Research On Co-simulation Of Operating Mechanism And Flow Field Of Arc-quenching Chamber Of High Voltage Circuit Breaker In No-load Environment

The establishment of the co-simulation model of the high-voltage circuit breaker operating mechanism and arc quenching chamber flow field is essential for the accurate calculation of the airflow field during the breaking process.It is difficult to solve the flow field equation and the dynamic equation directly,so an alternative method in which the dynamics model and the CFD model pass each other’s required parameters during the iterative solution process was adopted.In this paper,the following work was completed with a certain type of high voltage circuit breaker as the research object:1)The process of the circuit breaker operating mechanism was analyzed,and the mechanism for the breaker’s breaking movement was simplified into a spring-driven fourbar mechanism.The kinematics analysis of the operating mechanism was carried out to establish the constraint equation;the dynamic model of the circuit breaker operating mechanism was established after the Lagrange equation was established,and the fourth-order Runge-Kutta method was used to solve the equation with the load neglected so that the dynamic response of the operating mechanism was got.2)In order to establish the CFD model of the flow field of the arc quenching chamber,the two-dimensional axisymmetric geometric model was established after the arc quenching chamber structure was simplified.The dynamic mesh model was introduced to realize the transient simulation of the flow field during the breaking process.After comparing the three mesh updating methods,the layering method was used to reduce the grid distortion;the flow field mesh was divided into three regions to match the dynamic mesh model,including dynamic regions,static regions and layering needed regions.Then,these regions were assembled and the key areas were encrypted to form the flow field mesh;the code was written by using Fluent UDF to specify the motion of the dynamic mesh.Monitoring Surfaces was set up to monitor the distribution parameters of key points in the flow field.3)Four co-simulation methods-parallel co-simulation based on shared data file,parallel co-simulation based on TCP/IP communication,embedded co-simulation,co-simulation based on shared memory-were proposed.After the advantages and disadvantages of these methods were Analyzed and compared,embedded co-simulation method was selected as the co-simulation method.For embedded co-simulation,Matlab code was packaged as a dynamic library,which was introduced to write Fluent UDF code.Fluent was redeveloped by using UDF code to build co-simulation model of the operating mechanism-arc chamber flow field.After the boundary conditions were set and the co-simulation model was initialized,the flow field distribution and the pressure curve of the key points during the opening process were obtained.According to the flow field distribution,the arc-quenching capability and heat dissipation capability of the circuit breaker during the opening process were analyzed.4)The test platform of the circuit breaker arc-quenching chamber flow field was built,which includes pressure sensor and amplifier,ACDC power supply,BK voltage signal acquisition card,filter switch and acquisition analysis background.The pressure sensor was arranged at three key points: the inlet of the cooling chamber,the head of the static contact and the middle of the pressure chamber.Field experiments were carried out on the breaker to verify the co-simulation model.The dynamic mesh model and the co-simulation method proposed in this paper not only have great significance for the calculation the circuit breaker flow field,but also provide an effective solution for the calculation problem of the tight coupling of the flow field and the moving object.