| High-voltage direct current transmission has a good prospect in the field of ultra-long distance high-voltage power transmission due to its high stability,high efficiency,convenient adjustment and many other advantages.HVDC vacuum circuit breaker based on commutation principle is key device for short circuit failure interruption in HVDC system.Its breaking performance is not only determined by the inherent breaking parameters such as the rate of current change and the rate of recovery voltage change near the extinction of the arc,but also affected by dynamic factors such as arc time,commutation time and minimum safe stroke.Firstly,the principle and process of extinguishing HVDC arc by vacuum switch based on the principle of commutation were studied in this paper.Then the inherent and dynamic breaking parameters and their relationship with breaking performance were defined and analyzed.Secondly,the equivalence of the breaking process of the DC synthesis test circuit were simulated by the PSCAD platform,and the influence factors of the inherent breaking parameters were verified by simulation.At different interrupting current amplitude,commutation frequency and amplitude ratio of the commutation current to the interrupting current(commutation ratio),the influence of breaking parameters on breaking performance of DC vacuum circuit breaker were tested by a two power supply DC test circuit.Then the parameter range of arc time and safe stroke were studied by high-voltage DC breaking test.The minimum arc time is determined to changing the initial moment of commutation time,and the minimum safe stroke at different interrupting current amplitude and commutation frequency are tested by the travel curve of the circuit breaker moving contact.The results can be further extended to functional phase selection with larger interrupting currents and other commutation frequencies,which provide design basis and parameter improvement direction for HVDC vacuum circuit breaker. |
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