Generator Performance, Member Coordination Power Reliable Summer

Record set for weekend demand; forced outages down


Thanks to improved generator performance and the coordinated response of PJM members, PJM was able to keep the power flowing reliably this summer for the 65 million people in 13 states and the District of Columbia.

PJM’s analysis of performance this summer shows that the grid continues to be diverse and reliable. While the summer, as a whole, featured relatively mild weather, it also included a record weekend demand of more than 150,000 MW during a July heat wave.

Peak power use over the summer was more than 152,000 MW, occurring July 19. PJM’s all-time, one-day highest power use was recorded in the summer of 2006 at 165,563 MW.

A Responsive and Flexible System

Michael E. Bryson, senior vice president – Operations, said that the evolution of the system, characterized by sophisticated and responsive resources, enforceable performance standards and planned transmission improvements, has helped ease the stress on the grid during high summer loads. “We appreciate the cooperation and coordination with our member utility companies,” Bryson noted. 

 “The system would not have handled these high demands as smoothly a decade ago,” said PJM’s Kevin Hatch, supervisor, system operations – Dispatch. “We are seeing generators that are increasingly responsive to our operational requests, a transmission system that is more robust, and the benefits of efficient and reliable resources through the capacity market.”

No emergency procedures were called beyond Hot Weather Alerts during five-different periods throughout the summer, the lowest number of emergency procedures in the last five years. Hot Weather Alerts serve to prepare for potential capacity issues brought on by extreme hot or humid weather and accompanying high electricity demand.

PJM considers the summer period to last from June 1 to Sept. 15 each year. Much of the PJM footprint did experience unseasonably warm weather and corresponding high demand on Oct. 1 and 2, however, which resulted in PJM calling on demand response resources.

Those events are outside the scope of this report, but PJM will discuss them at the Oct. 15 meeting of the Operating Committee, when the findings of the Summer Performance Report will also be reviewed.

Outage Rates Decreasing

The system is becoming more reliable as the capacity market incentivizes and phases in better-performing resources and capacity performance requirements – which reward resources that perform during times of system stress and penalize those that fail to perform.

Generator performance is assessed by whether the unit produces electricity when called upon if it had not been previously scheduled for maintenance. If the unit cannot perform, it is considered to be on a forced outage. The average forced outage rate of all the units in the PJM region dropped from nearly 5 percent last summer to less than 3 percent this year, which is the lowest rate in five years.

This is part of a larger trend of decreasing outage rates, which is driving down the required reserve requirement in PJM, reducing wholesale costs to customers.

“More efficient generators mean fewer outages, greater reliability and a more efficient system overall,” Bryson said.

The fuel mix this summer was approximately 37 percent natural gas, 30 percent nuclear, 25 percent coal and 7 percent renewables. The average daily locational marginal price for electricity was approximately $25/MWh and the price during the daily peak was $46/MWh.