Direct coupling transformer for Upper Franconia


The Ostbayernring power line from Upper Franconia to Upper Palatinate in the German state of Bavaria regularly reaches its limits due to the increasing feed-in of renewable energy. The transmission capacity of the Ostbayerring must therefore be significantly increased in order to guarantee future security of supply and grid stability. For this purpose, a highly efficient replacement construction is planned along the existing route. In the context of this Ostbayernring upgrade, also the Mechlenreuth substation in Münchberg is being renewed and expanded since spring 2018.

The substation is operated by TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO). It is a central hub for regional and supra-regional energy supply, as here the existing and in future the new Ostbayerring is connected to the subordinate 110 kV level of the distribution grid. The modernisation of the substation is making great progress: On 11 October 2018, a heavy-load rail transport system delivers a new direct coupling transformer with a transport weight of 254t to Mechlenreuth.

The 300MVA transformer is scheduled to go into operation in April 2019. Like the Ostbayernring itself, the substation cannot be switched off completely for a longer period of time in order to guarantee constant power supply. All the particular components will therefore be individually dismantled, newly erected and put back into operation in several construction phases and  during ongoing operation. The modification of the entire Mechlenreuth plant should be completed in 2023.

TenneT expects the delivery of a direct coupling transformer to the Ostbayernring substation in Mechlenreuth (picture of a previous transformer transport: TenneT)

> See TenneT press release, in German (html)

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Transformer transport to Hardegsen substation


The Hardegsen substation operated by TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), is one of the central power hubs in the southern part of the German federal state of Lower Saxony. But the substation is also of supra-regional importance, as it will serve to connect the Wahle-Mecklar line currently under construction with the local distribution grids.

With a total length of 230 kilometres, the 380kV line from Wahle in Lower Saxony to Mecklar in the state of Hesse is one of the largest power line projects in Germany and belongs to those construction schemes that are essential for increasing the capacity to transmit green electricity from the main generation sites in the north to the consumption centres in the south of the country.

To meet regional and supra-regional uses, the 220kV station will be prepared for 380kV operation and equipped with a total of three transformers capable of spanning between the 380kV and 110kV levels and also between 220kV and 110kV. From 2 to 3 October 2018, the second 287-tonne transformer will be delivered to Hardegsen with a heavy-duty road transportation unit of around 53 metres in length and a total weight of 491 tonnes. The subsequent assembly of the 300MVA transformer at the substation is expected to take three months.

TenneT is supplied with the second of a total of three new transformers for the Hardegsen substation in Lower Saxony (picture: TenneT)

> See TenneT press release, in German (html)

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Second transformer for Pleinting substation


The substation in Pleinting near Vilshofen is one of the central hubs of the Lower Bavarian power supply, for which TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), is responsible. Also in terms of the energy transition and cross-border electricity exchange, the substation close to the Austro-German border is significant. This applies in particular to the transmission of surplus electricity from Lower Bavarian solar power generation and for the connection of Austrian pump storage power plants to the German grid.

A total of three new transformers will be installed in Pleinting, the first of which was delivered already in February 2017. The second transformer, manufactured in the Dutch town of Nijmegen, now has arrived at a nearby train station. On 6 August, the 286-tonne transformer will be delivered to the substation with a heavy-duty road transportation unit of around 45 meters in length and a total weight of 500 tonnes. The following assembly work at the substation will probably take three months.

After commissioning, the transformer will have an operating weight of 417 tonnes. It also offers an extended scope of possible applications, as it can be switched over on the high-voltage side. This means that the transformer works between the 380kV and 110kV voltage levels as well as between 220kV and 110kV. Thus it can immediately be integrated into the existing 220kV systems of the Pleinting-Pirach power line. After the completion of the planned 380kV Pleinting-Pirach line, the transformer will subsequently supply the region on this higher voltage level. By 2020, all modernisation and extension works in an around Pleinting are expected to be completed.

TSCNET shareholder TenneT is supplied with the second of a total of three new transformers for the Pleinting substation (picture of a previous transformer transport: TenneT / Screenshot taken from video “TenneT Trafo Schwertransport”, YouTube)

> See TenneT press release, in German (html)

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Seven onshore transformers for NordLink


During seven nights between 7 and 23 June 2018, TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), expects the supply of altogether seven 225-tonne transformers to the NordLink converter station near Wilster in the southwest of the German state of Schleswig-Holstein. NordLink is the first direct interconnector between Germany and Norway. The high voltage DC line with a capacity of 1,400MW and a total length of 623km ‒ including 516km submarine cable ‒ enables the exchange of Norwegian hydropower and German wind energy.

