Combined Grid Solution inaugurated

20.10.2020

On 20 October, the world’s first hybrid offshore interconnector was ceremoniously put into operation: the Danish-German Combined Grid Solution (CGS). This interconnector in the Baltic Sea links the transmission grids of two countries via national offshore wind farm grid connections. For this purpose, two submarine cables with a length of merely 25 kilometres and a capacity of approx. 200MW each were laid between the offshore transformer platforms of the German wind farm Baltic 2 and the Kriegers Flak wind farm in the Danish part of the Baltic Sea, which is currently under construction. The CGS – a joint project of TSCNET shareholder 50Hertz, one of the four German transmission system operators (TSOs), and TSCNET customer Energinet, the TSO from Denmark – thus not only connects the platforms with each other but also the existing onshore connections of the wind farms. This allows the transmission of offshore wind power to Denmark or Germany and also cross-border electricity trading.

The official opening ceremony, which took place on site in the German capital of Berlin as well as digitally, was attended by Peter Altmaier, German Federal Minister for Economic Affairs and Energy, Dan Jørgensen, the Danish Minister for Climate, Energy and Utilities, as well as Kadri Simson, EU Commissioner for Energy. With their appearance, these high-ranking political representatives acknowledged the CGS as a technical innovation with model character for future offshore power grids. The hybrid nature of CGS is that it is the first electricity interconnector between two countries, that not only provides capacity for electricity trading, but also transports offshore wind energy onshore – in both directions. The costs of the binational EU-funded project amount to around €300m.

A technical obstacle had to be solved in the realisation of CGS: Because the transmission grids in eastern Denmark and Germany do not operate synchronously, it was necessary to install a back-to-back converter at the 50Hertz substation in Bentwisch near the port city of Rostock in the federal state of Mecklenburg-Western Pomerania. The device converts the incoming AC into DC and immediately back. Only in this way is it possible for electricity to flow smoothly from Denmark to Germany and vice versa. But CGS has not only hardware but also software components. The central digital control unit of the system is the Master Controller for Interconnector Operation (MIO), located in the 50Hertz control centre near Berlin. The MIO balances market requirements with offshore electricity production, which depends on wind conditions in the Baltic Sea. Its main function is to ensure optimum use of the CGS while preventing any overload of the line and the operating facilities in the substation.

Stefan Kapferer, CEO of 50Hertz, commented at the inauguration: “With this project, 50Hertz and Energinet are pioneering the efficient integration of offshore wind farms into the cross-border European electricity market. It offers us several effective options to balance the frequency and voltage of our transmission grids at all times, to deal with the integration of renewable energy sources with more flexibility and to increase the stability of the overall system.” Thomas Egebo, CEO of Energinet, added: “The CGS is not only a very important milestone in reaching Denmark’s ambitious goal of a 100 percent green power system in 2030. The groundbreaking project also delivers an important building block for decarbonising the rest of the society.”

The Danish-German Combined Grid Solution has been ceremoniously put into operation (illustration uses photos of 50Hertz, one of which shows Minister Altmeier)

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> See 50Hertz press release (html)
> See Energinet news release (html)
> Watch CGS inauguration film (YouTube)

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Improving biodiversity for submarine cabling

15.10.2020

Looking at the big picture – the energy transition and the achievement of the European climate targets – there is no alternative to expanding offshore capacity for the generation and transmission of North Sea wind power. For that reason, both the Dutch and German governments have set ambitious targets for offshore expansion, which the Dutch-German transmission system operator (TSO) TenneT is gradually implementing and has even exceeded for its German North Sea control area. In the individual case, however, each offshore construction and operational measure obviously has an impact on the valuable North Sea and Wadden Sea ecosystems. As TenneT strives to apply and monitor nature-friendly solutions in all of its offshore grid projects, the TSO is now conducting pilot tests with stone coverings of submarine cable intersections.

