In July 2016, a storm with high winds hit the Twin Cities area, about 30 miles northwest of Minneapolis, Minnesota. After the storm passed, repair crews found multiple distribution lines blown down. Out in the countryside, two 8.5-mile parallel sections of 345-kV line — with 54 H-frame structures on each line — were on the ground in what was clearly a cascading failure. Fortunately, the dead-end structures contained the cascade.
In the immediate aftermath, more than 250,000 customers were impacted, but Xcel Energy workers were able to restore service to 204,000 customers in less than 24 hours. Additional employees, contractors and mutual aid crews were called in to assist in the repair and restoration process.
But there was more work to be done. Both transmission lines were rebuilt and back in service by the end of December 2016.
Following are images from immediately after the storm, and then pictures of the transmission rebuild process. For a more detailed article on Xcel Energy's successful rebuild, see "Storms Cause Chaos" published in the July 2017 issue of T&D World.