Comparative analysis on non-linear models of ultra-supercritical power unit and its simulation

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, two kinds of simplified non-linear model which are suitable for the controller design in coordinated control system of a once-through boiler-turbine unit are analyzed comparatively at first. Then the features and improvement suggestions of the two kinds of non-linear model are proposed. At last, Open-loop step forced simulation test and dynamic simulation for different operating conditions of the model are 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.