From pv magazine Germany
A supercapacitor-based grid-stabilization system has entered operation in Mehrum, Germany, marking a world first for power system control technology.
Siemens Energy and transmission system operator TenneT have installed an electronic static synchronous compensator (STATCOM) with supercapacitor storage, which the companies describe as the first system of its kind deployed on a live grid.
The technology is designed to provide instantaneous reserve and reactive power, functions historically delivered by the rotating masses of large fossil-fuel power plant generators.
The system, branded SVC Plus FS, differs from conventional STATCOM installations by using supercapacitors rather than batteries or mechanical inertia. The devices can deliver very high currents within milliseconds, enabling rapid compensation for frequency deviations.
“No one has ever built a supercapacitor-driven STATCOM before,” said Hauke Jürgensen, senior vice president of grid solutions at Siemens Energy. “This sets a benchmark for the global energy transition.”
Technology development took more than a decade, followed by roughly three years of construction.
Inside the facility, supercapacitors are arranged in racks, with each individual cell approximately the size of a beverage can. Together, the system forms a short-duration energy reservoir capable of providing artificial inertia to the grid. Modular power converters manage switching pulses and reactive power compensation. The installation operates fully automatically and can be monitored and controlled remotely, including its diagnostic and control algorithms.
TenneT expects around 30 comparable systems will be required across Germany, with additional projects already in the planning phase.
“Mehrum is a benchmark project,” Jürgensen said. “It demonstrates that grid stability can be maintained without fossil-fuel baseload power.”
The project remains in a testing phase and is expected to transition gradually to commercial operation in the coming months, demonstrating how supercapacitors can replace grid-stabilizing functions once provided by large rotating masses.
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