Optimization Control Strategies And Application Studies In Thermal System Of Power Plant

Developing with the tendency to large capacity,high parameters and high efficiency of ssil-fired unit,the most thermodynamic objects have large inertia and delay,and are nonlinear and slow time-variable;some of them are multi-variable has large uncertainty and strong coupling.This makes it difficult to construct accurate mathematic models,and makes PID controllers with fixed parameters unadapted to higher and higher control request in production.So the optimization control strategies of thermodynamic objects are studied in the paper to improve the control performance.After the concept of "time scale" about control system is presented,the method of engineering setting PID controller parameter designed which can complete overcome the limitation of the controlled object.And the Optimization Control Stratedies(Opt) is designed on the basic of analysing the characters of time-domain and frequency-domain of second order system.A state observer(OD) based the classical dynamic equation is designed,it is proved that the OD is correspondence,asymptotic and steady,and the SCOD control system is designed on the basic of OD,which can not only cancel the inner and outside disturbance of system,but also obtain better robust quality.Aiming at the time-unvarying delay control system,the two-step method of engineering setting PID controller parameter is designed,which can overcome effectively the influence of time-delay by adjusting an advance coefficient of PID,this makes adjust PID controller parameter of time-delay control object simplity.Aiming at the time-varying delay control system,two kinds of improved methods are presented.One is the improved Smith-predictor,which may direct compensate the system and cancel the influence of uncertainty factors by adding the Opt optimization strategy.The other is a state observer based the pole assignment,which can avoid effectively the dynamic decination and improve control performance by decomposing the time-varying delay system with several small time constant first-order system.A General Controller is designed on the basic of classical dynamics equation; which can make the controlled plant output is controlled and the desired output can be obtained by using feedback control of position,velocity and acceleration of the General Controller.And the paper analyses that PID controller,state feedback controller,robust controller,inner model controller and GPC/MPC controller are identical in classical dynamics.The programmed designing method weighting function in robust controller designing is presented,which can make the robust controller designing simplity and utility.And the non-linearity PID and self-correction PID controllers are designed, which can improve the shortcoming of PID controllers and the robust performance of system.The feedback linearization,system lacunarity and optimization control of the nonlinear control system are discussed.