Siemens Energy Delivers 600 Mvar Grid-Forming STATCOM to Amprion
- News Power Factor Power Quality
Marin Holt
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- 5 minutes read
- Rheinau STATCOM commissioned January 29, 2026 with reactive power range of +/-600 Mvar
- Grid-forming control replicates synchronous generator voltage-forming behavior with sub-cycle response
- SVC PLUS modular multilevel converter generates sinusoidal waveform without external harmonic filters
- Second identical +/-600 Mvar unit at Polsum in North Rhine-Westphalia remains under construction
- Doubles the +/-300 Mvar capacity of Siemens Energy 100th STATCOM installed at Kusenhorst in 2019
Siemens Energy commissioned a grid-forming STATCOM at Amprion’s Rheinau substation in Baden-Württemberg on January 29, 2026, delivering one of the most powerful reactive power compensation installations operating anywhere in the world. The SVC PLUS system provides a reactive power range of ±600 Mvar, directly replacing the voltage regulation and power factor support that retiring coal and nuclear plants previously supplied to Germany’s transmission grid.
Critical Perspective
Amprion’s Rheinau substation now hosts a STATCOM rated at plus or minus 600 Mvar — double the reactive power swing of Siemens Energy’s previous 100th-unit installation at Kusenhorst in 2019. Reactive power compensation addresses voltage stability but does not replace the synchronous inertia provided by the thermal fleet Germany is retiring; National Grid ESO in the UK reached a comparable STATCOM coverage milestone in 2017, then contracted a separate 2.4 GW synchronous condenser program because reactive devices alone proved insufficient when system inertia fell below 100 GVA during low-demand periods. The Rheinau STATCOM is equipped with grid-forming control. However, grid-forming inverters at transmission voltage levels are largely unproven beyond island grids and lab tests. Transmission engineers need to establish the point at which Germany’s synchronous inertia will drop below the level grid-forming STATCOMs can reliably manage. Amprion has not published this threshold.
Why It Matters
Germany’s energy transition concentrates wind generation in the north while demand remains in the south, creating persistent reactive power deficits at key grid nodes. As conventional generators retire, transmission system operators lose the synchronous machines that historically maintained voltage stability and power factor across high-voltage corridors. Amprion operates 11,000 km of extra-high-voltage lines and now relies on STATCOM installations at Kriftel, Kusenhorst, Gersteinwerk, and Rheinau to fill this gap.
The ±600 Mvar rating at Rheinau exceeds the ±300 Mvar Kusenhorst installation that Siemens Energy delivered as its 100th STATCOM in 2019, doubling the reactive power swing available at a single grid node. Grid-forming control addresses a growing concern among European transmission operators: as power electronic devices replace rotating machines, the grid loses the natural voltage-forming behavior that synchronous generators provide. The Rheinau STATCOM addresses this issue with response times under one cycle and advanced harmonic filtering, ensuring power quality at the connection point.
