Improvement of a non-linear model of ultra-supercritical boiler-turbine unit and its application

The characteristic of supercritical unit is not easily controlled, because the research on the coordinated control system of ultra-supercritical coal-fired (USC) power unit is usually based on a kind of mathematical model, which is used to test the correctness of the design concept and the effectiveness of the control strategy. If the mathematical model cannot reflect the intrinsic nature of the controlled object, the simulation results are difficult to explain that the control strategy designed is successful. In this paper, a simplified non-linear model which is suitable for the controller design in coordinated control system of a once-through boiler-turbine unit is analyzed at first. Then based on the study of the above model, features and improvement suggestions of the non-linear model are proposed. At last, step forced simulation test and comparison test with operation data were done to test the effectiveness and accuracies of the simplified non-linear once-through boiler model. Simulation results show that this model has same dynamic characteristics with the actual unit and can predict output changes with certain accuracy which means that it is fit for the controller design of coordinated control system of ultra-supercritical coal-fired (USC) power unit. This may serve as a reference for engineering analysis and simulator development of ultra-supercritical power units.