State of the System update

10 min

Welcome to AEMO’s second State of the System update, a regular round-up of developments in the east coast energy system. Its aim is to provide updates on recent developments, build awareness of emerging issues and highlight engagement opportunities on important initiatives and consultations.

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NEM connections update

In 2020, AEMO achieved a new record for both number of new projects connected and new megawatts (MW) coming in to the NEM. 

  • 12 generators with a total capacity of 1,560 MW completed their commissioning and are now in commercial operation.
  • 32 generators with a total capacity of 3,301 MW successfully completed the connections process and registered. These projects will be entering commercial operation in coming weeks and months.

Further, 2020 was also another year of growth for generators interested in connecting within the NEM. Despite the pandemic and the technical challenges in the transitioning network, the development of renewable generators continues to be strong.

  • 15 projects with a total capacity of 3,004 MW have successfully completed the first stage of the connection process and have now became committed projects.
  • A total of 342 proposed generators are currently in various stages of connecting and registering across all NEM regions.

Highlights of Q4, 2020

AEMO registered 13 new generators in the NEM with a total capacity of 1,362 MW and commissioned 4 new generators contributing a total of 516 MW. 

New generators registered: 

  • Middlemount Solar Farm (26 MW) - QLD
  • Bango 973 Wind Farm (155 MW) – NSW
  • Collector Wind Farm (219 MW) - NSW
  • Crudine Ridge Wind Farm (138 MW) - NSW
  • Jemalong Solar Project (50 MW) - NSW
  • Molong Solar Farm (30 MW) - NSW
  • Sunraysia Solar Farm (200 MW) - NSW
  • Wellington Solar Farm (170 MW) - NSW
  • Morgan-Whyalla Pipeline Pumping Station No 3 (6 MW) - SA
  • Cohuna Solar Farm (27 MW) - VIC
  • Moorabool Wind Farm (150 MW) - VIC
  • Glenrowan West Solar Farm (110 MW) - VIC
  • Yatpool Solar Farm (81 MW) - VIC

New generators commissioned:

  • Ross River Solar Farm (116 MW) - QLD
  • Rugby Run Solar Farm (65 MW) - QLD
  • Murra Warra 1 Wind Farm (225 MW) - VIC
  • Graville Harbour Wind Farm (110 MW) – TAS

Highlights of Q1, 2021 - to date

New generators registered:

  • Corowa Solar Farm (30 MW) - QLD
  • Morgan-Whyalla Pipeline Pumping Station No 1, PV Units 1-2 (4 MW) - SA
  • Morgan-Whyalla Pipeline Pumping Station No 2, PV Units 1-2 (4 MW) - SA
  • Morgan-Whyalla Pipeline Pumping Station No 4, PV Units 1-2 (4 MW) – SA
  • Berrybank Wind Farm (180 MW) - VIC

West Murray Zone update

We are continuing to make good progress with the assessment of committed projects. Two more solar farms and one wind farm were integrated and registered–Glenrowan West Solar Farm, Cohuna Solar Farm, and Berrybank Wind Farm. There are 2 projects in Victoria and 1 project in NSW to integrate and complete the assessment for committed projects.  

In October 2020, AEMO consulted with the industry on the proposed sequencing approach for uncommitted projects. The approach is now finalised and a copy of the final paper is published on the West Murray Zone webpage.

There are 29 projects in the application stage that the connecting network service providers and AEMO are processing, totalling around 3.6 GW. AEMO is reviewing the sequence based on the approach and information provided by the connecting network services providers.

The first System Strength and Inertia report 

In December, AEMO published its inaugural System Strength and Inertia Report, which considers the outlook for system strength and inertia in the NEM over the coming decade. In the report, AEMO observes increasing indications that, in the near future, projected system strength may be insufficient in Queensland, New South Wales, and Victoria, if certain conditions eventuate. Similarly, projected inertia may be in insufficient in Queensland.

Although for a ‘traditional operations’ projection these outcomes are not considered likely to occur within the planning horizon of five years, there is a strong risk this could occur earlier under a high renewable energy projection, both with and without considering the potential for flexible operation of synchronous generating units.

The report also: 

  • Updates the minimum system strength and inertia requirements across the NEM.
  • Declares the re-emergence of a system strength and inertia shortfall in Tasmania in 2024 (as well as a risk of larger, earlier shortfalls in Tasmania than previously declared).
  • Extends an existing inertia shortfall in South Australia by one year.
  • Notes that further analysis is required to confirm the scale of the Red Cliffs system strength shortfall in Victoria beyond 2022.

