Supercritical machine set steam temperature control method and system based on multivariable predictive control

The invention provides a supercritical machine set steam temperature control method and system based on multivariable predictive control. The method includes the steps of: conducting pre-stage designing of a multivariable predictive controller to determine the control variables, the controlled variables and the disturbance variables, wherein the control variables include first stage temperature reducing water spray, second stage temperature reducing water spray, reheated temperature reducing water spray and the opening size of a fume gas baffle, and the controlled variables include main steam temperature and reheated steam temperature; discriminating a module of a process object and building a multi-input and multi-output step response model of the steam temperature system by applying step disturbance, simulating the multivariable predictive controller and adjusting the parameters of the multivariable predictive controller according to the built step response model; starting the multivariable predictive controller and switching the multivariable predictive controller from the simulated state to the actual online operation and control state and applying the output of the multivariable predictive controller to a controlled object to carry out real-time control. The supercritical machine set steam temperature control method and system can well ensure that the overheated steam temperature in a boiler is within the required range.