Swissgrid analyses supply disruption in Valais

22.07.2020

On Friday, 17 July, the Swiss transmission system operator (TSO) Swissgrid carried out check-operations concerning the extension of the 220kV switchgear in the Chippis substation in the canton of Valais. At 4.23 p.m., the protection equipment of the 220kV grid node Creux de Chippis was accidentally tripped, causing the switchgear to lose voltage. As a result of the technical failure at Chippis, the switchgear of the substations in Stalden, Bitsch, and Mörel were also affected by the voltage drop, which led to a regional supply interruption in the distribution system.

The result was a one-hour power outage in a total of 60 municipalities with around 112,000 households as well as trade and industry in the Swiss Sierre district and the largest part of the Upper Valais. By 5.23 p.m., all affected switchgear and lines of the TSCNET shareholder were back in regular operation. Thanks to the good cooperation between Swissgrid and the five affected distribution system operators (DSOs) of the lower voltage levels, it was possible to gradually restore the electricity supply from 5 pm onwards. By 6.15p.m. almost all customers were back on power. Swissgrid immediately initiated a detailed investigation of the incident, which is currently in progress.

Swissgrid is investigating the voltage loss in the switchgear of the Chippis substation in Valais on 17 July (picture: Swissgrid)

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Worldwide unique equipment for TransnetBW substation

18.07.2020

European transmission system operators (TSOs) respond to the increasing need for grid regulation – resulting from the growing share of volatile renewable energies and the proceeding shutdown of conventional power plants – with reactive power compensation measures, such as the installation of shunt reactors. Shunt reactors are absorbers of reactive power and support security of supply and system management by keeping the grid voltage within the specified range, especially during low load periods. They thus stabilise the power grids and increase the energy efficiency of the transmission system.

In the Stuttgart-Mühlhausen substation, TransnetBW, one of the four German TSOs, has commissioned a variable shunt reactor for reactive power compensation developed especially for the TSCNET shareholder. Up to now in the TransnetBW control area, shunt reactors have only been used in the 110kV grid. Compared to customary reactors, the new system provides a much more precise control of the grid voltage. The 360-tonne reactor has a control bandwidth of 50-250MVAr in 33 stages and a permanently permissible system voltage of 440kV. With these specifications, the Mühlhausen shunt reactor is not only a novelty for TransnetBW, but for the entire energy sector.

TransnetBW has commissioned a state-of-the-art shunt reactor in the Stuttgart-Mühlhausen substation (symbolic picture: Siemens)

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TenneT installs first TCSC system in Germany

16.07.2020

Series compensation is an innovative technology that significantly increases voltage stability in transmission systems. The Dutch-German transmission system operator (TSO) TenneT is constructing Germany’s first series compensation system in the Stadorf substation in the Lüneburger Heath. From 2023, this will prevent grid bottlenecks in the German state of Lower Saxony. On 15 July 2020, the future heart of the upgraded substation reached Stadorf after an intricate transport by ship, rail and road and was placed on its foundation: a direct-coupling transformer with a transport weight of 528 tonnes.

The TSCNET shareholder supplies large areas of the eastern part of Lower Saxony with electricity via the Stadorf substation. Due to the energy transition and the corresponding transmission of wind power from the north of Germany to the consumption centres in the south, the substation will assume a supra-regional and important function in the future. For this purpose, Stadorf is being comprehensively modernised and extended by a so-called Thyristor Controlled Series Capacitor (TCSC) facility, the first of its kind in Germany.

TCSC allows a fast-dynamic modulation of the inserted reactance and in this case specifically to relieve persistently overloaded lines and redirect load flows. The new direct coupling transformer with a transmission capacity of 300MVA connects the 380kV lines of TenneT with the 110kV lines of the regional distribution system operator (DSO). It provides load flow in both directions, so that locally generated surplus green electricity can be transferred if required. As a result of the substation upgrade with TCSC equipment, the disconnection of wind turbines, regulatory intervention in the grid, and the associated costs will be reduced – and overall system security increased. TenneT anticipates annual savings in the double-digit million euro range.