Read the report here.

2020 Network Support and Control Ancillary Services (NSCAS) Report

Also, AEMO published the annual NSCAS report in December, which assesses the need for any additional system security and reliability services for the five-year period from 2020-21 to 2024-25.

Although AEMO has not identified any NSCAS gaps at this stage, the power system is changing rapidly, and operational measures are being relied upon more frequently to help manage voltages during low demand conditions. AEMO expects that the power system will operate close to its limits in some areas and under some conditions. 

AEMO will monitor the situation closely, in particular in Queensland and Victoria, and if conditions change then AEMO will declare gaps as required before the next scheduled annual review. 

The assessment has revealed emerging operational challenges and opportunities, including:

  • Reducing levels of minimum demand, potentially co-incident between regions, will require flexible operation of elements of the power system and possibly investment in new equipment.
  • The increasing installation of distributed photovoltaics (PV) and variable renewable energy (VRE) is expected to lead to operational changes in synchronous generation in the market, including withdrawals of units in low demand periods, and lower overall synchronous unit commitments outside of peak demand periods. Delivery of voltage management and reactive power support from non-synchronous generators will become more important than it has been in the past.
  • New large-scale renewable generation providers may be able to provide significant reactive power support at times of minimum demand on the system.
  • The shift of minimum demand to daytime periods is expanding the amount of time over the year that nearly all reactive power absorbing plant is needed to manage network voltages. As a result, challenges are emerging for critical maintenance works on generation and transmission equipment to prepare it for peak load periods such as summer.
  • Some traditional network planning assumptions may no longer be fit for purpose in the context of declining minimum demand. AEMO is investigating whether planning assumptions need to change so that the system is designed to more efficiently maintain reliability and security with manageable operational risks.

You can read the whole report here.

Transmission outage in South 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.

The next step is for outages of each circuit, in turn, to transfer the phase conductors and the OPGWs from the temporary structures to the new permanent double circuit structures. 

In our November 2020 State of the System update, we said that these outages were proposed for late 2020. Around this time, AusNet Services advised AEMO that the initially planned outage recall time of 2 to 2.5 hrs was not possible and instead issued an updated plan to undertake a seven to eight-day continuous outage with no recall for each circuit.

These outages are currently submitted in the Network Outage Scheduler (NOS), with no contingency days included for:

  • MLTS-HGTS:  25 February – 3 March 2021
  • MLTS-MOPS: 12 March – 19 March 2021

In the NEM, lengthy planned outages without recall are considered unusual for such critical circuits, which impact interconnection between Victoria and South Australia, and a number of market participants. In order for these outages to proceed, there are a number of criteria that need to be met. Over the last couple of weeks AEMO has undertaken a detailed cost and risk assessment and has taken the decision, that given the criticality of these outage works and the lack of feasible alternative options, it will be necessary for AEMO to change its normal outage approval criteria to assist the completion of this work in a timely manner.

As a result, AEMO has decided to allow for the possible use of pre-contingent directions in its outage assessment for both outages to transfer circuits back to permanent structures. That is, in considering the forecast power system conditions for each outage duration, AEMO may allow it to proceed if it considers that any identified power system security issues could be managed by issuing directions to available plant if that becomes necessary. AEMO considers these planned outages as unique cases warranting a departure from normal practice, meaning that this should not be considered as a precedent for other planned outages. It should be noted, that, despite this modification to AEMO’s assessment approach, there is still material uncertainty around whether these outages will go ahead, given forecast conditions will change as we get closer to the commencement of the outages. For example, in the event that there is a forecast shortage of reserve, AEMO will not allow each of the outages to proceed.

For more information or to see the latest update of these outages in Network Outage Scheduler.

SA constraints and the protected event submission to the Reliability Panel

In our last update in November, we wrote that: 

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.

In December last year, AEMO released its Power System Frequency Risk Review (PSFRR), stage two final report. The purpose of the PSFRR is to review the potential for “non-credible” power system contingency events to cause frequency changes large enough to initiate generator disconnections and result in widespread transmission outages or a “black system”.

The new PSFRR describes the formulation of the new constraint set that was implemented last October. It also expands on the Protected Event submission to the Reliability Panel, which formalizes the expanded and updated constraints. AEMO is targeting a submission in early 2021.

AEMO’s analysis of UFLS adequacy in other NEM regions is underway. It is anticipated that similar challenges will emerge as distributed PV levels grow in other regions. AEMO will communicate findings as they become available, and work with stakeholders on management approaches.

