Hydraulic Transients Of Water Power Station With Upstream And Downstream Surge Chambers

In the design of water power plant to set up upstream and downstream surge tank in hydro power waterway is needed for the reason of layout or geology. In order to reduce water-hammer pressure and to guarantee a good regulating characteristics of the generation units, two surge chambers are needed at upstream and downstream of the powerhouse and this forms a new water power diversion system of the power plant.It is more complex of the hydraulic circuit with double surge chambers at upstream and downstream than that with single tank. Two surge chambers influenced each other when the units decrease or increase load. Hydraulic transients mathematical model is difficult to established of this diversion system especially with combined surge chambers. The selection of items of calculation is important and some beyond standard specifications. Two surge chambers must be concerned in every case of possible operation. In fact, calculation was limited to most severe cases. To detect the maximal and minimal water level of the two surge chambers when load rejection happens, combined operation cases should be considered. Stability of the whole system with double surge chambers, when a little variation of the load occur, become one of the hottest issues for the design of this type of power plant. Investigations of this kind of power station will not only supply the scientific reliability for the design, but also be very important to the safety of the power station.A real project of Jinping II with double surge chambers is applied in this paper based on the characteristic method and the transient results are proved satisfactory. Mathematical model and some details are discussed widely. Programs can take into account every pipe, every type of turbine, and the combination of different types of surge chambers. The variation process of water fluctuation in the two surge chambers, the pressure of the spiral case, the over speed of units by load rejection are calculated and analyzed. Particular, sudden decrease or increase of the load is simulated. Dimensions of the two surge chambers are determined by optimizing the parameter of the system. Results of typical water levels of two surge chambers and the guaranteed calculation for regulation of Jinping II power station are given. Analyzed the stability of such system theoretically. Obtained the relative relationship of the section area of chambers of such system with double surge chambers and that of the system with only one surge chamber. The stability of Jinping II power station is verified satisfactory by the calculation of this program.