The COAG Energy Council has approved harmonising gas days, with the Gas Market Reform Group (GMRG) progressing implementation of changes to the National Gas Law (NGL) and the

National Gas Rules (NGR) (the rules). Under the changes, gas day harmonisation means a standard gas day starting at 6:00 am (AEST).

The NGR changes have been made by the South Australian Minister and the NGL changes were

enacted by the South Australian Parliament on 22 November 2018.

As part of these NGR changes, it is an obligation for natural gas facilities to prepare and provide to AEMO a transition plan by June 30 2019.

The use of standardised gas day timing takes effect from 1 October 2019.

1.1 Purpose

This document describes the activities that the Tasmanian Gas Pipeline (TGP) will undertake to facilitate a successful transition to a harmonised gas day.


2.1 Transition Day

The 30 September 2019 has been selected as the gas day harmonisation transition day, meaning that this will this day will be shorter than usual. It will start at 6:30am on the 30 September 2019 and finish at 1 October 2019 at 6:00am (AEST), being 23.5 hours.

2.2 Commercial

TGP will amend its Gas Transportation Agreements with Shippers to follow the standard market timetable as defined in Part 26 of the NGR, taking effect from 1 October 2019. Amendments will cover:

  • New gas day definitions
  • Adjusted nomination cutoff and scheduling times

2.3 Technical

TGP will amend its reconciliation, metering and IT systems to follow the standard market timetable as defined in Part 26 of the NGR, taking effect from 1 October 2019. Amendments will cover:

  • Adjusted timing of hourly meter reads
  • Adjusted reconciliation timing
  • Adjusted SCADA gas day timing
  • Adjusted nomination cutoff and scheduling times
  • Adjusted Day Ahead Auction (DAA) and Capacity Trading Platform (CTP) reporting times

It is not anticipated that all remote telemetry units will need to be physically adjusted, as hourly meter reads are saved into TGP’s OT systems.

2.3.1 Hourly Meter Reads

TGP will adjust the last hourly interval read and reconciliation for gas day 30 September 2019 to only include data from 5:30am to 6:00am (AEST). Thereafter, each hourly read will be on the hour as opposed to on the half hour.

2.3.2 Reconciliation Timing

TGP will adjust the reconciliation of gas data for gas day 30 September 2019 to reconcile from 06:30am to 06:00am (AEST).

2.3.3 SCADA Information

TGP will adjust daily aggregated reads for SCADA. These reads are purely for internal reporting and have no bearing on TGP’s commercial, market or technical activities.

2.3.4 Nomination Cutoff and Scheduling

TGP will adjust nomination cutoff times to 15:00 (AEST). TGP will perform scheduling activities by 16:30 (AEST).

2.3.5 DAA and CTP Interaction

TGP will adjust internal systems to adhere to the standard market timetable for DAA activities, including the submission of Auction Quantity Limits and nomination cut off times for auction quantities.

2.4 Interaction with the Declared Wholesale Gas Market (DWGM)

TGP operates as an Interconnected Transmission Pipeline connecting into the DWGM. These activities already adhere to a 6:00am to 6:00am (AEST) gas day and TGP does not anticipate any changes to these systems.