T&D World Magazine

Siemens to Supply Static Frequency Converters to Sweden and Switzerland

To strengthen the traction power supply networks in Sweden and Switzerland by establishing additional links to the public power supply grid, the Siemens Infrastructure & Cities Sector will supply Sitras SFC plus static frequency converters to the Swedish Transport Administration and to Swiss Federal Railways (SBB). The order volume for both projects amounts to approximately 60 million euros.

The orders include the delivery, installation and commissioning of eight multilevel direct converter blocks in Sweden and two converter blocks in Switzerland. The systems use state-of-the-art multilevel power converter technology, which makes it possible for them to convert energy highly efficiently and with almost no system perturbations. In addition, they are quieter than conventional systems and have a smaller footprint.

In Southern Sweden, Siemens will construct eight converter blocks over all near Astorp, Ystad, Älvängen and Lund with a total capacity of 180 MVA to feed additional power from Sweden's public 50-Hz power supply into the 16.7 Hz traction power supply network of the Swedish Transport Administration. The multilevel direct converter from the Sitras SFC plus series makes it possible to link the two networks, which use different frequencies. The first of these systems is to be commissioned already in the summer of 2015.

As part of the order from Switzerland, Siemens will construct two 60 MVA converter blocks in Winkeln in the Canton of St. Gallen directly next to a substation belonging to Swiss energy service provider Axpo. Axpo is expanding the substation's 220-kV switchgear specifically to link the converter to the public grid. On the rail network side, the converters will feed in into the 16.7-Hz high-voltage grid of SBB and are expected to go into service in the summer of 2015.

What's special about the Sitras SFC plus converters is their multilevel power converter technology: It uses multiple modular power transistor components (IGBT) switched in series and capacitors which create the desired voltage in small steps. This process reduces the switching frequencies and, as a result, the power loss by approximately 10 per cent compared to previous systems. The noise level is reduced as well, which benefits residents. In addition, the multilevel systems require approximately 20% less space because they can be built more compactly than other solutions on the market.

For more information, visit www.siemens.com/infrastructure-cities

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