HVDC Circuit Breakers

The HVDC circuit breaker is a switching device that interrupts the flow of normal and abnormal direct current. The challenge in breaking direct current is the absence of zero current crossings. The additional component must be used that either generate zero-crossings by application of special oscillating circuit and mechanical circuit breakers or power electronics to break the current. The HVDC circuit breakers are required for meshed DC-grids and multi-terminal DC links.


Technology Types

HVDC circuit breaker can be classified into four topologies:

  • Mechanical circuit breaker with passive resonance circuit: old technology, typically air blast circuit breaker with several interrupter unit
  • Mechanical breaker with active current injection
  • Solid-state: fastest topology, many semiconductor-based switches are connected in series
  • Hybrid DC breakers: controllable solid-state devices are used to break the current until a mechanical breaker or disconnector opens the circuit

Components & enablers

N/A


Advantages & field of application

Multi-terminal HVDC system are emerging to integrate bulk renewable energy, e.g. wind offshore, over long distances, or in a next stage could also be used for DC overlay grids. Such system require HVDC circuit breakers. Various protection strategies exist to clear a fault on a DC cable with different requirements for DC breakers (speed/rating). These strategies vary from direct line protection, to regional splitting, to wide area converter blocking with residual DC current breaking.


Technology Readiness Level

HV: TRL 6

EHV: TRL 3


Research & Development

Current fields of research: scaling hybrid and mechanical circuit breaker to EHV DC voltage, increasing response time and improving stability, reduction of space required for hybrid dc breaker.


Best practice performance

Current rating: 8 kA (mechanical circuit breaker), 9 kA (hybrid circuit breaker– anticipated to reach 16 kA), 5 kA (pure semiconductor – anticipated to reach 800 kV)

Voltage rating: 120 kV (hybrid circuit breaker– anticipated to reach 320 kV), < 70 kV (pure semiconductor – anticipated to reach 800 kV)

Standard definition: currently no standardisation exists

Expected lifetime: > 25 years


Best practice application

EU

Several projects 2016 - 2018

Description
Project ‘Progress on Meshed HVDC Offshore Transmission Networks’ (PROMOTioN) under the EU Horizon 2020 programme to accelerate meshed HVDC grid development; work packages on “WP5: Test environment for HVDC CB”, “WP6: HVDC circuit breaker performance characterization”, “WP10: HVDC circuit breaker performance demonstration”.

Design
WP5 - Mitsubishi mechanical circuit breaker with active current injection, WP6 – hybrid and mechanical circuit breaker.

Results
WP5 - successful demonstration of a DC fault current interruption.

Zhoushan, China

2016

Description
World’s first set of 200kV DC circuit breaker for 5-terminal VSC-HVDC.

Design
Combination of a high-speed mechanical switch and a hybrid cascaded full bridge module.

Results
Circuit breaker design has greatly improved the reliability of the HVDC project, circuit breaker successfully interrupted a short circuit current up to 15.6 KA.


References

[1] Mokhberdoran, A. et al. A review on HVDC circuit breakers. [Link]

[2] Muriithi, C. et al. Review of HVDC Circuit Breaker Topologies. [Link]

[3] Bucher, M., Franck, C. Analysis of Transient Fault Currents in Multi-Terminal HVDC Networks during Pole-to-Ground Faults. [Link]

[4] European Union. PROMOTioN - Progress on Meshed HVDC Offshore Transmission Networks. [Link]

[5] Zhou, J. et al. Research of DC circuit breaker applied on Zhoushan multi-terminal VSC-HVDC project. [Link]