Pumped Storage Hydro

Hitachi Energy installs static frequency converter at Austrian pumped storage plant

Hitachi Energy installs static frequency converter at Austrian pumped storage plant
(photo courtesy VERBUND)

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

This technology enables VERBUND to optimize the pumped storage process at 120 MW Malta Oberstufe (or Malta Upper Stage), a pumped storage plant that is part of the Malta-Reisseck power generation group, which has a total capacity of 1,500 MW. The plant, in the municipality of Malta in Carinthia, has been operating for 45 years. It produces average annual output of 37,870 MWh.

According to VERBUND’s website, the power plant is equipped with two 70,000 kVA motor generators, beneath which lie the 62.8 MW pump turbines connected by a vertical shaft. The machines were designed as isogyre pump turbines, which enables a much lower installed height than conventional pump turbines through the combination of pump and turbine in a single housing. This plant was the prototype for a combined pump-turbine machine of this size.

Using the SFC, VERBUND can switch the pumped storage plant’s 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, Hitachi Energy said.

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, according to a release.

Hitachi Energy said this is the result of “close and deep collaboration with VERBUND to enhance the performance and extend the operating life of one of its most important assets.”