Control of a PWR nuclear reactor core power using scheduled PID controller with GA, based on two-point kinetics model and adaptive disturbance rejection system

Abstract

Nuclear reactor dynamics has a non-linear nature, and some parameters depend on the output power level. Accordingly, a load-following issue is important. To this end, it is important to use the proper controller with a simple implementation such as a proportional-integral-derivative (PID). In this work, the load-following of a typical pressurized water reactor (PWR) is considered based on the two-point kinetic model and constant axial offset (AO) power-distribution strategy. Subsequently, the power level is controlled by the PIDs, which are tuned by a real-coded genetic algorithm (GA) with decision variables include the integral of time-weighted absolute error (ITAE) and a stability condition. The oscillations of the power distribution occur due to axial xenon oscillations in long-time operation conditions. Therefore, AO, normalized axial offset (ΔI), and axial xenon oscillation index (AXOI) must be considered. As well as, the Lyapunov approach is used to guarantee controlling system stability, and design an adaptive system to reject unwanted disturbance to the input of the plant. The simulation results show the high performance of the closed-loop real-coded GA-PID (RGA-PID) controller with the least errors. Also, the system outputs, ΔI, and AXOI are in the acceptable range based on constant AO power-distribution strategy, and these indexes are robust to parametric uncertainties of the dynamics model.