Design And Application Of Generalized Predictive Control For Boiler Reheated Steam Temperature

With the development of power industry,large capacity and high parameters units have become the development trend of power industry.In order to improve the thermal efficiency of supercritical units,intermediate reheating unit set is widely used in supercritical unit,which can heat the HP cylinder exhaust steam again heated to a high temperature,then sent it to the middle and low pressure cylinder and make it work.The boiler reheat steam temperature should be controlled within the range of standard,which is an essential part to improve the unit economic benefit and ensure the safe of the unit.However,due to the specificity of the thermal power production process and the complexity of the steam pipeline structure,it is difficult to control the temperature of the reheating steam.Especially,when the main steam flow fluctuate on a large scale.,it is more difficult to control the temperature of the reheating steam in a normal range.There are some limitations or defects in the existing methods about the steam temperature control,which makes it difficult to achieve desired results.This paper mainly introduces the generalized predictive control algorithm to the control of the reheating steam temperature.The main contents of this paper include the following two aspects:(1)In the control algorithm,it introduces the proportional integral GPC algorithm based on the conventional cascade PID algorithm,GPC-PID algorithm.Predictive control with multi-step prediction,rolling optimization and feedback correction three basic characteristics,which can effectively overcome the influence of dynamic object delay and uncertainty and time-varying factors,so as to achieve the goal of control can achieve better and make the system has strong stability and robustness.(2)From the point of switching logic design,the GPC thought is applied to the reheated steam temperature of the flue gas side and steam side,two smoothing,adjusting measures bumplesstransfer realized,and only need a way of regulating at any time.The simulation results show that the design of boiler reheat steam temperature based on generalized predictive control has a good control effect,improve the thermal efficiency of the unit,avoid a series of problems of the conventional control method design brings.