Why time-sync is so important to the smart power grid

Arthur Cole
Wind turbines

Perhaps no network is as critical to the world economy as the power grid. Without electricity, after all, there is no data, no connectivity, not even (gasp!) Netflix.

Increasingly, electric utilities are transitioning to smart power grids to enhance efficiency and drive down costs. By implementing two-way communications between smart devices in the field and centralized data facilities, and then coupling that with intelligent analytics, operators gain unprecedented insight into consumption patterns, grid performance and other metrics to ensure optimal levels of operation at all times.

Precision timing

Key to this functionality is precise synchronization between data points. Without that, operators have only limited ability to glean accurate information from the field or to implement effective changes to grid operations. For this reason, research into highly precise synchronization, even down to the sub-microsecond level, is a priority at leading organizations around the world.

In general, power networks are managed by controlling the 50Hz frequency, which requires a high degree of accuracy that can only be achieved with a very precise time reference. For instance, identifying the location of faults is done by analyzing timestamped measurement values, preferably with accuracies down to the 100ns level. The greater the inaccuracy in time, the harder it is to pinpoint where a fault occurs, and this can lead to performance degradation for applications with strict timing requirements.

As this graphic prepared for the National Institute of Standards and Technology (NIST) shows, there are a number of challenges when implementing precision timing across complex networks. Among them:

  • Assuring time integrity – This can range from the problems that discontinuities and anomalies cause to monitoring, detection and responsiveness to maintaining measurement accuracy to a traceable source. As well, operators must maintain conformance of time information across multiple devices and ensure interoperability in end-to-end system testing functions.
  • Resolving multiple time scales and time discontinuities – This must be done at the application level and must accommodate leap seconds, GPS week rollovers and other factors.
  • Maintaining pertinent time performance metrics and impact analyses – Research will be needed to understand how time performance metrics like accuracy and stability impact power systems application performance in both transmission and distribution settings. As well, additional metrics like clock stability and holdover will need constant review.

And all of this must be implemented under the normal business requirements of affordability, flexibility and sustainability

Equally important is the need to harden the smart grid against attack, and time sync is emerging as one of the key security vulnerabilities. According to Power Magazine’s Kennedy Maize, as the number of interactions on the grid proliferate, so too does the “attack surface,” the number of points that can be penetrated. Without proper synchronization between these points, conventional security tools like firewalls, encryption and authentication will become increasingly ineffectual.

Smaller and better

Clearly, the modern smart grid will need far more sophisticated time sync than a traditional grid, and this technology must be made available at low cost and on a small form-factor. This is why ADVA has extended the capabilities of two of its leading grandmaster clocks to deliver time-sync on the sub-microsecond level. The OSA 5401, in fact, is the industry’s smallest Precision Time Protocol (PTP) grandmaster clock, conforming to zero footprint small-format pluggable (SFP) specifications, while the OSA 5405 integrates a clock with dual GNSS antenna and receiver.

Coupled with their low power consumption, the devices provide precise timing at the network edge, enabling flexible, real-time decision-making, as well as automated monitoring and maintenance. In addition, they provide unique multi-layer jamming and spoofing detection capabilities to support autonomous disruption detection and intelligent protection and control.

There is no question that our electrical grids, like virtually everything else, will get smarter as the new decade unfolds. What remains to be seen is whether this will truly lead to a new era in power management or simply swap one set of problems for another.

Using tools like sub-microsecond synchronization, utilities will hopefully realize the benefits of smart technology while placing the challenges on a manageable level.

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