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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Construction progress for Oradea-Békéscsaba line

02.11.2020

In July 2020, the Romanian transmission system operator (TSO) and TSCNET shareholder Transelectrica finally was able to award the construction contract for the missing section of the 400kV Oradea-Békéscsaba power line. For more than ten years, the completion of the overhead line in the far west of Romania has been prevented due to unsettled property issues concerning this section, namely between the Oradea South substation and Nădab. Now that the ownership concerns have been resolved, the investment in the new line will ensure interconnection capacity in the region. Transelectrica expects the construction works to be completed by summer 2021.

Closing this transmission gap is important to Romania’s overall security of supply because the commissioning of the last 72 kilometres between the Romanian town Nădab and the Hungarian border town Békéscsaba not only completes the Oradea-Békéscsaba overhead line, but also contributes to the closure of the “400 kV Ring” in western Romania, a priority energy objective for Romania. The new line will also enable Transelectrica to reduce congestions and thus save considerable intervention costs. As regards European market integration, Romania’s interconnection capacity will be increased by 100MW in export and 300MW in import direction.

The management of Transelectrica represented by the Chairman of the TSO’s Directorate, Cătălin Nițu, and the members of the Directorate, Andreea Miu and Bogdan Marcu, have now informed themselves personally about the progress of the construction work. Mr Nițu emphasised the particular importance of the project for the Romanian energy landscape and the European electricity market

The management of Transelectrica has assessed the construction progress of the last section of the 400kV Oradea-Békéscsaba overhead line (picture: Transelectrica)

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> See Transelectrica press release, in Romanian (pdf, 188.5kb)

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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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Final court confirmation for Salzburg Line

21.10.2020

From the first submission of the project to the Salzburg state government in September 2012 until the approval of the construction of the second section of the Salzburg Line (“Salzburgleitung”) by the court of last instance, the beautiful Austrian state of Salzburg has certainly seen many sunsets. The Austrian transmission system operator (TSO) APG is now all the more content with the definite legal groundwork for Austria’s most important infrastructure project. Although the legally valid building permit for the Salzburg Line had already been granted by the Austrian Federal Administrative Court in March 2019, there were still final legal details in connection with the project, which the Supreme Administrative Court has now clarified on 20 October 2020, thus confirming the permit.

The new 380kV overhead line will replace the old 220kV line from the 1960s and will be capable of transporting seven times more electricity than the current line. To improve supply security in the city of Salzburg, the first 46-kilometre section of the Salzburg Line from the St. Peter grid node near the German border to the newly constructed Salzburg substation near Elixhausen was already commissioned in January 2011. The second section of the Salzburg Line, from Elixhausen to the Tauern grid node near Kaprun, will now close the western gap in the Austrian “380kV Ring”. This ring-shaped extra-high voltage grid is the backbone of the national electricity supply and crucial for the integration and transmission of renewable energies.

The total length of the new line, which has 449 pylons, is 128 kilometres. However, as old lines will be dismantled when the Salzburg Line is completed and some of them will run jointly on the new line, there will be 229 fewer masts in Salzburg than before. Commissioning of the Salzburg Line is planned for the year 2025, dismantling will be completed by 2026. “With €890m to be invested, the Salzburg Line is by far the most important investment project in the Austrian electricity infrastructure. Of the approx. €350m that APG is investing in the expansion of the electricity grids this year, the Salzburg Line alone has a share of €125m for the domestic economy,” comments Gerhard Christiner, CTO of the Austrian TSCNET shareholder, who also praised the day of the court ruling as a “good day for the energy transition and for the secure supply of electricity in Salzburg and Austria”.

The Austrian Supreme Administrative Court has definitively confirmed the construction permit for the 380kV Salzburg Line of APG (picture: Martin Lugger / APG)

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Construction start of Slovenian-Hungarian interconnector

16.10.2020

A glance at the guest list of the official ceremony for the start of construction of the Cirkovce-Pince overhead line reveals that a major project has been launched here. The Slovenian transmission system operator (TSO) ELES had the honour to welcome both the Slovenian Prime Minister Janez Janša and his Hungarian counterpart Viktor Orban to the opening event for the new construction. And indeed, the project is of historic proportions, as the 400kV AC line, a good 80 kilometres long, will be the first interconnector between the Slovenian and Hungarian transmission systems.

