Pump turbines are characterized by their ability to operate both as turbines and as pumps. They are primarily used in pump-storage hydroelectric plants as a means of load balancing by producing electricity during peak demand and operating in pump mode when surplus power is available. Ensuring an optimal fulfillment of these tasks presents a number of technical challenges:
- Short synchronization times
- Frequent change in operating mode between pump and turbine
- Short response times are necessary
- Broad operating range (partial load) is desired
- Improved reliability and availability
- Reduction of failure occurances (increasing safety)
The aim of research into pump turbines is a better understanding of the flow conditions, which can lead to instabilities (recirculation, flow separation, vortex formation and development, flow obstruction, stall,...). As a result, new guidlines for the design of pump turbines and their components can be derived, allowing for a broadening of the operating range of the pump turbine while avoiding instabilities.