Requirements for provision of Primary Frequency Response (PFR) were re-introduced to DUIDs in the NEM:

• from September 2020 (for Tranche 1),
• followed by smaller units later.

This was in response to a Rule Change made by the AEMC.

 

A couple snippets, from the Market Rules

Caveat – reader beware that we’re definitely not lawyers, just analysts seeking to understand … so there may well be mistakes in interpreting what’s in the rules!

As we prepare this article, the current version of the National Electricity Rules are version 245 as at Thursday 30th April 2026.   Within these rules, it is clause 4.4.2 that deals with Operational frequency requirements.

I was interest to have a quick scan with a view to trying to understand two questions…

Q1)  A DUID’s requirement to provide PFR?

Clause 4.4.2(b) reads:

‘each Generator and Integrated Resource Provider must ensure that all of its production units meet the technical requirements for frequency control in their performance standards established under clause S5.2.5.11;’

Clause 4.4.2(c1) reads:

‘subject to clause 4.4.2A(c) and any exemption or variation approved by AEMO under clause 4.4.2B, each:

(1) Scheduled Generator, Semi-Scheduled Generator and Scheduled Integrated Resource Provider that has received a dispatch instruction in accordance with clause 4.9.2 to generate a volume greater than zero MW or to consume electricity other than as an auxiliary load; and

(2) Scheduled Integrated Resource Provider that has received a dispatch instruction in accordance with clause 4.9.3A to provide a regulation service,

must operate its scheduled generating unit, semi-scheduled generating unit or scheduled bidirectional unit in accordance with the Primary Frequency Response Requirements as applicable to that unit;’

… plenty of rabbit holes to proceed down, with respect to all the other clauses noted there….

Q2)  A requirement (for AEMO) to publish PFR status?

Clause 4.4.2A (d) reads:

‘AEMO must publish on its website and maintain, a register of Scheduled Generators, Semi-Scheduled Generators and Scheduled Integrated Resource Providers who have been granted a variation or exemption from any primary frequency response parameters in the Primary Frequency Response Requirements.’

 

 

Reporting (we’re aware of) from the AEMO

With respect to that requirement to maintain a register of variations and exemptions provided per unit (and, or particular interest at this point, per Semi-Scheduled unit), we’ve been striving to understand where AEMO is publishing and maintaining … can any readers help us out please?

 

1)  There’s a general AEMO landing page ‘Primary Frequency Response’ here.

… Further down that page it has a sub-heading ‘Implementation of the Mandatory Primary Frequency Response Rule – status update’, from which the following has been noted…

2)  From 2020 (i.e. start of the rule) through until May 2023 there were 25 reports published by the AEMO with status updates:

(a)  There were 10 reports listed under calendar 2020:

i.  The latest of these reports had a publish date of 16th December 2020

ii.  Quickly scanning this report, we copy out this snippet of useful status for Semi-Scheduled units

‘Hence, where PFR Settings have been agreed for an Affected GS, but an effective PFR implementation has not yet been confirmed with the relevant OEM and tested with appropriate Affected GSs, there will be no implementation dates reported for relevant Affected GSs in Table 4, just a “#” symbol.’

… noting that my inference from this report is that there were no Semi-Scheduled units registered to provide PFR as at the date of this report.

… but if someone knows that this was incorrect, please do correct me?

(b)  There were 10 reports listed under calendar 2021:

i.  The latest of these reports had a publish date of 18th November 2021

ii.  Quickly scanning this report, we copy out this snippet of useful status for Semi-Scheduled units

‘At the time of writing, PFR setting changes have been implemented, or a target date for settings changes has been identified, across 17 Semi-Scheduled Affected GSs using three major OEMs’ equipment, as reported in Table 4’

(c)  There were 4 reports listed under calendar 2022:

i.  The latest of these reports had a publish date of 18th November 2022

ii.  Quickly scanning this report, we copy out this snippet of useful status for Semi-Scheduled units

‘At the time of writing, PFR setting changes have either already been implemented, or an agreement is in place for implementation of settings changes, across 31 Semi-Scheduled Affected GSs using six major OEMs’ equipment, as reported in Table 4. ‘

(d)  There was only 1 report listed under calendar 2023, as noted below.

3)  Many months ago we noted that the AEMO report ‘Implementation of the National Electricity Amendment (Mandatory Primary Frequency Response) Rule 2020 … Status as at 5 May 2023’

(a)  From page 2, we see the report was published at 8th May 2023

(b)  Helpfully, it contained section 3.2 as follows (with my emphasis added):

‘3.2 Implementation for Semi-Scheduled Generation

The Mandatory PFR Rule represents a material change to the operation of some Semi-Scheduled generation. Much of this generation had either not previously operated in frequency response mode, or had previously operated with PFR settings such that response to frequency was a relatively rare event.

