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摘要
In terms of compatibility of fast operation, flexible control and economy, common control switches for the commutation branch of mechanical DC circuit breakers have not yet fully met the requirements of large-scale application of distribution networks. For this reason, a gas gap switch scheme for the commutation branch of DC circuit breakers was innovatively proposed, whose operational performance was related to its trigger conduction performance. A prototype for the gas gap switch was further designed, and a trigger test platform was built to study the development characteristics and the influence law of the jetted plasma during the induced breakdown process. The results show that the breakdown process induced by the plasma jetting of the gas gap switch can be divided into 3 stages: rapid development, saturation and dissipation. With the increase of the working coefficient, the gas gap switch will transit from the saturated conduction mode to the fast conduction mode, and both the trigger conduction delay and the critical jet height of the plasma at the breakdown of the main gap of the switch will decrease. The strongly insulated electronegative gas SF6 has an obvious inhibitory effect on the development of the jetted plasma. The increase of gas pressure also has an obvious inhibitory effect on the jetting of the plasma. With the increase of the gas pressure, the jet velocity and jet height will decrease gradually, while the trigger conduction delay will increase. The main gap of the gas switch under low gas pressures can be triggered to break down during the initial jetting process of the plasma, while there is an obvious pre-breakdown effect under high gas pressures. The research results can provide theoretical guidance for the design of ultra-fast switches for the commutation branch of DC circuit breakers, and have reference significance for improving the economy and flexibility of the rapid opening-closing technology of the distribution networks. ? 2022 Science Press.
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