Frequency Stability in Island Networks: Development of Kaplan Turbine Model and Control of Dynamics

Large switching events can potentially threaten the frequency stability in small island systems. Simulation models of generators and loads therefore help to predict the frequency behavior and deviations after switching events. Standard models for hydraulic systems are often unable to represent real system behavior during critical events with sufficient accuracy. A dynamic simulation model for a real double regulated Kaplan turbine is presented in this paper. The model is easily adapted to represent other Kaplan turbines. A method for measurement and calculation of the required parameters is presented. Further, it is shown that, through minor changes in the turbine control, drastic improvements in the dynamic turbine behavior can be achieved, without the need to change hardware components. All results are validated with the help of measurement data taken from a real 5 MW Kaplan turbine built in a run-of-the-river power plant.