Will IEEE 1588 Finally Leverage the IEC 61850 Process Bus?

IEC 61850 introduced the concept of what is called process bus to substation automation systems. Not necessarily a separate communication bus, the concept introduces the possibility of connecting process equipment like switchgear and sensors directly with a digital interface to the rest of the system. Such an approach offers many benefits to the user. These include topics like simplified engineering and commissioning or a reduction of copper wiring within a substation. As an overall benefit, life cycle costs are expected to be reduced. That approach however provides some challenges. These challenges have prevented, so far, a wide scale introduction of process bus. One of the challenging topics is the accurate synchronization of the data sources providing the sampled values. The communication network used to transmit the sampled values does not support a constant or predictable transmission delay. Therefore, the mechanism chosen assumes a synchronised sampling at the source. All devices sample at the same time and add a reference to the sampling time. With the help of that reference, the application using the sampled data can correlate the samples received from multiple sources. Depending on the application and the requirements concerning acceptable phase errors, the required synchronization accuracy may be as accurate as 1 microsecond. While so far, a dedicated synchronization network has to be used, which adds to the unreliability of the system, the standard IEEE 1588 provides a solution for accurate time synchronization over an Ethernet network. The IEEE relay committee (PSRC) is currently defining a profile for the use of IEEE 1588 in power automation. The IEC TC57 working group 10, which is responsible for IEC 61850, plans to use time synchronization based on that profile in the future for a process bus. Once this is introduced, this could trigger a rapid adoption of IEC 61850 process bus. The presentation discusses the aspects of using IEEE 1588 for power automation and the work done in IEEE PSRC. This is compared with the different challenges of a process bus solution. Finally, the presenter discusses to what extent the introduction of IEEE 1588 will leverage process bus solutions, and what else will be needed to facilitate an easy adoption of a standardized process bus.