Extreme Cold: This Is Not a Test!

In January during the extreme cold, our system saw its highest electricity use ever.

Not only did we exceed our previous highest peak load, but we also had 25 hours that exceeded that previous peak. The very heavy load on our electrical system caused some of our equipment to trip offline to protect it from permanently damaging the equipment. NLI engineers and line crews had all hands on deck to try our best to keep everyone’s power on during the very cold weather. We had to switch load around between substations, change protection settings to allow for more load, and tinker with voltage regulators, among other tasks.

One could say this was a stress test of our system, but unfortunately, it was not a test. The reality is, we found some of the weak areas of NLI’s power system.

NLI has a 5-year construction work plan and a 10-year long-range plan. These plans look at load growth within each area for new connections and additional loads that a member may be adding to the system, such as more equipment to a manufacturing plant. This shows NLI’s engineering team where we will need to upsize conductors, cables, or substations to accommodate the growth. These plans are based off computer models that are stress-tested through simulations.

At some of our substations and feeders during January’s extremely cold temperatures and peak loads, we exceeded the projected growth we had at 5 or more years out of our plans. In some areas, we already have projects in the works knowing this load growth and extreme peaks were likely to happen. Unfortunately, these projects are still in the works.

We have 2 substation projects we started about 2 years ago. The large substation power transformers currently have a lead time of 4 to 5 years. We have 2 on order for these 2 substation projects. However, we are not expecting to receive them until 2026.

For the substation located by Priest Lake, we are coordinating with another nearby electric cooperative to buy a surplus substation transformer. This transformer will help NLI get by for the next 2 winters so we can keep the heat and lights on for all those members during the extreme cold and other harsh weather conditions.

Substation transformers come in different voltages and configurations, so it can be challenging to find a used one that will work at a specific substation.

NLI’s engineering team is also reprioritizing several of our line projects after what was observed during the extreme cold. Now that we have real-world stress system data, we can apply it to our models and review updated loading results. These projects are generally upsizing overhead conductor or underground cable sizes, or adding additional voltage regulation equipment or back feed options from other sources.

NLI will continue to monitor our power system and growth to ensure we can meet the needs of members during extreme temperatures in summer and winter and adapt our project priorities as needed.