Weathering the storm: BPA preserves transmission system reliability through high geomagnetic activity

Mid-May, the region caught a spectacular showcase of the northern lights thanks to the world’s strongest geomagnetic storm in over 20 years. At the same time, Bonneville Power Administration employees worked diligently to monitor potential impacts of the storm on the agency's transmission system operations.

Geomagnetic storms like this produce a high amount of geomagnetically induced currents that can impact radio communications, GPS and even overheat certain equipment. According to electrical engineer Daniel Goodrich, high voltage transformers with neutral winding are some of the most affected assets.

“Geomagnetically Induced Currents can flow through the neutral transformer,” he said. “If the GIC magnitude is high enough, it could cause the transformer to overheat.”

BPA monitors GIC in transformers in real time in more than a dozen locations across the agency’s system.

“During a geomagnetic event, Dispatchers are poised to take action as needed,” Goodrich said. “Such as taking a transformer bank out of service or limiting the flows among major power system paths.”

While some transformer banks did see relatively high currents, he said they were not high enough to cause overheating.

Fortunately, the agency receives advanced notice of potential geomagnetic activity that may pose a threat to transmission operations thanks to alerts from the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center. NOAA alerts are sent to Northwest’s reliability coordinator, RC West, who sends alerts to BPA’s dispatchers. Goodrich said BPA dispatchers received alerts a day before this storm. 

"While many of us gazed into the dark sky to behold the beauty of the aurora over the weekend, our dispatchers were vigilant to the invisible threat the solar flares posed to the transmission system," Vice President of Transmission System Operations Richard Bustamante said. "Thankfully, we were able to enjoy the splendor of the event, while preserving reliability of the transmission system."