Integrating Electrical Substations within the IoT using IEC 61850, CoAP and CBOR

Electrical substations are crucial elements of Smart Grids where they are mainly responsible for voltage transformations. However, due to the integration of distributed energy resources in the grid, substations now have to provide additional grid management capabilities which in turn require supervision and automation solutions for large low-voltage grids. A recurring challenge in such deployments are siloed systems that are due to non-interoperable communication protocols across substations: although most substations’ communication is based on the International Electrotechnical Commission (IEC) 61850 standard, deployed legacy protocols lag behind modern communication technologies in terms of performance, hindering the full transition to lightweight protocols. This paper demonstrates that IEC 61850 can be fully mapped to the Constrained Application Protocol (CoAP) in combination with the Concise Binary Object Representation (CBOR) format while improving system performance compared to existing alternatives (e.g. WS-SOAP and HTTP). On average, CoAP+CBOR needs 44% and 18% of the message size and 71% and 85% of the time compared to systems based on HTTP and WS-* Web Services, respectively – this is especially relevant for resource-constrained devices and networks in electrical grids. In addition, CoAP is based on the Representational State Transfer (REST) architectural style, which supports system integration and interoperability through uniform identification and interaction. This approach fosters the standard-compliant integration of legacy platforms with modern substations as well as current IoT systems in neighboring domains such as building management and infrastructure automation systems.