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)

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

See article on single page

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)

Linkup
> See TenneT press release (html)

See article on single page

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)

Linkup
> See TenneT press release, in German (html)

See article on single page

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)

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

See article on single page

Deep Dig-It starts work for Hollandse Kust (zuid) grid

24.09.2020

Hollandse Kust (zuid), an offshore wind area in the Dutch North Sea, is located a good 20 kilometres off the coast of the Dutch province of Zuid-Holland. The Dutch-German transmission system operator (TSO) TenneT is installing the related offshore grid to connect the new offshore wind farms in the area via two offshore platforms and submarine cables to the onshore high-voltage substation that is being built in the Maasvlakte industrial and port area. The jacket for the first of these two offshore platforms has recently been installed and the offshore connection project is now making further progress with the start of the laying of the submarine cables on 22 September.

Four 220kV AC cables with a total length of 42 kilometres each are to be installed in the seabed, of which the first two to the Alpha platform will be laid this year. The other two to the Beta platform will follow in 2021. First, the two cables were brought ashore to the planned Maasvlakte substation via direct drilling. Thereupon the TSCNET shareholder started the marine installation, with the first ten kilometres of the route from the coast at Maasvlakte being extremely challenging. Over this distance, the cables cross the entrance to the port of Rotterdam – Europe’s busiest cargo port – and thus need to be buried more than 5.5 metres deep. For this purpose, the contracted specialist company Van Oord uses its Deep Dig-It trencher, an enormous remote-controlled trencher.

The Deep Dig-It is one of the largest and most powerful devices in its class. The trencher weighs 125 tonnes, is more than 17 metres long, well over 8 metres high, and 11 metres wide. With its enormous power it can bury cables deeply even in very hard ground. The trencher is controlled from an offshore installation vessel equipped with a crane to lower and lift out the high-performance machine. The Deep Dig-It moves unmanned over the seabed and creates a deep trench for the cables by liquefying the seabed. Simultaneously, the Deep Dig-It inserts the cables into the trench and seals the seabed afterwards. With work progressing well, Tennet expects the 1,400MW Hollandse Kust (zuid) grid connection to be completed in 2022.

TenneT has started the laying of submarine cables for the Hollandse Kust (zuid) grid connection (picture: Van Oord)

Linkup
> See TenneT press release (html)
> Watch TenneT video of the Deep Dig-It at work (YouTube)

See article on single page

Cooperation to link offshore wind farms

22.09.2020

Realising the full potential of offshore wind energy in the North Sea will be crucial for the decarbonisation of the European economy and society. The transmission system operators (TSOs), whose control areas border the North Sea, are aware of this, including the Dutch-German TSO TenneT and National Grid from the UK. Both the Netherlands and the UK have set ambitious targets for their respective development of wind capacity in the North Sea. However, to achieve large-scale growth in offshore wind energy, significant amounts of new infrastructure and close cooperation between the countries around the North Sea will be essential.

On 22 September, TenneT and National Grid announced a cooperation agreement to examine the feasibility of interconnecting Dutch and British wind farms to the energy systems of both countries via submarine cables. The announcement is following a recent decision by the Dutch government to secure the first 2GW offshore transmission grids for high-voltage direct current (HVDC) in the Netherlands for the IJmuiden Ver wind farm zone, located some 80km off the Dutch north-west coast. Under the cooperation agreement, TenneT and National Grid will explore the development of a multi-purpose interconnector (MPI) to simultaneously connect up to 4GW of Dutch and British offshore wind energy between the two national electricity systems, thereby creating an additional 2GW of interconnection capacity.

By connecting to both systems, the MPI will allow the use of free transmission capacity for electricity trade between the two countries, thus improving the utilisation of offshore infrastructure – and possibly decreasing the need for additional infrastructure. This will also reduce the environmental impact on coastal communities compared to the current approach of separately developing and connecting interconnectors and wind farms. The two TSOs intend to have defined a “pathfinder project” by the end of 2021 with the aim of creating an operational system by 2029.

