Foundation laid for DolWin6 converter

28.05.2020

With a dozen operating offshore connection systems for wind farms in the German North Sea totalling a transmission capacity of 7.132GW, the Dutch-German transmission system operator (TSO) TenneT has already in 2019 exceeded the German government’s expansion target for offshore wind energy capacity for 2020 by more than half a million GW. A further 900MW will be provided by DolWin6, like the predecessor projects DolWin3 and BorWin3 a high-voltage direct current (HVDC) connection. The DolWin kappa offshore platform in the Wadden Sea near the island of Norderney will convert the three-phase wind current into DC for transmission via a 45 kilometre submarine cable to the East Frisian mainland and from the landing point via an underground cable, also around 45 kilometres long, to the TenneT site in Emden/East.

Here, the TSCNET shareholder is constructing the DolWin6 onshore converter station and a substation on 23,500m² to reconvert the DC into three-phase current for feeding into the onshore extra-high voltage grid. A significant milestone for DolWin6 was reached on 27 May: The laying of the foundation at the converter construction site was celebrated in Emden/East by embedding a time capsule with coins, a regional daily newspaper, and construction plans into the foundation stone. Due to the Covid-19 pandemic, the event was only celebrated with the most important project managers from TenneT and the plant constructor Siemens.

Concrete preparations for DolWin6 began in the summer of 2017 and 2018 with horizontal drilling on Norderney. In September 2019, the foundation work commenced in Emden/East. Work on the DolWin kappa offshore platform at a dockyard in Cádiz/Andalusia also started in mid-2019 and the DolWin6 cable laying will follow from summer this year. The completion of the HVDC offshore connection is scheduled for 2023.

TenneT celebrated the laying of the foundation stone for the DolWin6 converter in Emden/East (picture: TenneT)

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380kV line Beznau-Birr commissioned ahead of schedule

25.05.2020

The upgrading of the existing 220kV line between Beznau in the canton of Aargau and Mettlen in the canton of Lucerne to 380kV is a key component of the “Strategic Grid 2025“, the national expansion plan for the transmission infrastructure of the Swiss transmission system operator (TSO) Swissgrid. The voltage increase ensures energy distribution and supply security in the Zurich metropolitan area, Central Switzerland, and the Swiss Central Plateau. The TSCNET shareholder has now put the first section between Beznau and Birr in Aargau into operation, one year earlier than planned.

This stretch was partly installed underground, namely across the so-called Gäbihübel near Bözberg/Riniken about halfway between Beznau and Birr. The cable laying at the Gäbihübel is the first time that part of an extra-high voltage line in Switzerland has been implemented using underground cables. Twelve cables with a weight of 30 tonnes each were installed in the conduit blocks in the summer of 2019. This was followed by the completion of the overhead line section. To connect overhead lines and underground cables, special structures were erected at both ends of the approximately 1.3-kilometre-long underground section. After a construction period of around two years, the Swissgrid control centre connected the new 380kV line to the transmission grid on 19 May 2020. The reasons for the early completion were Swissgrid’s successful project and implementation planning as well as the rather warm and dry weather.

Swissgrid is providing scientific support for the construction, commissioning, and further operation of the underground cable. Investigations are carried out, for example, on the thermal behaviour of the cable conductors depending on the current load, the temperature variation in the soil above the conduit block and in the surroundings, and the biodiversity in the soil. In May, work began on dismantling the old 220kV overhead line and restoration of the pylon sites to their original condition. The deconstruction work is expected to last until the end of 2020.

Swissgrid has put into operation the 380kV line Beznau-Birr, the first Swiss extra-high voltage line partially laid underground (picture: Swissgrid)

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Amprion invests €1bn in 525kV cables for A-Nord

12.05.2020

The DC transmission line A-Nord represents the northern part of Corridor A, which is one of the main axes of the German energy transition. The 300-kilometre line from the port city of Emden at the Dollart Bay to Osterath in the Lower Rhine region is being implemented by TSCNET shareholder Amprion, one of the four German transmission system operators (TSOs). With a capacity of 2GW, A-Nord will transport wind power from the North Sea to the centres of consumption in the Rhineland and Ruhr district. The southern part of Corridor A is the Ultranet line, which is being implemented jointly by Amprion and further TSCNET shareholder TransnetBW.

Like other large-scale German DC interconnection projects that are essential to the country’s low-carbon energy future, A-Nord will be realised via underground cabling. The transmission capacity of 2GW will be achieved by 525kV cables whose efficiency significantly reduces the environmental impact but requires a special insulation material and highly competent suppliers. After extensive technical tests, Amprion has now contracted the underground cables for A-Nord. The specialist companies Prysmian Powerlink and Sumitomo Electric Industries are each supplying one cable system for A-Nord. The manufacturers will produce the systems concurrently with the construction of the line, scheduled to start in 2023.

