Testing an innovative hydropower operating regime at Frades 2

The Frades 2 hydropower plant in the north of Portugal is testing how Hydraulic Short Circuit (HSC) technology can enhance the power regulation services and operating ranges offered by pumped storage hydropower.

HSC, which allows the tandem operation of pumping and generating modes, is viewed as one of a number of innovative technologies that could expand hydropower’s role in renewable electricity grids across Europe.

Frades 2 is a 780 MW plant with two variable speed doubly-fed induction machine units. It is one of four EDP hydropower plants involved in the European Union (EU)-funded, XFLEX HYDRO initiative. The initiative is demonstrating how smart hydropower technologies can deliver a low-carbon, reliable and resilient power system.

“The HSC aims to maximise performance and increase flexibility by extending the power plant operating range,” says Pedro Diogo Pinto, Mechanical Engineer at EDP, one of the 18 partner organisations involved in XFLEX HYDRO. “This will increase the availability [of the plant] to provide balancing services to the market.”

In the first phase of the project, a series of initial tests using digital modelling and computer simulations have been performed by researchers from the University of Stuttgart. The University is looking at numerical flow field simulations to determine unsteady dynamic loads on pump-turbine components.

Members of the Voith Hydro and EDP team at the Voith Brunnenmühle research and development center in Heidenheim.

The Frades 2 XFLEX HYDRO project team is working to:

  • Maximise plant performance and increase flexibility using HSC to extend the plant operating range.
  • Increase the plant’s flexibility through the implementation of synthetic inertia and frequency containment reserve (also known as primary frequency control).
  • Improve maintenance intervals and minimum outage times via smart digital controls developed for the XFLEX HYDRO project, the Smart Power Plant Supervisor (SPPS).
  • Improve annual overall efficiency by reducing the power consumption of supporting equipment.

According to Professor Dr.-Ing. Stefan Riedelbauch, Director of the Institute of Fluid Mechanics & Hydraulic Machinery at the University of Stuttgart, initial research results from the project are encouraging.

Voith Hydro, a manufacturer based in Germany, is working on how to make the plant even more efficient, to increase its performance range, and to optimise its maintenance. Model tests have been performed by the company’s engineers at their lab in Heidenheim to add to the data generated from engineering analysis and computer simulation.

Dr Alexander Jung, Head of Digital Hydro Solutions at Voith Hydro, says: “The collected data will serve as input to adapt the plant and unit control software, which will be implemented in the Frades 2 plant for full scale demonstration, which is scheduled for summer 2022.”

Diogo Cordiero, Innovation Project Manager and PMO at EDP, said: “The Frades 2 demonstration will enable us to identify the best opportunities for improving the flexibility of pumped storage hydropower plants.”

A short video about the Frades 2 demonstration has recently been released.

XFLEX HYDRO is a four-year project running until 2023 and has been funded by the European Union Horizon 2020 research and innovation programme.

For more information about the project and to sign-up for progress updates, visit xflexhydro.net.