Interruption limits of mechanical circuit breakers and circuit upgrades for current injection in HVDC circuit breakers

Abstract

Current injection circuit breakers consist of a mechanical interrupter (MI) with a current injection and an energy dissipation branch in parallel. The performance of the complete device is largely determined by mechanical operation time and interruption performance of the MI. In the standard configuration, current injection is realised using a pre-charged inductor–capacitor circuit. A higher interruption performance of the MI makes it possible to scale down the resonant injection circuit, and thus have a more economical design. Additionally, the implementation of more complex injection circuits that quickly create zero crossings, while maintaining favourable conditions for interruption, can lead to economic benefits. In this study, the interruption performance of a model gas interrupter as part of a current injection topology is investigated. The results are used to verify a corresponding simulation model and two-dimensional upgrade circuits that influence the injection current to increase the range of interruptible fault currents. On the basis of experimental results, the simulation model is used to investigate the performance of upgrade circuits for the use in high-voltage direct current (HVDC) systems. The results indicate that using improved injection circuits can considerably increase the economic advantage of current injection circuit breakers compared with other topologies.