Improvement of Fiber-Optic Current Sensor Technology for Relay Protection and Commercial Metering in Power Grid

There is a traditional approach of implementing the robust, reliable and critical systems with several separate redundant hardware modules, achieving the required level of readiness and fail safety. However, the modern era of digital everything shifted the focus to software implementation of all the complicated systems, including critical ones. This shift allows eliminating expensive hardware redundancy with independent software modules, running on fewer hardware pieces, making it easier to fix issues, upgrade functionality and introduce new features to the existing installations. In the Power Grid this shift can be seen broadly starting with consumer side, represented with devices basically known as Internet of Things (IoT), to the Power Stations and Substations, that use an implementation called Industrial Internet of Things (IIoT), particularly Digital Substation model. In terms of critical systems this means that for example a digital relay protection device may as well perform as commercial electricity meter, running an appropriate software module, while equipped with precise and reliable sensor. The following article describes the attempt of improving a Fiber-Optic Current Sensor technology to correspond the needs of all protection, control and electricity metering systems. This includes the sensitivity, dynamic and static range, response time, measurement accuracy, environmental operation conditions, safety and reliability.