Application Of Multivariable Generalized Predictive Control Algorithm In Boiler Desuperheating Water Control

At present,the traditional thermal power unit still occupies the very important place in the field like energy industry and energy supply in our nation.Subject to the requirements of power grid frequency modulation,AGC,power grid deep peak-regulating operation,control quality of thermal power units become higher than before.The superheated steam temperature of the boiler is always lagging behind the load response of the unit due to the influence of multiple disturbances such as coal quality,combustion characteristics of the boiler,coordinated control of the unit,etc.,the main steam temperature model also varies greatly.The fundamental of power enterprises is to generate electricity safely and economically,as one of the main control parameters for thermal power unit,the boiler superheated steam temperature'function is to ensure the boiler superheated steam temperature in the normal range,which is of great significance.This thesis mainly tells the boiler desuperheating water system,and analyzes both static characteristics and dynamic characteristics of boiler water reduction system,it is concluded that the main factors influencing the superheated steam temperature changes.Using the recursive least squares(RLS)identification of the scene of the actual input and output data,combined with the daily work practice has established the boiler superheated steam temperature system in 50%BMCR(maximum continuous evaporation rate of the boiler),70%BMCR and 100%BMCR common relationship model of working conditions,and verify the accuracy of the model.In view of the traditional PID control and single-variable generalized predictive control cannot meet the control requirements of control system such as multi-variable and large delay.In this thesis,based on the system model of identification and the generalized predictive control algorithm,an improved two-stage linkage multi-variable generalized predictive control optimization strategy is presented.The strategy is applied to a 330 MW sub-critical,primary intermediate overheating thermal power company under stable load condition and variable load condition.by comparison,the practical application of the optimal control strategy can meet the control requirements well in terms of the regulating accuracy,regulating sensitivity and reducing temperature water consumption,improving the safe and economical operation of the boiler,a good practical control effect has been obtained.