Fuzzy logic based extended integral control for load frequency control

This study presents an application of fuzzy logic based method to determine the optimal parameters for the extended integral control scheme. The performance of the extended integral control is greatly dependent on the decaying factor. For an optimal or near optimal performance, it is necessary that the decaying factor as well as the feedback gains should be changed very quickly in response to changes in the system dynamics. However, because of its time-varing characteristic, the optimal decaying factor is difficult to be selected analytically. By adopting fuzzy set theory, the decaying factor can be determined quickly to respond to the variation of the feedback signals. This study builds a fuzzy rule base with use of the change of frequency and its rate as inputs. A set of decision rules is established to relate input signals to the decaying factor. The computer simulation has been conducted for the single machine system. The simulation results show that the proposed fuzzy logic based controller yields more improved control performance than the conventional PI controller.