Control For Steam Temperature Of Boiler Based On Immune System

Boiler is an important power equipment of energy source and heat source in power generation, oil refining, chemical industry and other industry department. Super-heated vapor, as an important indicator of boiler, reflect economy and security of equipment running. For the middle-pressure or high-pressure boiler of electric plant, the deviation of superheated vapor is not allowed to beyond±5℃of settings. No matter the super-heated vapor is too high or too low, it will bring negative impact in safety product;The super-heated vapor temperature object has the big delay characteristic. the big inertia characteristic and the variety model with variety time characteristic, it also has many disturbances, it is a more difficult adjust object.For the above characteristics of super-heated vapor, this paper analyzes many disturbance factors influencing vapor temperature. Such as vapor flux,burning medium,feed-water temperature, vapor enthalpy into the super heaters. On the basis of analyzing the three main disturbance factors in vapor temperature and main dynamic characteristics of the super-heated steam temperature control system in thermal power plant, this paper builds the vapor temperature mathematical model for simulation by use of mechanism analysis and experimental methods.This paper briefly describes the commonly cascade control system of super-heated vapor temperature used in power plant boiler. Because of the complexity of the controlled object, regulating quality of cascade system is not very good at certain times. It is not effective in overcoming the impact of the over-heated vapor temperature of substantial change in unit load and easily leading to over-heating temperature overshoot. In order to control the over-heated vapor temperature can adapt to changing conditions and disturbances, this paper proposes the concept of immune genetic algorithm and immune controller. In this paper, the principle of immune-genetic algorithm is introduced, all kinds of operators are analyzed qualitatively, the strategies of the traditional genetic algorithm are improved and the better global optimization ability is gained. The improved immune algorithm is applied in optimization of PID parameters of boiler vapor temperature. The methods have preferably general sense and precision. The simulating result indicates the algorithms are valid.In this paper, an immune controller is proposed which is based on the mechanism of biological immune response regulating. Combining with conventional PID controller, the design method of immune PID controller is proposed in this paper. Simulation results obtained for the superheated steam temperature control system with parameters changing and perturbations demonstrate the effectiveness of the immune PID controller, which can meet the requirements of fast response speed and enough stability. Compared to the traditional PID controller,immune PID controller could be better for the boiler steam temperature control.