PJM Interconnection issued load shed directives in the AEP service territory in Ohio June 14-15 related to thunderstorm damage that knocked out multiple 138-kV transmission lines and overloaded other lines, causing congestion and localized power price spikes.
Several emergency procedures remained in effect June 15, in addition to a hot weather alert.
“Starting at 10:41 am [ET June 15], PJM directed AEP to interrupt electricity services in limited areas to relieve and prevent additional overloads,” the grid operator said in an email, and a second load shed directive was issued at 11:40 am.
Severe storms June 13 caused significant damage to some large transmission lines that ultimately feed power to the Columbus area, AEP Ohio said on its website June 15.
“Combined with impacts from the heat, some of the remaining transmission lines became overloaded, requiring emergency outages to protect the electric system,” the utility said.
A total of 211,195 customers were without power in Ohio as of early afternoon June 15, according to PowerOutage.US , which aggregates utility outage data. There were 144,092 customer outages in the Columbus area, according to AEP Ohio ’s outage map.
“While crews continue to make progress on repairs, due to continued extreme temperatures, the electrical system will remain stressed until the damaged lines are returned to operation,” AEP said on its website.
Temperatures were forecast to reach 97 degrees Fahrenheit June 15 and an excessive heat warning was in effect until 8 pm, according to the National Weather Service. A high of 94 F was forecast for June 16 with a chance of additional thunderstorms, the service said.
“Some customers affected by [June 14] outages are experiencing new outages today as a result of our power lines becoming overloaded again. Additional emergency outages may occur through [June 16] for those customers previously affected,” AEP said.
“We ask that customers reduce any unnecessary electric usage between the peak hours of noon [ET] and 7 pm and strongly encourage all customers to have backup accommodations for their safety and well-being in the event of further outages,” the utility said.
PJM has been working with the impacted utilities to protect the broader power system and restore power to customers.
“Because several 138-Kv lines in AEP tripped yesterday [June 14], PJM directed AEP to interrupt electricity service in limited areas to relieve and prevent additional overloads in AEP and across the grid,” PJM spokeswoman Susan Buehler said in a June 15 email.
Several lines were restored but restoration continues on the system, Buehler said.
Market impacts
“It looks like some storm restoration and possibly load shedding could go on until at least tomorrow June 16,” Bill Dugan, director of optimization for wholesale services at Customized Energy Solutions, said in a phone call.
“It’s been a tumultuous couple of days with real-time power price jumps over $3,000/MWh into late-night June 13,” Dugan said.
“PJM was short reserves—both primary and synchronized—and that created a large adder to real-time prices. Additionally, export levels to the Midcontinent Independent System Operator were extremely high and that was somewhat of a driver,” he said.
Congestion on the transmission lines that remained in service after the storms have also been contributing to power price volatility in the region.
“PJM is experiencing congestion on facilities in the AEP zone,” which can occur when demand is high and some facilities are out of service, Buehler said, adding that hot weather “does create higher electricity loads and can contribute to congestion but we have adequate generation to meet demand.”
In the real-time market, there have been some $1,000/MWh congestion spreads, Dugan said.
“It looks like the Obetz 138-kV load bus, south of Columbus, is the tightest area with real-time prices ranging from $1,600/MWh to $1,850/MWh since 8 am this morning,” Morris Greenberg, senior manager for North America power at S&P Global Commodity Insights, said June 15.
AEP-Dayton Hub on-peak day-ahead power prices averaged $88.63/MWh in May, for comparison.
In addition to load shedding, PJM has called for Emergency Load Management Reduction Actions, most recently on the morning of June 15, requiring demand response resources to reduce their power consumption.
“AEP zone in Ohio has over 800 MW of registered demand response from almost 900 sites, but only a subzone (Marion) was called,” Peter Cavan, director of market development at Convergent Energy + Power, said in an email.
“It's very likely DR contributions—homes and businesses curtailing or dispatching storage—kept their neighbors online by reducing both the scale and frequency of load shed PJM had to direct,” Cavan said.