An automatic access standard is a level of performance that, if met, cannot be refused: the network service provider and AEMO must accept it. The minimum access standard is the floor below which no connection can be approved. A negotiated access standard sits anywhere between the two, and it is only accepted with evidence that it is justified and does no harm to the power system.
Every generator performance standard (GPS) in the NEM lands at one of those three levels, clause by clause, and which ones get negotiated shapes your studies, your equipment and your R1 timeline.
The Three Levels, and Who Has to Agree
The technical requirements for generating systems sit in Schedule 5.2 of the National Electricity Rules (NER), with the access standards themselves in S5.2.5. Most clauses define an automatic and a minimum standard. Our overview of AEMO Generator Performance Standards covers the framework and the R0/R1/R2 process, so here is only what matters for negotiation.
| Level | What it means | Who must accept it | Effort to get there |
|---|---|---|---|
| Automatic access standard | The benchmark level. If the plant meets it, the connection cannot be refused on that requirement | NSP and AEMO must accept a compliant proposal | Lowest. Demonstrate compliance with studies and data |
| Negotiated access standard | Any level between automatic and minimum, agreed for this connection | NSP, with AEMO agreement where the clause is an AEMO advisory matter | Higher. Proposal, reasons, supporting studies and usually several rounds of review |
| Minimum access standard | The floor. Nothing below it can be agreed | Not applicable below this level | A negotiated standard at the minimum still needs full justification |
The connection agreement is with the NSP, so the NSP is the party you negotiate with. But for the clauses classed as AEMO advisory matters, which covers most of the dynamic performance clauses, the NSP cannot agree a negotiated standard without AEMO.
The test a negotiated standard has to pass
NER clause 5.3.4A sets the criteria. In summary, a negotiated access standard must:
What a Negotiated Standard Must Show
- It is no less onerous than the minimum access standard
- It does not adversely affect power system security
- It does not adversely affect the quality of supply to other network users
- It is as close as practicable to the automatic access standard, having regard to plant protection, conditions at the connection point and the commercial and technical feasibility of meeting automatic
"We would rather not" is not a reason. "The inverter cannot do it without a second transformer that costs a known amount, and the network does not need it at this location, as these studies show" is.
Clause by Clause: What Each Standard Covers and Where Negotiation Happens
The table below summarises the S5.2.5 clauses: the long-standing S5.2.5.1 to S5.2.5.14, plus S5.2.5.15 and S5.2.5.16, which the system strength reforms added from 15 March 2023. It paraphrases; it does not reproduce the Rule text. The right-hand column is our experience of how these clauses tend to go for inverter-based resources (IBR). It is a pattern, not a rule, and every connection point is different.
Two caveats. The AEMC's NEM access standards Package 1 rule (final May 2025) rewrote Schedule 5.2, so for projects on the new standards check the current NER for exact clause titles, wording and numbering before relying on the table. And the outcome for a given clause depends heavily on network strength at the connection point.
