A PLL with FLC Aided Fast Protection of Strong Power System

In this paper a new method is proposed that can be used to differentiate faults from switching transients. The method is primarily intended for use in systems where fast fault detection and fast fault clearing before the first peak of the fault current are required. An industrial system, in which high short-circuit power is desired but in which high shortcircuit currents cannot be tolerated is an example of such a strong power system. A phase-locked loop (PLL) with FLC is used to perform the discrimination. Computer simulations have been performed and it has been demonstrated that the output of the PLL is completely different for a fault compared to a switching transient. This difference can be used for discrimination between a fault and a switching transient. The simulation work has been performed using MATLAB software. Keywords— Strong power system,Phase Locked Loop(PLL), VCO,Fuzzy Logic Controller(FLC),Clarke transformation,Low Pass Filter .