TenneT is implementing a TCSC facility in the Stadorf substation, the first of its kind in Germany (picture: TenneT)

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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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€30m for substation upgrade in Lower Austria

19.05.2020

The grid infrastructure of TSCNET shareholder APG, the Austrian transmission system operator (TSO), must comply with the changes in the power system. The APG projects in this regard are essential for the success of the energy transition and indispensable for Austria’s secure future electricity supply. One example of this is the modernisation of the Ternitz substation in Neunkirchen in Lower Austria, which was built in 1965. With its reconstruction, the TSO significantly improves the power supply of the industrial district south of Vienna, Upper Styria and the Mürztal valley in north-eastern Styria. In addition, a new phase-shifting transformer (PST) will increase failure safety for all of Austria and facilitate the smart integration of green electricity such as wind power from the Weinviertel region into the APG grid. All in all, the TSO is investing €30m in the substation upgrade.

The Ternitz substation is an important hub in APG’s supraregional power grid. Its infrastructural significance is emphasised by the new 220/110kV transformer, which will be one of three such PSTs in Austria. In the 220kV grid, it regulates the flow of electricity on the power lines in north-south direction and distributes it evenly to assure full electricity supply for the region and for all of Austria. To maintain reliability also during the time of the reconstruction, APG will be keeping the substation in operation with numerous temporary measures. Construction was originally scheduled to be concluded in December 2020, but due to the corona pandemic, completion is expected to be delayed by about three months and is now scheduled for March 2021.

Since mid-April, about 50 APG construction projects that were suspended after the Covid outbreak have been gradually resumed in compliance with the necessary distance and hygiene requirements. APG is thus living up to its responsibility not only towards the energy industry, but also as a driving force for the Austrian economy as a whole. In 2020, the investment volume of all APG construction projects in the areas of grid extension, renovation and maintenance projects will total €350m.

APG is investing €30m in the upgrade of the Ternitz substation in Lower Austria (picture: Christoph Breneis / APG)

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Demolition makes room for DC substation

14.05.2020

After TransnetBW, the transmission system operator (TSO) from the south-western German state of Baden-Württemberg, was granted building permit for the ULTRANET substation on the site of the former Philippsburg nuclear power plant in March 2020, the way is now finally clear for its construction. At 6.05 in the morning of 14 May 2020, the two cooling towers on the site of the former power plant were detonated. Now the necessary construction space of around 100,000m² is created. The Philippsburg plant was shut down completely on 31 December 2019 and the building construction of the ULTRANET substation is scheduled to start in the third quarter of 2020.

Since the future Philippsburg substation is the southern end point of the supra-regional high-voltage direct current (HVDC) line ULTRANET, it will be one of the most important energy hubs in Germany’s soon-to-be energy landscape. ULTRANET, a European Project of Common Interest (PCI), is jointly implemented by the two TSCNET shareholders TransnetBW and Amprion. It will transfer wind energy generated in the northwest of Germany to the more industrially developed southwest with low losses. In Philippsburg, the transmitted DC will be converted into AC and distributed regionally. In the reverse case, the substation enables the conversion of AC to DC, e.g. to transport excess photovoltaic power from the south to the north.

The fact that the “green” substation will feed renewable electricity into the transmission system instead of nuclear power is a representative of the entire German energy future. “The construction of our DC substation on the site of the cooling towers of the nuclear power plant is a visible sign and symbol of the progress of the energy transition,” comments Dr. Werner Götz, Chairman of the TransnetBW Executive Board. “In future, renewable electricity will flow from the Philippsburg site through the TransnetBW transmission grid to the entire region. Thus, as the TSO in Baden-Württemberg, we ensure that our country will have the electricity it needs even in a future without nuclear power and coal.”

With the cooling towers of the Philippsburg nuclear plant detonated, TransnetBW will begin construction of the ULTRANET substation (picture: screenshot taken from video “Sprengung der Kühltürme des Atomkraftwerks Philippsburg”, in German, YouTube channel of German newspaper “Die Rheinpfalz“)

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Construction of ULTRANET substation approved

27.03.2020

The Philippsburg nuclear power plant in the German state of Baden-Württemberg was shut down completely on 31 December 2019. On the power plant site, TSCNET shareholder TransnetBW, the Transmission System Operator (TSO) from the southwest of Germany, is planning a new DC substation with a required area of around 100,000m². The substation is to become one of the most important energy hubs in Germany’s future energy landscape, as the supra-regional high-voltage direct current (HVDC) line ULTRANET will be connected here to the regional 380kV AC grid.

