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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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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Construction permit for Pradella-La Punt

13.07.2020

As the extra-high voltage line in the Swiss Engadine between Pradella and La Punt constitutes a bottleneck in the Swiss and pan-European transmission system, the Swiss transmission system operator (TSO) Swissgrid has long aimed to increase its transmission capacity to 2 x 380kV. This will improve import capacity and security of supply in the canton of Graubünden and facilitate the transport of Engadine hydropower. The project is part of the “Strategic Grid 2025”, Swissgrid’s ambitious modernisation and expansion plan.

The Swiss Federal Inspectorate for Heavy Current Installations (Eidgenössisches Starkstrominspektorat-ESTI) now has approved the reinforcement and new construction of pylons between Pradella and La Punt. Swissgrid has already refurbished the pylon foundations in the past two years, so that work can commence soon. Approximately 3500 tonnes of steel will be needed to upgrade the around 50-kilometre-long overhead line. The construction will be carried out in two sections and is expected to be completed by the end of 2022.

To reduce the overall environmental impact in the region, Swissgrid is supporting a local grid operator in replacing a 60kV overhead line with a 110kV underground cable. As a result, 1100 pylons will be disappearing from the landscape.

Swissgrid can start with the 2 x 380kV upgrade of the Pradella-La Punt line (picture: Swissgrid)

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Work begins on the final section of Nant de Drance

15.06.2020

The Nant de Drance pumped storage power plant in the Swiss canton of Valais is being commissioned successively in sections since 2019. The plant has a capacity of 900MW, making it one of the most powerful pumped storage plants in Europe – when it is fully operational in 2021, it will be able to generate close to 2.5bn KWh a year. TSCNET shareholder Swissgrid, the Swiss transmission system operator (TSO), is responsible for connecting the power plant to the extra-high voltage grid and for to transmitting the hydropower to the urban areas of Switzerland.

Swissgrid is implementing the 380kV connection in three sections, two of which were already commissioned at the end of November 2018: the 6.5km underground cable line connecting the Nant de Drance power plant to the Châtelard substation via the plant’s access tunnel, and the 12.5km overhead line between the Châtelard and La Bâtiaz substations. The last section – from La Bâtiaz to the connecting point to the Chamoson-Romanel overhead line in Le Verney – crosses the Rhône valley over a length of 1.3km. An underground variant for this section was finally approved in January 2020 by the Federal Inspectorate for Heavy Current Installations (“Eidgenössisches Starkstrominspektorat”, ESTI). It provides for a tunnel with a diameter of around 2.5m and a depth of 12 to 20m to be drilled between different groundwater levels. This is the second underground extra-high voltage line built by Swissgrid, but the first to extend at great depth for more than one kilometre.

Preparations for construction work on the two sites in Le Verney and La Bâtiaz have been underway since mid-May. Excavation of the shafts at Le Verney will commence in mid-June. In August, the mini tunnel boring machine will be installed on the main construction site in Le Verney. Tunnel driving will take about eight months and start in September 2020 at the same time as the excavation of the shafts in La Bâtiaz. After around two years of work, the third section is scheduled to be commissioned, until which time a provisional solution has been found: In 2019, the voltage of one of the two overhead lines La Bâtiaz – Le Rosel was increased to 380kV.

Swissgrid is starting construction of the final section of the connection of Nant de Drance to the national 380kV grid (picture: Nant de Drance SA)

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New Rhône Valley power line operational in 2022

24.03.2020

In early 2018, TSCNET shareholder Swissgrid, the Swiss transmission system operator (TSO), began preparations for the construction of the new 380kV line in the Rhône Valley between the two substations Chamoson and Chippis, which is to replace the old 220kV line. This new line is of crucial importance for Switzerland’s security of supply, particularly for the transmission of electricity generated in the Valais hydroelectric power plants to the consumption centres in the central Swiss Plateau.

After about 18 months of actual construction, the extra-high voltage line is now taking shape and work is underway along its entire length. But not only do numerous safety measures have to be considered during construction, also the access to some plots of land has not yet been clarified at some pylon sites. These locations are distributed along the entire route of the line. As a decision by the responsible federal authorities is still pending in some cases, Swissgrid has now reviewed the construction plans and postponed commissioning of the new line until summer 2022. As the Federal Evaluation Commission (“Eidgenössische Schätzungskommission”) has given priority to the TSO’s applications, Swissgrid is confident about the further construction of the line.

Swissgrid expects the new 380kV line from Chamoson to Chippis to be commissioned in summer 2022 (picture: Swissgrid)

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Swissgrid and hydropower storage plants agree on minimum production

20.12.2019

To avoid an overload of grid elements in western Switzerland during the winter holidays, TSCNET shareholder Swissgrid, the Swiss transmission system operator (TSO), has agreed upon a minimum production with selected regional hydropower storage plants. This is intended to reduce the potential increased and costly need for redispatch during these low-consumption days.

The measure is also necessary because the availability of the transformer at the Bassecourt substation in the canton of Jura is currently limited and the new transformer at Mühleberg in the canton of Berne has not yet been fully installed. Both projects will be implemented in spring 2020. The agreed minimum production in the period from 20 December 2019 to 6 January 2020 is 200MW (off-peak) and 400MW (peak).

