State of the System update

10 min

Welcome to AEMO’s inaugural State of the System update, a bi-monthly round-up of developments in the National Electricity Market (NEM). It's aim is to share knowledge and highlight engagement opportunities on important initiatives and consultations.

Previously, we have provided updates on specific topics or projects, such as the challenges we’re working with the industry to overcome in the West Murray Zone. However, after receiving feedback from stakeholders and the rapid pace of change across the power system, we are expanding the coverage to bring you updates from across the NEM. 

We welcome any feedback or comments you may have via email to

If you would like to subscribe to this via email, you can subscribe to future bi-monthly State of the System updates here.

NEM connections update

AEMO continues to focus on improving the processes and capability of our national and Victorian connections functions to cater for increased volumes and complexity of projects connecting to the NEM.

The rapid scale and pace of inverter-based renewable generator connections, often in remote and congested regions of the power system, has resulted in globally unique technical issues, impacting connection assessments, grid performance and operational stability.

New Generators

During Q3 of 2020, AEMO has registered 5 new generators in the NEM with a total capacity of 542 MW and 4 new generators have commissioned, contributing a total of 338 MW. 

New generators registered:

  • Ferguson North Wind Farm (3 MW) - Vic
  • Darlington Point Solar Farm (275 MW) - NSW
  • Kiamal Solar Farm (200 MW) - Vic
  • Warwick Solar Farm 1 (32 MW) - Qld
  • Warwick Solar Farm 2 (32 MW) - Qld

New generators commissioned:

  • Cherry Tree Wind Farm (57 MW) - Vic
  • Nevertire Solar Farm (105 MW) - NSW
  • Hornsdale Power Reserve Expansion (expanded 50 MW) - SA
  • Lincoln Gap Wind Stage 1 (126 MW) - SA

West Murray Zone update

In the West Murray Zone, we have successfully completed assessments for 16 projects this year. This includes the integration of two solar farms in Victoria and NSW, and the registration of the 200 MW Kiamal Solar Farm and the 275 MW Darlington Point Solar Farm, the largest solar project in the NEM to date. We are also progressing assessment of another solar farm in NSW.

For uncommitted projects (those still in the connection application stage), AEMO has developed a sequencing proposal for its integration assessments under NER clauses 5.3.4A (access standards) and 5.3.4B (system strength remediation). The sequence approach is based on objectively ascertainable dates to ensure fairness and transparency, similar to the approach taken for commissioning and committed projects. Projects will be allocated a position in the first phase of the integration assessment sequence for uncommitted projects based on the date of application. This will be the date that the NSP determined the application submission was complete, meeting all the requirements of the NER.

The capacity of the existing network in the WMZ to host large scale inverter-connected generation has likely been reached or will be reached by the time already-committed projects are integrated. New and existing generation across large parts of the WMZ will be materially constrained for significant periods of time pending large-scale network investment. This will not only restrict commercial output but may prevent or delay completion of commissioning for new projects. Connections that rely on future regulated upgrades to the network and/or longer-term system strength solutions cannot be assessed until those upgrades and solutions are substantially progressed.

Prospective developers interested in connecting generation in the WMZ and surrounding area should contact their local NSP before making any financial commitments, to discuss whether, when and how they might be able to progress their project.

Revised system strength shortfall declarations in Victoria

AEMO has assessed the post-contingency minimum fault level requirement at the Red Cliffs fault level node in Victoria at 1,000 MVA (subject to operating conditions). For more information, you can read the notice here. AEMO will publish full details about these requirements in the 2020 NEM-wide 'System Strength Report' expected for release before the end of this calendar year.

In our role as System Strength Service Provider for Victoria, AEMO has secured sufficient services from facilities in the West Murray area (spanning north-west Victoria and south-west New South Wales) to meet the assessed Red Cliffs fault level requirement effective for two years from the end of August 2020.

AEMO thanks all proponents who responded to the Calls for Expression of Interest process seeking to procure a 'longer-term' system strength solution to address the System Strength Gap at Red Cliffs. Subject to the assessment of submissions, an Invitation to Tender process is expected to commence in December 2020.