When the TSCNET shareholder lays submarine cables, e.g. currently for the high-voltage connection of the Hollandse Kust (zuid) wind region, the cables sometimes cross with existing oil and gas pipelines. In such cases, the cables protrude above the seabed and are usually covered with a layer of granite to protect them. To replace granite with alternative solutions that promote biodiversity, TenneT has launched a pilot project in collaboration with the offshore specialist company Van Oord. In this project, different types of stones are deposited at cable crossings to investigate which of these stimulates biodiversity best. In total, the pilot involves twelve locations in the North Sea. In the case of the first six, recently laid submarine cables already cross existing oil and gas pipelines. Another six intersections will follow during the construction of the Hollandse Kust (Zuid) connection in 2021.

On 14 October, the different stones were loaded onto Van Oord’s special vessel to be placed at the cable intersections in the coming weeks. Among them are small calciferous stones from a marble quarry, which are placed at three of the six cable intersections. Comparison with the other three intersections without calciferous stones will allow to assess the difference in the type of marine life developing at these intersections. “Our expectation is that the calciferous stones will ensure that various benthic species will find it easier to nest here and that a different habitat will emerge at these sites. Over the years, ‛artificial reefs’ can emerge at these sites in the North Sea, where plants and small creatures can settle,” explains Saskia Jaarsma, Head Offshore Developments and Large Projects Offshore at TenneT.

TenneT has launched a pilot project to promote biodiversity at submarine cable intersections (picture: Van Oord)

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> See TenneT press release (html)

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Huge Schnabel car for Amprion

08.10.2020

The grid expansion, that is necessary to create a sustainable energy future, entails many tasks for transmission system operators (TSOs), like planning procedures, overhead line construction, underground cable laying, upgrading and new construction of substations – and also, increasingly often, the transport of heavyweight transformers. To be able to carry out such transports in a plannable, flexible, and reliable manner and exactly at the time when it is needed for the implementation of important projects, the German TSO Amprion has now put its own Schnabel car into service. A Schnabel car is a special type of rail freight car designed to transport heavy and oversized loads. The load is suspended between the two ends of the Schnabel car by lifting arms to distribute the weight of the load evenly over many axles.

Amprion’s new transporting device is over 50 metres long, around 4.2 metres high, three metres wide and has 32 axles. When empty, it weighs 220 tonnes. In fact, it is the largest Schnabel car ever produced for the German market. The rolling heavyweight is capable of transporting all types of transformers that Amprion intends to install – including transformers and rotating phase shifters with a transport weight of up to 500 tonnes. The TSCNET shareholder is thinking long-term: The Schnabel car is to provide its service for a secure transmission system for the next 40 years.

On 6 October, the TSO was handed over the new Schnabel car at the heavy goods terminal in the Rhine city of Mannheim in Baden by the specialist company Kübler Heavy Rail. Hendrik Neumann, Amprion’s designated CTO, comments: “To implement the energy transition, we must adapt and expand our grid in such a way as to enable the integration of large quantities of renewably generated electricity.” For this, Amprion needs a large number of additional transformers and phase shifters, which the TSO can now transport across Germany with its new king-size Schnabel car.

Amprion has put its own Schnabel car for the rail transport of heavyweight transformers into service (picture with designated CTO Neumann on the right: Amprion / Raphael Foidl)

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> See Amprion press release, in German (html)

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German field report on underground cabling

07.10.2020

The use of underground cables for power transmission in the extra-high voltage three-phase current range is partly still uncharted technical territory for the four German TSCNET shareholders 50Hertz, Amprion, TenneT, and TransnetBW. As most projects are in the planning, approval, or construction phase, no partial earth cabling project is yet in full system operation, let alone a project with exclusive cabling. However, Tennet has commissioned the Wilhelmshaven-Conneforde line as recently as last week: It is the first 380kV line with underground cable sections in three-phase technology connected to the meshed power grid by the Dutch-German transmission system operator (TSO).

