A centralized protection and control system using a well proven transmission class protection relay

The growing adoption of process bus digital substation is leading to a new interest in the concept of centralized protection and control, where all protection functions for a substation are combined into a single device. When considering implementations of this solution, it is important to remember that these devices will be installed in substations and must meet all the expected requirements for protective devices in substations. Importantly, they must be a technologically mature solution, using proven protection algorithms, scalable for any substation size, on hardware capable of the expected 20-year service life, while providing all the functionality of a complete protection system. This paper describes one specific actual implementation of such a system for distribution substations, based on an existing transmission class protection relay. This centralized distribution system takes advantages of features already developed for the transmission protection platform, including: - Proven protection algorithms for feeder, bus, and transformer protection - A robust cyber security implementation - Support for multiple SCADA protocols - Support for IEC 61850, including sampled values subscription - Numerous communications ports to support separate connections to station bus, process bus, and engineering networks simultaneously A growing requirement for distribution substations is the ability to integrate into wide area monitoring, protection and control schemes. As the device is based on a transmission-based relay platform, this ability is quickly met by including multiple Phasor Measurement Units, and the use of Routable GOOSE to provide inter-station events and control indications.