PJM issued three warnings on Feb. 27 to its generation and transmission companies that possible geomagnetic disturbances could impact the PJM system.
On the PJM Emergency Procedures page, PJM posted the first warning lasting between 2:50 a.m. and 7 a.m. on Feb. 27 for a geomagnetic disturbance warning of K-7 or greater. Later that morning, PJM issued a second warning lasting between 8:53 a.m. and 1 p.m. for geomagnetic disturbance of the same magnitude. A third warning was issued for the period between 2:25 p.m. through 7 p.m.
The warnings alert PJM generation and transmission operators of prescribed operations steps to take to offset possible impacts of such phenomena.
No impacts to operations were reported to PJM during the warning periods Monday.
Geomagnetic disturbances are fairly rare but pose potential impacts to the grid. The last time PJM issued such a warning was in May 2021. As is most often the case, there was no reported effect on the PJM system.
What Is a Geomagnetic Disturbance?
Geomagnetic disturbances, also known as 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. These ejections may induce powerful electric currents within the earth and on high-voltage transmission lines. These currents may flow up from the earth or down into the earth through grounded grid equipment, usually transformers. High levels of these currents have the potential to disrupt or damage transmission equipment.
For example, a major 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 and issues alerts and warnings to grid operators so they can prepare for the impacts of space weather events. NOAA alerts posted Feb. 27 prompted PJM’s Emergency Procedures notices.
How Does PJM Help 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 a potential impacts to equipment.
To help anticipate problems, PJM members have installed special equipment to detect and measure ground-induced currents caused by 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 details actions PJM and members take in response to a potential geomagnetic event. Read more about geomagnetic storms and their impacts on the NOAA website.