Modeling and LQG/LTR control for power and axial power difference of load-follow PWR core

• The two-point based model of a nonlinear PWR core is built.
• Linearized core models of two cases are proposed.
• Two linear models of core are augmented.
• LQG/LTR robust control is used to design controllers of the core.
• Two theorems are deduced to analyze the stability of the control systems.

The task of this investigation is to design a nonlinear Pressurized Water Reactor (PWR) core load following control system for regulating the core power level and axial power difference. A two-point based nonlinear PWR core model without boron and with the power regulating rod and Axial Offset (AO) rod is built. The linearized single-input single-output (SISO) or multiple-input multiple-output (MIMO) core model under Case 1 or Case 2 classified by two movable regions of power regulating rod is constructed. The linear SISO or MIMO model is further augmented with additional integrators to cater to the control design. The Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) robust optimal control is used to contrive a controller of the linear core model of each case. For Case 1 (Case 2), the nonlinear core model and the LQG/LTR SISO (MIMO) controller construct the nonlinear PWR core load following control system. Two stability theorems are deduced to define that the nonlinear core load following control system of each case is asymptotically stable. Finally, the control system of each case is simulated and the simulation results show that the control system is effective.