Multivariable Constrained Predictive Control With Applications To SCR Denitration System

In recent years, with the emission standards become more and more stringent, the control of SCR denitration system is particularly important. Because SCR denitration system is a large delay and inertia object with some non-linearity and input and output constraints, the traditional control strategy is often difficult to obtain satisfactory control performance under new emission standards.Model predictive control can predict the future output based on historical information and is able to control the inertial object as well as handle the constraint prevalently existed in control process. Therefore it has broad application in the control of SCR denitration.Firstly, in this paper, based on the particularity of the actual object of SCR denitration system (SCR reactor has A, B two sides) and the way of assessment for NOx in coal-fired power plant (assessment point is located in the chimney entrance), a multivariable control system is designed. For the constraints, the corresponding constraint solving method is given and with the theory of zone control introduced to predictive control, effectiveness and superiority of the control algorithm is proved. Secondly, for the model mismatch in control process, based on the Laguerre model, an adaptive model predictive control algorithm for denitration system is obtained by reserving the advantages of coordination control for ammonia injection valves and zone control. The final simulation shows the algorithm is better adapted to the model changes. Finally, based on MATLAB and C++ platform, the predictive control algorithm in denitration side is integrated into predictive control software. With the software being applied in the power plant, the control performance is analyzed and some corresponding solutions are provided for the certain problems.