| Hydroelectric power system as the most important part of hydropower station,the safe,stable and efficient operation is the fundamental guarantee for hydropower plant to ensure safe,high quality and economical power supply.In recent years,however,with the units of large capacity,high head,high speed are put into operation,the vibration of hydro-turbine generator unit and the stability of whole hydropower system are becoming more and more serious.Therefore,it is necessary to establish a more accurate nonlinear mathematical model of hydraulic power generation system by comprehensively considering the influence of stochastic disturbance,the complex external forces and internal parameters of the system,so as to explore the vibration characteristics and operation stability of hydropower system under the influence of stochastic disturbance and complex external forces.The main research contents and conclusions of this paper are summarized as the following three aspects:?1?For the problem of speed stochastic fluctuation of hydro-turbine governing system under the influence of multi-stochastic factors.This paper from the influence of stochastic factors on the hydroelectric power generation,on the basis of traditional nonlinear mathematical model of hydro-turbine governing system,the stochastic variables?1??2 and?3 were introduced into the flow q1,the bottom pressure of the surge tank h2 and pressure at the inlet pressure of hydro-turbine h3,respectively.So as to establish the multi-stochastic nonlinear mathematical model of the hydro-turbine governing system.Then the stochastic intensity was changed to 0.025,0.050 and 0.100,respectively.A large number of numerical simulation and data statistics by using Matlab,the influences of single stochastic factor,double stochastic factor and three stochastic factors on the stability of hydro-turbine governing system were analyzed,and some theoretical measures are put forward to avoid or utilize the stochastic factors in the system.?2?For analysis the influence of gyroscopic effect on the local and overall vibration characteristics of the hydro-turbine generator unit.This paper focused on the hydro-turbine generator unit of large capacity,high head and high rotation speed,a multi-degree nonlinear mathematical model of the hydro-turbine generator unit is established by considering the influence of gyroscopic effect,rotational inertia and unbalanced magnetic pull.Based on the actual installation parameters of a certain hydropower station,using the method of Runge-Kutta numerical simulation of the shafting model,and the influence of gyroscopic effect on the vibration characteristics of the generating unit is studied under different angular velocities?20rad/s,60rad/s,80rad/s,120rad/s?.The relevant conclusions can provide theoretical basis for the design,operation and safety evaluation of the hydropower set.?3?The hydraulic power generation system is a complex nonlinear system with Hydro-mechanical-electrical.The hydraulic factor,mechanical factor and electromagnetic factor in its operation process have a great influence on the stability of the whole system.To further study and analyze the influence low of these factors on the vibration characteristics of the system,the overall mathematical model of the hydraulic power generation system coupled with the hydro-turbine governing system with complex piping and the main shaft system of hydro-power generator unit considering the gyroscopic effect is established by analyzing the coupling relationship between the hydro-turbine governing system and the hydro-turbine generator unit.The influence of gyroscopic effect on hydraulic power generation system is explored through simulation,and the influence of different axial deviation?r=0.0001,r=0.0002 and r=0.0003?on the vibration response characteristics of hydro-turbine generator unit is studied on this basis.The relevant research conclusions can provide theoretical guidance for the design and installation of the unit,so as to minimize the vibration of the unit. |
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