The transformers are delivered by ship from their Swedish manufacturing site to Brunsbüttel port on the Elbe estuary. The last 16.5km to the converter station will be carried out with a heavy-duty road train with 36 axes, a length of almost 76m, and a total weight of 417 tonnes.

Nordlink, a green link in the truest sense of the word, is a lighthouse project for the European market integration and energy transition. The Wilster converter station has been under construction since September 2016, and the laying of the cables has begun in 2017. TenneT and the Norwegian project partner Statnett anticipate the completion of NordLink in 2020.

Picture: TenneT (picture of a previous transformer transport)

> See TenneT press release (html)

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CGS onshore transformers on site


The Bentwisch substation near the city of Rostock in Mecklenburg-West Pomerania is the future onshore converter station for the Combined Grid Solution, the first Danish-German offshore interconnector. The project is a joint venture of two TSCNET shareholders: 50Hertz, one of the four German Transmission System Operators (TSOs), and Energinet, the Danish TSO. The Combined Grid solution integrates the electricity markets of Denmark and Germany by linking the Danish Kriegers Flak wind farm with its German counterpart, Baltic 2. Now another significant step for the interconnector has been taken, as two transformers have been supplied to Bentwisch.

In combination with a double converter system, the large-scale equipment is essential for balancing the asynchronous transmission systems of Germany and Denmark. The transformers were transported from Rostock harbour to the substation per heavy-duty road transport. The second arrived in Bentwisch on the night of 29 to 30 May, and the first three weeks before. “We have thus reached another milestone on the way to commissioning the Combined Grid Solution. The transformers are the most important technical components for the back-to-back system on site,” comments Martin Henschel, specialist engineer at the 50Hertz Northern Regional Centre.

> See 50Hertz press release, in German (html)

Picture: visavis Filmproduktion GmbH

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Transformer transport marvelled by thousands


A heavy-duty road transport of a transformer weighing almost 300 tonnes might not be daily routine for a transmission system operator (TSO), but it is nevertheless part of the operational business. For the public, such a transport can be quite a sensation, as witnessed by TSCNET shareholder TransnetBW, one of the four German TSOs. Thousands of intrigued spectators lined the streets to watch the event: a slowly moving road train with 32 axes, a length of 75 metres, and a total weight of more than 530 tonnes.

It took three nights to complete the 40 kilometres from Tübingen in the German federal state of Baden-Württemberg to TransnetBW’s Engstlatt substation near Balingen at the foot of the Swabian Jura. At three o’clock in the morning of 30 May, the 380kV transformer finally reached its destination. Here, it will substitute the old transformer to improve the operational performance of the substation, which is the central hub for the power supply in the Zollernalb area.

Until well after midnight, the onlookers in the villages on the transport route marvelled the spectacle of the carefully navigating transport unit. Alexander Schilling, spokesperson of TransnetBW, commented on the public interest: “That really had the character of a funfair. Simply stunning. I have never experienced anything like that.”

> See report by German broadcaster SWR, in German (html)

Picture: Screenshot taken from video “Tausende Zuschauer bei Schwertransport dabei”, in German (SWR media library)

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Platforms for Combined Grid Solution installed


The installation of all three offshore platforms for the planned Danish wind farm Kriegers Flak in the Baltic Sea has successfully been completed on 7 May. A special heavy duty crane vessel was needed as the platforms weigh 800, 1,500 and 1,800 tonnes, respectively. The platforms will not only collect the electricity from Kriegers Flak, but one of them will also be used for the Combined Grid Solution, the first Danish-German offshore interconnetor, which is a joint venture of the two TSCNET shareholders 50Hertz, one of the four German Transmission System Operators (TSOs), and Energinet, the Danish TSO.

The Combined Grid Solution will link Kriegers Flak to the German wind farm Baltic 2 and thus integrate the electricity systems of Denmark and Germany. According to Jens Christian Hygebjerg, project manager at Energinet, the platform installation was the “most costly risk” of the whole project. “It is therefore a great relief to see all three platforms in their rightful place.” The platforms are scheduled to be put into operation in October 2018, but only after an intensive phase of further assembly work and a series of tests under real-life conditions.

