PJM Monitoring Solar Storms for Geomagnetic Disturbances


PJM will be monitoring through the weekend for potential impacts of the solar storms that began Aug. 14.

PJM issued a warning Aug. 17 to its generation and transmission companies that a possible geomagnetic disturbance could impact the PJM system that evening.

The alert, issued for all of the PJM footprint, warned generation and transmission operators in case they would have to take prescribed steps in their operations to offset the impacts of such a phenomenon. No impacts to operations were reported during the warning period Wednesday.

A solar storm that may affect the earth’s magnetic field is a fairly rare event, but one with potential impacts to the electrical grid.

The last time PJM issued a warning to prepare for a potential geomagnetic disturbance was May 2021. As is most often the case, there was no reported effect on the PJM system.

What Is a Geomagnetic Disturbance?

Geomagnetic disturbances, which are also called solar magnetic disturbances, are caused by activity on the surface of the sun.

Sunspots, solar flares or other phenomena can produce large clouds of plasma, called coronal mass ejections. Should these super-charged solar winds come close enough to the Earth’s magnetic field, they may induce electric currents within the ground and on high-voltage transmission lines. These currents can flow up from the earth or down into the earth through grounded grid equipment, usually transformers.

High levels of these unusual, volatile storm currents have the potential to damage transmission equipment.

For example, a major geomagnetic disturbance on March 13, 1989, caused a nine-hour power disruption in Quebec and also severely damaged a transformer at the Salem Nuclear Power Plant in Salem County, New Jersey.

The Space Weather Prediction Center of the National Oceanic and Atmospheric Administration (NOAA) monitors both solar activity and the earth’s magnetic field. NOAA issues alerts and warnings to grid operators, so they can prepare for the impacts of space weather events.

The storm watch issued by NOAA on Aug. 17 prompted PJM’s alert. As agency satellites continue to monitor the space storms emanating from the sun, NOAA predicted the strongest potential for impact on earth would take place Aug. 18 before subsiding Friday.

As conditions evolve, PJM will continue to monitor the bulk electric system to maintain grid reliability, likely through this weekend.

As the most recent solar storms brush against the earth’s atmosphere, unusual sightings of the colorful northern lights’ aurora may also be visible in the skies of southerly latitudes, including in Pennsylvania, according to NOAA.

How Does PJM Protect Against Geomagnetic Disturbances?

When the NOAA Space Weather Prediction Center issues an alert to PJM rated above a certain threshold, PJM issues a warning to generation and transmission operators to prepare for potential disturbances.

To help anticipate problems, PJM’s members have installed special equipment to detect and measure ground-induced currents caused by such geomagnetic disturbances. When a disturbance is forecast, PJM monitors the installed detectors at various locations. If sustained ground currents at a certain level are detected, PJM operates the system in a more conservative mode until the space weather event has ended. The PJM Manual for Emergency Operations provides greater detail on the actions PJM and members take in response to a potential geomagnetic event. Read more about geomagnetic storms and their impacts outside of the electricity industry on the NOAA website.