Optimization control for the coordinated system of an ultra-supercritical unit based on stair-like predictive control algorithm

This study proposes an optimal control scheme for the coordinated control system (CCS) of an ultra-supercritical unit. This scheme utilizes a stair-like predictive control algorithm as the core to solve fundamentally the control problem of large delay and inertia in boiler combustion and integrates the feedforward and decoupling control concepts to preserve the traditional control experience. This study aims to provide technical support for the clean and efficient use of coal and the large-scale consumption of renewable energy sources in China. Non-real-time and real-time simulation results show that the scheme can achieve optimal control for each controlled variable, especially in the decoupling control mode; moreover, the fluctuation of each controlled variable is considerably reduced, and the adjustment of each control variable is stable, thereby improving the stability and anti-interference capability of the CCS. From the perspective of practical application of engineering, the research results have been directly productized and applied to practical engineering, the engineering application shows that the control performance is basically consistent with the simulation, the response rate of the unit is considerably increased, and the fluctuation of main steam pressure and mid-point temperature is considerably reduced. In this case, the proposed scheme can guarantee the safety, stability, economy, and flexibility of the unit operation.