Robust wide-range control of steam-electric power plants

To facilitate daily cycling of large electric generating units that were originally designed for baseload operation, the control system has to be redesigned for plant manoeuvrability over the operating range. A methodology for synthesizing an integrated feedforward-feedback control (FF/FBC) strategy is proposed for wide-range robust control of commercial-scale steam-electric power plants. In the proposed methodology, the feedforward control policy is generated via nonlinear programming for simultaneous optimization of all control inputs under specified constraints. The feedback control law is synthesized following the H_∞-based structured singular value (μ) approach to achieve the specified stability and performance robustness. The major features of the integrated FF/FBC system are: 1) optimized performance over a wide operating range resulting from the feedforward element; and 2) guaranteed stability and performance robustness resulting from the feedback element. To exemplify this control methodology, a family of FFC policies has been synthesized based on a nonlinear state-space model of a 525 MWe fossil-fueled power plant. The results of simulation experiments are shown