Dr Hans-Jürgen Brick, CEO of Amprion, comments in view of the challenges to achieve a sustainable energy future: “It is essential that the grid expansion continues to progress swiftly.” Dr Klaus Kleinekorte, the TSO’s CTO, adds: “With this assignment, Amprion once again demonstrates that we are a driving force for innovative developments.”

Amprion has awarded contracts for the 525kV underground cables for the A-Nord power highway (picture: Amprion / Lutz Kampert)

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525kV cables for SuedOstLink

05.05.2020

The SuedOstLink is one of the major German DC interconnection projects that are essential to Germany’s low-carbon energy future by transporting green electricity generated in the north and east of the country – mainly wind power – to the centres of consumption in the south and west. Like the other so-called “Stromautobahnen” (power highways), SuedOstLink is primarily implemented via underground cabling. Its realisation is a joint effort of the two TSCNET shareholders 50Hertz, the transmission system operator (TSO) from northeast Germany, and TenneT, the Dutch-German TSO.

The European Project of Common Interest (PCI) now has reached an important landmark with the award of the contract for around 1000 kilometres of underground cables, the definitive centrepiece of SuedOstLink. The technology to be used for this is a global novelty: plastic-insulated underground cables for a voltage of 525kV. With these cables, the SuedOstLink connection will have a transmission capacity of 2GW. The higher capacity requires fewer cables to transmit the same power. The routing can therefore be designed narrower and the necessary civil engineering work is decreased. This significantly reduces the impact on the public and the environment.

The contracts were assigned to NKT for the northern part of the project in the 50Hertz control area and to Prysmian PowerLink for the section under TenneT’s responsibility. Both companies are internationally represented in numerous connection projects on- and offshore and both have proven the quality of their cables in extensive prequalification tests. The contracts include design, manufacture, delivery, laying of the underground cables, further installation work and the final high-voltage testing of the cable system. SuedOstLink is currently in the planning approval process. It should be completed by the end of 2025.

Dr Frank Golletz, Technical Director at 50Hertz, expects the cables to be laid from 2022 and describes the contract award as “a good signal for the SuedOstLink joint venture project as well as for the energy transition across Germany and Europe”. Tim Meyerjürgens, Managing Director of TenneT, adds: “We will use the innovative, plastic-insulated 525kV underground cables for the first time worldwide and will thus set new standards in technology and the reduction of environmental impact.”

50Hertz and TenneT have assigned the orders for the 525kV underground cables for SuedOstLink (picture: NKT)

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Swissgrid: Solid figures to promote innovation

23.04.2020

The primary content of the Annual Report 2019 just published by the Swiss transmission system operator (TSO) Swissgrid is summarised by Yves Zumwald, CEO of the TSCNET shareholder, as follows: “In a challenging year, Swissgrid laid the foundation to successfully meet the challenges of the energy future in Switzerland and in Europe.” These foundations include the expansion of the grid even against possible resistance, the strengthening of international cooperation despite the absence of an electricity agreement with the EU and the innovative further development of the electricity market. “Thanks to the fantastic effort and commitment of all employees, we can look back upon a successful year,” concludes Zumwald.

The implementation of the “Strategy 2022” for the reorganisation of the Swissgrid corporate structure to further increase efficiency within the company made good progress in 2019 – just like the grid extension measures according to the company’s ambitious plan “Strategic Grid 2025”, even if complaints sometimes delayed implementation. Projects worth mentioning in this respect include the grid extension works in the Swiss canton of Valais which are important for transporting energy from hydropower to the consumption centres of Switzerland or the progress made in Central Switzerland with the 380kV line between Beznau and Birr. This line is partially laid underground, representing the very first time that part of an extra-high voltage line in Switzerland has been realised by underground cables: Twelve cables with a weight of 30 tonnes each were installed in the summer.

In terms of key financial figures, the company’s net profit rose slightly year-on-year to CHF66.7m (€63.38m), while earnings before interest and taxes amounted to CHF102.4m (€97.31m), representing a decline of 14.2%, due to lower invested operating assets and the higher net surplus in volume- and tariff-related time differences. Looking ahead to the 2020 business year and beyond, high annual investments will continue to be required due to lengthy approval processes, especially regarding grid extension or modernisation. Swissgrid assumes a medium-term planning horizon of grid investments of approximately CHF150m (€152.54m) to CHF200m (€190.1m) annually.

