Discharge Calculation Of Hydrolic Turbine Based On Pressure-time Method

With the continuous development of the economy and the advent of the Internet era,the demand for electricity continues to grow in all industries.As a renewable clean energy,hydroelectricity plays a more and more important role in the supply of electricity.The economic benefit of the hydropower station has a great relationship with the performance of the turbine.The hydraulic performance test of the water turbine is required for the acceptance,debugging and maintenance of the hydropower station,and the most important and difficult task in the hydropower station is the measurement of the flow of the turbine.Therefore,it is of great technical and economic significance to study on the flow measurement method with convenient operation,accurate measurement and low cost.The common flow measurement methods,such as flow Velocity-area method,tracer method and ultrasonic method,will be restricted by the precision of the instrument,the complicated installation operation,the difficulty of data analysis,etc.The measurement and calculation of hydraulic turbine discharge by pressure-time method requires less downtime,lower cost,at the same time has higher accuracy and reliability.Thus it has a wide application prospect.Based on transient flow theory,some research on the flow calculation of pressure-time method has been done.First,based on the quasi-steady friction model,the pressure-time curve of the water hammer produced in a hydroelectric station with different valve rules is simulated.On this basis,a pressure-time discharge integral model is established,in which the pressure loss is calculated according to the steady friction.The calculation results show that the calculation value of the initial flow rate has a good precision,the minimum relative error is 0.04%.Comparing the initial flow calculation values under different simulation pipe lengths,it is found that the relative error is larger when the simulation pipe is longer.Secondly,considering the simulation of transient flow based on quasi-steady friction model,can not truly reflect the attenuation process of water hammer in the pipe,so the pressure-time curve due to valve closure is simulated and verified by the Brunone unsteady friction model.Two discharge algorithms based on steady and unsteady friction model are used to solve the valve flow,and the calculation results show that the steady friction algorithm can get good results,the maximum relative error is 1.5%,and the unsteady friction discharge algorithm with Brunone additional friction correction has higher accuracy and stability.Finally,results by the discharge calculation models used the steady friction and the Brunone unsteady friction are compared with the experimental da ta.The results show that the accuracy of engineering requirements can be obtained by using two kinds of discharge calculation models,the relative error of the flow estimation is within ±0.5%.And the stability and reliability of the Brunone unsteady friction discharge calculation model is better,compared with the steady friction algorithm,the relative error can be reduced by 0.14%.