> See 50Hertz press release (html)
> See Energinet press release (html)

Picture: Jakob Fynsk / Energinet

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Carinthian transformer connected to the grid


The substation in Obersielach in the southernmost Austrian state of Carinthia is an essential component of the nationwide modernisation process, with which TSCNET shareholder APG, the Austrian transmission system operator (TSO), adapts its grid to the high requirements of a sustainable energy future. Last September, a large additional 380/220kV transformer was delivered to Obersielach ‒ due to its heavy weight in three parts – and then it took six months of installation work and extensive functional testing, before the new device could finally be connected to the grid on 26 April 2018. Further upgrade measures at the substation are still pending and completion is scheduled for autumn 2019. Overall, APG is investing round €38m in the operating site.

The Obersielach substation is the most important power hub in Carinthia and one of the largest substations in Austria. The commissioning of the new transformer will not only ensure the regional long-term security of electricity supply, but also improve the use of climate-friendly wind energy by means of interconnecting the wind farms in Upper Austria with the Carinthian pumped storage power plants in Malta and Reißeck. Surplus wind power can thus be transported to these “green batteries” and stored there. If necessary, the electricity can then be retrieved again from the storage power plants. Apart from that, the five largest Carinthian hydropower plants on the river Drau feed directly into the Obersielach substation.

> See APG press release, in German (html)

Picture: Erich Varh / APG

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First hybrid Statcom facility in Germany


In the three-phase transmission system, reactive power must be in a well-balanced ratio to active power in order to keep the grid’s voltage on the required level. Without reactive power, the transmission of electricity would not be possible. In the “old” German energy landscape, mainly nuclear and other large power plants have been providing reactive power capacities. Since in the course of the energy transition more and more of these facilities go off the grid, the four German transmission system operators (TSOs) respond with the installation of reactive power compensation systems.

An outstanding example of this is given by TSCNET shareholder TenneT, the Dutch-German TSO, which is expanding the traditional Borken substation in the northern part of the federal state of Hesse to one of the most modern green power hubs of its grid. Here in Borken, practically in the middle of the German power system, the TSO is currently constructing a hybrid static synchronous compensator (Statcom) plant. From the end of 2019, the state-of-the-art facility will dynamically support the mains voltage and provide reactive power at 380kV level, thus making an important contribution to secure grid operation after the shutdown of the large power plants.

The Statcom plant in Borken, with its hybrid construction, will be the first of its kind in the entire German electricity grid. A mayor advantage of this system is its small space requirement ‒ in comparison to its wide reactive power control range. This considerably reduces the environmental impact. In the particular case of Borken, the renaturation of a nearby river has now become possible. Other reactive power compensation measures of TenneT include the new substation Bergrheinfeld/West with its phase shifting and direct coupling transformers. In addition to building new facilities, TenneT is also exploring other ways to provide reactive power, such as utilising wind power and photovoltaic systems.

> See TenneT press release, in German (html)


Picture: TenneT

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Second DCT reaches new TenneT substation


As a result of the energy transition, the four German transmission system operators (TSOs) all are heavily involved in compensation measures to maintain long-term security of electricity supply in light of the decommissioning of nuclear and other large-scale power plants. Since 2015, TSCNET shareholder TenneT, the Dutch-German TSO, has been building the completely new substation Bergrheinfeld/West in northern Bavaria, near the already shutdown Grafenrheinfeld nuclear plant.

Bergrheinfeld/West is one of the projects TenneT considers essential for Germany’s energy future. Hence, the TSO invests about €100m in the new facility which will be one of the most modern of its kind. Already on site are a rotating phase shifter with generator transformer, three compensating coils and the first of two direct coupling transformers (DCTs) to connect TenneT’s supra-regional 380kV transmission grid to the regional 110kV grid. With a transmission capacity of 300MVA each, the transformers can theoretically provide electricity for around one million households.

Today, the second direct coupling transformer was delivered to Bergrheinfeld/West. It was built by GE Grid Solutions in Mönchengladbach and initially transported by ship across the rivers Rhine and Main to the port of Garstadt, where it was reloaded onto a 67-meter heavy-duty road transport unit. The transport weight of the transformer is about 260t, and the subsequent operating weight of both units will be 370t each. Preparations for the initial set up of the transformers are expected to be finished in July 2018, followed by the commissioning of the substation’s 380kV system section. The completion of the entire Bergrheinfeld/West substation is scheduled for 2019.

> See TenneT press release, in German (html)

Picture: TenneT

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