Research On Dynamic Identification And Fuzzy Adaptive Control Of The Combustion System Of Large Circulating Fluidized Bed

Circulating fluidized bed boiler combustion technology developed in recent decades is a clean coal combustion technology. Its high combustion efficiency, fuel adaptability, low emissions, and has unique advantages compared to pulverized coal fired boilers. Combustion control system ensures the stable, security, and economic operation of CFB boiler. It is particularly important, and many scholars focus on it. However, due to the characteristics of nonlinear, time varying parameters, multivariable coupling, the effect of the conventional control method is unsatisfactory.Ant colony algorithm has high efficient search performance and Immune system has been proven to be of massive distribution and robust adaptation. This article introduces these mechanisms to process control field to provide a new approach to resolve the problems such as identification modeling of complex objects and dynamic adaptive control study. Details are as follows:(1) Analyzing the working principle and characteristics of basic ant colony algorithm, this paper introduces the mechanisms of antigen recognized, antibody diversity, and concentration adjustment by the immune system. The adaptive ant cobny algorithm adjusts the initial distribution of the pheromones, pheromone adjustment mechanism, other aspects of the selection probability function, to enhance the efficiency of the initial search and the ability to adjust the pheromone algorithm, thus the algorithm is adaptive and robust. By validating the test functions and solving simple thermal process, suggesting that compared with other intelligent algorithm, improved ant colony algorithm has better searching performance and recognition ability.(2) This paper analyses the control objectives and characteristics of the combustion system of the CFB boiler, confirms control objects, and under landing the control characteristics and difficulties of boiler bed temperature and bed pressure. Decentralized control strategy, considering only the return valve opening and primary air flow the two main factors, the controlled object model was established. Through studying the mechanism of the return valve opening and primary air flow, the transfer function model structure of bed temperature and bed pressure was determined. Then use the improved ant colony algorithm to identify. The results show that the model can reflect the trend object, basically meet the engineering requirements.(3) This paper introduces the idea of variable universe, designs a directly adaptive fuzzy controller by adjusting the quantization factor and scaling factor to adaptively change the fuzzy logic controller. While it uses fuzzy rules adjustment function, so that the fuzzy rule table can be adaptively adjusted according to the transfer function of the model parameters obtained above, to overcome the traditional fuzzy rule methodology flaws. Finally, some simulations are taken for a given value of the disturbance, internal disturbance, external disturbance and other conditions. The results show that the adaptive fuzzy controller has better control performance and anti-interference ability than the conventional PID controller.