Background: The proportion of nuclear power is gradually increasing in China’s energy structure. Purpose: On one hand

power grid and power plant coordination in the electricity grid system requires the nuclear power plants to adapt the needs of the peak regulation

frequence modification(FM)

and even the grid AGC(Automatic Gain Control) mode. On the other hand

it is necessary to design a control system that can adapt the model G for the operation requirements

and ensure the safe and economic performance. Methods: With an experimental reactor as the research object and MATLAB/SIMULINK as test toolkit

we designed an improved the reactor power control system

and adopted three-loop PID(Proportional

Integral

Derivative) control system to ensure the precision control of a control rod. Results: The simulation results show that the method presented in the paper achieved better tracking performance and robustness. It can work against the unmeasurable disturbances. Conclusion: It is of practical significance for the reactor participating in the peak regulation of power grid

and the three-loop PID control system shows its improvement for reactor power control.