Study On Control Strategy And Simulation Analysis Of Boiler Main Steam Temperature

Boiler is an important equipment of energy source in power generation,chemical,manufacturing,petroleum and other industry department.The main steam temperature as an important indicator of the boiler,which is the maximal temperature in the whole water/steam channels and affects the economy and security.With the development to large capacity,high parameter of boiler units,and characteristics of large inertia,nonlinear,large delay and time-varying,which make the traditional PID control difficultly achieve an excellent control level.In recent years,with deep study of the intelligent control theory,some intelligent control strategies have been put forward based on the traditional control methods to solve complex problems.First of all,characteristics of the main steam temperature,the objectives of control and cascade control system which is commonly used are detailed analysis in this paper.According to the main problems existing in the main temperature control system,design method of the fuzzy self-tuning PID controller based on theory.O n the one hand,it keeps characteristics about simple,easy to realize and good robustness of the traditional PID.On the other hand,combined with fuzzy control,there is no need to get the accurate mathematical model,and this composite intelligent control strategy uses the experience of human knowledge and can increase the intellectuality of the system.The model of 300 MW drum boiler unit is simulated by Simulink and the control system realizes the on-line auto regulation of PID parameters.Secondly,analyze the influence of quantization factor and scaling factor which include five parameters to the fuzzy self-tuning PID controller.Introduces the particle swarm optimization algorithm,and through the linker by using particle swarm algorithm to optimize the parameters of the model,and the optimal values are given.Compared with the traditional PID and optimization,the fuzzy self-tuning PID controller optimized by PSO has better performance which has the characteristics of less overshoots,shorter setting time and higher accuracy.Finally,the variable universe theory is proposed because of the two shortcomings of fuzzy controller about finite adaptive ability and bad precision.The variable universe fuzzy self-tuning PID controller is designed according to the theory and principle of variable universe.Through the impact of the universe flex factors and according to the error and error change of system response,it adjusts real-time the size of universe online.This control method has solved the contradiction between control rule quantity and control precision well,and realized the universe's adaptive flex along with the control request of the system.The simulation results indicate that the variable universe fuzzy self-tuning PID control is obviously superior to other control strategy on stability?disturbance and inhibit delay.The accuracy and quality of control has improved greatly,but time of rise is longer,and it is blind to choose flex factor.