Can the Grid Handle GMD and EMP Risks?
Image courtesy of NASA Goddard Space Flight Center under Attribution 2.0 Generic License, resized to 700 x 391 pixels.
Events triggered by a geographic disturbance (GMD) or electromagnetic pulse (EMP) would be a massive challenge to the power grid. While these disturbances are rare, they are not unprecedented.
For example, in 1989 a solar storm caused a blackout on Quebec’s grid that lasted 9 hours. And as recently as May 2024, PJM issued a GMD alert that lasted for 14 hours (after which it was downgraded to a GMD warning which lasted an additional 2 days).
Therefore, it is incumbent upon utilities to ensure they are prepared for such an event.
Overview of GMD and EMP Disturbances and How to Protect the Grid
At a high level, sunspots and similar solar events sometimes create large plasma clouds that can cause “ground-induced currents” that negatively impact transformers and could potentially cause power outages. Click here to learn more about the science behind these disturbances.
In response to this risk, the power industry has taken a number of steps to ensure preparedness. As an example, some PJM member utilities have installed special equipment to detect and measure “geomagnetically induced currents,” or GICs, which are triggered by these types of phenomena. In addition, when NOAA issues a potential geomagnetic storm warning at a certain level, PJM will initiate a GMD warning to its members.
Overall, according to the EPRI, the best defense involves enhancing monitoring and early warning mechanisms, and system hardening via the deployment of electromagnetic shielding to protect critical components, such as installing shielded control/signal cables, modifying substation control houses, and installing conductive concrete for control houses.
Best-in-class bonding and grounding practices are also recommended to safely dissipate GICs. For EMPs, fiber-optics can be utilized to help neutralize electromagnetic interference. For GMDs, the installation of “neutral blocking devices” and/or “GIC reduction devices” can help. Usage of low-voltage surge protection devices can also help.
I know, I know – the chances of your grid being impacted by one of these solar events is very low. That said, the odds are greater than zero, which is why GMD and EMP events must be part of every utility’s emergency plan.
