Planning Committee Examines Effective Load Carrying Capability


PJM and stakeholders continued to examine effective load carrying capability (ELCC) as a planning tool for intermittent resources at a special session of the Planning Committee Friday.

ELCC methodology determines the contribution that an individual generator or a fleet of generators makes to overall system resource adequacy. Specifically, ELCC is a measure of the additional load the system can supply with the particular generator(s) of interest, without a change in reliability.

The purpose of the special sessions was to look at the ELCC provisions as part of a package of changes to Manual 21: Rules and Procedures for Determination of Generating Capability. Manual 21 provides uniformity for planning, operating, accounting and reporting purposes.

Patricio Rocha-Garrido, senior engineer – Resource Adequacy Planning, reviewed the wind and solar system-wide updates, which PJM recalculated by using the 2018 Reserve Requirement Study capacity model. The results now include the impact of not using the forced outages independence assumption during the winter peak week.

The total nameplate capacities have been updated as well:

  • Wind: 14,620 megawatts
  • Solar: 5,290 megawatts

In answer to a stakeholder question, Rocha-Garrido said that new wind and solar units will be able to request capacity credits greater than the ELCC. However, submittal of the data to support the higher credit would need to occur prior to running the yearly ELCC study.

Joe Tutino, engineer – Resource Adequacy Planning, presented the details showing the aggregate wind/solar output as a share of nameplate capacity (slides 7–21) during the top eight daily peak hours of the past nine delivery years.

Growing Interest

With each meeting, interest in ELCC has taken on a life of its own, beyond the basic Manual 21 changes. On Friday, stakeholders expressed additional interest in discussing ELCC in a more comprehensive manner, such as how it might affect an asset owner’s decision for bidding into PJM’s annual Base Residual Auction.

Tom Falin, director – Resource Adequacy Planning, said that the original intent of the special Planning Committee meetings was to determine if using the median rather than the average summer output was a better method to determine the capacity credit value of intermittent resources.

Because of the growing stakeholder interest, Falin said that PJM can look into adopting a more extensive approach using ELCC to evaluate intermittent resources and he would bring the question up for discussion at the full January Planning Committee meeting.

Falin said PJM’s goal is to have all of the proposed Manual 21 changes in place for the next Base Residual Auction in August 2019. This means the parameters for the auction would be posted around May 1, giving PJM and stakeholders time to refine the changes.

He added the discussion could be of use to the market side as a valid way to look at renewables’ relation to reliability and PJM wants to be ready for that discussion. Falin said that the Manual 21 changes would first take effect in the 2022/2023 delivery year; with capacity interconnection rights affected two years later.

The special Planning Committee was the final stakeholder meeting for Dave Pratzon, who represents the GT Power Group. Pratzon spent 45 years in the industry, starting at PJM and PECO before moving to the GT Power Group, which represents PJM’s Power Providers.