Nonlinear finite-set control of clean energy systems with nuclear power application

For clean energy systems such as wind, solar and nuclear plants, the output power is usually regulated by controlling the motion rate of actuators, e.g. the stepping motors utilized for sun tracking of solar photovoltaic panels, yaw and pitch angle positioning of wind turbines and control rod driving of nuclear reactors. By constraining the actuators' motion rates to a finite set of values, the control system of a clean energy plant can be much simplified with obvious enhancement in operation reliability but requires developing finite-set control methods correspondingly. Motivated by the benefit of adopting finite motion rates, a finite-set control method is newly proposed for the nonlinear systems describing the dynamics of clean energy plants, compensating for the quantization and saturation effects induced by adopting a finite set of motion rates while ensuring globally bounded closed-loop stability strictly under a sufficient condition. The method is applied to design a finite-set power-level control of modular high temperature reactors, demonstrating stable power-level control during a reactor ramping-down from 100 % to 50 % reactor full power (RFP) with a constant rate of 5 % RFP/min. The simulation results also indicate that under the regulation of the finite-set control law, the steady error of hot helium temperature can eliminated, and the overshoot of neutron flux and that of hot helium temperature can be reduced by approximately 66 % and 75 % through properly adjusting control parameters, providing practical insights for engineering applications.