Load frequency control of multi-module high temperature gas-cooled reactor cogeneration unit based on nonlinear active disturbance rejection control

As the world's first Generation IV nuclear power plant, the HTR-PM demonstration project began commercial operations on December 6, 2023, and has since accumulated two reactor-years of operational experience. This achievement underscores China's leadership in the research and application of Generation IV nuclear technology. The multi-module high temperature gas-cooled reactor (mHTGR) cogeneration unit can supply hydrogen or steam for industrial uses by regulating high-temperature steam. Coordinated control is crucial for the safe and stable operation of the mHTGR cogeneration unit. Specifically, the coordination between electricity generation and the power system becomes critical when the unit connects to a district power system. The challenge of reconciling the rapid load-following demands of a power system with high renewable penetration and the safety constraints of the mHTGR cogeneration unit, coupled with the complex interactions among reactor modules sharing a common steam turbine in the secondary circuit, requires the development of an effective load frequency control strategy. This strategy must meet grid safety standards and its performance should be validated when advanced control algorithms are utilized for frequency regulation. Motivated by the distinctive attributes of nonlinear active disturbance rejection control (ADRC), including model independence, enhanced performance, and increased robustness, this study introduces a nonlinear ADRC-based controller for load frequency control in a specific mHTGR cogeneration unit. Performance comparisons among PID, linear ADRC, and nonlinear ADRC controllers highlight the superiority of the nonlinear ADRC approach. Comparative results indicate that nonlinear ADRC achieves reductions of 87.4% in the integral of absolute error (IAE), 97.9% in the integral of time-weighted absolute error (ITAE), and 94.5% in maximum dynamic deviation (MDD) under step disturbances, outperforming both PID and linear ADRC. Its model-independent nature and enhanced robustness further support its practical implementation in mHTGR cogeneration units.