Research On Advanced Control Of Coordinated Control System For Power Units

A coordinated control system is the control center of a power generation unit, and is the core of a modern power plant. This dissertation studies the design, tuning, and implementation of the coordinated control system of a power unit via linear multivariable and nonlinear control theories and methods, with the motivation to apply advanced control strategies in engineering practice and to improve the adaptability of the coordinated control system to the process nonlinearities.The main contributions of this dissertation are summarized as follows:(1) A simplified nonlinear model of a power unit is chosen as the basis of this dissertation by extensive selection and comparison based on physical principles. The typical model has a simple structure and can represent a wide range of power units, so it is suited for the design and synthesis of coordinated control systems.(2) A systematic research on the applications of linear multivariable methods in the coordinated control systems is done. A coordinated controller with a PID form is designed via decoupling method and internal model control method separately. Combining with the field tests, a practical tuning procedure for the coordinated controller is proposed.(3) The proposed design and tuning method for linear multivariable coordinated controllers are successfully applied to a 330MW power unit, by the overall structure design and combination with many control methods such as feed-forward, feedback and multi-model.(4) A direct nonlinear control of the coordinated system is studied via feedback linearization theory and its extension. By introducing measurable state variables, a simplified form of feedback control law is deduced, which can reduce the integral order of the pseudo-linear boiler-turbine system. Combining with a two-degree-of-freedom I-PD control structure, the proposed method can improve the robustness of the pseudo-linear system.