TransnetBW starts modernisation of Daxlanden substation

04.11.2020

The Daxlanden substation near Karlsruhe is an important node in the transmission grid of TransnetBW, the German transmission system operator (TSO) from the federal state of Baden-Württemberg. It is also the central link between two 380kV grid reinforcement projects included in the German National Grid Development Plan for Electricity. To prepare the substation for its future tasks, the TSCNET shareholder began with the upgrade and expansion of Daxlanden at the beginning of November.

The preparatory works will be completed in spring 2021, after which the TSO will start to replace the existing 380kV outdoor switchgear with two new gas insulated switchgears (GIS). For the Daxlanden GIS facilities, the TransnetBW has opted for the so-called Clean Air technology, which exclusively uses processed air as an insulating medium instead of sulfur hexafluoride (SF6). The greenhouse effect of the switchgear is thus radically reduced. Alongside this, the 220kV line between the Daxlanden and Eichstetten substations will be substituted by a 380kV line. The first switchgear is scheduled to be commissioned in 2024 and the second in 2027. The entire installation and grid connections are expected to be completed in 2030.

TransnetBW has commenced the modernisation of the Daxlanden substation (computer simulation of the future Daxlanden substation: TransnetBW)

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> See TransnetBW press release, in German (html)

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New intraday products on German, French and Benelux borders under SIDC

29.10.2020

The European Transmission System Operators (TSOs) are jointly striving for an integrated European electricity market. A key component for market integration is cross-border Single Intraday Coupling (SIDC), which was introduced in June 2018, then called XBID. SIDC aims to increase the overall efficiency of intraday trading through effective competition, increased liquidity, and more efficient use of generation resources. Further progress has now been made along the path to a common market: On 10 December 2020, the competent Nominated Electricity Market Operators (NEMOs), the Belgian and French TSOs Elia and RTE and the two TSCNET shareholders Amprion, one of the four German TSOs, and TenneT, the Dutch-German TSO, will launch new cross-border intraday products at the borders of the bidding zones between Belgium, Germany, France, and the Netherlands.

In concrete terms, 30-minute cross-border products are to be introduced in intraday continuous trading at the Belgian-French border and 15 and 30-minute cross-border products at the Belgian-German, Belgian-Dutch and Dutch-German borders. With the introduction of these intraday products, the TSOs fulfil their obligation to offer cross-zonal capacity for SIDC at their borders with least common multiple of the imbalance settlement periods (ISP) and this on both sides of the respective bidding zone borders. This innovation should improve the possibilities for imbalance management by market parties, closer to real time, as market participants will be able to sell or buy cross-border products with the same resolution as the ISPs of the Belgian, Dutch, French, and German-Luxembourg bidding zones.

Moreover, Belgian and Dutch market participants will then have access to the existing market liquidity of 15-minute products in Germany and Austria and 30-minute products in Germany and France respectively, where these cross-border products have already been established. The XBID platform for SIDC comprises a common IT system with a shared order book, a capacity management module, and a shipping module. Via this platform, the new products will be available for cross-border trade in Belgium and the Netherlands from 10 December 2020 and will complement the currently existing 60-minute cross-border products. Bids for 15-minute and 30-minute products will be included in the NEMOs’ shared order books.

As SIDC represents a pan-European solution, numerous TSCNET shareholders are involved in the solution for market integration. In addition to the above mentioned TSOs, 50Hertz, APG, ČEPS, ELES, HOPS, MAVIR, PSE, SEPS, Transelectrica, and TransnetBW as well as several TSCNET customers are also part of SIDC.

New cross-border intraday products will be launched in December 2020 under SIDC

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Middle Axis increases capacity sevenfold

27.10.2020

Since the 60s of the 20th century, a 220kV overhead line has been in operation between Hamburg and Denmark, thus crossing Schleswig-Holstein, the northernmost of the German federal states, in its entirety. Schleswig-Holstein is a true “wind power state” in terms of generation, but consumes very little energy in comparison to the southern and western German states. The green electricity produced here therefore has to be transmitted to the centres of consumption. As a result of the energy transition with increasing shares of wind energy, the capacity of the old line has long since been insufficient, resulting in grid bottlenecks. The Dutch-German transmission system operator (TSO) TenneT, whose control area includes the state between the North and the Baltic Sea, thus has replaced the old line with a new 380kV line capable of transmitting seven times as much green electricity.