Swissgrid has negotiated minimum production from hydropower storage plants

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Ernen-Ulrichen 380kV line in operation

21.10.2019

With the erection of the last of a total of 57 pylons, the new extra-high voltage line between the Ernen and Ulrichen substations in the Swiss canton of Valais has now been completed. The 30-kilometre section is part of the 380kV Mörel-Ulrichen line project of TSCNET shareholder Swissgrid, the Swiss transmission system operator (TSO). The line upgrade in the Rhône Valley is vital for the future of Switzerland’s energy supply: In order to fully transfer the hydropower generated in the Valais to the urban areas of Switzerland, the lines of the south-western canton must be connected to the supra-regional 380kV transmission grid, particularly in view of the commissioning of the new Nant de Drance pumped storage power station, scheduled for 2020.

The existing 220kV overhead line between Ernen and Ulrichen is already disconnected. Its 177 pylons will be dismantled from spring 2020 and the former pylon locations will be recultivated. Swissgrid is additionally carrying out nature conservation projects of national importance in the vicinity of the new line. Also starting next year, the Swiss TSO will continue its Valais upgrade project with the new construction of the next section between Ernen and Mörel-Filet, which is expected to be commissioned as 380kV line by the end of 2022.

Swissgrid has commissioned the new 380kV line between Ernen-Ulrichen (picture: Swissgrid)

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50 new pylons for the Pradella-La Punt line

19.09.2019

The extra-high voltage line in the Swiss Engadine between Pradella/Scuol and La Punt represents a bottleneck in the Swiss and the European transmission grid. To remedy this shortcoming, TSCNET shareholder Swissgrid, the Swiss transmission system operator (TSO), began upgrading the 380kV line to 2 x 380kV in October 2017. This will increase import capacity from the north, strengthen interconnections with Austria and Italy and facilitate the transport of hydropower in the canton of Grisons. The project also improves security of supply in Switzerland and is part of the “Strategic Grid 2025”, Swissgrid’s ambitious modernisation and expansion plan.

Basically, the upgrade means that Swissgrid will attach a second 380kV line to the pylons, which are originally fitted with only one line on one side. Over the past two years, the TSO has reinforced the mast foundations between Pradella and La Punt and will complete this work in autumn. But Swissgrid has also examined the static of the pylons and discovered that some of them have insufficient load capacity for the second circuit. For safety reasons, it was thus decided to replace 50 of altogether 127 masts instead of reinforcing them. This change has no impact on the routing, but on the schedule: The commissioning of the upgraded line will be delayed by at least one year and is now planned for 2022.

Swissgrid has to erect 50 new pylons for the Pradella-La Punt line (picture: Swissgrid)

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New 380kV line in Valais

17.04.2019

The complete transmission of hydroelectric power generated in the Swiss Canton of Valais to the country’s urban areas is essential for the future of Switzerland’s energy supply: Without the connection of the Valais transmission lines to the 380kV grid, only around two-thirds of Valais hydropower can be transmitted as soon as the new Nant de Drance pumped storage plant goes into operation. That is why increasing the voltage of the line between the Chippis and Mörel substations in the Rhone valley from 220 to 380kV is an important part of the “Strategic Grid 2025”, the grid modernisation and expansion plan of TSCNET shareholder Swissgrid, the Swiss transmission grid operator (TSO).

Swissgrid is planning the new construction of a 380kV overhead line with a length of around 44 kilometres, which will bypass and relieve settlement areas as far as possible. The existing 220kV line will be dismantled after the new line is commissioned. As with every grid project, Swissgrid has evaluated both cable and overhead line variants for Chippis-Mörel, with the result that underground installation would not only be very costly and time-consuming but would also not generate any significant added value for the natural landscape.

At the end of March 2019, Swissgrid submitted the planning approval procedure to the Swiss Federal Inspectorate for Heavy Current Installations (Eidgenössisches Starkstrominspektorat – ESTI) and also engages in dialogue with the population, the municipalities, the authorities and associations. The TSO’s current planning foresees commissioning of the line in 2025, but in the event of objections and legal proceedings, initial operation may be delayed by several years.

Swissgrid will build a new 380kv overhead line between Chippis and Mörel in Valais (picture: Swissgrid)

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Official opening of substation in Ticino

01.10.2018

The commissioning of the modernised Avegno substation in the district of Vallemaggia in the Swiss canton of Ticino is a landmark achievement for TSCNET shareholder Swissgrid, the Swiss transmission system operator (TSO): “Since Swissgrid took over the Swiss transmission grid in 2013, it has been the first substation project to be fully implemented by the national grid company,” explains Maurice Dierick, Head of Grid at Swissgrid.

The Avegno substation is an important hub of the Swiss transmission network, both regionally and nationally. In addition, it connects the Verbano hydropower plant to the national extra-high voltage grid. Construction work at Avegno began in October 2016 and will be completed by the end of November with the dismantling of the old 220kV open air switchgear. Already in April 2018, the new gas-insulated switchgear (GIS) was connected to the grid. All in all, Swissgrid has invested CHF17m (almost €15m) in the modernisation of Avegno.

Swissgrid has opened the new Avegno substation, equipped with a gas-insulated switchgear (picture: Swissgrid)

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