Nonlinear dynamic performance of the turbine inlet valves in hydroelectric power plants

Abstract

In practice, vibrations in the turbine inlet valves can develop flow rate and pressure fluctuations in the penstocks of the hydropower plants that can risk the safe operation of the power plant. Accordingly, this study has two aims: the first aim is to explain and simulate the valve’s periodic vibrations while considering the power plant’s relevant physical and geometrical parameters. The second aim is to provide recommendations to improve the dynamic stability of the valve’s vibrations. The theoretical model developed to explain the phenomenon comprises the nonlinear unsteady energy equations representing the fluid flow at the pipelines, the continuity equation modelling fluid flow through different junctions, and the valve’s seal equation of motion to compute the valve’s vibrations. The system governing equations are solved nonlinearly using the MATLAB toolbox SIMULINK. The study demonstrated that the origin of the valve’s vibrations is the leakage of the valve’s service seal. The presented model results exhibited that the unstable valve vibrations (of increasing amplitudes) are more prone to occur at higher input reservoir energy levels. Also, installing a valve that can be closed to a certain degree at the pilot pipeline can enhance the dynamic stability of the valve’s vibrations.