The Laufenburg substation in the Swiss canton of Aargau is not only one of the largest substations in Europe connecting the electrical systems of several countries, but also the birthplace of the European integrated network operation: In 1958, the “Star of Laufenburg” was put into operation as the first interconnection of the French, German and Swiss electricity grids. TSCNET shareholder Swissgrid is now upgrading the substation so that it can continue to guarantee regional and supraregional security of supply also in the future. With this upgrade, the Swiss transmission system operator (TSO) is implementing an important part of its grid modernisation and expansion plan, the so-called “Strategic Grid 2025”.
Already in 2017, the old 220kV outdoor switchgear in Laufenburg was replaced by a gas-insulated unit. The by now outdated transformer from 1966 is currently also being replaced, increasing the transformer capacity of the substation from 600MVA to 800MVA. The new 380/220kV transformer was manufactured in the Siemens plant in Weiz in the eastern part of the Austrian state of Styria and shipped from there to the Rhine port of Muttenz near Basel. The subsequent delivery of all individual parts of the device from the port to Laufenburg took around three weeks. The four poles of the transformer, each weighing about 200 tonnes, were moved individually on a special road transportation unit with twenty axes. At the same time, sixteen trucks brought additional material for the installation of the transformer to Laufenburg.
The new transformer will be installed with concrete walls surrounding each pole providing space for the connections of all poles, of which only three will be in operation simultaneously. Thanks to the installed connections, the reserve pole can be put into operation at short notice. Replacement of an active pole by a reserve pole is planned at five-year intervals, which will significantly increase the transformer’s lifespan. The commissioning of the new equipment is scheduled for mid-2019.