Active disturbance rejection control for the reheated steam temperature of a double-reheat boiler

As a state-of-the-art thermal power generation technology with high efficiency and low emissions, the double-reheat boiler is facing many control challenges on the reheated steam temperature (RST), such as nonlinearity, coupling, and large inertia lag. However, the widely used Proportional–Integral–Derivative (PID) may not efficiently handle these challenges. To this end, a control scheme based on active disturbance rejection control (ADRC) is synthesized, after analyzing the nonlinearity of the system and the decoupling of a control structure for the mean and deviation of temperature (MDT) in the frequency domain. The distinctive features of the proposed scheme are (i) the MDT structure is utilized to decouple; (ii) Modified active disturbance rejection control (MADRC) is used to handle large inertia lag; (iii) the compensation part of MADRC is adaptive to load, and the temperature setpoints and feedforward modules are optimized to reduce nonlinearity. The superiority of the proposed control system is examined by simulation experiments. Lastly, ADRC was successfully applied to the practical RST system, showing better temperature control quality than the initial manual mode. The analysis and practice in this paper demonstrate the feasibility of ADRC for the RST system and offer guidance for further study on RST control.