To comply with the requirements of the Mandatory PFR rule, Semi-Scheduled generators must be capable of overall active power control allowing for simultaneous MW curtailment, MW ramping, frequency response outside a relatively small frequency deadband, and ongoing variation in input energy.

It has been identified through testing that many existing Semi-Scheduled generators are unable to simultaneously coordinate these various requirements around overall active power control. These sites will require updates to control software, particularly to Power Plant Controllers (PPC) or similar, to comply with these requirements of the Mandatory PFR rule. This is materially different to Scheduled generation, where almost all Scheduled generators were able to comply by making setting changes to existing control systems.’

In some cases, control software supplied with the even the newest Affected GS for some OEMs is still unable to meet the requirements of the Mandatory PFR rule. In these cases, either further software development by the OEMS is required, followed by site upgrades, or alternately some form of variation to the PFR requirements will need to be granted, to allow compliance with the Mandatory PFR rule.

Control system software updates to allow compliance with the Mandatory PFR rule can involve the site operator, the local NSP, multiple teams within AEMO, and in some cases 3rd party consultants. The risk of unintended changes in plant performance when making control system software updates must be handled carefully. The complexity of this process, along with resource limitations across the industry, have seen ongoing delays.

AEMO have been prioritising PFR implementation for Semi-Scheduled generation for those OEMs with the greatest installed MW capacity. With around 20 different Semi-Scheduled generation OEMS in the NEM, this has delayed implementation for sites using equipment from OEMs used in a smaller number of sites.

At the time of writing, PFR setting changes have either already been implemented, or an agreement is in place for implementation of settings changes, across 36 Semi-Scheduled Affected GSs using seven major OEMs’ equipment, as reported in Table 3. While AEMO have agreed in-principle PFR settings for a number of additional existing Semi-Scheduled generators, in many cases implementation has been unable to proceed, due to lack of availability of suitable control system software. Where PFR Settings have been agreed but a planned implementation date has not yet been confirmed, Table 3 contains a “#” symbol for relevant Affected GSs in the relevant column regarding implementation date.

Work to rollout PFR across the semi-scheduled generation fleet remains ongoing.’

c)  the except above refers to Table 3,:

i.  which readers can reference in the AEMO source directly here; and

ii.  which was used as one input into our GSD2023 publication (see note below, and note that this has cascaded through to subsequent editions)

4)  It’s now almost exactly 3 years since the AEMO published the above report on 8th May 2023, and there’s been no more publications at that location … perhaps we’ve missed them elsewhere?

 

We’d ask that our readers – please do point out any references we’re missing, as (at least from what we can see currently) it does appear that it’s gone quiet on the AEMO end?

 

 

What did we do, in the annual Generator Statistical Digest?

Each year since 2019 we have released an annual Generator Statistical Digest – these are described here.  With respect to these updates:

1)  The GSD2019 and the GSD2020 did not contain any reference to the PFR registration status

2)  But since then, we did include a reference to the PFR status from the above AEMO reports:

(a)  the GSD2021 (with AEMO updates); and

(b)  the GSD2022 (with AEMO updates); and

(c)  the GSD2023 (with AEMO’s sole update in 2023)

(d)  then the GSD2024, and the GSD2025 (though noting there appears to have been a 3 year gap in the AEMO’s publication of these reports now!)

 

From the latest release (the GSD2025 was released on 28th January 2026)  we’ve collated a list of the Semi-Scheduled units in four columns … matching what our notation for each of these units were in the GSD2025:

 

