Research On Fuzzy PID Control Of Superheated Steam Temperature And Feed Water System Of Drum Boiler

Thermal power generation is still the main form of power generation in China.The steam water system,one of the five systems in a drum boiler,is a complex thermal process.The controlled objects in this system are usually nonlinear,uncertain and with large time delay.At present,the traditional PID control logic is still used in the thermal control of most power plants in China.When the load of the boiler unit changes in a large range,the expected control effect cannot be achieved.Superheated steam temperature and drum water level are two important control parameters in the boiler steam and water circuit.It is necessary to maintain the superheated steam temperature and the drum water level in the given range of operation to ensure the boiler's safe and stable operation.This paper is based on a 320MW boiler of Qinhuangdao Power Generation Co.,Ltd.Intelligent control of the two parameters,superheated steam temperature and drum water level,are realised by designed fuzzy controller,whose membership function is optimized.Firstly,the feed water system and superheated steam system of 320MW boiler for#3 unit of Qinhuangdao Power Generation Co.Ltd are introduced.The existing control methods of the system are analyzed.An adaptive fuzzy double closed loop controller for superheated steam temperature is designed for actual superheated steam temperature by means of fuzzy control steps,such as fuzzy process,fuzzy control rule and accurate calculation.Similarly,a three impulse parallel weighted fuzzy controller is constructed for actual drum water level.Secondly,membership parameters in membership function of the adaptive fuzzy double closed loop controller for superheated steam temperature and the three impulse parallel weighted fuzzy controller for drum water level are optimized by centre gravity optimization algorithm and particle swarm optimization algorithm respectively.It improves the adaptability of fuzzy control and strengthens the ability of gradual convergence and evolution,which meets the control requirements on adaptability and real-time performance of boiler steam and water circuit.Finally,the MATLAB software is used to simulate the fuzzy controller and the optimization algorithm,and the intelligent control scheme is proved to be robust,real-time and feasible.