Hydraulics of the Tail Race Surge Tank of Gouvães Pumped-Storage Hydropower

The 880 MW pumped storage hydro power plant Gouvães, part of the Alto Tâmega hydro power scheme from Iberdrola is currently under construction in the north of Portugal. The energy storage and grid regulating plant is equipped with four reversible Francis pump turbines with nominal power of 220 MW and a gross head of 660 m, the discharge in turbine mode is 160 m³/s and in pumping mode 128 m³/s. The current paper underlines the layout, the design criteria and the results of the physical small-scale test of the tail race surge tank in the hydraulic laboratory. Most unfavourable load cases were studied such as synchronous pump trip in resonance and multiple loading and unloading followed by full load rejection in generating mode. A collaborated transient investigation for water hammer and mass oscillation capturing was conducted and gives interdisciplinary design proof.