PFR Status Implemented (i.e. as in the GSD2025)	PFR Status Exempt or N/A (i.e. as in the GSD2025)	PFR Status Planned (i.e. as in the GSD2025)	PFR Status Unknown (i.e. as in the GSD2025)
In total there were 30 Semi-Scheduled units listed below.	In total there were 20 Semi-Scheduled units listed below (in  two groups).	In total there were 123 Semi-Scheduled units listed below.	In total there were 23 Semi-Scheduled units listed below.
Solar Farms: BOMENSF1 KIAMSF1 MAPS3PV1 WDGPH1 Wind Farms: BALDHWF1 BOCORWF1 BODWF1 BRYB1WF1 CHYTWF1 CROWLWF1 DUNDWF1 DUNDWF2 DUNDWF3 ELAINWF1 GRANWF1 GSWF1A GSWF1B1 HDWF2 KABANWF1 KIATAWF1 MACARTH1 MERCER01 MEWF1 MUSSELR1 PAREPW1 SALTCRK1 SAPHWF1 STWF1 TARALGA1 WGWF1	There are 11 x Wind Farm DUIDs in this list that we had marked as ‘Exempt‘ in the GSD2025: CLEMGPWF HALLWF1 HALLWF2 LKBONNY1 LKBONNY2 LKBONNY3 NBHWF1 OAKLAND1 SNOWTWN1 WATERLWF WOODLWN1 … and worth noting these other 9  x DUIDs marked as N/A in the GSD2025: ADPPV1 MANNSF2 MARYRSF1 MIDDLSF1 WRSF1 CNUNDAWF MTMILLAR STARHLWF WPWF	Solar Farms: AVLSF1 BANN1 BERYLSF1 BLUEGSF1 BNGSF1 BNGSF2 BOWWPV1 BROKENH1 CLARESF1 CLERMSF1 COHUNSF1 COLEASF1 COLUMSF1 CRWASF1 DARLSF1 DAYDSF1 DDSF1 EDENVSF1 EMERASF1 FINLYSF1 GANGARR1 GIRGSF GLENSF1 GLRWNSF1 GNNDHSF1 GOONSF1 GULLRSF1 HAMISF1 HAUGHT11 HAYMSF1 HILLSTN1 HVWWPV1 JEMALNG1 JUNEESF1 KARSF1 KERNGSP1 KINGASF1 KSP1 LILYSF1 LIMOSF11 LIMOSF21 MAPS2PV1 MBPS2PV1 MOKOSF1 MOREESF1 MOUSF1 MWPS1PV1 MWPS2PV1 MWPS3PV1 MWPS4PV1 NEVERSF1 NEWENSF1 NEWENSF2 NUMURSF1 NYNGAN1 OAKEY1SF OAKEY2SF RRSF1 RUGBYR1 SEBSF1 SRSF1 STUBSF1 STUBSF2 SUNRSF1 SUNTPSF1 TB2SF1 TBSF1 WANDSF1 WARWSF1 WARWSF2 WELLSF1 WELNSF1 WEMENSF1 WHITSF1 WINTSF1 WLWLSF1 WLWLSF2 WOLARSF1 WOOLGSF1 WSTWYSF1 WUNUSF1 WYASF1 YARANSF1 YATSF1 Wind Farms: ARWF1 BANGOWF1 BANGOWF2 BLUFF1 BRYB2WF2 BULGANA1 CLRKCWF1 COLWF01 COOPGWF1 CROOKWF2 CROOKWF3 CRURWF1 CTHLWF1 DULAWF1 FLYCRKWF GPWFEST1 GPWFEST2 GPWFEST3 GULLRWF1 GULLRWF2 GUNNING1 HD1WF1 HDWF1 HDWF3 LGAPWF1 LGAPWF2 MCINTYR1 MOORAWF1 MRTLSWF1 MTGELWF1 MUWAWF1 MUWAWF2 RYANCWF1 RYEPARK1 SNOWNTH1 SNOWSTH1 STOCKYD1 WRWF1 YENDWF1	Solar Farms: ALDGASF1 BRDDSF01 CHILDSF1 CRWARP1 CSPVPS1 CUSF1 GANNSF1 GESF1 GOESF1 GUSF1 KEPSF1 MANSLR1 METZSF1 MOLNGSF1 MUCRKSF1 PAREPS1 PARSF1 SMCSF1 WAGGNSF1 CATHROCK Wind Farms: CLRKCWF2 KEPWF1 WAMBOWF1

If any reader can help us understand more, or point out corrections/updates to the above (especially pointing us to information in the public domain!), we’d be very grateful.

 

 

PS1 (at Tue 5th May) about AEMO Test Guidelines

A couple different readers have suggested, for completeness, that we point to this AEMO page about ‘Primary Frequency Response Test Guidelines for Semi-Scheduled Plant’.

This page, and the documents linked there, were published 24th September 2025 – some might take their existence to reflect some of the challenges in testing PFR delivery for Semi-Scheduled plant.  There was:

1)   The Final Report on ‘Primary Frequency Response Test Guidelines for Semi Scheduled Plant’; and

2)  The Initial ‘Primary Frequency Response Test Guidelines for SemiScheduled Plant’.

On quick scan, neither of these documents provided DUID-specific reporting that might update the table above.