| Clause | What it covers | Typical outcome for solar, wind and BESS |
|---|---|---|
| S5.2.5.1 Reactive power capability | The reactive power the plant can supply and absorb at the connection point across its output and voltage range | Often negotiated. Losses through transformers and long reticulation cables erode capability at the connection point, especially at full output and voltage extremes. The trade-off is extra inverters, STATCOM or capacitor banks versus a lower agreed range |
| S5.2.5.2 Quality of electricity generated | Harmonics, voltage fluctuation (flicker) and unbalance the plant injects | Set largely by the NSP's emission allocation for the connection point. Negotiation is usually about the allocation and whether filters are needed |
| S5.2.5.3 Response to frequency disturbances | Staying connected through frequency excursions and rates of change of frequency | Modern inverters commonly meet automatic. Check auxiliary supplies and protection settings, which trip before the inverter does more often than people expect |
| S5.2.5.4 Response to voltage disturbances | Staying connected through sustained over- and under-voltage at the connection point | Usually automatic for the inverters. Negotiation tends to come from the balance of plant: transformer overfluxing at high voltage, auxiliary equipment ratings |
| S5.2.5.5 Response to disturbances following contingency events | Fault ride-through: riding through faults, multiple faults in a short window, reactive current injection during the fault and active power recovery afterwards | The most studied and most often negotiated clause for IBR. Weak networks drive negotiation of recovery times, current injection and the multiple fault requirement |
| S5.2.5.6 Quality of electricity and continuous uninterrupted operation | Continuing to operate when supply quality at the connection point is at the limits the network is allowed to have | Usually automatic, provided harmonic and unbalance withstand is confirmed with the OEM |
| S5.2.5.7 Partial load rejection | Continuing to operate through a sudden reduction in output demanded by the system | Written mainly with synchronous plant in mind. IBR generally meet it, but BESS behaviour in charging mode should be shown explicitly |
| S5.2.5.8 Protection from power system disturbances | Protection that keeps the plant connected unless disconnection is genuinely needed to protect it | Agreed alongside S5.2.5.3 and S5.2.5.4. AEMO pushes back on protection that trips the plant where it should ride through |
| S5.2.5.9 Protection systems that impact power system security | Protection design that affects the network: redundancy, clearing times, breaker fail | Largely set by the NSP's protection requirements. Rarely a matter of choosing automatic or minimum |
| S5.2.5.10 Protection to trip plant for unstable operation | Removing the plant from the system if it becomes unstable | Case by case. Proposals to trip because the plant cannot cope with low system strength are unlikely to be accepted |
| S5.2.5.11 Frequency control | Changing active power output in response to frequency, including droop and deadband | Usually automatic for BESS. Solar and wind commonly negotiate how response is limited by available energy, since they do not hold headroom by default |
| S5.2.5.12 Impact on network capability | Whether the plant reduces the network's ability to transfer power | Settled through the connection studies, sometimes with runback or control schemes rather than a choice of level |
| S5.2.5.13 Voltage and reactive power control | The control system: voltage set-point control, rise and settling times, stability of the response | Frequently negotiated. Weak grids, nearby plants with interacting controllers and long cable networks make the automatic response times hard to meet without instability |
| S5.2.5.14 Active power control | Following set-points, ramp rates and dispatch instructions | Usually automatic, with limits for energy source availability. Solar ramp-down under passing cloud is the common discussion point |
| S5.2.5.15 Short circuit ratio (system strength) | Remaining connected and operating stably at low system strength; AEMO describes the requirement as stable operation at a short circuit ratio of 3.0 or lower. Applies to plant with asynchronous (inverter-based) units | Demonstrated in PSCAD studies at the specified short circuit ratio. Closely tied to the system strength impact assessment, and plant at weak locations may need a negotiated level, retuned controls or supporting equipment |
| S5.2.5.16 Voltage phase angle shift | Remaining connected through a sudden shift in voltage phase angle at the connection point. Also applies to plant with asynchronous units | Usually a matter of confirming inverter and protection behaviour (including any vector shift or loss-of-mains protection) with the OEM |
The pattern behind the table
Three clauses carry most of the negotiation effort on a typical IBR project: reactive capability (S5.2.5.1), fault ride-through (S5.2.5.5) and voltage control (S5.2.5.13). They share a cause. Each depends on how the plant interacts with the network at the connection point, and that interaction gets harder as the network gets weaker. A clause that is trivial at a strong 330 kV bus can need months of PSCAD work at the end of a long 132 kV line.
How Negotiation Actually Works
A negotiated standard is a proposal you make and then defend. The sequence on most projects looks like this.
1. Find the gap early
Run the automatic standard first, for every clause, against the actual equipment and the actual network model. Where it fails, quantify by how much and under which conditions.
