Present and Future of DC Circuit Breakers for HVDC Grids

Abstract

The DC Circuit Breaker (dcCB) has remained one of the most challenging research topics to achieve commercially viable solutions with sufficiently low loss, high power density, and high reliability at an affordable cost. This is particularly true for circuit breakers for high-voltage dc transmission (HVdc) as the result of high-voltage and high-fault current in complex and mission-critical systems.
A hybrid DCCB was introduced by ABB in 2012, followed by different hybrid DCCB solutions at higher ratings, such as the one from Alstom (now GE Vernova) and witnessed by a third-party lab. In the last decade, demonstrations of those hybrid DCCBs stimulated heightened interest and a wave of research and development efforts around the world. Significant progress has been made since then in terms of the capability and performance of high voltage DCCB, including both mechanical DCCB and hybrid DCCB technologies, with their rated voltage and interrupted current having been improved from 80 kV / 9 kA to 535 kV / 25 kA. They went from lab units to operational field units, such as the Nan’ao, Zhoushan, and Zhangbei multi-terminal (MT) HVDC projects in China. While the capability and performance questions for HV DCCBs have been nicely answered through the units deployed in those projects, the key challenges of cost, power density, and robustness still need to be addressed satisfactorily before HV DCCBs can be widely adopted in commercial projects.
With the recent substantial growth of renewable energy around the world, particularly offshore wind, offshore DC grids enabled by HV DCCBs have received considerable interest because of their unique ability to protect the integrity of multi-terminal DC grids by quickly isolating faulty sections and reclosing after faults have been cleared. Based on the authors’ design and operational experience, this article intends to share the opinion of what needs to be done to make commercially viable HV DCCBs a reality to support the growth of offshore wind and DC grids.

Richard Zhang, Colin Davidson, Wolfgang Grieshaber, Tomas Modeer, David Smith, Bing Yang, Zhanqing Yu, Richard Zhang.

Published in IEEE Power & Energy Magazine.
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