Application Of Multivariable Generalized Predictive Control Algorithm In Coordinated Control System

Although the proportion of thermal power generation in total power generation has decreased slightly in recent years,it is still the most important power generation mode.The coordinated control system(CCS)is responsible for responding to external instructions in thermal power units.Its principle is to regulate the output of boiler side and turbine side,complete the load command task and ensure the safe,stable and efficient operation of the unit.As an important part of unit control system,coordinated control system plays an important role in balancing the output of boiler and turbine and maintaining the stable and efficient operation of unit.As a typical predictive control method,generalized predictive control algorithm(GPC)has been mature both in theory and practice.Its application scope includes metallurgy,chemical industry,electric power,machinery,medicine and other fields.Especially for the object with large delay and large inertia,GPC algorithm has the advantages of low model accuracy,strong robustness and rolling optimization of internal parameters.Now the distributed control system(DCS)is widely used in power plants,and the coordinated control system should also be applied in this platform.In order to make generalized predictive control play a role in the control process of coordinated control system of unit,it is necessary to develop a generalized predictive control algorithm which can be applied to DCS system.In this paper,the coordinated control system of 600 MW supercritical unit full simulator platform is used to do the experiment of load command change,observe the control effect of PID algorithm,and identify the parameter model and dynamic characteristics of 600 MW load coordinated control system.After analyzing the control performance,this paper puts forward a control scheme using generalized predictive control algorithm instead of PID.In order to solve the problem that it is difficult to calculate the process of RAID inversion in PLC,an improved generalized predictive control algorithm is proposed to change the objective function and get the inverse RAID indirectly through identification.Then,combined with the characteristics of dual input and dual output of coordinated control,the multivariable generalized predictive control is deduced,and the program is compiled on PLC platform.The communication between PLC and DCS is connected,and the application of GPC algorithm in coordinated control system is completed.The results are compared with the original control strategy of the simulator,and the better control effect is obtained.