By Rich Heidorn Jr.

FERC last week approved SPP’s new rules for how it commits and pays “multi-configuration” combined cycle plants, an innovation that will also result in changes to settlement procedures for all generators (ER17-358).

Previously, the Tariff did not permit generators to offer multiple operating configurations. Combined cycle plants could register individual plant components as separate resources, register the plant as a single resource representing all the plant’s components, or register as a pseudo combined cycle resource (one combustion turbine and a portion of a steam turbine).

Under the new rules, SPP will be able to model up to three of a multi-configuration resource’s (MCR) operating configurations, providing additional flexibility for SPP’s commitment and dispatch of such plants.

The Tariff revisions also will affect SPP’s settlement practices for all resources, making changes to how the RTO determines make-whole payments, out-of-merit energy amounts and reliability unit commitment (RUC) make-whole payments. The RTO said the new rules “do not substantially modify eligibility for make-whole payments for non-MCRs, but instead more accurately reflect cost causation principles in the calculation of make-whole payments.”

In approving SPP’s proposal, the commission said the changes “will more accurately model the operating characteristics” of flexible combined cycle plants. “In addition, we find that SPP’s proposal to modify its market settlement procedures for both MCRs and non-MCRs will more accurately reflect commitment optimization and cost causation principles in cost recovery and thus benefit market efficiency.”

The commission ordered SPP to make a compliance filing clarifying how it will “ensure MCR configurations, when mitigated, reflect the lowest cost unit capable of participating in the configuration.” The commission said revisions proposed by SPP “should also inhibit physical withholding by requiring one valid configuration to represent the maximum capacity of the combined cycle resource.”

The changes are effective March 1, when software allowing the modeling of the MCRs goes live. Participants completed testing of the software in January.