Case study of rotor lifting in a pumped storage hydropower plant in Norway

The Duge pumped storage power plant in Norway currently experiences a problem with rotor-lifting. One of the two vertical 100 MW units lifts up off its bearings when operated above a certain load. The vertical forces on the units have been known to be marginally balanced, but the problem increased when the turbines, commissioned in 1979, were refurbished in 2017. One of the reasons is the significant submergence of the units combined with a 12 km long tailrace tunnel, which produces significant friction losses and therefore high downstream pressure. A one-dimensional (1D) numerical model of the power plant's waterway is established with the software LVTrans and calibrated with field measurements to accurately simulate the hydraulic transients. Three different measures to solve the problem are considered. An economic analysis is conducted to assess the economic feasibility of the three solutions.