Stuttgart-Mühlhausen, 4 November 2020 – SPIE, the independent European leader in multi-technical services in the areas of energy and communications, installed a state-of-the-art 380-kV shunt reactor, complete with switch field, at the Stuttgart-Mühlhausen substation. This work was commissioned by the transmission network operator TransnetBW. By stabilising the high-voltage grid, this reactor is a key ingredient for successful energy turnaround. It ensures a reliable power supply in the face of increasing shutdowns of conventional power plants as well as fluctuating solar and wind power feed-in. The project began after a bid invitation in November 2018, and in July 2020 the new system started operating.
Challenging installations during ongoing operations
The shunt reactor weighs 360 tons and has a permanently allowed system voltage of 440 kV (kilovolt) and a regular range from 50 to 250 MVAr (Mega-Volt-Ampère reactive) in 33 stages. Specifically designed for the transmission network operator, the reactor is a world first, using cutting edge technical equipment. To ensure an uninterrupted power supply to households and companies connected to the grid, its installation took place during ongoing operations. “We were proud to be able to implement this pilot project. It was extremely challenging due to the size of the reactor, its technically demanding equipment and the local geological conditions. Throughout the project, we constantly faced new situations that required us to adapt and develop suitable solutions”, says Christoph Bausch, Project Manager at the High Voltage Operational Division of SPIE Deutschland & Zentraleuropa.
To facilitate the installation of the new system, the four-metre difference in height to the previous site had to be compensated for. The multi-technical service provider expanded the site through terraces and erected a four-metre high angular retaining wall along the entire width of the plant. “In the pre-planning for the bid invitation, the stipulated height of the wall was only three metres. We increased it because of the statics”, says Christoph Bausch. “We subsequently closely coordinated with the client and the supplier of the sound insulating cover and the shunt reactor in erecting the reactor’s foundation trough, which is 13 metres wide and 20 metres long, together with the 380-kV switch field. We also expanded the two existing bus bars by adding two panel widths in order to connect the new panel to the existing plant. We then electrically integrated the reactor in the plant”, explains Christoph Bausch, commenting on his team’s work.
Essential for ensuring a reliable power supply
The new shunt reactor began operating in mid-July and is of great importance to ensure a reliable power supply in the Stuttgart-Mühlhausen region. It enables the transmission network operator to guarantee the stability and operating security of the power grid when the input of solar and wind power decreases or increases. “The new shunt reactor enables us to respond to voltage fluctuations within the shortest possible time – for instance by reducing an increasing system voltage during low capacity utilization, in order to keep it within the limits required to ensure system stability. If required, the shunt reactor is simply switched on in stages”, says Sebastian Schröter, Project Manager at TransnetBW. The increasing share of renewable energies in our power supply and the continuous shut-down of conventional power plants means that there is also an increasing need for controlling the 380-kV high-voltage grid. Until now, reactors were only used in the 110-kV power grid in the region covered by TransnetBW’s network. In contrast to these previous models, the new controllable shunt reactor enables the system voltage to adjust far more precisely and optimally as is needed.
TransnetBW and SPIE have been partners in numerous projects for many years. “Our cooperation in this demanding project was excellent. We are particularly proud that TransnetBW commissioned us with a follow-up contract for the installation of a similar shunt reactor in Goldshöfe substation. This project is scheduled to be completed in November”, says Christoph Bausch.
As a product and manufacturer-independent service provider, SPIE stands for service provided from one source and operational excellence. The multi-technical service provider has evolved into a reliable partner for power grid operators to implement the energy transition. Shaping a CO2-neutral future is currently one of the biggest market opportunities. SPIE has a high level of expertise in the energy sector, and for many years its solutions have been used to sustainably improve the energy efficiency of buildings and facilities and to enable access to energy sources with low carbon footprints.
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