Transmission & distribution |
The converter stations will be ready for multiterminal configurations. The converter contract for Brunsbüttel– Großgartach – at around 770 km the longest HVDC link of the German corridor projects and the world’s longest underground HVDC cable installation – was placed by the TSOs TenneT and TransnetBW. The German north–south corridor HVDC projects – see maps and tables – allowing integration of wind power from the north and solar power from the south of Germany into the transmission grid can be seen as an essential enabling technology for the energy transition. “The north of Germany has abundant power, that’s for sure,’’ says Hauke Jürgensen, senior vice president, HV grids, Siemens Energy, but the load centres tend to be in the south. “That is why we need the HVDC corridors, otherwise the energy transition would not be complete. The new transmission system is its backbone.” The next award will be for Project 4, the Wilster– Grafenrheinfeld part of SuedLink, currently in the tendering phase, with the contract expected in 2022. Due to siting problems and the lack of public acceptance of overhead lines, it was decided to spend more money and use underground cables for SuedLink, SuedOstLink and A-Nord, as already mentioned, and for all future HVDC corridor projects in Germany. This was also reflected in a new law, which allows overhead lines only in specific cases. The routing is mostly finalised, “more or less”, says Jürgensen, even though there are still issues with some stakeholders, such as farmers and locals in some regions, to be resolved. Beyond the 6 GW of projects awarded and in the execution phase plus 2 GW in the tendering phase, there are a further 10 GW of HVDC links in planning. These projects are in addition to a large number of other HVDC links in the pipeline worldwide, particularly in Europe. To achieve the ambitious targets required for the energy transition, Hauke Jürgensen would like to see simplification and speeding up of the proposals, approvals and permitting processes, eg for cable routing. He estimates that it takes more than ten years to get from the idea of building an HVDC converter to commissioning, allowing for project development, competitive tendering, proposal submission and selection, and execution.
Such lead times would make it “really difficult to meet the targets in the timeframe that we would like to meet them. So, these processes have to be simplified and they have to be much faster.”
German HVDC north/south corridor projects Projects in execution
Award: 2015
Ultranet and A-Nord (Project 1 aka Corridor A)
Emden–Osterath-Philippsburg Amprion and TransnetBW Overall length ca. 660 km
SuedOstLink (Project 5)
Wolmirstedt–Isar 50Hertz and TenneT Overall length ca. 580 km
SuedLink (Project 3)
Project in tendering phase SuedLink (Project 4)
Projects in planning phase Corridor 5a DC20
Corridor B DC21B Corridor B DC25 DC 31 DC34
Brunsbüttel–Großgartach TransnetBW and TenneT Overall length ca. 770 km
Wilster–Grafenrheinfeld TransnetBW and TenneT Overall length ca. 620 km
Klein Rogahn–Isar TenneT and 50Hertz
Wilhelmshaven 2–Hamm TenneT and Amprion
Heide/West–Polsum TenneT and Amprion
Heide/West–Klein Rogahn TenneT and 50 Hertz
Rastede–Bürstadt TenneT and Amprion
In operation: 2024 Capacity: 2000 MW
Cable suppliers: Prysmian and Sumitomo/Südkabel
Award: 2021
In operation: 2027/28 Capacity: 2000 MW
Cable suppliers: NKT and Prysmian Award: 2021
In operation: 2027/28 Capacity: 2000 MW
Cable suppliers: NKT and Prysmian Award: 2022
In operation: 2027/28 Capacity 2000 MW
Award: ca. 2024 Capacity: 2000 MW
Award: ca. 2024 Capacity: 2000 MW
Award: ca. 2024 Capacity: 2000 MW
Award: ca. 2028 Capacity: 2000 MW
Award: ca. 2028 Capacity: 2000 MW
Cable awards
When it comes to winning cable awards for the German corridor HVDC projects, Prysmian has so far proved to be a dominant player, winning contracts to provide cable for Project 5 (SuedOstLink), Project 3 (eastern part of SuedLink) and A-Nord (northern part of Project 1) – around 2300 km in total, or some 44% of the cable awarded to date, the Milan based company estimates. It has opened three new regional offices, in Bayreuth, Würzburg and Wuppertal, to support project execution and has set up a project development and management team of over 200 people.
The cable for SuedOstLink (Project 5) has been awarded in five lots, two lots, the southern portion, going to Prysmian and three lots, covering the northern part, to NKT (headquartered in Copenhagen). Since a voltage level of 525 kV for land DC cable represents a new benchmark, to meet TSO quaification requirements all the cables have been subject to a 12 month testing programme. For SuedOstLink, Prysmian says it is providing around 270 km of its P-Laser cable, starting at Isar, the southern connection point. Prysmian notes that P-Laser employs “100% recyclable” insulation based on HPTE (High Performance Thermoplastic Elastomer).
Left: NordLink. In the north, the two German corridor HVDC links comprising SuedLink (Projects 3 and 4) will both connect to NordLink via Wilster. The 1400 MW NordLink 500 kV HVDC interconnector, inaugurated in May 2021, is 623 km long, with 516 km of submarine cable
18 | October 2021 |
www.modernpowersystems.com
NKT (which acquired ABB’s high voltage, including HVDC, cable interests in 2016) describes SuedOstLink as “the world’s first large commercial 525 kV XLPE high-voltage DC 2GW transmission line.”
NKT’s three SuedOstLink cable lots total about 275 km, terminating at Wolmirstedt. NKT is in addition supplying cable for the full 770 km Brunsbüttel–Großgartach (western) portion of SuedLink (Project 3). At its northern end this will connect to the recently inaugurated NordLink, via Wilster, giving Germany access to hydro power in Norway via a 525 kV DC offshore cable, also provided by NKT. It will also enable Norway to import power from Germany in dry years. Project 4 (Grafenrheinfeld–Wilster), the eastern portion of SuedLink, will also connect to NordLink. A further cable supplier to A-Nord is Sumitomo Electric. It is providing approximately 300 km of XLPE 525 kV DC cable.
Sumitomo Electric has nominated Südkabel, headquartered in Mannheim, as its German based technology partner for the project. So far, all the corridor converter project tenders have been won by Siemens Energy, and this, as Hauke Jürgensen points out, is helpful in terms of integrating the links. “It is currently easier to deal with the technology of a single supplier rather than having different suppliers, who still have, for example, different control and protection schemes.” However, “this is an issue that needs to be addressed in future grid development”, he notes.
Meanwhile, for the cables, there has been a policy of encouraging multiple suppliers, “for cable manufacturing capacity reasons and to reduce potential risks.”
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