Research On Water Level Sliding Mode Control System Of Nuclear Steam Generator

In order to ensure the safety of nuclear power plant during operation, the U-Tube steam generator's water level must be controlled in a certain range. The control problem is challenging due to its "swell and shrink" effect, in addition, the dynamics of steam generator varying as the power level changes. The cascade PID control system of steam generator level is prevalent used in nuclear power plant. However, limited by the technology development, it does not make its best effect.In this paper, a gain scheduled sliding mode control (SMC) method is developed for the U-Tube Steam Generator (UTSG) level control problem. Based on Irving's lumped parameter level model, Linear Parameter-Varying (LPV) theory can describe the non-linear behavior effectively with dependency parameters. In the first place, the system's states are assumed all measured,a piecewise dynamic sliding mode control method based on pole-assignment and a robust global sliding mode controller based on Linear Matrix Inequalities (LMI) for water level control is presented, and simulation shows the effectiveness of the proposed method. In the second place,this paper, applying robust control theory,dynamic output feedback sliding mode controllers under different operating conditions are proposed. Furthermore, an inner-loop/outer-loop dual-loop control structure of the UTSG level control system are studied, on the basis of this structure, traditional PID controller is introduced, which formed the hybrid control system of nuclear water level. The simulation results show that the designed control system has good control performance. Finally the performance of three sliding mode control systems studied in this paper is evaluated by calculating their values of Mean Square Error(MSE) and values of Maximum overshoot(MO), In addition, we check the strong robustness of the proposed methodology if the water level model with parameter uncertainty and external disturbance.The simulation results show that the three control systems have good control quality in different conditions and each has its peculiarity. This effort could provide some guidance for design of advanced control system of UTSG water level.