Multi-model Robust Control For Superheated Steam Temperature Of Thermal Power Station

Superheated steam temperature control is one of the most basic and challenging problems in the operation of power plant boilers.In order to maximize the operating efficiency of the unit without damaging the superheater,the pressure and temperature of the steam at the outlet of the superheater should be strictly adjusted.The superheated steam temperature system has the characteristics of large delay,large inertia and uncertainty,so the conventional PID cascade control method is difficult to achieve satisfactory control results.Aiming at the nonlinear problem of superheated steam temperature control of power station boiler,the temperature characteristics of superheated steam are analyzed comprehensively,taking into account the factors such as imprecise model and disturbance in the actual industrial field.a multi-model robust controller is used to control the superheated steam temperature.The main work is as follows:（1）since there is no global model of superheated steam temperature in the existing literature,through the comprehensive analysis of the characteristics of superheated steam temperature,the original four operating point models are interpolated by particle swarm optimization algorithm.the global model of superheated steam temperature is obtained.（2）the robust controller is solved by the method of linear matrix inequality,the original robust H_∞controller and robustH_∞/H₂ controller are improved,and the design matrix of the controller is extended by introducing relaxation variables.the gain matrix of the controller is decoupled from the Lyapunov matrix variables.compared with the original method,the improved controller design method is less conservative and improves the performance of the controller to a certain extent.（3）for the superheated steam temperature system in the full load range,a multi-model robustH_∞/H₂ controller is designed by using the weighted algorithm of mixed output and robust control theory.Taking the load as the dispatching variable,the simulation and comparison experiments are carried out for the superheated steam temperature system in the full load range.The results show that,compared with the original multi-model robust controller,the proposed multi-model robust controller has better control effect and robustness,and the conservatism of the controller design is reduced to a certain extent.Many problems existing in the actual industrial field can also be better dealt with,and it is easy to be applied in the actual industrial field.