AEPC_2025_18 Essential System Service Quantities

The consultation process

The consultation process is outlined below. Dates are indicative only and subject to change.

Procedure change proposal

Electricity System and Market Rules – Clause 2.10

Date of Notice: 29 September 2025

Matter under consultation

AEMO commenced the Procedure Change Process to propose amendments to the WEM Procedure: Essential System Service Quantities to align with amendments to the ESM Rules under Schedule 4 of the Wholesale Electricity Market Amendment (Cost Allocation Reform) Rules 2024 (Amending Rules). 

The primary amendments relate to:

• Paragraph 3.2, to reflect changes to the Dispatch Algorithm to co-optimise for the Largest Credible Load Contingency, as per clause 7.2.4(nA) of the Amending Rules.
• Paragraph 4.1 (previously paragraph 5.1), to change the methodology that AEMO uses to determine the Minimum RoCoF Control Requirement, to use a more accurate, dynamic mechanism based on actual dispatch conditions (as opposed to the previous statistical approach based on historical data).  

Minor editorial amendments were also made throughout the Procedure to improve clarity, correct typographical errors, update in-text references, update definitions, and align with AEMO’s current WEM Procedure template.

On 6 February 2025 the State Electricity Objective (SEO) replaced the Wholesale Market Objectives under section 3A of the Electricity Industry Act 2004. Following an assessment, AEMO considers the Procedure is consistent with the SEO. Further information is provided in the Procedure Change Proposal below.

Invitation to make submissions

AEMO invited written submissions on this Procedure Change Proposal, including any alternative or additional proposals may improve the Procedure or better meet the State Electricity Objective under section 3A of the Electricity Industry Act 2004.

AEMO requested that respondents identify any parts of their submission that they wish to remain confidential, explaining why. AEMO advised that it may still publish that information if it does not consider it to be confidential, but will consult with the respondent before doing so.

When making a claim for confidentiality, AEMO encouraged respondents to familiarise themselves with Chapter 10 of the Electricity System and Market Rules (ESM Rules), which imposes obligations in respect to the release of documents.

Meetings

AEMO advised that before the closing date for submissions, any person may request a meeting with AEMO to discuss the issues and proposed changes raised in the Procedure Change Proposal, stating why they consider a meeting is necessary or desirable.

If appropriate, meetings may be held jointly with other stakeholders. 

Subject to confidentiality restrictions, AEMO generally makes details of matters discussed at meetings available to other stakeholders as part of the final published Procedure Change Report (or earlier, where applicable). 

Closing date and time

AEMO advised that submissions in response to this Procedure Change Proposal should be sent by email to [email protected], to reach AEMO by 5.00 pm (AWST) on 28 October 2025.

AEMO advised that all submissions must be in electronic format (pdf or Microsoft Word) and should use the Procedure Change Submission form.

AEMO noted that it is not obliged to consider submissions received after the closing date and time, and that any late submissions should explain the reason for delay and the detriment expected if AEMO does not consider the late submission.

Publication

AEMO advised that all submissions will be published on AEMO’s website. Confidential information will not be published, other than as specified above. 

Submissions

One informal submission was received during consultation. Details about this submission and AEMO’s response can be found in the Procedure Change Report.