What is Solar Cycle 25? It’s an 11-year cycle of the Sun’s activity that started in December 2019. Its maximum solar activity is expected in 2025. Experts predicted that solar activity would be less during this cycle than the previous one, but it’s been pretty active so far. It started ramping up last May and it’s expected to max out in next summer. That’s good news for aurora borealis watchers, but possibly not so good for the power grid and communications sector to name a few.
According to NASA, the solar cycle’s progress is tracked by the numbers of sunspots recorded. Sunspots are associated with solar activity like solar flares and coronal mass ejections (CMEs) that emit solar energy into space. Low levels produce the peaceful aurora borealis everyone loves, but when the levels are up it’s a different story. That brings solar incidents with high levels of energy pushing things like aurora borealis displays far beyond their normal limits.
This summer the aurora borealis have even been seen in the skies over New Mexico and further south. I have missed the New Mexico lights so far, but I have seen photos of the lights over famous state landmarks, and they were beautiful. As photogenic as these light displays are, it’s the geomagnetic storms that really captured my attention. When the aurora borealis are this far from the North pole, it’s an indication of how powerful these geomagnetic disturbances (GMDs) are.
Solar Storms
Without getting too technical, solar flares are flashes of light that reach Earth and typically don’t have much of an impact on the Earth. CMEs, however, are GMDs of large, superheated bubbles of solar plasma and radiation ejected into space. The slow moving CMEs can take from eight to fifteen hours to make the trip to Earth, so there is time to prepare.
Damage from solar flares and CMEs vary. Strong solar flares can affect satellites. Powerful CMEs, however, interact with the Earth’s magnetic fields producing geomagnetic inducing currents (GICs). They can form in the long conductors found in transmission and distribution lines, which is a problem for the power grid. Also, they can generate EMPs (electromagnetic pulses), which are not good for digital electronics or the power grid either.
The first recorded CME event happened in 1859. It knocked the world’s telegraph systems out of service due to GICs in the wires. There were also fires in telegraph stations caused by sparking wires, and operators were injured by electrical shocks. Since that 1859 event, there have been several other occurrences reported, but the most famous gridwise happened in March 1989.
Observers reported a massive explosion on the Sun on March 10th, and on March 13th a powerful CME hit the Earth’s magnetosphere. That resulted in Hydro-Quebec’s power grid failing. The entire province of Quebec suffered a blackout that lasted about nine hours and affected roughly 6 million people. One newspaper reported, “Transformers overheated, circuit breakers tripped, and strange frequencies (harmonics) started to flow through the lines.” In the U.S. there were over 200 power grid issues reported including the destruction of a power transformer in New Jersey by GICs.
GIC Protection
The 1989 CME event generated numerous studies and papers from our national laboratories concerning the GMDs’ GICs. The work focused on what could be done to lessen their impact like the neutral blocking device WAPA installed a few years ago in the neutral of a large power transformer.
The device takes advantage of the fact that GICs act like direct currents, which are blocked by capacitors. The device has “a solidly grounded metallic path, a GIC-blocking path using a capacitor bank, and an overvoltage protective path through a spark gap.”
This points out the power grid has options. One comes from PJM. They said they issued a geomagnetic disturbance alert to their generation and transmission companies on May 10th and extended it to May 12th. PJM followed up reporting there were no major impacts to their grid operations. They went on to say their members have installed special equipment to detect and measure GICs, with procedures to follow if there was an issue.
There are a growing number of countermeasures that can be applied to our power gird. That’s fortunate since solar storms with CME and EMP events are a growing threat, and the grid is exposed. We can’t afford to be reactive on GMD. Proactivity is needed for grid resilience, and inactivity is too expensive!
