Development of power system differential protection based on optical current measurement

A theoretical evaluation of a novel, all-optical differential current protection scheme employing low voltage piezoelectric transducers, fiber Bragg grating sensors and Rogowski coils is presented in this paper. The optical power reflected from the sensors is monitored by means of a single photodetector, whereas fault occurrence is detected by a simple optoelectronic threshold detector. We demonstrate through simulations that an immediate response to an increase in differential current can be achieved even at low voltage levels such as these generated by Rogowski coils providing a low-cost and fast-acting fault detection system.