Main Steam Temperature Control System Based On Fuzzy PID In Variable Universe

With the development of science and technology and social economy,boilers are the energy equipment of important industrial sectors such as thermal power generation,industrial manufacturing and petrochemical industry.The boiler unit has also developed and made progress constantly,which moves toward the direction of large capacity and high parameter.The main steam temperature is not only an important parameter to firing unit,but also the highest temperature in the boiler water system.Therefore,the measure and control of the main steam temperature is vital to ensure efficient and safe operation of the generators.Main steam temperature is a kind of controlled object with nonlinear,large inertia,large delay and easy to be affected by many factors.Now,it is difficult to control main steam temperature by cascade PID and the leading differential signal in thermal power plants.Therefore,it is necessary to explore control strategy of main steam temperature system to improve the control quality.By analyzing the difficulties and dynamic and static characteristics of the main steam temperature control system,fuzzy control is introduced into ordinary cascade PID control.In the main loop,three control parameters of PID are adjusted in real time by fuzzy controller,so that the system can achieve good dynamic and static characteristics.At the same time,the control accuracy of fuzzy PID control is reduced when the error trend is zero,introducing the idea of variable universe.The quantitative factor and proportional factor are adjusted by scaling factor,so that input and output theoretical domain can be changed,and the adaptive ability and control precision of the control system can be improved.MATLAB simulation results show that variable universe fuzzy PID control has many advantages such as small overshoot,short rise time and short adjustment time.Then,by adding smoke disturbance and extended delay,fuzzy PID control system is compared with variable universe fuzzy PID control system.And the results show that variable universe fuzzy PID control has stronger anti-interference ability,can quickly restore stability.And after changing control parameters and time delay of main steam temperature system,fuzzy PID control and variable universe fuzzy PID control are compared,which proves that variable universe fuzzy PID control has advantages of short adjustment time and strong adaptability.