Design of stability and performance robust fuzzy logic gain scheduler for nuclear steam generators

A robust fuzzy logic gain scheduler (robust FLGS) is designed, based on the synthesis of fuzzy logic inference and the H_∞ technique. The robust FLGS has a set of robust control gains in a gain pool. The fuzzy inference engine chooses one of the most desirable control gains considering the steam generator (S/G) operating condition. The robust gains in the gain pool are obtained by the time-domain H_∞-control technique such that both of the weighted H _∞ norms of two transfer functions are minimized: the transfer functions between the steam flow disturbance and the mass capacity portion of S/G level, and the reverse dynamics of S/G. The FLGS rules are automatically generated using a genetic algorithm (GA). The GA gives a set of the gain scheduling rules that reflect given performance design specifications well. Computer simulation confirms that the proposed controller shows both guaranteed stability and good performance in terms of small overshoot and fast settling time in spite of S/G parameter variations and steam flow disturbances