The double circuit line with 264 pylons will increase the operational reliability of the Slovenian transmission system and import transmission capacity, facilitate access to energy sources from the North and East, and allow for the integration of larger amounts of renewable energy from the whole region into the grid. The line runs from the Cirkovce substation in the northeastern Slovenian region of Lower Styria to the border settlement of Pince, which is not only on the Hungarian border, but also in the triangle of Slovenia, Croatia, and Hungary. Therefore, in addition to the substation of the Hungarian TSO MAVIR in Hévíz in Zala County, the substation of the Croatian TSO HOPS in Žerjavinec near Zagreb can also be connected to the new line, truly a European Project of Common Interest (PCI). The power line will thus even interconnect three countries. The presence of Gordan Grlić-Radman, Croatian Minister of Foreign and European Affairs, confirmed the trinational dimension of the Cirkovce-Pince line.

At the ceremony with symbolic unveiling of the construction panel, Aleksander Mervar, CEO of ELES, illustrated the supraregional significance of the power line: “This project is of great importance not only for Slovenia but also for the wider region and Europe. That is why this project was included on the list of Projects of Common Interests in 2015, while in 2019 we managed to acquire €50m funds.” Mr Mervar also explained that the project, which includes major upgrades of switchgears in Cirkovce, is the largest investment in transmission infrastructure in the history of ELES, totalling some €150m. Finally, he emphasised the good cooperation of the three TSCNET shareholders ELES, HOPS, and MAVIR: “Without this cooperation, this project would surely not be happening today.”

ELES has started construction of the Cirkovce-Pince 400kV line, which will connect the transmission grids of Slovenia, Hungary, and Croatia (picture: ELES; from right to left: Gordan Grlić-Radman, Viktor Orban, Janez Janša; second from left: Aleksander Mervar)

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> See ELES press release (html)
> Visit project website (html)

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Line maintenance under extra high voltage

14.10.2020

For the maintenance of extra-high voltage overhead lines, transmission system operators (TSOs) normally have to shut down the line in question. This practice is more than understandable in view of occupational safety. On the other hand, it also reduces transmission capacity and increases the workload of the staff in the TSO’s network control centre who are in charge of coordinating the shutdown. An ideal solution must thus take both into account: first and foremost, the protection of employees and then the best possible utilisation of the facilities.

The Swiss TSO and TSCNET shareholder Swissgrid has carried out a pilot test on the 380kV line Chamoson-Romanel near Lausanne. At the beginning of October, just a few hundred metres from the Romanel substation and in the landing corridor of Lausanne-Blécherette airport, an orange signal ball was installed on the ground wire of the line, which had not been switched off beforehand. Swissgrid drew on the expertise and technology of Airtelis, a subsidiary of the French TSO RTE. Since the 1980s, Airtelis has been working on methods and technologies that allow maintenance work on extra-high voltage lines to be carried out safely and without switching off the power.

An Airtelis/RTE team of around 15 specialists travelled to the western Swiss canton of Vaud. An RTE helicopter also arrived on site, adapted to the work under voltage and equipped with various mirrors and an on-board camera. A special nacelle was attached to the helicopter with insulating anti-rotation ropes. Two Airtelis team members climbed into the nacelle to install the signal ball during the flight. They wore a suit specially designed for work under voltage, which protects its wearer like a Faraday cage. The installation work was carried out exactly as planned and was safely completed after 30 minutes. Swissgrid will now analyse the experience gained from this pilot project, in which the first maintenance work under voltage was carried out in Switzerland, and assess whether this technology should be used generally in future.