After intensive planning, TransnetBW submitted the application for construction permit to the competent district administration for examination in June 2018. The Landratsamt Karlsruhe has now approved the plans of the TSO. “The DC substation plays a central role in integrating renewable energies into the transmission grid,” explains Dr. Werner Götz, Chairman of the TransnetBW Executive Board. “In the future, renewable electricity will flow from the Philippsburg site to the entire region. We are thus laying a cornerstone for supply security in a future without nuclear power and coal.”

ULTRANET, a European Project of Common Interest (PCI), is jointly implemented by TransnetBW and the further TSCNET shareholder Amprion. It will transfer wind energy generated in the northwest of Germany to the industrially highly developed southwest. The Philippsburg substation represents the southern end point of ULTRANET. Here, the DC transmitted via ULTRANET to Philippsburg is converted into AC and distributed throughout the region. Vice-versa, the substation allows the conversion of AC into DC, e.g. to transport surplus photovoltaic power from the south to the north.

TransnetBW has received official approval for the construction of the ULTRANET substation in Philippsburg (architectural sketch of the substation: Codema International GmbH / TransnetBW)

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Germany’s first hybrid Statcom facility in operation

27.01.2020

Since January 24, Germany’s first hybrid static synchronous compensator (Statcom) system is connected to the power grid. For about two years, TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), has been modernising its long-established substation in Borken, in the German state of Hesse, practically at the centre of the German transmission system. The heart of the conversion work was the installation of the Statcom system. Due to the limited space available at the site, TenneT decided to build the Statcom system in hybrid construction, thus reducing the additional space requirement to less than one hectare.

With the high-performance technology in operation, TenneT uses the historic substation in Borken, which boasts a tradition of almost a hundred years, for a task that will contribute significantly to the success of the energy transition: the provision of dynamic voltage support and reactive power to compensate for the decreasing capacities previously provided by large power plants that are being successively shut down. The TSO invested around €30m in the Borken substation, that now has become one of the most modern hubs for green power in the German grid.

Last Friday, Axel Schomberg, Head of TenneT Grid Operations, together with high representatives of local politics, officially commissioned the Statcom system, underlining the significance of the facility for the energy transition. In combination with the numerous other reactive power compensation systems operated in the 129 German TenneT substations, including compensation coils, MSCDN systems and the first rotating phase shifter in the German power grid at the time of installation, the Statcom system contributes to the static reactive power supply.

TenneT has commissioned Germany’s first hybrid Statcom system (picture: TenneT)

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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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First pylon of new East Bavarian Ring erected

16.11.2019

The Ostbayernring (East Bavarian Ring) is an existing power line operated by the Dutch-German transmission system operator (TSO) TenneT, that stretches about 185km from the Upper Franconian town of Redwitz via Mechlenreuth and Etzenricht to Schwandorf in the Upper Palatinate. After the shutdown of Northeast Bavarian nuclear and conventional power plants, the Ostbayernring primarily transports renewable energies. On several days of the year, more energy is generated by wind turbines and photovoltaic plants in the regions along the East Bavarian Ring than is needed locally. Due to the resulting increase in the amount of renewable energy fed into the grid, the East Bavarian Ring regularly reaches its capacity limits.

To ensure the security of supply and the reliability of the grid and to prevent grid failures for the entire region of Upper Franconia and Upper Palatinate, the transmission capacities of the East Bavarian Ring need to be significantly improved. A replacement construction for the East Bavarian Ring was therefore included in the German Federal Requirements Plan and the urgency of the project for the energy market was legally determined. The new line is being constructed along the existing route, extending the current 380/220kV systems to two 380kV systems.

In the course of the construction of the new East Bavarian Ring and the related grid reinforcement, the Redwitz, Mechlenreuth, Etzenricht and Schwandorf substations of the TSCNET shareholder are also being upgraded. Now the first pylon of the new Ostbayerring has been erected on the site of the Etzenricht substation. TenneT has captured the construction on film in order to give a well-founded impression of the erection process.

The first pylon of the new East Bavarian Ring of TenneT has been erected (picture: TenneT / screenshot taken from TenneT-video “TenneT Ostbayernring: Der Projektleiter stellt sich vor”, YouTube)

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