Efficient Linearized Model of Pressurizer System in Pressurized Water Reactors for Control Purposes

Abstract

The pressurizer has an important role to ensure the protected operation of pressurized water reactor (PWR) by keeping the reactor coolant system pressure among allowed tolerances. In this paper, a non-equilibrium two-region nonlinear pressurizer (PZR) model was linearized using Taylor technique to introduce the linear models of pressurizer transients for the controller design purposes. Taylor series expansion of functions around an equilibrium point was calculated. The same assumptions of the reference model are considered in linearized model. The linearized model consists of five states; rate of changes for: mass of steam &water in the PZR, mass of water in the PZR, mass of water in the PC, steam temperature in PZR, and water temperature in PZR. The nonlinear and linear PZR models was implemented in MATLAB/Simulink. The linearized model of PZR is verified. The performance of linearized model of PZR and nonlinear model is consistent with small and acceptable errors. The closed-loop of the linearized model of PZR pressure and water level is implemented and investigated using standard Proportion-Integration-Differentiation (PID) controllers. Simulation results and the evaluation performance indicate that the proposed linear model of PZR is efficient, and it can be used for control purposes.