Swissgrid has carried out a test on the maintenance of high-voltage overhead lines without disconnecting them from the grid (picture: Swissgrid)

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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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Tunnel drilling for last section of the Nant de Drance connection

03.10.2020

The Nant de Drance pumped storage power plant in the Swiss canton of Valais is one of the most powerful power plants of its kind in Europe, generating around 2.5bn kWh per year, when it goes fully operational in 2021. The plant has been commissioned successively in sections in recent years. TSCNET shareholder Swissgrid, the Swiss transmission system operator (TSO), is responsible for connecting the power plant to the extra-high voltage grid and for transmitting the hydropower to urban areas in Switzerland. Two of the three sections of the extra-high voltage link to Nant de Drance – an underground cable of 6.5 kilometres between the power station and the Châtelard substation via the access tunnel of the plant and an overhead line of 12.5 kilometres between the Châtelard and La Bâtiaz substations – have been in operation since the end of November 2018.

Tunnel boring has now begun for the third and final section between the substations of La Bâtiaz and Le Verney, which belongs to the municipality of Martigny. The mini tunnel boring machine, weighing around 60 tonnes, was traditionally given a female name on 2 October 2020 at the construction site in Le Verney and will in future be known as Giorgia. Shortly after its christening, it was lowered into the shaft, where it will take around eight months to dig and secure the tunnel between the substations. The tunnel will have a diameter of 2.5m and is dug 12 to 20m deep into the ground. Giorgia is controlled entirely from the control centre at the construction site in Le Verney.

Construction of the underground cable link commenced in June 2020 with the excavation of the shaft at Le Verney and will take two years. The shaft at La Bâtiaz will be dug at the same time as tunnelling work. The finishing work in the tunnel will follow from summer 2021, after which the gantry to connect the Nant de Drance link to the 380kV Chamoson-Romanel overhead line in Le Verney will be built. Finally, the cables will be laid in the tunnel. Commissioning of the 1.2km long underground line is scheduled for 2022. Nant de Drance is already now connected to the transmission grid even before the last section of the link is commissioned: An interim solution was introduced in 2019 by increasing the voltage of one of the two overhead lines between La Bâtiaz and Le Rosel to 380kV.

Swissgrid has started tunnel drilling for the final section of the connection of Nant de Drance to the national 380kV grid (picture: Swissgrid)

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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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New power line for west-central Switzerland

17.09.2020

Switzerland’s national sustainable energy strategy and the resulting growth in hydroelectricity generation in the cantons of Berne, Valais, and Ticino require a significant increase in electricity transmission capacities, particularly to transport green energy to the Swiss Central Plateau and to ensure long-term security of supply throughout the country. This requires the upgrade of existing lines to 380kV and the construction of new high-capacity lines. One example of this is the 220kV line from Innertkirchen in the district of Interlaken-Oberhasli (canton of Bern) to Ulrichen/Obergoms in the district of Goms (canton of Valais), most parts of which are over 60 years old.

To maintain a secure connection between Haslital and Obergoms in the future, the Swiss transmission system operator (TSO) Swissgrid has developed various planning corridors for the construction of a new extra-high voltage line and submitted them to the Swiss Federal Office of Energy (FOE). The TSCNET shareholder has defined three main corridors, some of which include sub-corridors: The first option is a pure overhead line, which crosses high alpine terrain in parts. The second is partial cabling. Here, the middle section is implemented as underground cables, mainly in existing tunnels up to Obergoms. The third variant provides for underground cabling almost exclusively. Either in a new, yet to be built tunnel and then, as in the second alternative, in largely existing tunnels – or in the proposed multifunctional Grimsel Tunnel (envisaged for rail transport and power transmission). If the tunnel is used, the corridor variants for the last section to Ulrichen are possible as overhead line or underground cable        .

Each of the submitted options has specific advantages and disadvantages in terms of spatial planning, environment, technology, and economic efficiency. What they all have in common is the relief of settlements in the affected area, where overhead lines currently run partly through villages. The FOE is now discussing and evaluating the planning corridors. Its recommendation will then be submitted to public consultation, and the Swiss Federal Council is expected to determine the planning corridor and transmission technology between Innertkirchen and Ulrichen at the end of 2022.

Swissgrid has designed and submitted corridor variants for the new Innertkirchen-Ulrichen 380kV line (picture of the existing line: Swissgrid)

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