The new overhead line is called Middle Axis (“Mittelachse”), as it is flanked by two other line projects of the TSCNET shareholder, the East-Coast-Line and the West-Coast-Line. On the Danish side of the border, the Danish TSCNET customer Energinet continues the Middle Axis from Frøslev to the Kassø substation, thereby increasing the electricity trading capacity between Denmark and Germany. On 21 October, TenneT put officially into operation the two northern sections of the Middle Axis between the Audorf substation near Rendsburg and the border with Denmark. With a symbolic push of a button at the substation Handewitt near Flensburg, Thomas Bareiß, Parliamentary State Secretary at the German Federal Ministry for Economic Affairs and Energy, Jan Philipp Albrecht, Minister of Energy, Agriculture, the Environment, Nature and Digitalisation of Schleswig-Holstein, Henrik Riis, CEO of Energinet-Eltransmission, and TenneT COO Tim Meyerjürgens connected the new 82 kilometres long power line to the grid.

The southern section of the Middle Axis from Hamburg/North to Audorf with a length of 70 kilometres was commissioned by TenneT in early 2018. Since 2015, a total of 388 new pylons have been erected along 152 kilometres between Hamburg/North and the border with Denmark, including the required substations Audorf/South, Schuby/West and Handewitt. The extension of the line by Energinet across the border by 30 kilometres into the Danish grid area increases security of supply for both the German and Danish electricity markets and enables the exchange of renewable energy between the two countries.

Tim Meyerjürgens explained: “With the 82 kilometres from Audorf to the Danish border, we are completing the important Middle Axis in the energy transition region of Schleswig-Holstein for the transmission of electricity from renewable sources between the river Elbe and Denmark.” Henrik Riis added: “The Middle Axis is a tremendous success, and it provides a new, continuous electricity highway that runs all the way from Denmark to Hamburg and on to Lower Saxony across the river Elbe. A strong cross-border infrastructure and well-functioning energy markets are essential for all of us – both at national and European level – to shape a future with high security of supply, large amounts of renewable energy and an efficient green energy transition.”

TenneT and Energinet commissioned the northern section of the Middle Axis, a new 380kV line from Denmark to Hamburg (picture showing from right to left Thomas Bareiß, Henrik Riis, Tim Meyerjürgens and Philipp Albrecht at the far left: TenneT)

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> See TenneT press release, in German (html)

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Cascade process of C/sells demonstrated successfully

25.10.2020

59 partners cooperate in the southern German smart grid project C/sells, including research institutions, distribution system operators (DSOs), municipal utilities, generators, service providers and consultants in the energy and IT sector – and the two TSCNET shareholders TransnetBW, the south-west German transmission system operator (TSO), and TenneT, the Dutch-German TSO. The aim of C/sells is to make the energy infrastructure renewable, decentralised, flexible, and participatory. The focus here is on the intelligent networking of generation and consumption and the use of innovative grid technologies and operating concepts. The “cell” is the basic unit of C/sells. It can be of a geographical nature, such as a city or district, or it can be a single object, such as an airport or even a single property. These “cells” assume a variety of functions and tasks that serve to stabilise the grid and provide flexibility. C/sells is funded by the German Federal Ministry for Economic Affairs and Energy in the framework of the innovation programme “Smart Energy Showcases” (“Schaufenster intelligente Energie” – SINTEG).

TransnetBW now reports a significant progress for C/sells, because together with the municipal utility of Schwäbisch Hall in the in the German state of Baden-Württemberg and the DSO Netze BW, the partially automated cascade process of C/sells was demonstrated live. A cascade process is usually understood as any process that takes place in a series of steps, and in this case, it is the step-by-step control of plants from downstream networks to remedy critical grid situations in an emergency. In the demonstration of 21 October, a simulated threat to system balancing was resolved by means of the partially automated cascade process and an intelligent measurement system. In the process, facilities were controlled right down to the lowest voltage level. The selected scenario was a realistic situation and required the cooperation of all grid operators.

The demonstration was based on the coordinated power grid cascade developed in C/sells which defines clear rules and processes for the respective grid operators. By means of control centre coupling, information on the state of the grid is continuously exchanged across all voltage levels. Several defined signal phases visualise the grid status in the control centres involved and indicate the measures to be derived from it. Thanks to the communication technology coupling of TransnetBW and Netze BW and the bidirectional exchange of information in real time, emergency situations can now be mastered jointly across voltage levels within just a few minutes. Dr. Rainer Enzenhöfer of TransnetBW and sub-project manager of C/sells comments on the successful demonstration: “With the partial automation of the cascade, it is possible, together with DSOs, to control a large number of decentralised plants in a simple and uncomplicated manner within a very short time in order to eliminate a critical grid situation.”

TransnetBW and its partners successfully demonstrated the cascade process of the C/sells smart grid project (picture: C/sells)

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> See TransnetBW press release, in German (html)
> Visit C/sells website (html)

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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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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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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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