Study On Transient Process And Rule Of Water-level Of Tubular Hydropower Station

With the deepening of China's hydropower resources development, cross-flow low-head power station more and more. General low-head power station with a small capacity, open channel river runway characteristics. Hydropower units often in the power system to assume the frequency modulation peak, as well as flood control flood discharge and other tasks. When the cross-flow unit conditions change greatly, the unit flow corresponding changes, in the upstream and downstream rivers in the formation of large water level fluctuations. In this way, not only will affect the stability of the unit output, but also on the hydropower station hydropower buildings and shipping safety adversely affected. Therefore, in view of this problem, this paper analyzes the fluctuation law of the upstream and downstream water level of the hydropower station by analyzing and calculating the load shedding process of the tubular hydroelectric generating unit.In this paper, the mathematical models of the open channel and the water flow are established. Secondly, the unsteady flow of the open channel and the pressure pipeline are calculated by the characteristic line method according to the flow characteristics in the open channel and the pipeline. The two are selected for different time steps, and each boundary condition: when calculating the change of the water level of the open channel, the flow boundary condition is required according to the calculation time step. When the flow rate of the pipeline is calculated, the water level boundary condition Finally,the calculation model of the hydraulic system of "diversion channel + pressure pipe + unit + pressure pipe + tailrace open channel" is constructed. The static characteristic curve of the turbine model is stored in a three-dimensional array and stored in MATLAB language Transition process calculationprocedure,The fluctuation curve of water fluctuation in the upstream and downstreamopen channel of the cross mflow unit is caleulanted when length and cross .secrionak arca of different open channel are different, amd the distance between the guide vane and the blade isdifferent.The results show that the inlet pressure of the pipe unit will be negative at the initial moment of the load. The smaller the open channel area is, the greater the water level fluctuation range of the open channel, the longer the open channel length, the larger the water level fluctuation period In the case of the same guide leaf closing time, the longer the blade is off, the smaller the rate of increase of the speed, the smaller the water level fluctuation. Especially in the blade does not move, the speed rise rate, open channel water level fluctuations, axial thrust and turbine inlet pressure fluctuations significantly reduced.