Increasing grid flexibility through ancillary services – Virtual Inertia and Fast Frequency Response implementation and testing in a PSPP with double-fed induction machines

Abstract This paper describes the implementation and testing of Virtual Inertia (VI) and Fast Frequency Response (FFR) at the Frades 2 pumped storage power plant (PSPP) in Portugal to verify preceding numerical investigations and to demonstrate the potential of these ancillary services. This work was part of the activities of the EU-funded H2020 project XFLEX HYDRO. Frades 2 is equipped with two reversible Francis-type pump turbines, each coupled to a 420 MVA double-fed induction machine. The test results are compared to numerical simulations for various grid frequency scenarios in generating and pumping mode. It is shown that a single unit in VI mode can inject or extract a peak load of ±110 MW within less than 500 ms in to support the grid in the case of a sudden frequency change. In FFR mode the units can provide control energy of 40 MW in less than 2000 ms. The impact of these modes on wear and tear of the asset is analysed by means of strain gauge and shaft torque data collected during the site test campaign.