A New Nonlinear Coordinated Control Strategy for Coal-Fired Boiler-turbine Units

This paper presents a new nonlinear coordinated control strategy for overcoming the influence of process nonlinearities and improving the load-following capability of coal-fired boiler-turbine units. A feedback linearization law is deduced via the dynamic extension algorithm of vector relative degree for a typical boiler-turbine unit model. By the law, exactitude feedback linearization in universal can be realized. And then a two-degree-of-freedom I-PD structure is presented to improve the robustness and exact tracking ability of the pseudo-linear object which is obtained by the feedback linearization law. The parameters of I and PD controllers are tuned by comparing with the corresponding coefficients of an anticipant close-loop transfer function matrix. Several simulations based on a real 500 MW boiler-turbine unit model are tested to prove the performance of the developed nonlinear coordinated control strategy.