Decoupling and controller design of multivariable systems for small modular reactors

Abstract According to the characteristics of multi-variable control object in small modular reactors control system, a design method of control system is presented in this paper. Firstly, the nonlinear differential equations of the system are constructed according to the principle of mechanism modeling, and then the transfer function of the system is obtained by linearization. Then, the coupling characteristics of the system are analyzed by using Gershgorin Circle Theorem in modern frequency domain analysis method. On this basis, the inverse Nyquist array method is used to decouple the two key channels of reaction-exit temperature channel and feed-water valve-steam pressure in small modular reactors. Then the PI correction network is designed by frequency response method. In order to fully verify the performance of the decoupling controller, the system is verified based on linear model and nonlinear model respectively, and the pre-compensation matrix processing strategy under variable load conditions is proposed. Simulation results show that this method can significantly reduce the coupling degree between the two channels, and the performance of the control system after decoupling is significantly improved compared with that before decoupling.