Modeling Of Bed Temperature And Main Steam Pressure Control For 350MW Circulating Fluidized Bed Unit

With the adjustment of China's economic structure,the supply and demand situation in the power industry has reversed,and oversupply has become the new normal;due to the rise of new energy,clean energy such as wind energy and solar energy have been connected to the power grid on a large scale,making the power grid demand for peak and frequency regulation of thermal power units.Continuous improvement,and frequent peak and frequency regulation make the thermal power unit run in a non-rated state for a long time,which brings great pressure to the unit's safety,stability and economic operation.In order to alleviate this huge pressure,the control methods and control strategies of thermal power units need to be improved to meet the requirements of the new situation.To this end,the author carried out bed temperature-main steam pressure control modeling and control of a 350 MW supercritical circulating fluidized bed unit in a power plant in Shanxi.Optimization research to improve the control quality of circulating fluidized bed units.Bed temperature is an important parameter in the operation of a circulating fluidized bed unit.It can maintain the temperature in the furnace and ensure the safe operation of the boiler.When the unit runs stably,the bed temperature should be maintained at about 850-950 ° C.This is the best temperature for the boiler combustion and the best temperature for the desulfurization agent decomposition.At this temperature,the desulfurization effect in the furnace is the best and can be effective.Reduce the amount of NOx generated,but the frequent peak and frequency adjustment of the unit makes bed temperature control very difficult,which will affect the stable operation of the unit.Correlation analysis was performed on various variables in the combustion system by extracting long-term operating data from the unit's DCS system.It wasfound that the bed temperature and the main steam pressure under the disturbance of fuel and secondary air volume had certain coupling characteristics,and the main steam pressure was also the boiler.One of the important parameters of safe and economic operation,and the operability of the fuel volume and secondary air volume adjustment is strong,and then it is determined that the fuel volume and secondary air volue are used as inputs,the bed temperature and the main steam pressure are used as outputs,and a 2x2 system identification model is established.The particle swarm algorithm was used to find the optimal value of the model parameters,and finally its mathematical model was determined,and the accuracy of the model was verified.Due to the problems of the coupling of the related variables and the large delay in the circulating temperature bed unit's bed temperature-main steam pressure control,the conventional PID control is not effective,so this paper applies the intelligent control algorithm-fuzzy self-tuning PID control algorithm to this In the 2x2 system,and compared with the conventional PID control method through Matlab simulation,the results show that fuzzy PID control can effectively solve the above problems,has good adaptive ability and robustness,and greatly improves the control quality of the system.This project is a research carried out while stationed in a graduate workstation of a power plant in Shanxi.Based on the actual operating conditions of the circulating fluidized bed unit of the power plant # 1,the historical identification of the field operation data is used to identify the system.An optimized control system model is obtained here Control simulation and optimization are carried out on the basis,which has certain reference significance for system control optimization of similar units.