Development of a Waste-Heat Boiler Model Based on a Fuzzy Logic Apparatus

Abstract

The work is devoted to the problems of modeling systems with incomplete or complex mathematical description using the fuzzy logic apparatus. The object of modeling is the heat-recovery boiler of the gas turbine power station. The object is represented as a complex, thermodynamic system with non-stationary dynamics and a variety of forms of communication of input and output parameters, which influence the heat exchange processes. Due to the complex specifics of the system or the conditions of incomplete information about the object, the creation of an adequate mathematical description using the methods of the classical theory of automatic control becomes a difficult task. The use of the apparatus of fuzzy logic for modeling objects with complex dynamics has several advantages: they function well in conditions of incomplete information about the object of research, do not require a strictly mathematical description of the object, have the ability to adjust existing models without making many changes to them. Having information about the processes in the object of research, knowing the degree of influence of input parameters on the output characteristics of the object and knowing the limits of changing parameters, one can create a model that will describe the dynamic characteristics of the object with a sufficient degree of adequacy by means of the fuzzy logic apparatus. As a result of the research, a model of a heat recovery boiler was developed using a fuzzy logic apparatus. Linguistic variables, membership functions of linguistic terms, focused on the subsequent solution of the identification problem are defined. A rule base has been developed to describe the behavior of the model. The method of defuzzification of output linguistic variables is selected. The identification of a fuzzy model based on historical trend curve in equipment operation has been carried out.