Hitachi Energy has completed and handed over to VERBUND, Austria’s biggest power generator, the world’s first static frequency converter (SFC) solution to use modular multi-level technology in a pumped hydro storage application.

This groundbreaking innovation enables VERBUND to optimize the pumped storage process at Malta Oberstufe, a pumped storage plant belonging to the VERBUND’s Malta-Reisseck power generation group, which has a total turbine power of 1.500 Megawatt.

The Hitachi Energy solution enables the 45-year-old pumped storage plant to switch its two pump-turbine units from traditional fixed-speed to state-of-the-art variable-speed operation. Instead of constantly running at the same speed, the pump turbines adjust their speed automatically according to grid conditions and reservoir water levels. This considerably improves the efficiency of the pumped storage process.

The solution enables the operator of the Malta-Oberstufe power plant to actively participate in balancing the Austrian power grid. Moreover, it improves the integration of more green energy, such as wind and solar into the European grid.

“This technology breakthrough is the result of a close and deep collaboration with VERBUND to enhance the performance and extend the operating life of one of its most important assets,” said Marco Berardi, Head of Hitachi Energy’s Grid & Power Quality Solutions global product group. “By making the plant more efficient and by stabilizing the power grid, our unique technology and application know-how is advancing the world’s energy system to be more sustainable, flexible, and secure.”

“The defining features of the Hitachi Energy solution are its low losses, robust modular design, limited maintenance requirements, and durability,” said Karl Zikulnig, Head of the Electrical Engineering Department at VERBUND. “Its inherent redundancy is also key – we need exceptional reliability and availability, as the plant is inaccessible during the heavy winter snows.”

Hitachi Energy has been innovating static frequency converter solutions for more than 40 years. SFCs have a unique ability to control voltage, frequency, and power flow. This technology makes them crucial to several power applications, particularly rail, grid interties, shore-to-ship, and pumped hydro storage. SFCs are based on Hitachi Energy’s high-performance power semiconductors, which are an integral part of many Hitachi Energy power technologies, including high-voltage direct current (HVDC) and flexible AC transmission systems (FACTS).