Studies about the low voltage ride through capabilities of variable-speed motor-generators of pumped storage hydro power plants

In order to fulfil the new challenges within power grids arising from an increasing utilization of renewable energy resources, there is an upcoming demand for pumped storage hydro power plants. Thereby, a full flexibility of active and reactive power production in generating mode as well as power consumption in pumping mode in conjunction with the best available efficiency of both electric and hydraulic devices gains in significance. Nowadays, the utilization of variable-speed pump-turbine units with either synchronous or doubly-fed asynchronous motor-generators can be applied for these tasks. Since these variable-speed units have a very different behaviour in comparison to fixed-speed synchronous machines, more detailed analyses should to be carried out in the design phase of such units. In order to achieve accurate data about steady-state as well as transient behaviour, simulation models of both mentioned arrangements are developed.