Study On The Variety Of Characteristic Curve And Its Effect On Hydraulic Transient Process In Pumped Storage Plant

With the development of economy and the improvement of living standard, the differences between daily peak and minimum loads in power systems are bigger and bigger. It is urgent to generate electrical source that can undertake peak regulation and trough filling. Pumped storage plant is the answer people often have chosen. It uses excess electrical capacity to pump water into an elevated reservoir at times of low electrical demand and release water to generate hydroelectricity at time of high peak demand. Comparing with ordinary hydropower plants, it is characterized with high head, frequent operation status transition and bi-directional flow. Therefore the hydraulic transient process is much more complex. As the complete characteristic curves of reversible pump turbine are often used to calculate the instantaneous parameters, this paper studies the characteristic curve and the wicket closure and opening law in pumped storage plants.Chapter 1 presents the importance and the necessity of this study and reviews the previous related research on hydraulic transient process and valve regulation in pumped storage plants.Chapter 2 analyzes the six collected characteristic curves of reversible pumped turbine and studies their diversification from the point of view of specific speed. The six collected discharge and moment curves with maximum efficiency have been fitted to piecewise continuous curves. This curve-fitting procedure is listed.Chapter 3 takes Liyang Pumped storage plant as an example and analyzes the effect of different characteristic curves on regulation guarantee parameters and the variety of its trochoid during the same operation status.Chapter 4 takes three pumped storage plants with different heads (high, medium and low) as examples and studies the characteristic of coordinated closure with wicket gate and ball valve and its effect on dynamic pressure in the spiral case, inlet pressure in the draft tube and the rise of rotating speed.Chapter 5 summarizes this paper and point out what should be done in the future research.