Research On The Water Level H_∞ Robust Control Of Steam Generator Of Nuclear Power Station

With the continuous improvement of the construction of a new energy system,nuclear power has become an important direction for China’s energy development with its clean and efficient advantages.The steam water level control system is an important part of the control system of the nuclear power plant.The stability of steam water level plays an important role,which is characterized by strong interference and strong nonlinearity.Due to the complex dynamic characteristics of the system and the serious false water level under low working conditions,it is difficult for conventional control to achieve good results.In this paper,the robust model predictive control strategy is applied to the design of the steam water level control system,which can effectively suppress the interference of the system and ensure the safe and efficient operation of the steam water level control system.Based on the study of the dynamic characteristics of the steam water level,combined with the robust model predictive control theory,this paper designs a controller that meets the requirements of the actual system.The main contents of this paper are as follows:(1)For the mathematical model of the steam water level,the dynamic characteristics of the water level of the steam generator are first explored,the causes of the "false water level" phenomenon are analyzed,and the simulation verifies that the "false water level"phenomenon of the system under low working conditions is more serious.In order to solve this problem,on the basis of Irving’s proposed water level model,the water level error integral is introduced,and a spatial model of steam water level augmented matrix is constructed,using Linear Parameter Varying(Linear Parameter Varying,LPV)theory establishes the LPV augmenting model of steam water level.(2)Aiming at the control problem of steam water level,based on the LPV augmenting model of water level,the H∞ robust controller of the steam water level is constructed.Based on the H∞ robust control theory,a fixed-gain H robust controller and variablegain H∞ robust controller are designed,and the effectiveness of the controller is verified by simulation.In order to highlight the advantages of the controller,it is compared with H∞ robust controller designed when the system model is not introduced into the tracking signal.Compared with the controller designed without the tracking signal in the system model,the results show that the design is positive based on the augmented model.The results show that the H robust controller designed based on the augmentation model has better control and tracking performance.(3)Aiming at the inherent problems and external disturbance problems of steam water level system,a robust model prediction controller with mixed H2/H∞ index is designed.On the basis of the steam water level augmentation state space model,according to the definition of membership function,the model at 5 stable operating points is fuzzy weighted to fit the global model of the system.Mixed H2/H∞ Robust Model Predictive Controller is designed by combining the H2/H∞ index theory and robust model predictive control theory.Aiming at the problem that the previous Mixed H2/H∞ Robust Model Predictive Controller can not guarantee the recursive feasibility of the system.By adding new constraints,the system has a guarantee of stability and good control performance.