Amendment of the Market Ancillary Service Specification (MASS) – Very Fast FCAS

Market National Electricity Market
StageFirst Stage
ConvenorAEMO NEM
Accepting submissions?Yes
Submissions close14/06/2022


  • First Stage - Issues Paper and Notice of First Stage of Consultation
    2 May 2022
  • First Stage - Submissions Close
    14 June 2022
  • Second Stage - Draft MASS determination and Notice of Second Stage of Consultation
    12 July 2022
  • Second Stage – Submissions Close
    8 August 2022
  • Third Stage - Final MASS Determination published
    19 September 2022

Key contact

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The Australian Energy Market Operator (AEMO) has initiated consultation on the Market Ancillary Service Specification (MASS) with regards to incorporation of very fast frequency control ancillary services (very fast FCAS).

This consultation is being conducted in compliance with clause 3.11.2(d) of the National Electricity Rules (NER) which requires AEMO to “comply with the Rules consultation procedures when making or amending the market ancillary service specifications.”

Background (or Proposed changes)

On 15 July 2021, the AEMC published a final determination and a final rule to introduce two new market ancillary services, very fast raise, and very fast lower frequency control ancillary services, collectively known as very fast FCAS, to help control power system frequency. 

As a result, AEMO is commencing a review and consultation on proposed amendments to the market ancillary services specification (MASS) to include the new services. The MASS amendments are due to be published by 19 December 2022.

The MASS review will focus on technical and measurement requirements for the two new FCAS markets.


Public Forum

AEMO held a public forum on Friday 13 May 2022 to provide stakeholders with an opportunity to discuss and ask questions about the content included in the MASS Issues paper.

A copy of the presentation slides presented in this session is available below.


Submissions on the MASS Issues Paper should be forwarded to by 5.00 pm (AEDT) on Tuesday 14 June 2022.

Consulted Persons are encouraged to use the Response template when preparing their submissions.

Submissions containing confidential information should be marked confidential.

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