“We need them as a backup for the growing use of wind power,” says Wolfgang Kölliker, CEO of Alstom Austria. Wind power has one major drawback for grid operators: it is pretty unplannable. Unexpected shortfalls need to be compensated immediately, and this can only be achieved with peak current from pumpedstorage plants.
“As market liberalisation boosts electricity trades on the stock exchange, pumped-storage plants are coming back into fashion,” says Kölliker. Especially variable speed (Varspeed) technologies have become the state of the art for many applications. Alstom is a leader in this field.
Varspeed technology adds optimum efficiency to pumps and turbines, especially in partial load operation and in case of major head fluctuations. While in conventional synchronous machines the nominal output needs to be exceeded to set the pump in operation, Varspeed technology allows the pump to operate even when power surplus is minimal.
This has a positive stabilising effect on the power grid: if grid frequency exceeds 50 Hz (in case of oversupply), Varspeed machines are able to balance out electricity consumption in partial load operation much earlier, thus keeping power frequency constant.
In Switzerland, the new hydropower station of Nant de Drance is one of those equipped with Varspeed technology. Alstom’s scope of supply comprises four vertical reversible Francis pump-turbines (157 MW each), four vertical asynchronous motor generators (170 MVA each) and other major plant components. With a power output of 628 MW, the new plant will cover the average electricity demand of 600,000 households.
Alstom is basically involved in all hydropower projects in Austria; project examples include Reisseck 2, Limberg 2 and Koralpe.
ALSTOM Hydro Austria GmbH
Phone: ++43/1/60 888-2422
(Source: aqua press Int. 2/2009)