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  • Flexible ramping constraint
    Implementation of a new flexible ramping constraint in the market optimizations will help ensure sufficient ramping capability is available to meet conditions in the five-minute market interval when conditions have changed from the assumptions made during the prior procurement procedures. Enforcement of the constraint can produce opportunity costs for resources that resolve the constraint. Through this initiative the ISO and stakeholders will address how to appropriately compensate resources that resolve the constraint.
    • Outcome
      The ISO implemented a new flexible ramping constraint in the five-minute market optimization as an interim measure until market bid-based products are developed through the Flexible Ramping Product initiative. Resources that resolve a constraint are compensated at the shadow price, which is the marginal unit’s resource specific opportunity cost. — Implemented: Dec. 13, 2011; FERC approval: Dec. 12, 2011; Tariff amendment filing: Oct. 7, 2011 (ER12-50); Board of Governors approval: Aug. 25, 2011

      Update Oct. 6, 2016: FERC approved the flexible ramping product tariff amendment on Sept. 26. This product will replace the interim flexible ramping constraint effective Nov. 1, 2016 pending FERC’s approval of the ISO’s petition to modify the effective date and a separate amendment to remove flexible ramping constraint language. See Draft Tariff Language - Certain Flexible Ramping Constraint References for more information. — FERC approval: Oct. 31, 2016; Tariff amendment filing: Oct. 6, 2016 (ER17-40)
    • Flexible ramping constraint - papers and proposals