A steam generator model identification and robust H-infinity controller design with nu-gap metric for a feedwater control system

Abstract

A robust H-infinity controller for the feedwater system of KSNP (Korean Standard Nuclear Power Plant) vertical U-tube type steam generators (UTSG) is presented herein. As the first step of the controller development, a precise thermal-hydraulic model for the steam generator is built. A series of model experiments are per-formed using the developed thermal-hydraulic model in order to acquire the input-output data sets which represent steam generator characteristics. These data sets are utilized to build simplified steam generator models for control through a system identification algorithm, Simple Process Models. Among the developed steam generator models, the representative models for the designated power ranges are selected by a criterion of nu-gap metric. The representative robust controllers for the selected models are designed utilizing the loop-shaping H-infinity design technique. Finally. the robustness and performance of the proposed controllers are validated and compared against those of PI (proportional-integral) controller. The validation results demonstrated that the proposed H-infinity robust controller has a superior robustness and an enhanced control performance. (C) 2009 Elsevier Ltd. All rights reserved.