Concerning innovation in the ancillary services market and market integration, the Swiss TSO will continue to develop the market platform on which requested products for frequency regulation and international redispatch are combined. To compensate for frequency fluctuations due to increasingly volatile energy generation, Swissgrid is preparing the “Crowd Balancing Platform” for the control energy market, a pilot project aimed at the use of storage technologies in the field of primary control energy. The “Crowd Balancing Platform” is based on block chain technology and the internet of things. The Dutch-German TSO and further TSCNET shareholder TenneT has already verified the technical feasibility of such processes. Now Swissgrid, TenneT and the Italian TSO Terna have formed a consortium for the European use of this technology, the potential of which Swissgrid will investigate in a pilot project in Switzerland. The project will start in the summer of 2020 and run until the end of the year.

Swissgrid reports solid results in its Annual Report 2019 (picture: Swissgrid)

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525kV technology for Germany’s “power highways”

04.12.2019

SuedLink, SuedOstLink and A-Nord are large-scale DC connection projects that are essential for Germany’s low-carbon energy future, since these so-called “Stromautobahnen” (power highways) will transport green electricity generated in the north and east of the country to the consumption centres in the south and west. The three power lines will be implemented predominantly via underground cabling and are collaborative efforts of the four German transmission system operators (TSOs). TenneT and TransnetBW cooperate on SuedLink, 50Hertz and TenneT join forces on SuedOstLink and A-Nord is carried out by Amprion. Together with Ultranet, a joint project with TransnetBW, A-Nord forms the Korridor A.

The four TSCNET shareholders intend to install innovative plastic-insulated DC cables with a voltage level of 525kV in these projects. So far, 320kV cables have been used for comparable DC connections in Germany. As a matter of fact, it will be the first use of 525kV underground cables worldwide, which underlines the pilot character of the three high-performance connections. The decision by the TSOs was preceded by an extensive test phase on the technical suitability of the 525kV cables. The pre-qualification tests according to international standards of the Council on Large Electric Systems (CIGRE) were successful and proved that the 525kV cables are reliable and safe.

A higher voltage level of the cables translates into more transmission capacity. This has two possible effects for the planned DC lines, assuming technical feasibility for the entire system: On the one hand, more electricity can be transmitted in a certain corridor with the same number of cables. On the other hand, fewer cables are required to transmit the same power compared to 320kV cable systems. This allows the routing to be designed narrower, which reduces excavation work and environmental impact.

The four German TSOs opt for innovative 525kV solution for power highways with underground cabling (picture: TenneT)

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> See 50Hertz press release, in German (html)
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> See TransnetBW press release, in German (html)

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Randstad 380kV North Ring in operation

14.10.2019

The four largest Dutch cities (Amsterdam, Rotterdam, The Hague and Utrecht) and their surroundings constitute the Randstad region in the Netherlands. With a population of more than 8 million people, it is Europe’s most densely populated area. Randstad has a high energy demand, which needs to be reliably met and secured also in the future. However, infrastructure construction measures are particularly challenging in such a conurbation. TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), has now made an elementary contribution to security of supply of the Randstad.

After a construction period of five years, the 60-kilometer-long Randstad 380kV North Ring power line was put into operation on 10 October. More than 1000 people from the region, 300 landowners, over 25 responsible authorities, 13 contractors and 200 TenneT employees were involved in its construction. The new high-voltage line will reliably supply millions of households and companies with electricity. It will also provide the transmission capacity required for green electricity from North Sea wind farms. As a complementary measure, the existing 150kV connections in the region were adapted and two new high-voltage substations have been built in Beverwijk and Vijfhuizen.

At 151 locations along the route, Tennet installed innovative Wintrack pylons that consume less space, reduce magnetic field zones and, due to their slim and streamlined shape, fit much better into their surroundings than conventional steel lattice pylons. Ten kilometres of the North Ring have been laid underground. The aluminium cables used by TenneT are a novelty. They are cheaper than conventional materials and conduct electricity more efficiently, which means that their carbon footprint is smaller.

TenneT has commissioned the Randstad 380kV North Ring (picture of the opening ceremony with TenneT CEO Manon van Beek and COO Ben Voorhorst: TenneT)

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First cables of ALEGrO installed

27.09.2019

The “Aachen Liège Electricity Grid Overlay” (ALEGrO) will be the first direct interconnector of the German and Belgian electricity grids. Its transmission capacity of 1,000MW is going to significantly increase cross-border electricity flows and security of supply in the regions surrounding the new converter stations at the respective ALEGrO end points, Niederzier in Germany and Lixhe in Belgium. The European Project of Common Interest (PCI) is jointly being implemented by TSCNET shareholder Amprion, one of the four German transmission system operators (TSOs), and the Belgian TSO Elia.

