Notice of consultation - NTESMO Amendment of the Secure System Guidelines – System Frequency Control

Date of notice: 14 July 2025

This Notice of Expedited Rules Consultation (Notice) informs all relevant parties including:

The Consultation is being conducted under clause S3.5.2 of the System Control Technical Code, Version 7.0, 14 February 2024 , consistent with the expedited rules consultation procedure presented in the National Electricity Rules as in force in the Northern Territory – v125 – Chapter 8.9.3 .

The amendments to the Secure Systems Guideline (SSG) include the following:

Consultation paper - SSG amendments and system frequency v1.0
Power and Water, as the Power System Controller, is consulting on proposed amendments to the Secure System Guidelines (SSG), including structural updates and revised System Frequency Guidelines. This paper outlines the scope of changes and invites feedback from System Participants and Interested Persons.
Open "Consultation paper - SSG amendments and system frequency v1.0" PDF File 176.2 KB
  • A set of discussion papers that further explain amendments regarding frequency control, including:
    • A discussion paper on the application of Frequency Operating Standards aligned to the prescriptions of frequency standards within the Network Technical Code.
    • A discussion paper on the system frequency response (SFR) method proposed for the application of Contingency Frequency Control Ancillary Services (C-FCAS).
    • A discussion paper on the system load rate of change (SLROC) calculation method proposed for the application of Regulating Frequency Control Ancillary Services (R-FCAS).
    • R-FCAS requirements methodology discussion paper v1.0
    This NTESMO paper outlines updated methodology for calculating Regulating Frequency Control Ancillary Services (R-FCAS) requirements in NT power systems. It addresses short-term load changes and the growing impact of behind-the-meter (BTM) solar generation on system stability.
    Open "R-FCAS requirements methodology discussion paper v1.0" PDF File 432.6 KB
    C-FCAS requirements methodology discussion paper v1.0
    This NTESMO paper outlines a proposed methodology for dynamically scheduling Contingency Frequency Control Ancillary Services (C-FCAS) in the Darwin-Katherine Power System. It aims to replace manual spinning reserve processes and improve real-time system frequency response.
    Open "C-FCAS requirements methodology discussion paper v1.0" PDF File 462.9 KB
    Application of Frequency Operating Standards v1.0
    This discussion paper by NTESMO reviews the operational application of Frequency Operating Standards for the NT regulated power systems. It outlines proposed updates to the Secure System Guidelines to support modernisation, system security, and integration of renewable technologies.
    Open "Application of Frequency Operating Standards v1.0" PDF File 477.5 KB

    Matters under consultation

    The changes (Changes) proposed (Proposal) are to:

    • Reformat the SSG consistent with the format of the SCTC, update all cross references, and structure the SSG into themed sections:
      • Guidelines for System Frequency
      • Guidelines for System Adequacy
      • Guidelines for System Voltage
      • Guidelines for Power System Operations
      • Registration Thresholds
      • Related Records
      • Document History
    • Amend the Guidelines for System Frequency to include:
      • Operational Application of Frequency Operating Standards
      • Frequency Control Ancillary Services (FCAS) and their application
    Proposed Draft Secure System Guidelines Version 5
    Draft Secure System Guidelines Version 5 outlines operational standards for frequency, voltage, system adequacy, and ancillary services across NT's regulated power systems. Developed by NTESMO, it supports safe, stable, and efficient electricity operations aligned with the System Control Technical Code.
    Open "Proposed Draft Secure System Guidelines Version 5" MS Word Document 508.7 KB

    The consultation process

    NTESMO invites written submissions on the matters under consultation, including any alternative or additional proposals which may provide a more pragmatically implementable method for FCAS.

    Submissions in response to this Notice should be sent by email by 5:00pm (ACST) on 4 August 2025 to market.operator@powerwater.com.au.

    NTESMO is not obliged to consider late submissions. If submitting after the deadline, please explain the reason for the delay and the potential impact of not being considered.

    Please identify any confidential parts of your submission and explain why you believe they should remain confidential. NTESMO may still publish such information if it determines it is not confidential, but will contact you beforehand. Please note: confidential material may carry less weight in decision-making.

    You may request a meeting with NTESMO to discuss the matters under consultation. Please explain why a meeting is necessary or desirable.

    If appropriate, meetings may be held jointly with other Consulted Persons. NTESMO will generally share key discussion points from meetings with all stakeholders, unless restricted by confidentiality.