The Nonlinear Model And The Control Method Of The Bulb Hydraulic Turbine

The Bulb Hydraulic Turbine is one kind of newer turbine than traditional turbine.For example mixed flow,axial flow and counterattack turbines.Its main characteristic is to adapt to the development of low head water power resources,and its flow rate is larger,which brings higher speed of this kind of turbine.So the free wheel moment of force is low for this kind of turbine.Between the load rejections,the race of speed is very fast.At the same time,because of the low-water and the large flux,this kind of turbine has the large current inertial constant.Besides,the Bulb Hydraulic Turbine appears rather later,the research of its characteristic curve is incomplete.Finally,the characteristic curve is difficult to acquire.This problem makes the difficult for the modeling.The hydro turbine system involves the complex problems,including the liquid,machinery and electric,these problems are interrelated.The nonlinear characteristics of the system is particular prominent.For the normal turbine regulator,most of them use the PID control method.This control method is difficult to resolve nonlinear when the electrical power system is running.So it is dependent on this multi-index nonlinear control method to counter change the state equation of the system,in order to get an appropriate control law for the hardware.The mentioned method could get the complete or partial Linearization steady state equilibrium point in some part,and get a new control strategy.This kind of control could improve the control performance to a certain extent.This mean of control method could solve some control problems of nonlinear model in power systems.Because of the traditional transfer function method,it is difficult to model the tubular turbine.In this paper,a common equation of state in hydraulic engineering design and calculation is used to assist in obtaining relevant parameters.These methods are seldom used in the modeling of hydraulic turbines in power systems.Using the hydraulic turbine state equation in the transition process of hydraulic machinery,combining the transfer function of hydraulic turbine,substituting some known running points,under the absence of a hydraulic characteristic curve,with the aid of the transition process equation,the remaining parameters of the operating point are solved.The coefficients of the state equation are solved by using the parameters of these running points.By this way,a simulation model of the Kaplan turbine can be obtained.Then,finding the relationship between blade and blade copilot control,combining the two order generator equations,a nonlinear equation of state with multiple inputs and outputs is formed.Then,a nonlinear control law is solved by the multi index nonlinear control method introduced in this paper.Finally,a hydraulic turbine simulation model is established under different control methods.MATLAB simulation is used to verify the reliability of the simulation model of tube turbine.The characteristics of traditional PID control method and multi index nonlinear control method are compared.From the running curves of the two simulation models,on the one hand the running curves of the hydraulic turbine operating characteristics show that this modeling method has high reliability and wide adaptability;on the other hand it can also be proved that the multi index nonlinear control method is more effective than the traditional PID control.