Augmentation of transient stability by fuzzy-logic controlled braking resistor in multi-machine power system

This paper presents a fuzzy logic switching of the thyristor controlled braking resistor to augment the transient stability in a multi-machine power system. The time derivative of total kinetic energy deviation (TKED) is proposed as the fuzzy controller input for braking resistor switching. The performance of the time derivative of TKED as the controller input is compared to that of the TKED as the controller input. Again, with a view to minimizing high installation and operation cost as well as computational burden, this paper directs to the use of the reduced number of braking resistors at suitable locations instead of installing one braking resistor at each generator terminal bus in the power system. The concept of coherency is exploited to reduce the number of braking resistors required for transient stability control. Simulation results of both balanced and unbalanced faults at different points in the system indicate that the time derivative of TKED instead of TKED as the fuzzy controller input exhibits better system performance. Moreover, the use of the reduced number of braking resistors minimizes the total installation and operation cost as well as computational burden. As a whole, the proposed fuzzy control strategy provides a simple and effective means of transient stability enhancement in a multi-machine power system.