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Transient Stability is the capability of a system to be able to return to its normal state after experiencing large disturbances. The static var compensator (SVC) is a shunt device of the flexible AC transmission systems (FACTS) family using power electronics to improve transient stability in power system. For the SVC control, it is usually used a PI controller, although PI controller is simpler and cheaper but not suitable when power system is subjected to transient stability since power system become non-linear system. In order to overcome this problem, the PI controller combined with Fuzzy controller is designed. Two types of faults were considered for this study to examine the effect of the fuzzy-SVC controller on system transient stability, the proposed fault types are single line to ground fault and three lines to ground fault. The performance and behavior of the designed fuzzy controller compared with that of the conventional PI controller in term of terminal voltage, rotor angle, and transmission line active power. [ABSTRACT FROM AUTHOR]

The increased power system loading combined with the worldwide power industry deregulation requires more reliable and efficient control of the power flow and network stability. Flexible AC transmission systems (FACTS) devices give new opportunities for controlling power and enhancing the usable capacity of the existing transmission lines. This paper presents a combined application of the particle swarm optimization (PSO) and the continuation power flow (CPF) technique to determine the optimal placement of static var compensator (SVC) in order to achieve the static voltage stability margin. The PSO objective function to be maximized is the loading factor to modify the load powers. In this scope, two SVC constraints are considered: the reference voltage in the first case and the total reactance and SVC reactive power in the second case. To test the performance of the proposed method, several simulations were performed on IEEE 30-Bus test systems. The results obtained show the effectiveness of the proposed method to find the optimal placement of the static var compensator and the improvement of the voltage stability. [ABSTRACT FROM AUTHOR]