In the summer of 2019, several teams were working simultaneously at different points along the 41km-long ALEGrO section in Germany on the installation of the conduit system for the underground cables. Underground cabling is used exclusively for the entire German-Belgian power bridge. Due to the dry summer, construction work on the DC link has progressed rapidly: 60 percent of the cable conduits have already been completed. Amprion is now beginning to pull the 320kV cables successively into the conduits, initially in Niederzier, where the construction of the new ALEGrO converter plant is also progressing well.

Amprion starts the installation of ALEGrO underground cables (picture: Rheinhard Nießing / Amprion)

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Central project management and office for SuedLink

24.09.2019

The SuedLink extra-high voltage line is not only the most important individual project of the energy transition in Germany, but also the largest underground cable project in the world: Around 700 kilometers of cable will be laid and around ten billion euros invested. By connecting the windy regions of northern Germany with the consumption centres in the industrially highly developed south, “power highways” such as SuedLink are indispensable for achieving Germany’s and Europe’s climate goals. SuedLink is implemented jointly by the two TSCNET shareholders TenneT, the Dutch-German transmission system operator (TSO), and TransnetBW, the TSO from southwest Germany.

In order to efficiently advance the further approval procedure and the subsequent construction of SuedLink, the two TSOs have commissioned the international technical service company Jacobs as central service provider. The aim is to coordinate and control the various tasks such as planning, approval, obtaining easements and construction under one roof. This makes SuedLink the first major project in Germany in which an external central service provider is involved. TenneT Managing Director Tim Meyerjürgens explains why the two partners decided on a model that has proven itself many times in such large-scale projects on the international market: “The schedule for implementation is challenging. At the same time, the expectations of politics and the public continue to rise. For this very reason, controlling and coordination play such an important role.”

The commissioning of Jacobs is accompanied by the opening of the central SüdLink office in Würzburg, Lower Franconia. Together with the central service provider, TransnetBW and TenneT will initially create 130 jobs there, the number of which will rise to 250 in the course of the project. To better incorporate regional knowledge into the planning process, further decentralised project offices are to follow along the route. Dr. Werner Götz, Chairman of the TransnetBW Executive Board, comments on the development: “By commissioning a central service provider and setting up a joint project facility in Würzburg, we have laid the foundations for the successful implementation of this major project.” The staff in Würzburg will include engineers, archaeologists, landscape planners, biologists, geologists, and project managers, all joining forces for Europe’s energy future.

TenneT and TransnetBW commission a central service provider for the implementation of SuedLink (picture: TenneT / Katja Schubert)

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> See TransnetBW press release, in German (html)
> See TransnetBW press release on the office opening, in German (html)

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New ploughing technology for cable laying under test

10.07.2019

The 380kV line from Wahle in the German federal state of Lower Saxony to Mecklar in the state of Hesse is one of the underground cable pilot projects laid down in the German Power Grid Expansion Act (Gesetz zum Ausbau von Energieleitungen – EnLAG). For the construction of the line, TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), is testing a new ploughing technology for laying empty conduits, into which the three-phase underground cables will later be inserted.

The so-called multiple ploughing method was presented today in the Lower Saxony village of Wartjenstedt (near Hildesheim) to representatives from politics, authorities, associations and the media, as well as farmers and land users. At a test track of around 200 metres, the cable plough specialist company Frank Föckersperger and TenneT demonstrated how the specially developed cable plough can be used for the Wahle-Mecklar project.

Olaf Lies, Minister for the Environment, Energy, Construction and Climate Protection of Lower Saxony, was impressed by the demonstration: “The test in Wartjenstedt shows that when installing underground cables, it is possible to minimise interference with the existing soil structure and reduce construction costs and time by using new laying techniques.” TenneT Managing Director Tim Meyerjürgens complements: “TenneT aims to introduce the multiple ploughing method to the state-of-the-art technology to accelerate the grid extension. After about three years of research, it is a great success to test this important innovation on site for Germany’s longest 380kV underground cable section.”

If the test phase for the plough, which is to last until mid-October 2019, is successful, TenneT intends to use the new method on suitable sections of the Wahle-Mecklar project on a trial basis in spring 2020. Depending on the test results and the respective local conditions, TenneT expects a significantly reduced construction time for underground cable lines when using the multiple plough. Since experience with cable ploughing technology has so far only been available for lower voltage levels, TenneT is once again doing pioneering work to design the energy transition grid and establish new technologies.

TenneT is conducting field tests on new ploughing technology for laying underground cables (picture: TenneT)

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