Manon van Beek, CEO of TenneT, comments on the agreement: “TenneT has been at the forefront of developing multi-purpose interconnection to enable the large-scale growth of offshore wind in the North Sea. This agreement allows us to work with National Grid in the North Sea to develop innovative infrastructure that uses every spare electron of offshore wind generation to reach our decarbonisation targets.”

TenneT has concluded an agreement with National Grid to investigate the interconnection of UK and Dutch offshore wind farms (exemplary picture: TenneT)

Linkup
> See TenneT press release (html)

See article on single page

Foundation stone laid for ULTRANET substation

17.09.2020

On the site of the former Philippsburg nuclear power plant, which was shut down completely on 31 December 2019, a new DC substation for the German supra-regional “power highway” ULTRANET is being constructed. The Philippsburg substation in the German state of Baden-Württemberg represents the southern end point of ULTRANET, where the high-voltage direct current (HVDC) line will be connected to the regional 380kV AC grid. The new substation is thus to become one of the most important energy hubs in Germany’s future energy landscape. It is being built on behalf of TSCNET shareholder TransnetBW, the transmission system operator (TSO) from Baden-Württemberg. In its entirety, ULTRANET is a joint project of TransnetBW and further German TSCNET shareholder Amprion. It will transmit wind energy generated in the northwest of Germany to the industrially highly developed southwest. On the other hand, the Philippsburg substation will enable the conversion of AC to DC, e.g. to transport excess photovoltaic electricity from the south to the north.

In March 2020, the construction of the ULTRANET substation was approved by the competent authority and in May, the demolition of the two cooling towers of the former power plant created the necessary construction space of around 100,000m². Now, the ceremonial laying of the foundation stone took place in Phillipsburg in the presence of high-ranking representatives from politics, business, and society – and in strict compliance with the Corona regulations. Dr. Werner Götz, Chairman of the TransnetBW Executive Board, commented: “It was nevertheless very important to us not to let this important day pass without expressing our thanks to politicians, partners, and the project team.”

Andreas Feicht, State Secretary at the German Federal Ministry for Economic Affairs and Energy, recognised the progress of the European Project of Common Interest (PCI): “The converter in Philippsburg illustrates that the grid expansion is progressing in large steps.” Franz Untersteller, Minister of the Environment, Climate Protection, and the Energy Sector of Baden-Württemberg, emphasised the specific nature of the location and its symbolic value: “There are few places where the energy transition can be visualised in such a condensed form as here in Philippsburg. After the two cooling towers were detonated in May of this year, the old world made way for the new.”

TransnetBW has celebrated the laying of the foundation stone for the ULTRANET substation in Philippsburg (picture: TransnetBW)

Linkup
> See TransnetBW press release, in German (html)

See article on single page

Jacket for Hollandse Kust (zuid) Alpha platform installed

08.09.2020

The offshore wind area Hollandse Kust (zuid) is located 22 kilometres off the coast of the Dutch province of Zuid-Holland. The Dutch-German transmission system operator (TSO) TenneT will connect the wind farms in this area to the onshore substation in the industrial and port area of Maasvlakte via two offshore platforms – Alpha and Beta – and submarine cables. The jacket for the Hollandse Kust (zuid) Alpha platform was transported to the operation site by a heavy-duty vessel on 5 September and successfully installed on the seabed. The Alpha jacket is 29 meters long, 20 meters wide, 46 meters high and weighs 3200 tonnes. It will be further installed in the coming days.

The two 220kv submarine cables will be connected to the jacket over the next few months. In 2021, the platform top side will be placed on the jacket. The Hollandse Kust (zuid) Alpha platform is expected to be operational by the end of 2021. The projects in this new wind area are part of the large-scale offshore expansion programme of TenneT. By the end of 2023, the TSCNET shareholder will have installed 3.5GW of offshore grid connections in the Netherlands, of which the first 1.4GW have already been achieved with Borssele Alpha and Beta. The connection to follow Hollandse Kust (south) will be Hollandse Kust (nord). For all the wind farms in these two areas, TenneT will deploy five identical 700MW transformer platforms and identical 220kV cable connections. “Such standardisation enables TenneT to complete these projects more efficiently, more quickly, and more economically,” explains TenneT COO Tim Meyerjürgens.

