By Tom Kleckner

FERC last week denied the SPP Market Monitoring Unit’s request for rehearing of a December 2014 order that rejected the Monitor’s use of a market-impact test to track physical withholding.

The commission found the test to be “overly limiting” and said the Monitor failed to demonstrate FERC was mistaken in requiring the test’s elimination (ER15-21-001).

FERC’s 2014 order required SPP to eliminate proposed revisions that added the market-impact test as a monitoring threshold for instances of physical withholding and said the RTO did not show how its proposal addressed FERC concerns.

The Monitor requested the rehearing in late December, saying including the market-impact test in its withholding screen was consistent with other grid operators’ practices. The Monitor said the test is “designed to be liberal in identifying capacity withheld” and if it is not used, monitoring for physical withholding “will continue to produce excessive false positive screen failures for the [Monitor] to analyze.”

FERC noted the Monitor did not challenge allegations that the proposed changes to the physical-withholding provisions “would sufficiently limit the number of screen failures.” The commission further said neither SPP nor the Monitor explained how the SPP proposal addressed FERC’s concerns about the test’s overly limiting nature.

“Thus,” FERC said in its order, “neither SPP nor the MMU supported the contention that the [market-impact test] was just and reasonable.”

The SPP Monitor had said MISO uses the impact test for physical withholding and argued the SPP Tariff should also have limits for the Integrated Marketplace.

FERC said the Monitor had not explained why the MISO mitigation test was appropriate for SPP. “The use of a specific threshold for mitigation purposes in one market does not necessarily make the threshold appropriate to use in monitoring and referral in another market,” the commission said.