Impact of Dual Variable Speed and Inlet Valve Control on the Efficiency and Operating Range of Low-Head Contra-Rotating Pump-Turbines. - Daan P. K. Truijen; Justus P. Hoffstaedt; Jonathan Fahlbeck; Antonio Jarquin Laguna; Håkan Nilsson; Kurt Stockman; Jeroen D. M. De Kooning (IEEE Access, 2024)