2. Decide whether to close it or negotiate it
Every gap has a hardware option: more inverters for reactive range, a STATCOM or synchronous condenser for voltage control, different transformer tap ranges, tuned controller settings. Cost it. Closing the gap is sometimes cheaper than the delay of negotiating it; where the hardware is clearly disproportionate, that becomes part of your justification.
3. Build the evidence
The proposal needs to show the clause 5.3.4A tests are met. That means:
- PSS®E and PSCAD™ studies across the range of system conditions the NSP and AEMO specify, showing the proposed level does not harm security or other network users
- The reason automatic is not practicable, with cost and technical detail
- A level set as close to automatic as you can reasonably get, not at the minimum by default
- OEM evidence that the plant can actually deliver the proposed level
Our guide to PSS®E and PSCAD modelling explains why both tools are needed and where each one is relied on.
4. Expect questions, and answer them completely
AEMO and the NSP review the proposal and come back with questions. The commonest cause of long negotiations is an inconsistent submission, where model, settings and proposed standard disagree. Our article on common pitfalls in AEMO GPS applications covers those failure modes.
5. Live with what you agree
The agreed standards become registered performance standards. They are tested at commissioning and R2, and the plant must keep meeting them for its life.
How Package 1 Affects Negotiation
The AEMC's "Improving the NEM access standards, Package 1" rule was finalised on 22 May 2025 and commenced on 21 August 2025. It made two structural changes: the access standards now apply by plant type rather than registration category, and Schedule 5.2 was rewritten to cover generating systems, integrated resource systems and synchronous condensers, with more prescriptive drafting intended to reduce negotiation. By default it applies to projects that had not received a connection enquiry response by 21 August 2025. Projects already further along can generally continue on the old standards or opt in to some or all of the new ones. Our article on NEM access standards Package 1 covers applicability and the changes in more detail.
For negotiation, the practical points are:
- Check which version applies to your project. The applicable access standards depend on where the project was in the process at the cut-off. A negotiation based on the wrong version wastes a round of review.
- Some automatic and minimum levels moved. A gap you would have negotiated under the old wording may close, or a new one may open. Re-run the automatic case against the revised clauses rather than reusing an old assessment.
- Changed definitions change the evidence. Where the rule replaced or redefined terms used to judge dynamic response, the way AEMO interprets them is still settling. Expect closer questioning on oscillatory behaviour in the studies.
Get Support With GPS Negotiation
Negotiation is mostly an evidence problem. Projects that move quickly know their gaps before they submit, close the cheap ones and justify the rest with consistent models.
ElectraGlobe prepares and manages GPS proposals for solar, wind, BESS and hybrid projects, including the PSS®E and PSCAD studies behind each negotiated standard and the responses through AEMO and NSP review. See our AEMO GPS applications service, or contact our team to talk through where your project's access standards are likely to land.
Frequently Asked Questions
What is the difference between automatic and minimum access standards?
The automatic access standard is the benchmark: if the plant meets it, the NSP and AEMO cannot refuse the connection on that requirement. The minimum access standard is the floor, and nothing below it can be agreed. Anything between the two is a negotiated access standard and must be justified with evidence.
Which GPS clauses are most often negotiated?
For solar, wind and BESS, reactive power capability (S5.2.5.1), fault ride-through (S5.2.5.5) and voltage and reactive power control (S5.2.5.13) carry most of the negotiation. All three depend on network strength at the connection point, so weak network locations negotiate more. This reflects common experience, not a rule, and each connection is assessed on its own merits.
Who approves a negotiated access standard?
The NSP agrees the standard as part of the connection agreement. Where the clause is an AEMO advisory matter, which covers most dynamic performance requirements, AEMO must also agree. Both will review the supporting studies against the criteria in NER clause 5.3.4A.
Can a negotiated standard be changed after connection?
Yes, but not informally. Altering the plant in a way that affects its performance, such as adding a battery or replacing inverters, triggers a process under the NER where the affected performance standards are reassessed and may be renegotiated with the NSP and AEMO. Until a change is agreed, the plant must keep complying with its registered standards.