Influence of Communication Delay on the Performance of Fuzzy Logic-Controlled Braking Resistor Against Transient Stability

This paper analyzes the influence of communication delays introduced in online calculation of the global input variable of the fuzzy logic controller for braking resistor (BR) switching on the transient stability of a multi-machine power system. The time derivative of the total kinetic energy deviation (D) of the synchronous generators is used as the global input of the fuzzy logic controller in this work. The Global Positioning System (GPS) is proposed for the practical implementation of the calculation of the global input of the fuzzy controller. Communication delays may affect the control system, and consequently, the transient stability of the power system also. A prediction function is proposed to minimize the negative effect caused by the communication delay on the transient stability. Also, the performance of the fuzzy logic-controlled BR is compared to that of the conventional proportional-integral (PI) controlled BR. Simulation results of both balanced and unbalanced faults at different points in the system show that the communication delay associated with the fuzzy controller input calculation has an influence on the transient stability. Moreover, the negative effect caused by the communication delay on the transient stability enhancement using fuzzy-controlled BR can be minimized by the prediction method. Also, the performance of the fuzzy logic-controlled BR is better than that of the PI-controlled BR.