Ausschaltverhalten eines Hybridschaltgerätes aus Vakuum- und Gasleistungsschalter

Götte, Nicolas; Schnettler, Armin (Thesis advisor); Niayesh, Kaveh (Thesis advisor)

1. Auflage. - Aachen : Verlagshaus Mainz GmbH (2021)
Book, Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2021

Abstract

Nowadays, gas circuit breakers are used almost exclusively in high-voltage and extra-high-voltage grids to interrupt operating and short-circuit currents. Due to its outstanding quenching and insulating properties, sulphur hexafluoride (SF6) is currently used as filling gas. As SF6 is the most potent greenhouse gas known, there are worldwide efforts to substitute it with alternative, environmentally friendly gases in the future. However, all potential gas alternatives have a lower performance than SF6. Vacuum circuit breakers have become established in medium-voltage networks due to their reliability and cost-efficiency. For rated voltages up to Ur = 145 kV vacuum circuit breakers are in operation, while solutions up to Ur = 245 kV are in the focus of ongoing research and development activities. In order to realize environmentally friendly circuit breakers also at the high and extra-high voltage levels, new concepts are therefore being investigated. One possible approach is a series connection of gas and vacuum circuit breaker as hybrid circuit breaker. The lower breaking capability of the gas circuit breaker when using alternative gases is compensated by the vacuum circuit breaker. The gas circuit breaker takes over a large part of the dielectric requirements, thus allowing the ratings of the vacuum circuit breaker to be adjusted. The aim of this work is to characterize the interaction between gas and vacuum arcs in the vicinity of current zero. The post-arc-current of the vacuum circuit breaker is identified as an important parameter for the interaction between the two circuit breakers in the series connection. In the case of high current and voltage loads, the vacuum-post-arc-current ensures that in the first phase after current zero, the vacuum circuit breaker takes over a large part of the transient recovery voltage. Thereafter, a transition phase leads to a capacitive voltage division between the two circuit breakers. In order to influence the voltage distribution between the circuit breakers, both capacitive and resistive voltage controls are investigated. A resistive control of the hybrid circuit breaker is particularly suitable. The capacitive control has a negative influence on the switching behavior of the series connection in addition to the voltage distribution.

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