Day-Ahead Ancillary Services Initiative (DASI)

Last update: 03/05/2024

Below, affected ISO New England (ISO-NE) participants can learn more about changes to existing systems and procedures related to the Day-Ahead Ancillary Services Initiative (DASI). This project is one of several that ISO-NE has undertaken, in collaboration with stakeholders, for the continued development of the region’s wholesale electricity markets.

See the Participant Readiness Project Outlook for a summary of specifically affected participants and systems for this and other major projects. To receive outlook and project page announcements and training notices, please subscribe to the Participant Readiness and ISO Training mailing lists, which can be managed in Ask ISO. Refer to the How to Manage Your Mailing Lists article for instructions.

• Project Overview
• Required Participant Actions
• Participant Training Opportunities
• Technical Documentation, Rules, and Procedures
• Project Development Materials

Project Overview

ISO New England will introduce ancillary services and constraints in the Day-Ahead Market (DAM) for operating date March 1, 2025, to develop a day-ahead operating plan that satisfies both the load forecast and contingency reserve requirements. Participants with generators, demand response resources (DRRs), or dispatchable asset-related demand (DARDs) that want to provide ancillary services will be required to bid into the DAM to offer these services.

Currently, the methods used to meet reliability requirements are out-of-market actions, which introduce a number of issues. These include:

• Participants may not be aware that their resources are being counted to fulfil contingency reserve requirements.
• Participants are not compensated in the DAM for their resources’ contribution to meeting reliability requirements.
• Participants may not commit to making fuel arrangements to ensure their availability, and penalties for an inability to operate are minimal.
• The costs of meeting reliability requirements are not reflected in the DAM, which distorts pricing.

Two new ancillary services categories with distinct purposes will be offered in the DAM to address these concerns.

• Flexible response services (FRS) are analogous to the 10-minute spinning reserves (TMSR), 10-minute non-spinning reserves (TMNSR), and 30-minute operating reserves (TMOR). All three represent fast-start or fast-ramping capabilities to aid in the recovery from the loss of large transmission or generation facilities.
• Energy imbalance reserves (EIR) are a new product that will allow ISO New England to call on resources to operate above their day-ahead energy schedule when there is a need to bridge a gap between the day-ahead cleared supply and forecast demand.

A new constraint will be introduced and existing constraints will be enforced in the day-ahead security-constrained unit commitment (DASCUC) and day-ahead security-constrained economic dispatch (DASCED) processes.

• A new forecast energy requirement (FER) will be enforced in both the DASCUC and DASCED to ensure that physical suppliers clear a sufficient amount of energy and EIR offers to satisfy the load forecast in the DAM.
• The 10-minute spinning reserve, 10-minute reserve, minimum total reserve, and total reserve constraints will be enforced in both the DASCED and DASCUC.

Participants with generators, DRRs, or DARDs that will provide FRS or EIR must submit ancillary services offers for their resources with the maximum MWh values they are willing to provide and the minimum price they must receive to clear in the DAM. The price and quantity pairs are submitted for a specific hour, or range of hours, and can vary by hour.

Participants can also opt to provide a maximum daily award limit (MDAL) to indicate the maximum total energy and ancillary services MWhs a resource can clear over the 24-hour DAM horizon. The MDAL is similar to the maximum daily energy (MDE) offer parameter in that it represents the total energy MWhs available for a resource on an operating day. Participants can provide the MDAL and MDE parameters, one or the other, or neither.

Required Participant Actions

Affected market participants are required to take specific steps or adapt to changes in ISO-NE systems as described below, and should be mindful of additional time-bound items, some of which may require participants to take specific steps or adapt to changes in ISO-NE systems both before and after the project implementation date.

Participant Training Opportunities

ISO New England may offer online or classroom-based training, information sessions, and other opportunities for affected customers to learn about changes and ask questions in advance of project implementation.

Technical Documentation, Rules, and Procedures

Market participants affected by the project should consult the following documents for specific instructions on completing related tasks or processes and helpful answers to frequently asked questions.

Technical Specifications and Documentation

Rules and Procedures

Project Development Materials

• ER24-275-000, FERC Order Accepting the Day-Ahead Ancillary Services Initiative
• 2024-01-09-11 MC A06 - Revise Energy Offer Mitigation to Address FERC Show Cause Order - ISO Presentation
• 2024-01-09-11 MC A06 - Revise Energy Offer Mitigation to Address FERC Show Cause Order - ISO Tariff Redlines (with DASI)
• ER24-275-000; ISO Answer to DASI Proposal Comments
• ER24-275-000; Internal Market Monitor Comments in Support of the Day-Ahead Ancillary Services Initiative
• ER24-275-000; Revisions to Establish a Jointly Optimized Day-Ahead Market for Energy and Ancillary Services
• 2023-05-09-11 MC A03B Day-Ahead Ancillary Services Initiative (DASI) – ISO Presentation on Mitigation
• NEPOOL Markets Committee Day-Ahead Ancillary Services Initiative (DASI) Presentation (Dec 6-8, 2022)
• Day-Ahead Ancillary Services Initiative Key Project page