Dynamic Matrix Control for Cold Helium Temperature of Multi-Modular High Temperature Gas-Cooled Reactor Plant

Abstract The coordination control strategy for operational multi-modular high temperature gas-cooled reactors primarily considers process variables such as neutron flux, main steam temperature, and hot helium temperature, yet it does not address the control of cold helium temperature. Inappropriate cold helium temperatures can lead to structural material fatigue, impact the lifespan of instrumentation at the core’s top, and consequently degrade the operational reliability of nuclear power plants. Additionally, cold helium temperature reflects the thermal balance between the primary and secondary loops, underscoring the necessity of controlling cold helium temperature. In response, a method using dynamic matrix control (DMC) is proposed to control cold helium temperature by adjusting the hot helium temperature setpoint. A step response model with cold helium temperature data is used to design DMC. Utilizing the stability of the existing proportional-integral-derivative (PID) controller and the optimization capabilities of DMC, a cascaded control structure is established. PID acts as the inner loop for stability, and DMC as the outer loop corrects the hot helium temperature setpoint, achieving cascaded control for cold helium temperature in multi-modular high temperature gas-cooled reactors. Numerical simulations based on a 1000MW ten-module high temperature gas-cooled reactor program validated the effectiveness of the proposed control method. The results demonstrate that the controller can effectively regulate the cold helium temperature without compromising the control of other key variables.