Flexibility Enhancements in Pumped Hydro Storage Power Plants through Variable Speed Drives

The rapidly increasing number of renewable energy installation that are not able to contribute to grid stabilisation, together with the shut down of thermal power plants requires additional measures to ensure future grid stability. Pumped hydro storage power plants conventionally operating at fixed speed can contribute to grid stability and flexibility by being equipped with a variable speed drive. This paper analyses the scenario where a single unit of an existing power plant is retrofitted into a variable speed drive. The benefits of such a retrofit on the unit itself, as well as the impact on the operation of the existing fixed speed units operating is analyzed and simulations of various scenarios to demonstrate those benefits are developed in this paper.