit breaker.While the research object is the vacuum arc image of long arc test in T10,through calculating parameters of field emission in full period,current zero-crossing and temperature distribution at maximum energy,through calculating contact points,the current zero region,field emission,maximum arcing moment,arc blowout,complete segmentation joint point time,trip,breaking current to study the arcing characteristics of vacuum arc,a set of arc characteristic analysis scheme has been put forward by combining arc image semantics and experimental data,which is used to study the current and voltage variation of the arc with the change of arc time and travel distance between the break.In order to solve the problem of spoiler alerts of arc image semantics in vacuum during interruption,by combining the classical median filtering method and image morphology method and dynamic tracking marking of the connected region between arc core and outer flame,an ergodic connected domain labeling algorithm has been proposed.Compared with the classical pixel algorithm,the efficiency of the algorithm is nearly two times higher.Finally,the arc thermal field inversion and reconstruction pretreatment are realized.In order to solve the problem of arc image semantics caused by the sharp rise of arc core temperature and the response range of high-speed camera with far light intensity,an image blind restoration inversion algorithm is improved.L₀ norm is used as regularization constraint term to calculate point spread function,WATV is improved as image prior constraint condition,and Begman iterative algorithm is combined to solve the problem of ill-posed arc thermal field imaging.In order to solve the problem of no edge and texture in arc distortion region,the evolution rule of image pixels in arc variation process is fitted and calculated,and the edge of distortion region in sequence image is extracted,to reconstruct the information of arc edge region and realize the blind restoration of arc thermal field.At the same time,the temperature distribution of arc has been obtained by colorimetric method.The insulation of the arc extinguishing system and arc dynamic behavior are studied by combining the fine simulation of electromagnetic field of vacuum circuit breaker with the analysis of arc dynamic characteristics under direct test conditions.It provides an independent copyright design platform and numerical simulation basis for the precise solution of electromagnetic field and the research of interruption performance of switch gear.