Effect of water elasticity in hydropower’s pressurized pipeline on stability of low frequency oscillation

For the hydropower stations with longer pressurized pipeline and/or far transmission line, the effect of pipe flow´s water elasticity on stability of low frequency oscillation is necessary to be further analyzed. Based on the easily-decoupled elastic model of water flow with different order, the effect of water elasticity on damping analysis of low frequency oscillation is studied in detail by qualitative analysis and computation verification. Furthermore, the coupling resonance in hydro-mechanical-electro system induced by hydro-mechanical system´s disturbance is analyzed. The results indicate that: the computational damping of low frequency oscillation is varied with different model order of water flow and its trend is closely related with the inertia time constant of pipe flow; the possible coupling resonance in hydro-mechanical-electro system will lead to power oscillation and following unstable accidents. Especially, this research has great theoretical significance and applied value for power transmission from west to east in Southwest China.