Telecom Timing Systems to Support Digital Substations with IEC-61850

Abstract Description: Digital substations, like those using IEC-61850, rely heavily on time synchronization between protection relays and merging units for Sampled Measured Values (SMV). Redundancy in timing systems is crucial, similar to other critical substation protection systems. Some vendors address this by allowing a relay or merging unit to act as a timing source using its internal oscillator during clock failures. However, this can lead to unacceptable drift and misalignment of event timelines during large-scale outages.
A promising alternative is using a backup IEEE 1588 Precision Time Protocol (PTP) signal from a telecom Wide Area Network (WAN) to the substation Local Area Network (LAN). Vendors now support clocks that can distribute multiple PTP profiles, allowing a backup clock to be located far from the substation, reducing the risk of local interference. This enhances system resiliency and maintains synchronization with neighboring assets for coordinated event recordings.