Abstract
A large power system is often subjected to stability problem. This paper deals with the investigations regarding the transient stability enhancement of the electric power system making use of a fuzzy logic controlled braking resistor scheme. Following a fault, variable rotor speed of the generator is measured and the firing-angle of the thyristor switch in the braking resistor is determined from the crispy output of the fuzzy controller. By controlling the firing-angle of the thyristor, braking resistor can control the accelerating power in generators and thus improves the transient stability. The effectiveness of the proposed controller 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 near the generator. Moreover, the performance of the braking resistor scheme with fuzzy controller is compared to that of with the conventional PID (Proportional-Integral-Derivative) controller. Simulation results indicate the better performance of fuzzy controller in comparison with conventional PID controller. Thus, the proposed fuzzy control strategy provides a simple and effective method of transient stability enhancement.
