Research On Coordination Control Method Of Boiler-Turbine-Grid Based On Predictive Control

With the increasing proportion of new energy in power grid,traditional thermal power units are facing opportunities and challenges.In this paper,an intelligent predictive control method is designed for supercritical units,which is different from the traditional control method.It not only prolongs the life of the units,but also improves the ability of the units to participate in frequency modulation.Firstly,a supercritical unit model is established to study the coordinating of boiler,turbine and grid.Based on the combustion,feed water and cooling water system of supercritical once-through boiler,and the model of condensing steam turbine is established based on the control mechanism of primary and secondary frequency regulation.Secondly,the coordinated advanced control strategy is designed based on the boiler control system.On the basis of qualitative comparison of different advanced control loop mechanisms,this paper quantitatively analyses the energy status of boilers and units,puts forward a coordinated intelligent advanced control strategy for boiler and engine.Different amendments are given at the burning rate command for different states,which effectively suppresses the fluctuation of main steam pressure of supercritical units and improves the load following characteristics.Then,based on model predictive control,this paper adds additional correction to the regional control deviation to predict and adjust the regional frequency reference value online,thus improving the frequency regulation effect of supercritical units.Finally,the contribution of the proposed control method to the unit at the boiler side and the grid side is quantitatively studied.At the boiler side,the effect of the new control method on the stress of supercritical units is studied quantitatively;at the gird side,the improvement of CPS and SCPS by the new control method is studied quantitatively.A comprehensive evaluation index system is established based on the vector angle cosine method,the weights of each parameter in the evaluation system are calculated.The simulation results show that the new control method can effectively improve the equipment and frequency modulation capability of supercritical units,and improve the performance of units in an all-round way.