Frades 2, Portugal
Frades 2 is a pumped storage hydropower plant, equipped with two variable speed units composed of two 390 MW reversible pump-turbines coupled with doubly-fed induction machine (DFIM) motor-generators. The aims of the XFLEX HYDRO demonstration are to test an innovative operating regime by running both units in Hydraulic Short Circuit (HSC) mode; and to optimise the provision of ancillary system services to the electricity grid, using smart digital controls developed by EPFL for the project, the Smart Power Plant Supervisor (SPPS). HSC enables regulation of the power in pump mode to a larger extent, and for more plant outputs, than the original set-up. Furthermore, HSC will also allow for smaller plant outputs in generating modes.
As some of the additional grid services were not part of the original delivery scope for the plant, not all of the data required to operate the plant under these new conditions are available.
New data needs to be collected from engineering analysis and simulations as well as reduced scale model tests.
In 2021, initial studies were carried out by the University of Stuttgart to identify the potential risks of running HSC mode, using engineering computer analysis and simulations. These achieved excellent results, showing that HSC mode is possible at the plant.
In August 2021, tests using a 1:9 scale model of the Frades 2 pump-turbine were successfully performed at Voith Hydro’s Brunnenmühle research and development center in Heidenheim
Preparations are underway for the demonstration and operation phase, which is expected to start in late summer 2022. The demonstration will involve implementing the HSC and SPPS methodology as well as data collected at site.