A fuzzy controller for the steam generator water level control and its practical self-tuning based on performance

The water level control system of the steam generator in a pressurized water reactor and its control problems are analysed. In this work a stable control strategy particularly during low power operation based on the fuzzy control method is studied. The control strategy employs substitutional information using the bypass valve opening instead of incorrectly measured signal at the low flow rate as the fuzzy variable of the flow rate during low power operation, and includes the flexible scale adjusting method for fast response at a large transient. A self-tuning algorithm based on the control performance and the descent method is also suggested for tuning the membership function scale. It gives a practical way to tune the controller under real operation. Simulation was carried out on the Compact Nuclear Simulator set up at Korea Atomic Energy Research Institute and its results showed the good performance of the controller and effectiveness of its tuning. 13 figs., 3 tabs., 7 refs. (Author)