Transient stability augmentation by fuzzy logic controlled braking resistor in multi-machine power system

The dynamic braking resistor is a very effective device for transient stability control. Fuzzy logic has been found to be very suitable for embedded control applications. This paper makes use of the fuzzy logic controller (FLC) for the switching of the thyristor controlled braking resistor to improve power system transient stability. The braking resistor is installed at each generator bus, where rotor speed of the generator is measured to determine the firing-angle of the thyristor switch. By controlling the firing-angle of the thyristor, a braking resistor controls the accelerating power in generators and thus improves the transient stability. The effectiveness of the proposed method has been demonstrated by considering both balanced (3LG : three-phase-to-ground) and unbalanced (1LG: single-line-to ground, 2LG: double-line-to ground and 2LS: line-to-line) faults at different points in a multi-machine power system.