Time and Frequency Synchronized

Solutions for Smart Grid & Utilities

Modern power grids require synchronized timing across protection relays, phasor measurement units (PMUs), event recorders, and SCADA systems. IEEE C37.118 and IEC 61850 standards mandate sub-microsecond time accuracy for PMU data aggregation and fault analysis. Wide Area Monitoring Systems (WAMS) depend on precise timestamps to correlate grid events across geographically dispersed substations, enabling operators to detect instability and prevent cascading failures.

Smart grid timing must also be resilient to GPS jamming and spoofing attacks, which have become an increasing threat to critical infrastructure. A robust timing architecture provides multiple reference sources, redundant distribution paths, and extended holdover capability to maintain operations during GNSS outages.

System Requirements

A smart grid timing system must provide:

• UTC-traceable timing with better than 1 microsecond accuracy at all substations

• IEEE 1588v2 (PTP) Grandmaster capability for IEC 61850 substations

• IRIG-B and 1PPS outputs for legacy protection relays and PMUs

• 10MHz reference for frequency monitoring equipment

• Redundant timing sources with automatic failover

• Extended holdover (hours to days) during GNSS outages

• Centralized monitoring and management of all timing assets

Recommended Products

GS5500 NTP/PTP Time Server

The GS5500 serves as the primary PTP Grandmaster for the substation LAN, distributing IEEE 1588v2 timing to IEDs, Merging Units, and PMU devices over the substation Ethernet network. It also provides NTP for SCADA systems and management workstations.

GS5620B Rubidium Time Server

With rubidium holdover providing better than 1 microsecond accuracy over 24 hours, the GS5620B ensures continuous timing during extended GNSS outages caused by jamming, spoofing, or antenna damage.

GS3100 GPS NTP Time Server

For distribution network substations requiring cost-effective NTP timing, the GS3100 provides reliable GPS-synchronized NTP with excellent value for large-scale deployments.

GS5600 Time Synchronization Server

The GS5600 provides centralized timing management for large utility networks, aggregating timing status from multiple substations and providing unified monitoring, alarm management, and reporting.

GS5210 Grandmaster Clock

For substations with legacy equipment requiring 10MHz, 1PPS, and IRIG-B, the GS5210 generates all required reference signals from a single GNSS-disciplined platform.

GS5710 Fiber Optic Transmission Equipment

The GS5710 enables long-distance timing transfer from regional control centers to remote substations over existing fiber infrastructure, eliminating the need for individual GPS receivers at each location.

System Architecture

At the regional control center, redundant GS5500 and GS5620B units provide primary and backup timing references. The GS5600 aggregates status from all substations for centralized monitoring.

Timing signals are distributed to substations via two paths: PTP/NTP over the utility WAN (managed Ethernet), and dedicated timing links via GS5710 fiber optic transmission for critical protection systems.

At each substation, GS5500 or GS3100 units receive timing and distribute PTP/NTP on the local LAN. GS5210 units generate 1PPS, 10MHz, and IRIG-B for legacy relays and PMUs. Dual-input redundancy ensures automatic failover between the WAN timing path and a local GPS receiver.

Source	Signal Type	Distributor	Typical Consumers
GS5500	PTP (1588v2)	Network Switch	PMUs, IEDs, Merging Units
GS5500	NTP	Network Switch	SCADA, RTU, workstations
GS5210	1PPS (TTL)	GS6605A	Protection relays, event recorders
GS5210	IRIG-B(DC)	GS6606	Legacy PMUs, sequence of event recorders
GS5620B	1PPS + 10MHz	GS5227	Backup reference for all substation timing

Integration Recommendations

• Deploy redundant timing sources at each substation: primary from WAN/fiber, secondary from local GPS

• Configure automatic input switching with a 3-pulse loss threshold to avoid nuisance switching

• Use GS5710 fiber links for protection-grade timing, independent of the WAN network

• Monitor all timing assets via SNMP and integrate alarms into the existing SCADA system

• Test holdover performance quarterly by disconnecting GNSS antennas for 24-hour periods

Conclusion

This smart grid timing architecture provides a complete solution for utility synchronization requirements. The combination of PTP/NTP network timing, dedicated fiber timing links, rubidium holdover, and centralized management ensures continuous, accurate synchronization across the entire power grid, even during extended GNSS outages. The architecture meets IEEE C37.118, IEC 61850, and NERC CIP requirements for critical infrastructure timing.