New Dynamic Line Rating Tool strengthens BPA’s real-time grid monitoring

The Bonneville Power Administration integrated a new tool this summer to improve its real-time transmission system monitoring. The Dynamic Line Rating Tool helps engineers determine how much electrical current can run through a transmission line as temperatures change.

The project was led by Real-Time Operations, the Transmission Services organization responsible for the safe and reliable operation of BPA's transmission network and fulfilling BPA's functions as a transmission operator and balancing authority. One of the group's many responsibilities is to monitor ambient temperatures surrounding transmission lines, as the temperature outside affects transmission line ratings. These ratings determine how much electrical current can run through a transmission line. As temperatures warm, less current can pass through the lines, and as temperatures cool, more current can pass through the lines.

Traditionally, Real-Time Operations used three fixed seasonal ratings: spring, summer and winter. Engineers would monitor and adjust current throughout BPA's transmission system using the fixed seasonal temperature ratings as baselines. Ratings deviating from the baseline were then investigated by engineers who performed manual calculations to determine if there was actual negative effect on the system.

Now, the Dynamic Line Rating Tool produces hourly, accurate line ratings, and helps engineers better monitor and maintain a reliable transmission system. From there, engineers monitor the data the tool produces for any potential problems.

“It's still a part of our process to conduct manual calculations," supervisory electronics engineer David Kleinschmidt said. “If we see a line nearing its limit, the study engineer will still do a manual check."

Supervisory electronics engineer Gage Marek explained how the tool bolsters transmission system reliability by better preparing the agency for unusual weather temperatures, like the recent heat wave that hit the Pacific Northwest. “We had temperatures higher than we expected for the summer period," he said. “The tool is able to calculate ratings above those seasonal limits, so we have an accurate picture of what the loading on our transmission facilities are."

Teams from BPA's Power, Transmission and Information Technology organizations collaborated throughout the implementation of the tool. Real-Time Operations worked extensively with BPA's Weather and Streamflow Forecasting group to gather and import weather data for the tool. “This was a cross-agency effort – we came together to provide value to many internal teams and external partners," Marek said. “It's a great example of BPA being an industry leader."

Going forward, Real-Time Operations is already looking at updating the tool. Currently, the tool provides accurate temperatures for BPA substations and can set midpoints on transmission lines and provide temperature data for that specific point. Marek said his team is looking into using that capability to set midpoints on some of BPA's larger transmission lines. “So we can get a midpoint for the Ashe-Marion line that's 200 miles long across the Cascades," he said. “We can find those midpoint temperatures to get even more accuracy in our data."

In addition to increasing the agency's system reliability, the tool's implementation satisfies part of the Federal Energy Regulatory Commission's Order 881, which mandates transmission providers to implement and use real-time ambient-adjusted ratings by 2025. While BPA does not fall under FERC jurisdiction, the agency still administers best practices to improve its system. Marek said BPA will also share knowledge pertaining to the tool with other utilities in the region in efforts to aid them in setting up their own tools.