PJM issued a series of warnings on June 22 to its generation and transmission companies that a possible geomagnetic disturbance could impact the PJM transmission system between 3 p.m. yesterday and about 7:30 a.m. today. There was no reported disturbance impacting PJM’s system during that time.
The warning was directed to operators for their awareness should any operational procedures be needed.
Geomagnetically-induced currents flowing through power system equipment and facilities caused by a geomagnetic disturbance may result in major increases in system reactive requirements, equipment damage and disruption of interconnected system operation. The PJM dispatcher notifies generation and transmission members via the PJM All-Call of GMD warnings that reach certain levels issued by the National Oceanic and Atmospheric Administration. This GMD was rated at a level within the threshold for a warning.
To help anticipate problems, PJM’s members have installed special equipment to detect and measure ground induced currents that are caused by GMD. When a solar disturbance is forecasted, PJM monitors the detectors that PJM members have installed at various locations. If sustained ground currents at a certain level are detected, PJM operates the system in a more conservation mode until the space weather event has ended.