PJM is changing the way it estimates Tier 1 Synchronized Reserves and is open to lifting the cap on demand response participation in Tier 2, officials told the Operating Committee last week.

A review of more than 40 Synchronous Reserve events since January 2012 found that only 71% of estimated Tier 1 reserves responded when called upon. The response rate drops to 62% when two outlier events — in which there was over-performance — are excluded.

PJM officials decided to take a look at their estimation methods after an SR call during the Sept. 10 heat wave provided only 12% response.

PJM plans to implement several changes in its methodology by the end of the year:

• Cap all units used in the Tier 1 estimate at the lesser of Eco Max or Spin Max (by end of year).
• Remove all hydropower units – which don’t respond automatically to synch reserve events — from the Tier 1 estimates (already done).
• Remove all combined cycles units from the Tier 1 estimate except units that have submitted a Spin Max < Eco Max (done).
• Remove units with a manual dispatch instruction from the Tier 1 estimate (by end of year).
• During hot or cold weather alerts, the Degree of Generator Performance (DPG) modifier will be used to adjust the Tier 1 response estimate (by end of year).

Units assigned regulation, which are assumed to be able to respond with the MWs outside their regulation band, will remain in the Tier 1 estimate.

Units providing constraint control are expected to respond to a Synch reserve event and will remain in the estimate.

Tier 2 Unchanged

Also unchanged are the Tier 2 calculations. PJM filed new Tier 2 penalty rules for nonperformance Nov. 1 (ER14-297).

The new rules were approved by the Members Committee Oct. 24 in response to concerns that the existing penalties were insufficient to ensure compliance.

Demand response and generation have each provided 59% of requested MWs for Tier 2 events of 10 minutes or longer in 2013, according to a PJM analysis provided last week to the Operating Committee. That was a decline after steady increases in performance from 2009 through 2012.

PJM officials said they don’t know the reason for the fall off in performance. “There’s nothing that jumped out” as a cause, said PJM’s Tom Hauske.

DR Cap

Although the cap on DR participation was raised to 33% last fall, it provided only 224 of the 925 MW (24%), with generation providing the remainder.

DR typically offered between 200 and 250 MWs per hour into the market. Mike Bryson, executive director of system operations, said the decline in SR prices affected the volume of DR bidding into the market, rendering the cap moot.

Asked by EnergyConnect’s Bruce Campbell whether PJM still sees a need for a limit on DR participation, Bryson responded: “I think it’s certainly worth discussing.”

Adam Keech, director of wholesale market operations, said that PJM would need to improve its data collection before considering a change in the cap. About 9% of MWs assigned to DR failed to provide PJM with data in 2013, down from 46% in 2012.

Officials said one concern with removing the cap would be the operational impacts because of differences in the ramp rate of DR versus generation in the first 10 minutes of spin events.