Design Of Engineering Application On Holistic Robustness For Boiler-turbine Coordinated Control System

The definition of the generalized robust system was that the robust system still has the prospective performance, although, there are prominent uncertainties in the control system. The model of the coordinated control system in the thermal power plant with drum was described as a double inputs/double outputs object of feed coal flow and jaw opening of the turbine versus the unit load and the throttle pressure. Lots of mechanism analysis and engineering practice show that the time-variant characteristics was the main reason affected the performance of the control system except the characteristics of nonlinearity, big inertia, multi-variables and strong-coupling. The requirement for load response velocity of thermal power units was improved continually. The coal quality became very unstable for the rising price of the primary energy. So it is difficult for the traditional coordinated control system scheme to meet all of the control indexes.Using the combination method of mechanism modeling and data analysis, the process of modeling for the object of unit load versus throttle pressure was researched. And the model was linearized. Based on the statistical analysis on the operation data of the units, the change scope and the change law of the main parameters were gained. The basic coordinated control system of boiler following and turbine following was designed. The influences of every parameter on the control performance were researched by comparing the different control structure. The simulation results show that the operation point of load-pressure, the changes of the heat value of coal, the grindability index, the exhaust steam pressure and the heat storage coefficient and the disturbance will cause the decreasing of the control performance due to the big inertia and big lag of the object.The performance of a robust coordinated control system design method was tested in simulation platform, that is unidirectional decoupling coordinated control system with boiler following. And the results show that the control performance was enhanced greatly. The key issue was the engineering design of the decoupling link. By balancing the change and the change law of every parameter, a representative operation point was gained to set the controller parameters, and to ensure the finer control performance of the coordinated control system within the scope of50%-100%load, the heat value of coal, the grindability index, the exhaust steam pressure and the boiler storage coefficient.Based on the overall simulation test of the scheme and the load-pressure model of600MW direct air-cooling unit under the representative operation point, the turbine-boiler unidirectional decoupling coordinated control with boiler following mode was designed. And the parameters of controller were set and debugged. The response velocity of load and the primary frequency index can meet the requirement of the power grid, and the fluctuation of the throttle pressure can satisfied the safe requirement of the boiler. The control system has finer control performance.