Automatic under-frequency load shedding (AUFLS)

Guidance for AUFLS providers about AUFLS asset testing and submitting profile information to us.

Overview

Automatic Under-Frequency Load Shedding (AUFLS) is designed to maintain the stability of New Zealand’s power system during severe under-frequency events. The scheme significantly reduces the risk of cascading outages and system collapse, limits the extent of customer interruptions, and supports the timely recovery of the power system. AUFLS automatically disconnects approximately 32% of electrical demand following a loss of net injection that drops the system frequency to below 47.9 Hz (or 48.5 Hz in exceptional circumstances) in the North Island or 47.5 Hz in the South Island.

We have prepared the following videos for you to learn more the AUFLS scheme:

A playlist explaining the findings of AUFLS Scheme Design Report, including a video illustrating what AUFLS is
Guidance videos showing how to use the AUFLS Data Portal.

Status

North Island Connected Asset Owners (CAOs) have either implemented AUFLS systems in accordance with the four-block requirements, or as agreed with the System Operator under individual equivalence arrangements. Further information is available on the AUFLS Project web page and the System Operator Register.

South Island CAOs co-operate with the Grid Owner (GO) to implement the two-block AUFLS scheme, with an equivalence arrangement for the demand at Tiwai.

Submitting AUFLS Profile Information

The Code requires North Island CAOs to provide their AUFLS profile data at least once every 12 months. Use our System Operator Customer Portal to do this. You must submit this information by April 1^st for the previous calendar year.

If you have not already registered for the System Operator Customer Portal, you will need to register by following the instructions here, where you will also find some guiding documents to help you navigate the application and learn how to add other users.

Submitting Post-event Data

For any system event that triggers, or would be expected to trigger, an AUFLS system, North Island CAOs and South Island GOs should gather AUFLS scheme data as soon as possible, regardless of whether their AUFLS system operated. This data must be submitted to [email protected] within 30 business days in the format detailed in the AUFLS Technical Requirements Report.

If you wish to use a different data format, complete this AUFLS data agreement form and submit it to [email protected] for consideration.

Further Information

We have compiled the documents and templates below to support you following our process. Please review the appropriate section below to learn more about each topic, and if you have any questions, reach out to us at [email protected].

Distribution Assets Testing

Document	What’s it for?
GL-EA-766 Companion Guide for Testing of Distribution Assets	Outlines the general requirements of routine testing that apply to all asset tests prior to commissioning generation and for testing after any modification.
DT-EA-1181 AUFLS Routine Testing Results Template	Template capturing and consolidating an AUFLS provider’s testing data to perform a self-check or self-assessment before sending to the System Operator. Send to [email protected] once complete.
DT-EA-1182 Statement of compliance - AUFLS	Template for CAOs to confirm to the System Operator the 4 block AUFLS system is in compliance with the Electricity Industry Participation Code 2010. Send to [email protected] once filled out and signed by an accountable manager.

Data Templates for North Island Annual AUFLS Submissions

Document	What’s it for?
GL-EA-941 AUFLS Data Template Guide	A guide to support you with providing data for the annual AUFLS data submission.
DT-EA-942 GXP Load Profile Template	Spreadsheet for Distributors to populate the average off-take load (MW) at each GXP for each trading period over the specified 12-month period.
DT-EA-943 AUFLS Feeder Load Profile Template	Spreadsheet for Distributors to populate the average load (MW) at each AUFLS feeder for each trading period over the specified 12-month period.
DT-EA-944 Total Distributors Load Profile Template	Spreadsheet for Distributors to populate the total load (MW) for each trading period over the specified 12-month period.
DT-EA-945 AUFLS Feeder Configuration Template	Spreadsheet for Distributors to populate the location, configuration and status of AUFLS feeders for the submission period.