Impact of Dual Variable Speed and Inlet Valve Control on the Efficiency and Operating Range of Low-Head Contra-Rotating Pump-Turbines - Truijen, Daan; Hoffstaedt, Justus; Fahlbeck, Jonathan; Laguna, Antonio; Nilsson, Håkan; Stockman, Kurt; Kooning, Jeroen De (Augmenting grid stability through Low-head Pumped Hydro Energy Utilization & Storage (ALPHEUS) IEEE Access, 2024)