Friday, June 21, 2024

Prolonged low temperatures test Chelan PUD grid

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CHELAN – “It was a test for our system,” said Chelan County PUD senior communications specialist Rachel Hansen describing power outages that affected about 2,000 Chelan area customers on Saturday, Jan. 13.

The outages affected parts of the South Shore, Manson, and Plain and while power was restored to most homes in less than a day, the crisis identified vulnerable parts of the PUD’s power delivery grid that will get extra attention to absorb any future emergencies.

Hanson said the PUD’s distribution network is designed to operate at temperatures as low as zero degrees for sustained periods, but the prolonged event of minus zero days taxed the system to its limits and beyond.

From Friday, Jan 12, through Tuesday, Jan. 16, National Weather Service records for Wenatchee’s Pangborn Field recorded the following low temperatures: 

Friday, Jan. 12 -7 degrees

Saturday, Jan. 13 -10 degrees

Sunday, Jan. 14 - 4 degrees

Monday, Jan. 15 - 2 degrees

Tuesday, Jan. 16 1 degree

The consecutive string of unprecedented freezing days sent homeowners cranking up the thermostats and setting a new megawatt usage record for the PUD. Hanson said the previous high of 553 megawatts set in December 2022 was eclipsed by the 583 megawatts used on Saturday, Jan. 13.

Compounding the restoration of power after an outage is a term called “cold load pickup” when customers do not switch off breakers or disconnect unnecessary appliances. When power is restored following an outage, the pent-up electrical demand can sometimes overload the system, resulting in another outage.

“To avoid cold load pickup, customers were asked to unplug all electrical items and wait about a half hour after power was restored before reconnecting the electric powered items,” said a PUD advisory. “Restoration has been slow because customers—residents affected by the outage—are not aware of the need to unplug items.”

To be clear, Chelan PUD did not run out of power, it experienced an interruption in the delivery of that power to some of its users. The utility has an abundance of low-cost, hydroelectric power to supply its customers. The evolving challenge is to keep the delivery system ahead of growing demands and crisis events like the one that just happened.

Mike Maltais: 360-333-8483 or michael@ward.media

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