Study Of The Constrained Generalized Predictive Control Based On Compensation For Model Errors For Generating Unit In Heat Power Plant

Generating Unit in heat power plant is a multivariable, strong couple and long time delay complex nonlinear system. It is difficult to set up the exactly mathematic model and it is a challenge for the design of the control system. Generalized Predictive Control (GPC) has emerged as a powerful control strategy that has been widely applied to complex industrial processes. Since 1987 when it was presented, GPC has been fully developed in theory and proved to have a good control performance. As is logical, however, it also has some disadvantages in the practical applications. Current Generalized Predictive Control algorithm, commonly whose predictive model of predictive output is based on the mathematical model, rarely considers of the influence of model error. Though common GPC algorithm has some restraining influence on model mismatch, the restraining ability is limited.After reading abundant relevant literature, this paper presents the constrained GPC algorithm based on compensation for model errors. This algorithm uses error predictive to compensate predictive based on model, and the control strategy is attained by quadratic programming. For Generalized Predictive Control, constrains are imposed on the magnitude of input and its velocity, and the magnitude of output. Finally, the proposed method is applied to the simulation of the coordinated control system of 300MW unit, and the simulation results show that the controlled system has quicker load-tracking ability and better characteristics of overcoming disturbances and stronger robustness. The control performances are improved compared with the traditional PID fixed value control, and the proposed method has more practical values in the Generating Unit in heat power plant.