Communication bandwidth considerations for digital substation applications

Essential for the power industry's move towards digital substations is empowered by reliable data communication infrastructure designed for the exchange of digital information between intelligent electronic device (IEDs), primary switchgear and other substation equipment. Understanding data communication needs is important for proper communication system design and fulfillment of digital substation applications requirements. The communication bandwidth is constrained by the physical characteristics of the transmission medium and processing capabilities of the IEDs. Communication bandwidth is a major concern for Ethernet-based data exchange and is one of the key characteristics to consider when designing a digital substation. This paper analyzes communication bandwidth usage by various digital substation technologies including IEC 61850 sampled values and Generic Object-Oriented Substation Event (GOOSE) messages. Network technology and communication protocols are reviewed. It then provides communication bandwidth calculations for typical applications, scalable for number of devices, based on Ethernet frame structure and settable transmission rates., Theoretical data is validated by measurements made for various digital substation projects and lab installations in North America. Such theoretical and empirical data will help utilities to understand practical data communication bandwidth needs of digital substation applications; assisting them in properly and optimally designing communication infrastructure to achieve the highest accuracy and reliability for digital substation protection and control systems.