High Speed Switch with Series Linkage Switching of Vacuum and Nitrogen-Hydrogen Gas Mixture and Its DC Fast Transfer Application

Hybrid DC circuit breaker (HDCCB) is the significant equipment for protection and control in DC grids. However, forced commutation has the shortcomings of great power consumption and high cost. Natural commutation is limited by arc voltage, resulting in poor performance in high-capacity breaking. In order to achieve fast natural transfer, combined with the advantages of high gas arc voltage and fast recovery speed of vacuum, a HDCCB topology based on a disc-type multi-contact nitrogen-hydrogen gas mixture contact and vacuum contact series linkage switch is proposed. The switch experimental prototype is developed, and an experimental platform for arc characteristics is built. The effects of different gas media, contact opening distance, magnetic field strength and gas pressure on arc pressure are studied. When the opening distance is 12mm, the magnetic field is 25mT, and the gas medium is 0.3Mpa nitrogen-hydrogen gas mixture (N2:H2=3:7), the arc pressure can reach 336V. The simulation model is established to compare and analyse the opening process, and the current transfer time is shortened from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1900\mu\mathrm{s}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$200\mu \mathrm{s}$</tex>. This paper preliminarily verifies the effectiveness of enhancing the current transfer performance in the new HDCCB, and provides a reference basis for the development of high-performance prototype.