PHYSICAL MODEL FOR PREDICTIVE PLANT-WIDE CONTROL OF A GENERATING UNIT

This paper describes the formulation of an object-oriented model of a 200MW power plant and its use in plant-wide model based controller. The cost of development of the physical model has been significantly reduced by the use of object oriented technology. This cost is usually the prohibitive factor when incorporating physical models in control schemes. The controller makes effective use of the physical plant model in a non-linear model predictive controller (NMPC). The NMPC is based on an EKF estimator and a linear model obtained by continuous linearisation and discretisation of the non-linear physical plant model. The NMPC provides an optimal load demand (or set-point) transition by effective handling of plant-wide interactions and system disturbances. Use of a physical state-space plant model facilitates application of constraints on state variables in addition to input and output variables. Metal temperatures of heat-exchanger tubes are modelled as state variables in the non-linear plant model.