ENTSO-EHVDC Circuit Breakers
Overview
The High Voltage Direct Current (HVDC) circuit breaker is a switching device that interrupts the flow of normal and abnormal DC. The challenge in breaking DC is the absence of natural zero current crossing. To break the DC, either additional oscillatory circuits for the generation of zero-crossings or additional power electronics are needed. Moreover, for interoperation in the HVDC grid, the operating speed of the HVDC circuit breaker needs to be adapted to the abilities of the high voltage source converters (VSCs). The VSC not subjected to the fault should be able to immediately (within 2–10ms) carry on its operation. For these reasons, the HVDC circuit breakers are much more complex devices than the well-known Alternating Current (AC) circuit breakers.
Technology types
There are three different technology types for HVDC circuit breakers:
- Mechanical Circuit Breaker (MCB): with passive resonance circuit. This is an old technology, typically an air blast circuit breaker with several interrupter units with a very long operation time.
- Solid-State Circuit Breaker (SS-CB): with use of power electronic in series, and is considered as the fastest option; however, operational losses need to be considered.
- Hybrid DC Circuit Breaker (HCB): a combination of an ultra-fast disconnector with controllable solid-state devices. There are many different approaches for this type of breaker. HCB has Low losses; however, longer operation times compared to SS-CB.
Benefits
The HVDC circuit breakers are required for meshed HVDC-grids and multi-terminal HVDC links to increase the availability of the DC system in that they disconnect only the faulty component so that the remaining part of the system can carry its operation. The realisation of HVDC offshore systems that are planned (see Offshore Network Development Plan) shows the apparent need for this kind of devices.
The extensions of the HVDC grid are possible only if the HVDC circuit breakers are available and are fully adapted to the planned half bridge HVDC VSC.
Current Enablers
For the application of the HVDC circuit breakers and the realisation of more complex HVDC grids, the interoperability of HVDC VSC is absolute prerequisite. For this reason, the successful finalisation of the ongoing Horizon Europe Project InterOPERA “Enabling interoperability of multi-vendor HVDC grids” is essential for the application of the technology.
R&D Needs
The first and major point in the application of the HVDC circuit breakers is to show their benefits in the considered HVDC network. The Offshore Network Development Plan reveals that it is possible to build multi terminal HVDC networks, either with or without the use of the HVDC circuit breaker. Therefore, the major issue is to define the abilities of breakers as the present manufacturers of VSCs offer different technical solutions that are not compatible. Hence, the agreement on the HVDC network parameters and interoperability of VSCs are key aspects. Subsequently, the best and most appropriate technology of the breaker can be chosen and developed further.
The technology is in line with milestones “Demonstration of innovative technologies for power flow control and increasing grid efficiency” and “Advanced reconfiguration and control of network and assets” under Mission 1 and milestone “Demonstrator of tools for compliance validation” under Mission 3 of the ENTSO-E RDI Roadmap 2024-2034.
TSO Applications
Examples
| Location: Zhangbei, China [1] | Year: 2020 |
|---|---|
| Description: A 500kV/25kA HCB with current commutation drive circuit (CCDC) with forced commutation was installed in a flexible DC grid in Zhangbei. | |
| Design: A 500kV/25kA HCB with CCDC with forced commutation. | |
| Results: In operation. | |
| Location: Nan’ao, China [2] | Year: 2018 |
|---|---|
| Description: A MCB 160kV / 9kA HVDC circuit breaker was installed in a Nan’ao multi-terminal HVDC system. | |
| Design: MCB 160kV / 9kA HVDC circuit breaker | |
| Results: In operation | |
| Location: EU [3] | Year: 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 – mechanical circuit breaker with active current injection, WP6 – hybrid and mechanical circuit breaker. | |
| Results: WP5 – successful demonstration of a DC fault current interruption. | |
Technology Readiness Level The TRL has been assigned to reflect the European state of the art for TSOs, following the guidelines available here.
- TRL 6 for SS-CB at voltage rating 525 kV.
- TRL 6 for HCB at voltage rating 525 kV.
- TRL 5 for MCB at voltage rating 525 kV.
References and further reading
X. Zhang et al., “A state-of-the-art 500-kV hybrid circuit breaker for a dc grid: the world’s largest capacity high-Voltage dc circuit breaker”, IEEE Industrial Electronics Magazine, vol. 14, no. 2, pp, 15–27, Jun. 2020.
Z. Zhang, “Research and development of 160 kV ultra-fast mechanical HVDC circuit breaker,” (2018) Power Syst. Tech, vol. 42, no. 19, pp. 2331–2338, 2018.
European Union. “PROMOTioN – Progress on Meshed HVDC Offshore Transmission Networks.”, promotion-offshore.net
CIGRE Technical Brochure 873, “Design, test and application of HVDC circuit breakers,” Cigre JWG B4/A3.80, 2022
M. Barnes et al., “HVDC Circuit Breakers – A Review,” IEEE Access, doi: 10.1109/ ACCESS.2020.3039921, Nov. 2020,
A. Choubey and R. Gupta, “Voltage source converter based HVDC transmission,”, International Journal for Technological Research in Engineering, vol. 4, pp. 2347–4718, 2016.