Communications for Substation Automation and Integration

In the past decade, new communications schemes have been designed and retrofitted into the substations by the utilities to integrate data from relays and Intelligent Electronic Devices (IEDs) and capitalize on the protection, control, metering, fault recording, communication functions available in digital devices. A modern power system is one of the largest complexes constructed and operated both in terms of geographical distances as well as generated and transmitted power. Such a system needs precise and high quality control with protection functions as primary due to the top priority safety reasons. Traditionally protective relays have been electromechanical devices whose purpose was only to protect electrical power systems against system failures. Application of microprocessors to power system relaying has increased the functionality of protective relays and brought new concepts, which considers control, protection and monitoring functions integrated together. This paper describes substation communications and the ongoing communication standardization efforts discussing the IEC 61850 and the Utility Communications Architecture (UCA) standards.