Digital Substation with Process Bus - a Comparative Review of IEC61850-9-2 and IEC 61869-9 Standards

The digital substation is an emerging concept adopted by utilities globally. This concept employs two predominant standards - IEC 61850-9-2 and IEC 61869–9, defining a path for technological innovation in power systems, leveraging digital communication to enhance automation, monitoring, and control capabilities. The paper provides a comparative review of the IEC 61850-9-2 and IEC 61869–9 standards, critical in the design and implementation of process bus technology. The IEC 61850-9-2 standard defines the specifics for Ethernet-based communication of sampled values, emphasizing interoperability and real-time data exchange in substation automation systems. In turn, the IEC 61869–9 standard establishes the protocols for the digital interface of instrument transformers, facilitating the accurate and efficient transmission of measurement data. The paper highlights the functionalities and applications of both standards and the resultant implications on substation design and operation. Paper discusses benefits and limitations inherent to each standard family, offering substation engineers guiding principles to align standard selection with application specific requirements and operational efficacy.