In this paper a new lead-lag supplementary damping controller is introduced for damping power system oscillations using SVC, which it's gain is controlled with a mamdani type fuzzy logic controller. Here the global signals are used as the input of damping controller, because some of the oscillating modes aren't seen in the local signals. The residue index function method is used to select this input signal. The phase compensation method is used to design the lead-lag controller parameters. To validate this controller, some computer simulations are used on a 4-machine 2-area test system. The results show the effectiveness of applying the fuzzy gain in damping controller.

SUMMARYGround fault in the rotor winding of generators can cause serious damage to the generators and consequently, to the power plant. This paper proposes a practical online technique to determine the ground fault location in the rotor winding of a synchronous generator. The proposed technique is based on the analysis of the measured voltage and input/output currents of the rotor winding. The main distinguishing feature of the proposed technique is that, contrary to the existing technique, it is applicable to various types of excitation system. The accuracy and applicability of the proposed technique is demonstrated through both computer simulations and experimental tests. The experimental tests have been carried out using a new device which works based on the proposed technique. The results show that the proposed technique can determine ground fault locations with a higher accuracy compared with the existing techniques.

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