To inform politics and public about the current status of underground cabling in the national transmission system, the four German TSOs have, at the request of the German Federal Ministry for Economic Affairs and Energy, jointly prepared a field report on the use of underground cables in the extra high-voltage three-phase current range. The 65-page report examines seven different key issues in respective main chapters, covering technical, administrative, economic, environmental, and social aspects: dialogue and acceptance, approval procedures and the environment, design and construction, operation and operational safety, underground cable technology, systems engineering, and finally economic efficiency. Key findings of 50Hertz, Amprion, TenneT, and TransnetBW can be summarised as follows:

  • Partial underground cabling does not per se lead to a greater acceptance of line construction projects – compared to the construction of overhead power lines, the concern merely shifts from the residents mainly to landowners and farmers.
  • As far as planning, approval, and construction times are concerned, current experience shows that partial underground cabling requires at least one to two years more than overhead lines. More extensive implementation planning, intensive soil investigations, and negotiations with the owners consumed a great deal of time in the pilot projects. The construction itself is also more complex due to the necessary crossing of infrastructures, 40 to 60-metre-wide aisles, and major interventions in the soil ecosystem.
  • Regarding operational and system safety, underground cable installations have a lower availability rate than overhead lines, as repair times are significantly longer in case of damage. Moreover, with an increasing share of partial underground cabling, the complexity of grid operation and thus the risk to system stability also rises.
  • In terms of economic efficiency, the costs of partial underground cabling are significantly higher than those of overhead lines, and this applies to planning, construction, and operation. Depending on the project-related terrain and soil conditions, the investment costs are usually six times higher.

The four German TSOs have published their joint “Field report on the use of underground cables in the extra-high voltage three-phase current range” (picture: TenneT)

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> See TransnetBW news release, in German (html)
> Open Field Report, in German (pdf, 2.9MB)

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Wilhelmshaven-Conneforde line put in operation

05.10.2020

With the Wilhelmshaven-Conneforde line, the Dutch-German transmission system operator (TSO) TenneT has commissioned an important grid expansion project for the German and European energy transition. The 380kV line from the new substation Fedderwarden near Wilhelmshaven on the German North Sea coast to the Conneforde substation in Ammerland, both in the federal state of Lower Saxony, is not only crucial for the transmission of mainly wind power and electricity from regional generators, but also for strengthening security of supply in northern Lower Saxony. Furthermore, it represents a novelty for the TSCNET shareholder in terms of technical implementation: “With this new line, we have put into operation the first pilot project with two underground cable sections in three-phase technology and connected it to the meshed power grid in Germany,” explained Tim Meyerjürgens, COO of TenneT.

The commissioning ceremony on 2 October 2020 in Fedderwarden was attended by representatives from politics, including Andreas Feicht, State Secretary at the German Federal Ministry for Economic Affairs, and Energy and Olaf Lies, Minister for the Environment, Energy, Construction, and Climate Protection of Lower Saxony. The new line is only about 30 kilometres long, but – together with the new construction of the Fedderwarden substation – “of great importance for the entire European electricity trade”, commented Olaf Lies. The Minister was impressed by TenneT’s latest milestone in the energy transition. State Secretary Feicht referred to the newly gained potential for integrating large amounts of wind power into the German electricity market and the technical relevance of the pilot project: “Knowledge obtained in such pilot projects about the construction and operation of the technology will be of great benefit for further power grid expansion in the future.”

The line project was successfully completed after less than two years of construction. Almost 5 kilometres of the line were implemented as underground cables. However, even if TenneT can be satisfied with what has been accomplished so far and is strongly committed to expanding the transmission of green electricity throughout its entire grid area, Meyerjürgens sees a need for further action, especially in view of the increasing offshore wind volumes: “Still, we already see today a further demand for expansion in the Wilhelmshaven and Friesland region.”

TenneT commissioned the new Wilhelmshaven-Conneforde line (picture: TenneT)

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> See TenneT press release, in German (html)

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TenneT commissions North German grid node

02.10.2020

The town of Wilster is located about 10 kilometres north of the Elbe river in the German federal state of Schleswig-Holstein, which falls within the control area of the Dutch-German transmission system operator (TSO) Tennet. Schleswig-Holstein is of eminent importance for the generation of wind power. In Wilster, after a four-year construction period, the TSCNET shareholder commissioned the renewed Wilster/West substation on 1 October, a significant grid node for the energy transition in the north and beyond. This is because the so-called Westküstenleitung (West-Coast-Line), the NordLink interconnector, which directly links the electricity markets of Germany and Norway, are converging here – and later also the SuedLink “electricity highway” for the transmission of green electricity to the German consumption centres.

