Hydraulic Transition Process Analysis Of Mu Zhati Third Hydropower Diversion

The hydraulic transition process refers to the process of a water flow changing from one steady state to another in water system of hydropower station. Under a certain external disturbance, the hydropower generating units may start, stop and load shedding. Which lead to a sudden significant increase in unit speed and a rapid rise of pressure in the water diversion pipeline, the water diversion system and the generating units of the power station will be destroyed. Transition process calculation has an important role in the design process of the hydropower station. It is directly related to the safety and reliability of hydropower station operation. The rationality of the calculation of the hydraulic transient process, is related to the design of diversion system and the safe operation of the hydropower station as well as the quality of the power supply.In this paper, Mu Zhati third hydropower diversion system for the study background, according to the characteristic line method, using the MATLAB/Simulink toolbox to build hydraulic transition process simulation model station, then carry out simulation analysis. Carrying out computer simulation study on large fluctuations and small fluctuations of hydropower station of Mu Zhati third hydropower station. The main research results of this paper are as follows:(1)In the selection of the optimal closing time of the guide vane of the turbine, with respect to load rejection, calculation for different guide vane closing time. Fitting analysis the simulation data, and the fitting curves of the speed increasing rate and the inlet pressure of the spiral case were obtained. Choosing the reasonable guide vane closing time of Mu Zhati Hydropower Station as 8 seconds.(2)Adopt the method of enlarging surge upper section area, by calculating water level of different surge upper section area, we can see that the larger surge upper section area, the lower surge water level; the lower elevation of surge upper section area change, the lower surge water level, the more can meet the requirements. After comparison, choose a adjustment program that on the elevation of 2172.00 m to increase the surge upper section radius to 11 m which can not only meet the water level requirement but excavated volume is small.(3) The transition process of load shedding and load shedding can cause a rise in speed turbine units and dramatic change of system parameters such as pressure increases. When the upstream water level is dead water level, it can’t meet four units together to produce electricity. In other conditions, the surge chamber water level, the unit speed increase rate and the inlet pressure of the spiral case are within the control range. Small fluctuations in the water system and the small fluctuations in the water turbine in accordance with the requirements of the specification. Hydraulic anti-interference ability is strong surge chamber under hydraulic interference, fluctuation processes are convergence and meet the hydroelectric station transition process calculation requirements. Simulation results of hydraulic transition process show that using MATLAB to simulate the transitional process a feasible method. This method has the characteristics of simple parameter value change and short simulation time. This is a kind of economic and efficient research method that can solve the problems in the construction of the physical model and the parameter change of the hydropower station, and also can reduce the input of manpower, material and financial resources.