Magnetic Arc Control Of Composite Contact Based On DC Vacuum Circuit Breaker

HVDC transmission technology is an effective way to solve long-distance,high-power transmission.HVDC transmission system at both ends has gradually developed into a multiterminal system composed of multiple converter stations.The high-voltage DC grid is formed.As an important part of the HVDC system,High voltage DC circuit breaker ensure the safe and reliable operation of HVDC systems.it is very important to improve its breaking performance.The AMF-TMF contact generates special magnetic field can control DC vacuum arc,make it easier to extinguish.Firstly,under the condition of DC intermediate frequency commutation,the paper analyzed the magnetic field distribution characteristics of two types of contacts which commonly used in vacuum arc interrupters.A new type of AMF-TMF contact structure is proposed.The contact has a spiral-groove Transverse Magnetic Field contact structure(TMF)inside to ensure that the initial DC vacuum arc continuously rotates outward.The outside is a cup-shaped Axial Magnetic Field structure(AMF),which drives the DC vacuum arc to maintain a diffuse state until it is extinguished.Based on this new AMF-TMF contact structure,a simulation model is established.The magnetic field distribution under the condition of 5kA / 3000 Hz is analyzed,and its characteristics are compared with the contact of single magnetic field structure.At the same time,the force analysis of the arc posts at different positions between the contacts was carried out,the arc trajectory was predicted.Secondly,the simulation further analyzed the magnetic field distribution of the new AMFTMF contact in the U-shaped double-break DC vacuum interrupters.The effects of the center distance of Interrupters on the offset distance of the TMF,the difference in TMF at the maximum radius and the remaining AMF in the region of the AMF contact piece are obtained.In addition,the influence of the magnetic shield with iron-nickel alloy coating on the magnetic field distribution is analyzed.The results show that increasing the center distance of Interrupters and installing a magnetic shield can effectively improve the magnetic field distribution of the double-break DC vacuum interrupter with AMF-TMF contact.Finally,a high-voltage DC vacuum circuit breaker experimental platform based on a threepower synthesis test circuit was built.Using AMF-TMF contacts for DC breaking experiments,At the same time,arc images were captured using high-speed photography.By changing the magnitude of the current,observe the shape and movement of the DC vacuum arc,combined with the characteristics of contact ablation,summarize the characteristics of the control of the AMF-TMF contacts on the DC vacuum arc.It shows that the new AMF-TMF contact has the ability of DC vacuum arc control under DC frequency of 3000 Hz and 6kA level current...