Modeling Of Supercritical Unit Based On Modelica And Study Of Multi-Model Predictive Control

The coordinated control system of the supercritical unit is a complex nonlinear system with strong coupling, large delay, time-varying parameters and immeasurable disturbances. Using the traditional control method is often difficult to achieve satisfactory control performance, so it needs to search for new control strategies. The researchers need to understand features of the unit well, then to adopt the appropriate control strategy. So an accurate mechanism model reflecting the static and dynamic characteristics must be first established. Multi-model predictive control algorithm has become a practical and feasible method. The main contents are as follows:1.Based on the object-oriented modeling language Modelica and lumped parametric method, the mechanism models of the pulverization system are built to add to the existing model libraries, such as the coal-media models, coal feeder models, mill models and separator models. Based on the established model libraries, the model of a 600 MW supercritical unit is established by system combination. With the Dymola simulation platform, the main technical parameters’ dynamic response characteristics are studied.2. Due to the immeasurable disturbance of the coordinated system of the unit, a multi-model predictive control algorithm considering immeasurable disturbance compensation is proposed. A modified decoupling and disturbance observer based multi-model dynamic matrix control (DeDOBDMC) is proposed to handle the coupling effects and immeasurable disturbances. Finally, the simulation results are provided to verify the effectiveness and excellent control performances of the algorithm.3.The coordinated control software based on multi-model predictive algorithm is developed. The software solves a lot of practical engineering problems, such as the design of software architecture, system communication realization, the modifications of the DCS configurations, the tracking and undisturbed switching in two controllers. These worksare essential to the application of new control method.