Automatic Under Frequency Load Shedding (AUFLS)

Subscribe for updates

Subscribe to this page to receive email notifications when this page has been updated.

Enter your email address to subscribe to this page.

AUFLS describes the set of relays in New Zealand which automatically trip blocks of load, following a severe under-frequency event, to restore the system frequency.

Transpower, as the System Operator relies on these relays to prevent system collapse following under-frequency events which have the potential to cause a system black-out. 
New Zealand's current AUFLS scheme is made up of two blocks of at least 16% of demand in each island. This means that 32% of customers' load can automatically disconnect to restore stability to the power system following the loss of net injection which drops the system frequency to below 48 Hz.

To improve overall performance and therefore reliability of the scheme, the System Operator and the industry will be moving to a four block AUFLS scheme, which the Authority anticipates will be in place by June 2025. See the AUFLS Project page  for more information on the project. 

AUFLS Animation/video

We have prepared a two sets of animations/videos:

  • the first one summarises the findings of the AUFLS Scheme Design Report and is available here.
  • the second is a set videos shows how to use the AUFLS Data Portal and is available here

AUFLS Project

Transpower is in the process of transitioning to a four block scheme. The first phase of the project is currently underway and is focusing on establishing a data portal for North Island Distributors to be able to submit their two block AUFLS data to the system operator. Refer the AUFLS Project web page for more information.

Related Documents

Document Description
Distribution Assets Testing Guide
GL-EA-766 Companion Guide for Testing of Distribution Assets [ pdf 1.18 MB ] This document sets general requirements of routine testing that apply to all testing that is carried out on assets prior to commissioning and for testing after any modification.
AUFLS Customer Portal  – User Guides and FAQs
UG-SD-940 AUFLS Customer Portal Distributor User Guide [ pdf 2.01 MB ] A user guide for Distributor users of the AUFLS Portal (a copy is also available in the portal itself).
GL-EA-941 AUFLS Data Template Guide [ pdf 259.89 KB ] A guide to accompany the data templates which provides detail on how to populate these.
AUFLS Project FAQs [ pdf 127.66 KB ] A document that covers key messages and frequently asked questions relating to the AUFLS Project
AUFLS Customer Portal  – Forms and Templates
Link to Customer Portal  
FM-EA-938 Distributor AUFLS Customer Portal Admin Users Form [ docx 70.09 KB ] A form that the Distributor uses to nominate the Admin users that they would like to be initially created in the portal.
DT-EA-945 AUFLS Feeder Configuration Template [ xlsx 37.93 KB ] An excel template for Distributors to populate the location, configuration and status of AUFLS feeders for the submission period.
DT-EA-943 AUFLS Feeder Load Profile Template [ xlsx 548.14 KB ] An excel template for Distributors to populate the average load (MW) at each AUFLS feeder for each trading period over the specified 12-months period.
DT-EA-942 GXP Load Profile Template [ xlsx 376.86 KB ] An excel template for Distributors to populate the average off-take load (MW) at each GXP for each trading period over the specified 12-months period.
DT-EA-944 Total Distributors Load Profile Template [ xlsx 281.99 KB ] An excel template for Distributors to populate the total load (MW) for each trading period over the specified 12-months period.