Simulation of steady-state and transient operational behaviour of variable-speed motor-generators of hydro power plants

Renewable energy resources like hydro power plants play a more important role in the upcoming future of power grids. Thereby, a full flexibility of utilizing the grid capabilities in terms 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, this can be done by utilizing variable-speed pump-turbine units with either synchronous or doubly-fed asynchronous motor-generators. In order to achieve accurate data about steady-state as well as transient behaviour, simulation models of both arrangements are developed. In particular, the low voltage ride through capabilities according to various grid code requirements have to be analyzed in detail.