For the two high-voltage direct current (HVDC) transmission projects NordLink and SuedLink, the capacity of the former Wilster/West substation was no longer sufficient. An extension of the switchgear was necessary to exclude impermissible load flows and guarantee the short-circuit resistance required in future. Thus, a new 380kV switchgear was built on the ground of the former 380kV substation and the new construction now replaces the old substation on the same site. Furthermore, the connection facilities for the converter stations of SuedLink and NordLink had to be provided. And finally, a 110kV switchgear was installed, which enables the dismantling of the 220kV switchgear in the near substation Itzehoe-West.

“This substation is a central hub for electricity transmission from north to south,” explains TenneT’s COO Tim Meyerjürgens. “Here, electricity from renewable sources is fed into the grid and distributed to regions with high consumption. The Wilster area is of outstanding importance for the energy transition. Because in the grid area between Wilster, Brokdorf, Itzehoe, and Brunsbüttel, three new extra-high voltage lines from TenneT converge: the Westküstenleitung, NordLink, and later also SuedLink.”

TenneT has put into operation the new substation Wilster/West (picture: TenneT)

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> See TenneT press release, in German (html)
> Watch video on the construction and commissioning of Wilster/West, in German (YouTube)

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TransnetBW modernises Herbertingen-Hoheneck line

01.10.2020

Like any transmission system operator (TSO), TransnetBW, the TSCNET shareholder from the southwest of Germany, regularly evaluates the condition of its facilities and transmission infrastructure to define necessary modernisation measures. This has revealed the need to renew the 380kV overhead line from Herbertingen in the south of the federal state of Baden-Württemberg to the Hoheneck substation in Ludwigsburg, about 20 kilometres north of the Swabian metropolitan city of Stuttgart. As part of the modernisation, several steel parts of 53 existing pylons will be replaced. The basic mast structure, that is height, width, and foundations, is not affected.

For the work on the line in the voltage range of the mast cantilever arms, disconnection of the corresponding electrical circuits is required. This has no effect on the regional power supply. Work on the roughly 120-kilometre-long transmission line began in the last week of September and is expected to be completed by the end of November 2020.

TransnetBW modernises the 380kV overhead line from Herbertingen to Hoheneck (exemplary picture: TransnetBW)

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> See TransnetBW press release, in German (html)

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Amprion commissions new Statcom facility

30.09.2020

The rising share of volatile renewable electricity generation and the increasing transmission distance from the places of generation to the centres of consumption require power grids to be adjusted, with immediate voltage regulation being a key element. To balance out voltage fluctuations, which are more and more occurring at the grid nodes, the European transmission system operators (TSOs) employ reactive power compensation systems. German TSCNET shareholder Amprion is no exception and already using a wide range of innovative technologies. On 29 September 2020, the company commissioned one more Statcom (static synchronous compensator) system, in this case on the site of the Kusenhorst substation in Haltern am See in the federal state of North Rhine-Westphalia. Almost exactly one year ago, Amprion commissioned an identical system at the Kriftel substation between Frankfurt and Wiesbaden in Hesse.

Amprion has invested a total of €37m in the expansion of the Kusenhorst substation. According to demand, the Statcom system can feed in reactive power in the range of about 300Mvar, thus raising or lowering the voltage in the grid to contribute to grid stability. The new Statcom can also be combined with the mechanical switched capacitor with damping network (MSCDN) already on site in Kusenhorst. Together, the two technologies form a so-called hybrid facility for reactive power compensation, making it the most powerful of its kind in the German grid alongside the Kriftel substation.

The Statcom system consists of several building sections, which are up to ten metres high and cover an area of approximately 1,000m². They contain the converter, chokes, and the regulation and protection technology. The transformer and the external cooler of the system are outside the buildings. Amprion operates the Statcom system remote-controlled via its system operation and control centre near Cologne.