Victorian Annual Planning Report

The 2020 Victorian Annual Planning Report (VAPR) builds on AEMO’s Integrated System Plan (ISP) and assesses the capability, performance and adequacy of the state’s transmission network – the Declared Shared Network (DSN) – to meet Victoria’s energy reliability and security needs over the next 10 years. The report highlights that while the DSN remained secure under typical operating conditions, the operational landscape in Victoria is increasingly complex. 

Strong investment in large-scale renewable generation projects and distributed photovoltaic (PV) are impacting the stability and complexity of power system operations, including record minimum demand levels. The VAPR outlines a suite of committed and future network development projects to address changing network needs, captured in the report’s ‘Transmission Roadmap for Victoria’.

ISP draft Inputs, Assumptions and Scenarios Report

AEMO published the draft 2021 Inputs, Assumptions and Scenarios Report (IASR), which is critical to AEMO’s forecasting and planning publications, and Regulatory Investment Test for Transmission (RIT-T) assessments. The draft IASR commenced formal consultation on the scenarios, inputs and assumptions that are proposed for use in the 2022 Integrated System Plan (ISP). The draft 2021 IASR also provides detail on the process by which any inputs and assumptions will be updated and consulted on prior to modelling commencing, to mitigate risks associated with data latency and maintain publication relevance. 

In developing the IASR, AEMO sought to engage widely with stakeholders through webinars and workshops, seeking important views on the proposed scenarios for further consultation. Click here to access webinar recordings and presentations.

NEM Operational Forecasting and Dispatch Handbook 

AEMO published the NEM Operational Forecasting and Dispatch Handbook for wind and solar generators which highlights key requirements of relevant parts of the NER and references formal guidelines, procedures and standards published by AEMO under the NER. The handbook provides an overview of:

  • Registration requirements from an operational forecasting perspective.
  • Integration into AEMO’s Australian Wind Energy Forecasting System (AWEFS) and Australian Solar Energy Forecasting System (ASEFS)
  • Ongoing requirements for data inputs for bidding and dispatch, pre-dispatch and PASA, and the potential consequences for generators and participants of inaccurate inputs to the AWEFS/ASEFS forecasting model, and non-compliant behavior
  • Process for generators to register and participate in self-forecasting

NEM Generation maps

The NEM generation maps are updated and can be found here. These have been updated with the latest information available as at February 2021. The maps are intended to facilitate more informed decision-making by potential investors, allow NSP to consider potential future network expansion, and for AEMO to identify potential operational constraint and emerging security issues.

 Interesting points to note:

  • Progression of projects and interest in new projects doesn’t seem to be affected by the recent pandemic.
  • The number of enquiries and applications for batteries have increased substantially.
  • New projects sites are trending towards being close to load centers and areas of high system strength.

Connections website and document updates

The National Connections team has been reviewing the documents published on the Connections webpages to ensure that the information provided is relevant and up-to-date. The team has also created new documents to provide proponents more guidance through the connection process.

In the last 2 months, the following documents were published:

Generator Connection Application Checklist – Updated - in Stage 3 Application

This document has been updated. It contains a number of checklists designed to assist Connection Applicants in ensuring that an application to connect under clause 5.3.4 of the National Electricity Rules (NER), and Generators proposing to alteration of generating plant, under clause 5.3.9 of the NER, contains all relevant and necessary information to enable AEMO to complete its assessment for the purposes of assessing the application or alteration, as applicable.

Generator Performance Standards template – Updated - in Stage 3 Application

This template has been updated. The changes made are related to the Primary Frequency Response rule change. There are also other editorial updates, such as addition of Reactive Plant and System Strength Remediation Scheme rows in the Background table, and a Revision table.  

Generator Connection R1 Submission Checklist – New - in Stage 6 Completion

This is a new checklist designed to assist Connection Applicants in ensuring that their R1 submissions contain all relevant and necessary information. This will enable AEMO to assess the material for the purposes of approving the application for registration as a Generator and to meet the National Electricity Rules requirements post-commissioning.

Communication System Failure Guidelines – New - in Stage 6 Completion

This is a new guideline that sets out AEMO’s expectations for the operation of generating systems following a communication failure in the main communication links within their generating system.

Useful resources

Recent publications:


Join us at our State of the System Q&A Webinar

AEMO will be holding the State of the System Q&A Webinar on 23 February from 11 am - 12 pm AEDT.

This event will be an opportunity to ask questions on these topics and hear direct from expert AEMO staff.

Click here to register for our State of the System Q&A Webinar. Please note that we'll be accepting registration only until 22 February 5 pm AEDT.

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