Research On Nonlinear Coordinated Control System Of Supercritical Unit

Under the background of the state's advocating the sustainable development of energy,with the increasingly serious environmental problems,supercritical coal-fired power generation units are playing a leading role in the field of thermal power generation due to their advantages such as low power consumption and low pollutant emission.On the other hand,wind power,solar power and other new energy power generation mode has a great impact on the power grid frequency.At the same time,the power grid's demand for fast response load instructions of thermal power units is increasingly demanding.The characteristics,such as large delay,strong nonlinearity and strong coupling of supercritical units,have higher requirements for control quality of unit coordinated control system.Therefore,it is of great significance to analyze and optimize the nonlinear coordinated control system of the supercritical unit to improve the safety and economy of the operation of the unit.The internal structure and dynamic and static characteristics of supercritical unit are introduced and analyzed.Based on the Gramian method,the controllability and observability of supercritical unit control system is analyzed,and the dynamic model of supercritical unit is simplified.Based on the mechanism analysis method and the IAPWS-IF97 standard,the water wall is segmented.It is effective to solve the difficult problem of changing the working state of boiler water wall under supercritical conditions.Taking the structure and operation parameters of a 1000MW supercritical once through boiler as an example,the thermal storage coefficient of the boiler is calculated in detail,and the calculated result is in line with the actual value of the unit during operation.The basic knowledge of dissipative theory is introduced in detail.A stabilization control law for a class of three input three output nonlinear systems is presented.In the theorem proving process,the construction process of the system stabilization control law is systematically expounded.The control method is applied to the dynamic model of the supercritical unit with condensate throttling,and the L₂ gain controller of the supercritical unit is designed.The simulation results show that the L₂ gain controller of the supercritical unit is superior to the traditional PID controller in the control quality under the condition of load setting disturbance,anti-jamming performance and wide range variable conditions.In order to apply the dissipative theory to the practical engineering,the dissipative theory is combined with the traditional PID controller.This paper introduces the construction method of state feedback control law for a class of linear systems,and the construction method of stabilization control for a class of two input and single output nonlinear systems.The dynamic model of supercritical units is simply preprocessed,and the processed model is divided into three independent subsystems.According to the subsystem structure,we use the above system control law construction method to design each subsystem controller.Finally,the integrated subsystem controller is a dissipative PID coordination controller for the supercritical unit.The simulation results show that the control effect of the controller can meet the requirements for the coordination control system of the supercritical unit.