On Friday, April 7, 2017, Genscape Transmission RT data showed that the new Byron-Wayne 345kV line in western ComEd is now energized after years of anticipation. Now fully in service, the line will be able to carry 1,679 megawatts (MW) from the Byron nuke east towards Chicago. Its path runs parallel to the Cherry Valley – Silver Lake 345kV line and the Nelson – Electric Junction 345kV line, both of which are two of the top contingencies not only in ComEd, but across all of the PJM and MISO regions. These two lines total to 2,698 MW of west-east capacity.
Around 3:00pm (EDT) on April 7, the Byron-Wayne line was activated and immediately took 800 MWs (Figure 1). Genscape’s Transmission RT data confirmed a large drop in flows on Cherry Valley – Silver Lake 345kV from 760 MWs to 530 MWs (Figure 2). This was roughly a 30 percent reduction in flows.
The foremost result of the new Byron-Wayne line is reduced flow on the ever-present Cherry Valley-Silver Lake. As it stands, Byron – Cherry Valley is the primary destination for Byron generation. This allows the Silver Lake pathway to be the main artery for the nuke to send power to Chicago. In fact, the Generation Shift Factor (GSF) for Byron 1 on the line is 0.30 in a recent state estimator file. This means that 30 percent of Byron 1’s generation ends up flowing on Cherry Valley – Silver Lake. Inserting 1,679 MW of takeaway capacity from Byron and reduces its GSF on Cherry Valley – Silver Lake by 30 percent down to 0.21.
Due to the line insertion, a similarly large reduction was found on Nelson – Electric Junction, decreasing the GSF by 39 percent from 0.18 to 0.11. While these two contingencies are clearly impacted, Cherry Valley – Silver Lake appears to be the one most resolved by the Byron – Wayne line, reducing more MWs from Byron, which is also the top source generator. Despite a larger percentage drop in GSF, Nelson – Electric Junction sees a larger impact from generation at closer units such as Nelson, Lee County, and Quad Cities. Inserting Byron – Wayne had the added effect of reducing the GSF from each of the generators on the Nelson line, although this is unlikely to completely prevent risk from developing on the contingency when source-side generation is high.
Another way of evaluating the impact of the Byron-Wayne on the two contingencies is by computing its Line Insertion Distribution Factor (LIDF) on the two lines. The LIDF measures how flows are displaced on a specific line of equipment by inserting a new piece of equipment into the network. Byron-Wayne LIDFs reveal that flow on Cherry Valley and Nelson lines are reduced by 32 percent and 25 percent, respectively. For Cherry Valley – Silver Lake, this percentage reduction is close to the 30 percent as shown by Genscape’s Transmission RT data.
Genscape’s PJM Power Market Intelligence Team analyzed the impacts for the new transmission line build in its 2017 Spring Outlook. By examining periods of strong congestion on the Cherry Valley 345kV transformer and Belvidere – 15623 138kV for the loss of Cherry Valley – Silver Lake, the analysis inserted Byron-Wayne into the network and studied the contingencies. Genscape’s PJM Power Market Analyst, Pat Finn, who analyzes ComEd congestion daily, explained the results: “In the flow cases we analyzed, we saw a significant reduction in flows over the chronically congested areas around Nelson – Electric Junction and Cherry Valley – Silver Lake.” Finn noted that although the analysis was limited to a small sample size, “the new line is being immediately tested by outages on the Cherry Valley transformer and Nelson – Electric Junction, and in a high wind scenario it has thus far handled the situation.”
Utilizing its vast network of in-the-field monitors, Genscape’s Transmission RT service provides a more robust view of the power grid by showing both generation output and the direction of power flows in near-real-time. Customers receive unparalleled insight into congestion flow patterns resulting in better analysis, trading strategy, and asset optimization. Please click here to learn more or request a free trial of Genscape's Transmission RT.