The California Independent System Operator (ISO) on Oct. 15 asked the Federal Energy Regulatory Commission to let it amend its tariff to revise how multi-stage generating resources register their unit parameters and how the ISO generates bids for multi-stage generating resources with resource adequacy obligations that do not submit bids to meet such obligations.
The ISO asked that the tariff changes become effective as of Dec. 17. To ensure market participants and the ISO have time to prepare their software systems for this change and implement contingency plans in the event this amendment were not granted, the ISO asked that the commission issue an order in this matter no later than Dec. 11.
This amendment does not present a departure of existing policy regarding the registration of multi-stage generating resources or how multi-stage resources can participate as a resource adequacy resource, the ISO noted. In 2012 the commission approved enhancements to the multi-stage resource functionality generally, including specific changes to how that functionality interacts with the resource adequacy program.
The ISO is now proposing an additional refinement to an existing rule to maximize the benefit of the multi-stage functionality for resource adequacy resources, more fully implement the policy behind the already-approved enhancements, and account for intervening market rule changes.
Accordingly, the ISO seeks to require that all multi-stage generating resources provide a table that identifies the default configuration applicable for each segment of the unit’s output from its minimum operating level (PMin) to its maximum operating level (PMax). This will replace the current mandate that multi-stage resources submit a single resource adequacy default path.
The current single default path inhibits the ISO from accessing a resource’s capacity that a scheduling coordinator has replaced or uses for a replacement. The table containing the multiple available options for multi-stage generating resources with a resource adequacy obligation will enable the ISO to generate bids for any configuration that has a minimum output below the resource adequacy level.
“The Commission should accept this modest rule change as it enables the ISO and resources to get the full benefit of existing market rules previously approved by the Commission,” the ISO added.
A multi-stage generating resource is a resource (including certain generating resources outside the ISO’s Balancing Authority Area) that operates in various configurations but that can only operate in one configuration during any single dispatch interval. Multi-stage resources can be a: combined cycle gas turbine resource; a generating unit with multiple operating or regulating ranges that can operate in only one of these ranges at any given time; or a generating unit that has one or more forbidden operating regions.
Until recently, the ISO’s resource adequacy operations assumed that resource adequacy resources provided a constant monthly amount of resource adequacy capacity. Multi-stage resources submit a default resource adequacy configuration corresponding to the monthly resource adequacy capacity and a preferred single configuration path to get to the default configuration. If the scheduling coordinator for the resource fails to submit a bid or self-schedule for the resource’s capacity under a resource adequacy must-offer requirement, then the ISO uses the default configuration and default transition path to generate a bid on behalf of the resource. The default configuration and transition path are only relevant for market purposes to the extent a resource fails to submit a bid that covers its resource adequacy obligation, which occurs on very limited occasions.