Optimization control of a 330 MW drum boiler unit based on DMC algorithm and DEB strategy

This paper firstly established a nonlinear dynamic model of a 330 MW drum boiler unit, which has a clear physical meaning and is conducive to the design of coordinated control system (CCS). On this basis, the boiler energy storage coefficient is calculated, and its relationship with that in direct energy balance (DEB) strategy is analyzed. Secondly, this paper proposes a CCS based on dynamic matrix control (DMC) algorithm and DEB strategy, in which: (1) energy demand and status signals of DEB are taken as the setting point and process value of DMC controller, so as to overcome the internal disturbance of the boiler; (2) a compensation signal is constructed as the feedforward input of DMC controller, so as to overcome the external disturbance of the turbine and realize the timely utilization and supplement of boiler energy. Simulation shows: (1) there is a certain deviation in main steam pressure when the energy demand and status signals are taken as the setting point and process value, but this is an illusion of insufficient energy, and in fact the energy status can already meet the demand; (2) compared with the main steam valve, the constructed compensation signal takes into account more operating parameters of the unit, which greatly improves the accuracy of the compensation. Practical application shows: the grid dispatch order can be well tracked by the unit, the maximum deviation of main steam pressure is ±0.6 MPa in constant pressure mode, and that is ±1.2 MPa in sliding pressure mode, thereby improving the control performance of the unit under high, medium, low, and overall load conditions.