The Investigation On The Method Of Parallel Couple Computation Of Electric Field And Flow Field In High Voltage SF₆ Circuit Breaker

The calculation of dielectric recovery characteristic of high voltage circuit breaker (HVCB) in the interrupting course is an important part for the investigation of the interrupting characteristic of HVCB. The research on the dielectric recovery characteristic of HVCB is a complex processing including multi-physic field coupled action, in which the electric field and the flow field during the interrupting course is the cardinal influencing factor. Therefore, in this thesis the investigation on dielectric recovery characteristic has been studied on the base of these two fields.In order to precisely calculate the dielectric recovery characteristic, the method of parallel calculation of flow field and electric field are proposed. At first, because of the complicated structure and multi-dielectric medium of HVCB, the sub-region meshing method is presented, which is the preparation for the parallel calculation. Based on the sub-region meshing method the elements can be generated. Moreover, the uniform elements information in the calculation region of flow field and electric field can be effectively obtained. At the same time, at the region with the severe variation of flow field and electric field, the elements are densified. On the basis of the above analysis, the couple computation of electric field and flow field has been parallel calculated, and the solving technique has been studied. Furthermore, the distribution on flow field velocity vector, Mach, density, pressure, and the distribution of equal potential electric field are figured out. Accordingly, the parameter of gas flow and electric field during interrupting course has been analyzed.In computing the dielectric recovery characteristic of HVCB during the interrupting course, the numerical results of parallel couple calculation on flow field and electric field has been performed. And the comparison analysis on different structure of nozzle has beeninvestigated emphatically. From the simulation results were compared, it can be drawn that for small opening stroke, the structure of the nozzle almost has less influence on the value of the dielectric recovery characteristic, and the curve of dielectric recovery characteristic was nearly match together in different cases. However, with the increase of the opening stroke, the dielectric recovery characteristic value of the circuit breaker with multistage convergent-divergent nozzle is higher than that of the none-stage convergent-divergent nozzle.At the same time, the locations of the maximum of electric field strength and the minimum of dielectric recovery voltage during the interrupting course have been traced in this thesis. During the whole interrupting course, in small opening stroke, the maximum electric field strength on the head of stationary arcing contact, with the opening of the contacts, the point moving towards the head of the movable arcing contact, which approaches the nozzle, especially the opening stroke is over 30%. During the interrupting course, the station with the minimum of dielectric recovery voltage was always occurred on the head of stationary arcing contact. So when designing the circuit breaker, the region near the stationary arcing contact and movable contact must be taken more attention.The calculation region of flow field and electric field is different, and the initial condition and boundary condition are also different. In computing, for overcoming the disadvantages of the traditional method, that is the meshing grid in the two field is different and hard to ensured to be uniformed, the parallel calculation method is proposed and the dynamic simulation in the course of interrupting has been realized in this thesis. The program combining the preprocessing modeling, grid meshing, parallel computing, data coupling and calculation post processing has been achieved.