Comparison between a continuous and a discrete method for the aggregation and deffuzification stages of a TRIGA reactor power fuzzy controller

This paper presents a comparison of the performance of two different methods to realize the aggregation and the centre of gravity stages of a fuzzy controller that is under development for its integration, as an alternative power control algorithm, in the control console of the TRIGA Mark III reactor of the Mexican Nuclear Centre. In one case, an innovative method determines, in every control cycle, the group of lines that define the fuzzy aggregated set of the rule base in the continuous domain of the output variable. Likewise, the centre of gravity of this aggregated set is analytically obtained, and the corresponding controller is named exact or continuous. In the other case, a method is used to determine, in one step, both the aggregated set and its centre of gravity using the classical discretization of the universe of discourse of the output variable, thus leading to the discrete fuzzy controller. These methods were simulated in the ascent and regulation of neutron power in a TRIGA Mark III reactor. The performance parameters used for the comparison between the two methods were: The required number of floating point operations, the time required to attain a certain power level, the neutron power time response, and the reactor period values.