51st CIGRE Session - CIGRE 2026, Paris (France). 23-26 August 2026
Summary:
Speed control of large hydro generators has become feasible due to the development of high-power electronics. Hence, hydro generators can operate at the maximum efficiency point with respect to output power and head.
Speed control of hydro generators can be implemented by controlling either a doubly fed induction machine or a synchronous machine connected to the grid through a full-power converter.
In the case of a synchronous machine connected to the grid via a full-power converter, the converter comprises two voltage-source converters (the machine-side converter and the grid-side converter) operating in pulse-width modulation, coupled via a DC link capacitor. The hydro turbine is equipped with a speed governor. A unit controller coordinates the control of the synchronous machine and the hydro turbine.
A large Spanish generating company is converting two of the four units at the Torrejón pumped-storage hydro station (4x32 MW) to variable-speed operation. The Torrejón pumped storage hydro station belongs to the Tagus river system. The conversion aims to extend the Torrejón head's operating range in pumped mode, enabling the storage of up to 210 GWh by connecting the upstream and downstream reservoirs of Torrejón (Valdecañas and Alcántara). The rapid expansion of renewable energy sources in Spain is making energy storage facilities highly attractive. By the end of 2025, the installed capacity of wind and solar photovoltaic (PV) generation was 33 GW and 40 GW, respectively, accounting for 22% and 19% of total generation.
[...]
Keywords: Hydro generator, Variable speed, Full-power converter, Grid code compliance, Model identification
Publication date: 23-Aug-2026.
Citation:
L. Rouco, J. Suárez-Porras, F. Perán, A. Gómez Sánchez, "Model Validation of Full-power Converter Variable Speed Hydro Generators", presented at 51st CIGRE Session - CIGRE 2026, Paris, France, 23-26 August 2026
IIT-26-124C_poster
