Verification of simulation program for high head hydro power plant with air cussion

Abstract

Europe's energy production is experiencing a shift towards larger volumes of renewable energy. This developement, however benificiary, poses several challenges. One of them being the lack of regulation, as the energy is available when nature permits. As a consequence, Norwegian hydroelectric plants, risk operating under conditions not anticipated in their planning/construction stage. This occurs during large influx of unregulated power, where grid stability needs to be maintained by these plants. Presented herein is a model implemented to investigate grid influence on system components, down to the waterway. The model was verified on the Driva hydropower system. The background data was provided by Norconsult, as the measurements could not be conducted be the author himself. This was due to circumstances around the plant owners.Simulated load rejections overestimated the runaway speed and slightly underestimated the pressure surge, compared to measured data. Simulated behaviour of remaining online unit seemed reasonable and maintained good stability. The model output compares well with analytical solutions. The turbine model behaved as expected during transient load changes, however unit output did not change as expected when changing the grid frequency. This was a result of the governor models not operating as expected. The model was also able to simulate highly undesirable conditions in the wateray due to grid frequency fluctuations.The program generally compare well with rejection trial data as well as expected physical behaviour of the various components. A few points for improvement was suggested, including a further investigation into the governor models.