Three major high-voltage direct current (HVDC) technology giants—GE Vernova, Siemens Energy, and Hitachi Energy—will join forces with four German transmission system operators—50Hertz, Amprion, TenneT and TransnetBW—to develop multiterminal hubs with direct current circuit breakers.
The initiative is the latest development in ongoing European collaboration to enhance the interoperability of HVDC systems, facilitate the integration of renewable energy sources, and bolster the efficiency and reliability of power grids.
The “innovation partnership,” announced on July 15, will seek to realize a “large-scale meshed direct current grid” for the first time in Europe, said Tim Meyerjürgens, COO of TenneT, a TSO for the Netherlands.
A Vision for the Future of HVDC Grids
Today, “most HVDC systems are designed by European HVDC suppliers as point-to-point transmission systems and are provided by a single vendor,” explained experts from TenneT, Europe’s transmission and distribution trade groups, and several universities in a recent Energies journal article. But, given the rapid expansion of large-scale and remote renewable energy sources, the region has recognized it will need to transition to multiple-terminal HVDC grids. So far, these have been envisioned as three-terminal concepts, which can be expanded in the future.
Examples include the Caithness-Moray-Shetland System, which, initially a two-terminal HVDC link, has been designed for a three-terminal configuration. The Heide Hub, launched in Germany in November 2022 under a collaboration between 50 Hertz and TenneT envisions a “meshed HVDC grid at sea and on land.” The concept, endorsed by the German government, involves the establishment of an innovative multi-terminal hub in the Heide region. Italy’s €11 billion Hypergrid, described in Italian TSO Terna’s March 2023 development plans, could include the construction of “five new electricity backbones” and multiple HVDC connections across Italy. It seeks to double exchange capacity between market zones and integrate renewable energy efficiently.
The German TSOs earlier this week noted the first multiterminal hubs to be built in northern Germany will consist of a converter and a substation in addition to the direct current (DC) switchgear, where the direct current lines are linked together. “The DC switchgear is the centerpiece of the multiterminal hub,” TenneT said. “This is where the direct current lines are directly connected to each other in order to channel energy flexibly and as required.”
However, DC circuit breakers as part of the DC switchgear are “a technical innovation,” TenneT noted. “In the event of a fault, they can identify faults in fractions of a second and switch off the affected areas. The aim of the project is to demonstrate the technical feasibility and economic viability of multiterminal technology.”
“As part of the innovation partnership that has now been concluded, the four German transmission system operators have joined forces with the leading technology companies in the sector to develop a common European standard for smart power hubs,” noted Stefan Kapferer, managing director of 50Hertz. “This should enable us to connect the large direct current lines with each other in the future and create a direct current grid instead of straight point-to-point connections. This will strengthen the resilience of the entire European grid and increase security of supply, flexibility and stability.”
TransnetBW CEO Dr Werner Götz noted that the “innovative meshing” of power lines will allow transmission developers to minimize required space and “keep costs stable for consumers.”
According Tim Meyerjürgens, COO of TenneT, the applications are promising. “In the German North Sea alone, 70 GW of offshore wind energy are planned, which must not only be brought ashore efficiently but also distributed throughout the country in the most area- and cost-efficient way possible,” he said. “At the same time, the further integration of renewable energies is increasing the demands on grid stability and security of supply.”
GE Vernova Bags R&D Contract for Innovative DC Circuit Breaker
Under one of the first contracts unveiled under the partnership, the four TSOs will partner with GE Vernova’s Electrification business to conceptualize, design, and develop a new-to-market 525 kV Direct Current Circuit Breaker (DCCB). The DCCB will allow the TSOs to “trip and isolate faults in the HVDC system,” GE Vernova said.
The initial R&D award will cover the design phase through December 2025. If successful, implementation will begin in 2026, with commercial deployment slated in 2029. For now, GE Vernova is currently working “in the development phase” of the DCCB. When completed, the DCCB will become part of GE Vernova’s market offer.
“We believe GE Vernova’s technology will be essential to the efficient integration of renewable energy and the future of the energy transition,” said Johan Bindele, head of Grid Systems Integration at GE Vernova’s Grid Solutions business. “This truly transformative and groundbreaking innovation could change fundamentally how we deliver electricity.”
European Industry Working to Implement Multi-Terminal HVDC to Support Multiple Vendors
The “innovation partnership” is just one facet of several initiatives underway in Europe to enable more advanced and interconnected HVDC transmission. The region is acting quickly given that it recognizes that large offshore wind power generation operations alongside increased decentralized and distributed generation and demand facilities are poised to change the power flows across Europe. Industry observers have flagged these trends’ direct impact on the transmission infrastructure and observable cross-border power flows.
Along with multi-terminal concepts—which are still spearheaded by single vendors—several groups have called for multi-terminal/multi-vendor (MTMV HVDC) systems.
“The question emerges if there is a need for an HVDC ‘supergrid’ spanning multiple European countries and serving as transmission infrastructure in coexistence with the pan-European AC transmission grid,” TenneT and others have explained.
However, among the key challenges is that multi-vendor systems need standardized functional requirements for the HVDC converters and switching stations from various vendors, along with standardized interfaces with the grid to ensure interoperability.
In May 2022, several TSOs, technology providers, and the wind industry launched the READY4DC project to address the technical and legal concerns associated with MT-MV HVDC systems. The project garnered backing from the EU’s R&D funding arm Horizon Europe.
In addition, the European Network of Transmission System Operators (ENTSO-E), T&D Europe, and wind industry group WindEurope published a joint paper in May 2022 outlining steps for the essential development of MTMV HVDC grids. Stakeholders said insight from the effort would also shed light on concerns affecting the broader context of future power grids, including multi-vendor power electronics interfaced devices (PEIDs), such as flexible alternating current transmission systems (FACTS), wind turbines, and solar panels.
After the READY4DC project concluded in November 2023, laying essential foundations for the development of Europe’s first MTMV HVDC project, industry stakeholders kicked off the InterOPERA project, which seeks to make future HVDC systems interoperable by design and to improve the grid forming capabilities of offshore and onshore converters. Ultimately, InterOPERA aims to enable “real-life” projects through commercial tenders, possibly by 2027.
“InterOPERA is not only about developing technical standards but also about agreeing on the procurement, commercial, legal, and regulatory frameworks that will facilitate the tendering, building, and operation of full-scale HVDC multi-terminal, multi-vendor, multi-purpose real-life applications anticipated by 2030,” says the SuperGrid Institute, a privately owned company that is coordinating InterOPERA.
—Sonal Patel is a POWER senior editor (@sonalcpatel, @POWERmagazine).