The Dutch national roadmap for offshore development provides for an additional 6.1GW of offshore wind farms in the wind energy areas Hollandse Kust (West), Ten Noorden van de Waddeneilanden, and IJmuiden Ver from 2024 to the end of 2030. For the first two areas, TenneT will again use standardised 700MW offshore platforms. The efficient connection of IJmuiden Ver, which is located further out in the North Sea, partly requires other technologies based on DC instead of AC. IJmuiden Ver will have two offshore transformer platforms with a capacity of 2GW each, which is unique in the offshore wind industry.

TenneT has installed the jacket for the Hollandse Kust (zuid) Alpha platform (picture: TenneT)

Linkup
> See TenneT press release (html)

See article on single page

TenneT commisions “green” substation

04.09.2020

In recent years, the seaport of Eemshaven in the province of Groningen in the north of the Netherlands has become more and more important for the Dutch energy transition. Eemshaven has taken on the role of an energy port: with power plants, sustainable generation, connections to offshore wind farms, and submarine cable interconnectors to Norway and Denmark. The Dutch-German transmission system operator (TSO) TenneT – together with regional distribution system operator (DSO) Enexis Netbeheer – now has commissioned the new high-voltage substation Eemshaven as the first substation entirely built for the suply of wind and solar energy.

The station was built as part of the grid reinforcement for the growing amount of sustainably generated energy in the north of the Netherlands which requires an increase in transmission capacity. Other measures of the TSCNET shareholder include a 380kV connection between the Eemshaven (Oudeschip) high-voltage substation and Vierverlaten near Groningen as well as the extension of the Vierverlaten substation. This new 380kV “power highway” will replace the existing 220kV line. Until it is put into operation – scheduled for 2023 – TenneT will commission a provisional 380kV substation in Eemshaven (Oostpolder) in October 2020.

TenneT has put into operation the new substation Eemshaven for the supply of green electricity (picture: TenneT)

Linkup
> See TenneT press release, in Dutch (html)

See article on single page

Building permit for the Uckermark line of 50Hertz

13.08.2020

Since 2005, 50Hertz, the transmission system operator (TSO) from the north-east of Germany, has been engaged in the planning of the new, higher capacity Uckermark Line (“Uckermarkleitung”). The new 380kv overhead line is to replace the existing 220kv line that went into operation in 1958, whereby the TSCNET shareholder takes account of the growing relevance of renewable energies in its control area. The new Uckermark Line will run from the Bertikow substation near Prenzlau to the Neuenhagen substation in the north-east of Berlin and connect further substations, one of which is an important interconnector to Poland. It will be capable of transmitting up to five times more electricity, so that in future more wind and solar power from the German states of Brandenburg and Mecklenburg-Western Pomerania can be transported to the southern consumption centres.

The start of construction of the 115-kilometre-long new line was delayed for reasons of bird protection: A German nature conservation association had filed a complaint against the planning approval decision granted in 2014. This necessitated a supplementary planning procedure, expert reports on bird protection, consultations, and modifications. The competent authority now granted the building permit, which maintains 50Hertz’ originally planned routing. The future Uckermark Line will no more affect the biosphere reserve Schorfheide-Chorin and thus pays considerable attention to nature conservation. Special permits have been issued for other bird sanctuaries that cannot be bypassed due to their size, including compensation measures to preserve biodiversity. The dismantling of the old power line plays an important role here, but also bird protection markers or special pylons with reduced height.

50Hertz has been cooperating for several years with various nature conservation organisations and ornithological observatories to better assess the possible threats to birds. A nationwide cooperative portal of TSOs and distribution system operators (DSOs) in conjunction with the Renewables Grid Initiative (RGI) for data on detected accident birds is particularly noteworthy in this context. To increase acceptance of a project as essential for the energy transition and climate protection as the Uckermark Line, it is important to reconcile the substantial ecological added value of the capacity expansion with other nature conservation interests. Hence, the commitment of 50Hertz both to the ecologically necessary grid extension and to other environmental interests is highly to be appreciated.

50Hertz has obtained construction permit for the new 380kV Uckermark line (symbolic picture: 50Hertz) 

Linkup
> See 50Hertz press release (html)

See article on single page