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Siemens Energy To Build Two SVC PLUS STATCOM systems to further stabilize German grid

April 23, 2021
The plants will be in Polsum (North Rhine-Westphalia) and Rheinau (Baden-Württemberg).

German transmission system operator Amprion has commissioned Siemens Energy with the construction of two SVC PLUS series static synchronous compensator (STATCOM) systems to further stabilize the German transmission power grid.

The plants will be in Polsum (North Rhine-Westphalia) and Rheinau (Baden-Württemberg). Both systems are designed for a reactive power range of +/- 600 Mvar, and will feature grid-supporting control mechanisms, allowing the systems to efficiently compensate for increasing voltage fluctuations in the electrical transmission network.

While the share of renewable energies is growing worldwide, their volatile feed-ins put significant strain on the power grids. Due to the geographical arrangement of renewable energy generation, the distance to the consumption centers is growing. In Germany, for example, the space is growing between large wind farms that feed into the energy grid in the north and load centers in other parts of the country. This makes the transmission network more susceptible to voltage fluctuations and interference. For a long time, large power plants have provided the reactive power necessary for grid stabilization. However, due to the energy transition many of these conventional power plants, which are operated with nuclear or fossil fuels, are being taken off the grid.

As a result, transmission system operators like Amprion set up STATCOM systems at important grid nodes. They compensate for the voltage fluctuations by regulating the reactive power as required, keeping the grid voltage in a stable range. In addition, the expansion of renewable energy generation allows greater use of power lines, reinforcing the need for increased reactive power compensation. This requires STATCOM systems with increasing capacities up to +/- 600 Mvar reactive power.

German transmission system operators have calculated a minimum expansion requirement for stationary and controllable compensation units for reactive power compensation in the network development plan. This controllable expansion requirement was defined to be between 23 and 28 Gvar and is expected to be covered to a large extent by STATCOM systems. Due to the increasing use of power electronic equipment in the network, network operators are also calling for new control concepts with grid-forming behavior for all STATCOM systems. These lead to a control behavior of the converter similar to rotating synchronous generators, such as those used in conventional power plants. Like generators, STATCOMs could keep the voltage in the network constantly stable by themselves.

The STATCOM systems available today do not yet have these comprehensive network-supporting properties. They use common current control schemes that are state-of-the-art power electronic equipment for transmission grid applications. Technology companies like Siemens Energy will further develop the control algorithms and possibly the hardware accordingly. The new turnkey STATCOM system that Siemens Energy will build in Polsum and Rheinau will have these new grid-supporting features.

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