Design And Analysis On Hybrid Magnetic Contact Structure And Magnetic Field For DC Vacuum Circuit Breaker

The demands of consumers for electricity requirements,power quality and power supply reliability continue to increase,with the rapid development and wide application of new energy,new materials,information and power electronics technology.There are lots of new challenges which the existing AC power system has to face with,such as the diversification of load and electricity demand,the complication of power flow equilibrium coordinated controlling,and the power supply stability and economy etc.With the improvement of DC transmission technology and the development of distributed new energy system,the DC system is applied more and more widely.As the control and protection equipment in DC system,DC insulation circuit breaker will directly affect the safe and reliable operation of the system.Based on the analysis of the contact structure of vacuum circuit breaker and the regulation of vacuum arc magnetic field,the contact structure of a new type of hybrid magnetic field for vacuum interrupter system is put forward,through effective control of the vacuum arc controlled fracture magnetic field.Based on the analysis of the structure and magnetic field characteristics of the transverse magnetic field(TMF)cup contact and the axial magnetic field(AMF)cup contact,a fitting model of the TMF-AMF contact is established,the internal cup-shaped axial magnetic field benefits to maintain the arc in the central region of the contact surface to be diffused.The external cup with transverse magnetic contact blowout magnetic forces to produce effective dissipation of arc energy to extinction.Based on the numerical calculation of the contact center plane,the steady magnetic field and the residual magnetic field distribution of the new type of transverse and axial magnetic contact,the comparative analysis and quantitative description of the new type of contact with the traditional cup contacts are obtained.According to the arc extinguishing moment of VCB,this is in contrast to AMF that TMF has shorter retention time of in the arc zone,faster escape velocity.Through the analysis of the spiral groove of transverse magnetic field contacts and a cup-shaped transverse magnetic contact structure,the coaxial transverse magnetic contact model is established.Whose inner spiral groove contact is slightly prominent,so as to reduce the resistance of the closed contact body and the heat generation.Based on the analysis of the electron density of the coaxial transverse contact,the control strategy of arc motion locus is proposed;the physical and mathematical model of the field calculation is established,and the magnetic field and the force are simulated and calculated.The comparison between the traditional spiral groove transverse magnetic contact and the cup transverse magnetic contact is carried out.