Fast Transition between Operational Modes of a reversible Pump-Turbine

Abstract

The future demands of energy production to balance more intermittent energy sources creates two main technical challenges for the hydro power production. Increased off-design operation, including both operation outside Best Efficiency Point and more starts and stops, are needed to facilitate use of more intermittent energy resources. In addition to this there is a demand for rapid change between storing and generating energy in pump storage power plants. There is therefore a need to improve the fundamental understanding of transient operation of the reversible pump turbine during different modes of operation. The present work investigates the four quadrant characteristics of a reversible pumpturbine. With focus on the fast transition between pump and turbine mode of operation. The research has consisted of both experimental work and transient simulation. A fast transition is described in this thesis as a method to change from pump to turbine mode of operation, using the head to change the direction of the pumpturbines rotational speed from pump to turbine direction. The procedure start in normal pump mode of operation and end at idle speed in turbine mode of operation, and the guide vanes are open during the whole transition. The most important contributions in this thesis is connected to the fast transition, where the field experiments is a proof of concept for the fast transition method. The pressure pulsations during the fast transition are also compared to a normal procedure of change from pump to turbine mode of operation. The fast transition is also simulated using a 1D numerical model capable of simulating both pump and turbine mode of operation. The laboratory characteristics have been important in comparison to the improved 1D simulation model. The numerical and measured results show a good correlation.