Inertia report for SA

Under the NER, AEMO calculates inertia requirements in each region of the NEM. AEMO recently reviewed inertia requirements in South Australia and declared an immediate inertia shortfall in that region.

ElectraNet is the Inertia Service Provider in South Australia, responsible for addressing inertia shortfalls. While ElectraNet works towards solutions, AEMO will continue to apply operational arrangements to securely operate the South Australia power system if it is islanded.

For more information, you can read the report here.

Transmission outage in Western Victoria 

On 31 January 2020, several transmission towers collapsed on the double circuit Moorabool – Mortlake and Moorabool – Haunted Gully 500 kV lines (MLTS-MOPS and MLTS-HGTS lines) due to a severe convective downburst during thunderstorm activity. This resulted in the separation of the Mortlake Power Station, the APD Portland aluminium smelter and South Australia from the rest of the NEM for 17 days. Both circuits were restored using temporary structures.

Outages are now required to return the circuits to the rebuilt permanent structures. As of today, these outages are currently proposed for (including contingency):

  • MLTS-HGTS: Thursday,12 November to Wednesday, 25 November
  • MLTS-MOPS: Monday, 7 December to Friday, 18 December

For more information or to see the latest update of these outages, please see our Network Outage Schedule page.

New constraint on Heywood Interconnector to better protect South Australia’s system security 

The South Australian Under Frequency Load Shedding (UFLS) scheme is an important last resort “safety net” protecting South Australian consumers from widespread system collapse when severe contingencies occur, such as the separation of South Australia from Victoria at the Heywood interconnector.

AEMO’s studies have found that growth in distributed PV has significantly reduced UFLS capability, making the UFLS much less effective to stop an uncontrolled frequency decline in some periods.<

As part of a suite of recommendations to restore UFLS capability and mitigate risks, AEMO is updating and expanding existing network constraints to keep power flows across the Heywood interconnector within limits that we expect will allow South Australia’s UFLS to operate effectively if needed. To learn more please see the fact sheet here.

New system normal constraint equations for thermal overload in south west Victoria

AEMO has reviewed the thermal limits in south-western Victoria with the recent addition of generators in the area. With a further increase in generation capacity in this region, AEMO has identified potential thermal issues on the south-west Victorian 500 kV network and will implement three new constraint equations which will manage thermal overloads. These constraint equations will manage loading on the Haunted Gully to Moorabool, Mortlake to Moorabool and Moorabool to Sydenham lines for other 500 kV line trips in south-west Victoria. These constraint equations are unlikely to bind until there is a further increase in generation in south-west Victoria.

The constraint equations include generators in western Victoria and the Heywood and Murraylink interconnectors on the left-hand side and are named:

  • V>>V_NIL_15
  • V>>V_NIL_16
  • V>>V_NIL_17

For further details on these new constraint equations please contact Ben Blake.

Update on Power Systems Frequency Risk Review

The Power System Frequency Risk Review (PSFRR) is a periodic review of major power system frequency risks that are associated with non-credible contingency events in the NEM. The 2020 PSFRR Stage 1 report was released in July following industry consultation.

In developing the Stage 2 PSFRR, AEMO has continued engagement with TNSPs in relation to the identified priority events. The Stage 2 report will be released for consultation towards the end of 2020, and AEMO will be seeking input and contributions from all interested stakeholders. The Stage 2 PSFRR will report on:

  • Development of frequency control models to adequately assess system frequency performance and risks.
  • Studies to assess Emergency Frequency Control Schemes adequacy in response to identified priority non-credible contingencies, and recommendations for modifications or additional schemes if appropriate.
  • Consideration of recommendations for further protected events if justified based on the analysis.

For more information, please see the PSFRR consultation page.

We have just recently updated the generator maps for each region of the NEM. These maps not only show the grid-scale generators connected but also highlight the volume of interest across each region and sub-region.

These maps are intended to facilitate more informed decision-making by potential investors, allow network service providers to consider potential future network expansion, and for AEMO to identify potential operational constraint and emerging security issues.

The set of NEM generation maps can be accessed here.

Cookies help us improve your website experience.
By using our website, you agree to our use of cookies.