Automatic under-frequency load shedding (AUFLS) describes the set of relays in New Zealand that can automatically trip blocks of load following a severe under-frequency event to restore system frequency.
Transpower, as the System Operator, relies on this scheme to prevent system collapse following under-frequency events. The current AUFLS scheme is made up of two blocks of at least 16% of total demand, one in each island. This means that 32% of customers' load can automatically be disconnected to restore stability to the power system following the loss of net injection that drops the system frequency to below 48 Hz.
Without the AUFLS scheme, system collapse would result in widespread blackouts, potentially taking out all of one or both islands and requiring a black start to get the system operating again. A black start could take up to several days to fully restore power.
To improve overall performance and therefore reliability of the AUFLS scheme, the System Operator and North Island AUFLS providers will be moving to a four-block AUFLS scheme, which the Authority expects will be in place by end June 2025. See the AUFLS Project page for more information on the project.
Submitting AUFLS profile information
North Island AUFLS providers are required to provide their AUFLS profile data to the System Operator at least every 12 months in line with their requirements in the Code. This information is to be submitted by 1st April for the previous calendar year through the Operations Customer Portal.
Submitting pre- and post- event data
All AUFLS providers must submit pre-and post event data to the System Operator within 30 days of an AUFLS event as detailed in the AUFLS Technical Requirements Report or in a format agreed with the System Operator. To assist AUFLS Providers a template for an alternative format is available here, once filled out it should be submitted to the System Operator to [email protected] for consideration
AUFLS animation/video
We have prepared two sets of animations/videos related to the AUFLS scheme:
- the first summarises the findings of the AUFLS Scheme Design Report here.
- the second is a set of videos showing how to use the AUFLS Data Portal here.
AUFLS project
The System Operator is in the process of transitioning to a four-block AUFLS scheme. The third phase of the project is currently underway and is focusing on preparing for the commencement of the AUFLS transition period. See the AUFLS Project web page for more information.
Related Documents
| Document | Description |
|---|---|
| AUFLS Project | |
| AUFLS Provider indivdual transition plan template | An excel template for connected asset owner to populate their individual transition plan. |
| AUFLS Transition FAQs | A document that covers key messages and frequently asked questions relating to the AUFLS Project. |
| Distribution Assets Testing Guide | |
| 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 | |
| A user guide for Distributor users of the AUFLS Portal (a copy is also available in the portal itself). | |
| A guide to accompany the data templates which provides detail on how to populate these. | |
| A document that covers key messages and frequently asked questions about the AUFLS Project relating to the Customer Portal. | |
| AUFLS Customer Portal – Forms and Templates | |
| Link to Customer Portal | |
| AUFLS Data Agreement Template | |
| A form that the Distributor uses to nominate the Admin users that they would like to be initially created in the portal. | |
| An excel template for Distributors to populate the location, configuration and status of AUFLS feeders for the submission period. | |
| An excel template for Distributors to populate the average load (MW) at each AUFLS feeder for each trading period over the specified 12-month period. | |
| An excel template for Distributors to populate the average off-take load (MW) at each GXP for each trading period over the specified 12-month period. | |
| An excel template for Distributors to populate the total load (MW) for each trading period over the specified 12-month period. | |