Simulation Research On Coal-Fired Steam Boiler Combustion Control Based On Fuzzy Decoupling

The distribution of the world's energy is very balanced,the energy problem is that most countries can not avoid to face. It will not be changed that coal is still the major energy source in China now and the future. Boiler combustion process is very complicated a process,involving many parameters,many child processes,slower movement time. It is a typical hard control process. For a long time, the boiler combustion process often used independent closed-loop PID control strategy, in the control process, the coupling phenomenon between the circuits have been often ignored, but the coupling phenomenon between the circuits is objective presence. PID control can not eliminate the coupling between the circuits, so it is difficult to get ideal control result, seriously even not work.In this paper,the article studies is based on the combustion system of a 20t/h coal-fired steam boiler. Firstly,the technology of coal-fired steam boiler and main tasks of boiler combustion automatic control system are introduced and then analysis the mechanism model of combustion process, mechanism model of the combustion process is very complicated and very difficult to simulate. So then its steam pressure control loop,flue gas oxygen content control loop and furnace negative pressure control system are analysised deeply,focusing on analysising the coupling relationship between the various loops. On this basis, using step response method identify each channel model. It gets a good result while using traditional decoupling methods method to decoupling the coupling part of boiler combustion system. But the boiler combustion system is a time-varying system. System parameters will change as operating conditions varying. Therefore, by combining the fuzzy theory with decoupling theory,the fuzzy decoupling controller is designed to decoupling the coupling part of the boiler. Then,the decoupling controllers are simulated on matlab/simulink environment. In the case of changing the system parameters, while using fuzzy decoupling, output can remain fast response, smaller overshoot and steady-state error, compared with traditional decoupling the output dynamic response is not good, or even uncontrollable. So fuzzy decoupling have better adaptability and robustness, also demonstrates the value of the fuzzy decoupling method in the paper.