Pumped-storage Portugal

GE Energy's Power Conversion business announced recently that it will supply its advanced power conversion technology to Voith for the new Frades II pumped-storage hydropower plant. Frades II is one of six new hydropower plants that Portuguese utility Energias de Portugal (EDP) is building throughout the country.

Voith's pump turbine in Portugal

The facility is being built on the left bank of the Cávado River in the Braga region of northern Portugal. When construction is completed in 2014, it will be one of Europe's most powerful pumped storage power plants and will complement the existing Frades I and Vila Nova facilities.

Flexible energy storage

Pumped-storage plants help to conserve energy and handle load generation fluctuations in wind power. When wind is not blowing, power is produced from pumped-storage to balance out the net power available in the grid. The demand for such plants is increasing due to their flexible energy storage and grid stabilizing capabilities that can help utilities more effectively manage the intermittency of wind energy and other renewable sources.

The variable speed pumps will allow for better grid regulation, which will become increasingly important as Portugal seeks to increase renewable energy production. The country currently generates about 15 percent of its electricity from wind power but is planning to add another 5.4 gigawatts of wind power capacity in the next 10 years. Portugal is one of Europe's pioneers in the development of renewable, and despite the high power levels, Frades II will still meet all of Portugal's stringent grid-connection requirements.

Germany-based Voith is supplying two reversible pump turbine sets and electromechanical equipment for the project, which represents the next generation of hydropower facilities. The two-pump turbine sets will feature GE's variable-speed power conversion technology, making Frades II the first pumped storage power plant in Portugal to use this system. At 420 MVA each in generator mode, the sets also will be the most powerful variable-speed systems in Europe.

Speed variability of the pump turbines enables continuous control of the hydropower plant's output. Traditionally, operators have controlled pump output in fixed-speed, pumped-storage power plants by activating or deactivating individual machine sets. However, by using GE's variable-speed drive technology at Frades II, EDP will have greater control over the plant's turbine performance in pump mode, with each of the pump turbine sets able to handle a wider range of energy for the grid. Also, EDP will achieve higher efficiency levels-especially in partial-load conditions-because the plant's equipment can be adjusted to meet the grid's changing requirements.