Ukraine's high-voltage electricity substations rely on GPS for time synchronization.
Many of Ukraine's high-voltage electrical substations - which play a vital role in the country's domestic transmission of power - make extensive use of the availability of precise GPS timing information to help operators anticipate, react and diagnose a complex high-voltage electric grid.
The GPS timing issue wouldn't leave my head. I tried to look at it from all different angles.
To truly understand the layers of solving this issue, I need to talk about why GPS clock timing is so important to electric grids.
Most people are familiar with GPS because we rely on it for navigation, but it has also become the dominant system for the distribution of time and frequency signals globally.
These satellites send very precise time data to GPS receivers on the ground that receive and decode the signals, effectively synchronizing each receiver to the same clock.
Because GPS time is so accurate, GPS-disciplined clocks are commonly used in industrial systems, like Ukraine's power grid, that require extremely precise time across a vast geographic area.
The frequency reference is provided by an internal crystal oscillator within the device, and that crystal tells the device how fast time is going.
These times are never perfectly accurate due to manufacturing variations and other variables in the crystal oscillators, causing time to advance at slightly different rates across various devices.
Devices can use the GPS satellites' time signal to determine how accurate its local time reference is and then adjust the time accordingly, thereby enabling all devices running GPS-enabled clocks to be aligned to the exact same time.
These GPS time signals are crucial for making a key piece of power equipment called a phasor measurement unit run effectively.
PMU data is time-stamped - to the precision of a microsecond - using the timing signal from GPS satellites.
Without the ability to analyze the precise timing of an electrical anomaly as it propagates through a grid, grid operators have difficulty diagnosing the exact issue that requires correction.
Relatedly, if GPS timing is down, grid operators will have increased difficulty balancing power during the adverse events that occur during wartime.
Industrial Ethernet switches do not have atomic clocks for holdover accuracy - but they have a good enough clock, able to measure time accurately in microseconds, to sustain an accurate time sync.
Most network hardware devices use an internal crystal oscillator to generate their clock time, but these crystals' frequencies can oscillate widely based on local conditions.
Holdover is the time period to keep the clocks in sync until timing signals can be restored.
We modified the Industrial Ethernet switch's code to provide trusted time.
With an Industrial Ethernet switch deployed to Ukraine's substations, it measures the difference between the PMU's local time reference used by the PMU and GPS time while GPS is still active.
Of course, we must thank our partners in Ukraine, the U.S. government, and ICS vendors and experts who lent us their time, empathy, and expertise.
This Cyber News was published on blog.talosintelligence.com. Publication date: Mon, 04 Dec 2023 13:13:04 +0000