A wide-area prospective on power system protection: A state-of-art

As the increase in demand for electricity is not been supplied by adequate increase in electrical power generation, the pressure on the electric grids is tremendously growing. so, reliability and integrity is becoming more difficult, sometimes, which may leads to large blackout. In addition, the grid experiences sudden changes due to the inability of the relays to adjust to the prevailing network conditions on the occurrence of a disturbance. This can be reduced by continuous monitoring of system transmission capacity margins and increasing stress on the system. The invention of measuring device, called Phasor Measuring Unit (PMU), that measures the phasor data across the system and communicates to dispatch center through a communication channel, made it possible to redesign network protection schemes to make them more adaptive and thus improve the security of the system. This paper presents the applications of the PMU data in making the relays more adaptive and in the monitoring of grids behavior under disturbances.