Amprion has commissioned a Statcom system for reactive power at its Kusenhorst substation (picture: Amprion)

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> See Amprion press release, in German (html)

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Network Agency decides on southern routing of SuedLink

25.09.2020

700 kilometres of underground cable to be laid and an investment volume of around €10bn – this makes the 525kV line SuedLink the largest and probably most important individual project of the energy transition in Germany. The exclusive use of underground cables in the project is politically specified to increase the acceptance of the project by the population: For only if one succeeds in effectively connecting the windy regions of northern Germany with the centres of consumption in the industrially highly developed south and west via such “electricity highways” as SuedLink, the German – and European – climate targets can be achieved.

SuedLink is jointly implemented by the two TSCNET shareholders TenneT, the Dutch-German transmission system operator (TSO), and TransnetBW, the TSO from southwest Germany. The project is making step-by-step progress in the regulatory, planning, and implementation areas. This year, for example, regional planning offices have already been set up and the contracts for the cables awarded. Now the competent government authority, the Federal Network Agency (Bundesnetzagentur), has decided on the southern section between the Lower Franconian Arnstein near Schweinfurt and the Großgartach substation in the Stuttgart Metropolitan Region (SuedLink section E). This 137 kilometre long section runs through the control areas of both TSOs involved.

The Bundesnetzagentur’s decision largely follows the proposal by TenneT and TransnetBW, according to which the Würzburg metropolitan area is largely bypassed in the west. The proposal of the two TSOs had already incorporated the results of the application conferences and requirements of the Bundesnetzagentur. The last 16 kilometres to the Großgartach substation are a special construction feature. Here an existing salt mine is to be used for an underground course of the cable project. This increases construction costs, but these are outweighed by other benefits, in particular the reduced impact on the environment and residential areas. After the completion of the federal sectoral planning for the SuedLink section E, planning approval procedures are to follow which will determine the exact route of the line within the corridor and the technical implementation.

The German Federal Network Agency has decided on the southern section of the SuedLink power line, a joint project of TenneT and TransnetBW (picture: TenneT)

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> See press release by Bundesnetzagentur, in German (html)

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50Hertz joins new UN sustainable economic initiative

23.09.2020

With its strategy of 100% integration of renewable energy, 50Hertz, the transmission system operator (TSO) from the north-east of Germany, is deeply committed to a sustainable design of the future energy and economic landscape. For this reason, the TSCNET shareholder, together with a vast number of other international companies, has joined a new UN economic initiative, whose supporters have committed themselves to global cooperation and sustainable development goals. “United in the Business of a Better World” is the headline of the statement by the “Business Leaders for Renewed Global Cooperation”.

The initiative is in the context of the UN Global Compact, a UN pact to stimulate businesses all over the world to pursue sustainable and socially responsible policies. The statement was presented on 21 September in New York at this year’s UN General Assembly. Over 1,000 CEOs of companies from more than 100 countries have signed the declaration, which calls for more cooperation across borders, sectors, and generations: “Public and private institutions need to show they are accountable, ethical, inclusive and transparent. This is the only way to strengthen public trust and achieve a more sustainable future for all.” Therefore, the signatories are obligated, inter alia, to ethical leadership, values-based strategies, inclusive, participatory and representative decision-making, accountability and transparency, legal certainty, equality, and human rights.

“From 60 to 100 by 2032”, the TSO’s own sustainability initiative to cover 100% of the electricity demand in the 50Hertz grid area with renewable energies by the year 2032, fully complies with the UN goals. “The transformation of the energy system towards climate neutrality is the central element of a sustainable, global climate protection policy,” commented Stefan Kapferer, CEO of 50Hertz, on the publication of the declaration. “With this new strategic ambition, we are not only contributing to the achievement of climate policy goals, but also quite explicitly to the sustainable strengthening of the industrial sites in our grid area. This is the very concrete contribution of 50Hertz to meeting the Paris Climate Change Agreement and thus the Sustainable Development Goals of the United Nations.”

50Hertz joins the UN initiative “Business Leaders for Renewed Global Cooperation” for sustainable development goals (picture: 50Hertz)

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> See 50Hertz press release, in German (html)
> Open Renewed Global Corporation statement (pdf, 847.77kB)

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