Requests for expressions of interest for non-network solutions to address fault level shortfalls.


Under the National Electricity Rules (NER) the responsibility to resolve a fault level shortfall lies with the System Strength Service Provider, who is the Transmission Network Service Provider (TNSP) or jurisdictional planning body for the region. In Queensland, Powerlink is the System Strength Service Provider who must address these technical issues as efficiently as possible once they are identified.

REQUEST FOR SYSTEM STRENGTH SERVICES

On 9 April 2020, the Australian Energy Market Operator (AEMO) published a report 'Notice of Queensland System Strength Requirements and Ross Fault Level Shortfall' to the National Electricity Market (NEM) under Clause 5.20C.2(c) of the National Electricity Rules (NER). The report declares an immediate fault level shortfall at the Ross 275kV node, includes other pertinent technical information and advised that system strength services should be in place to meet this shortfall by 31 August 2021. At that time, the shortfall was forecast by AEMO to continue beyond 2024-25.

Powerlink commenced an Expression of Interest (EOI) process for both short and long term solutions to address the Queensland Fault Level Shortfall at Ross in April 2020 and received a very strong response to the EOI offering a range of system strength support services. 

In June 2020 AEMO approved the approach for the short-term solution under NER clause 5.20C.4(e), up until the end of December 2020. As a result, Powerlink entered into a short-term agreement with CleanCo Queensland to provide system strength services through utilising its assets in Far North Queensland.

In August 2020, Powerlink entered into an agreement with Daydream, Hamilton, Hayman and Whitsunday Solar Farms in North Queensland to validate the expected positive benefits of inverter tuning during the daytime. Powerlink has also been working with Mt Emerald Wind Farm and AEMO on changes to control settings. 

In December 2020, Powerlink published an update document on the status of the EOI. 

As a result of retuning of the solar farms and an update of the control settings at Mt Emerald Wind Farm, AEMO's most recent analysis has found that the system strength requirements at the Ross node have changed since the 2020 Notice was issued, that the minimum fault level requirement at Ross is being met and no shortfall has been identified. Please refer to AEMO's Notice published on 28 June 2021.

Based on AEMO's most recent assessment, Powerlink's regional System Strength Service Provider obligations have now been fulfilled in relation to the Notice issued in April 2020 under the NER.

A summary of Powerlink's EOI process is available in the Final Report.

 

System strength is a measure of the stability of a power system under all reasonably possible operating conditions. It describes a system’s overall performance and its ability to recover quickly from sudden events.

Synchronous generators – like coal, gas and hydro power stations – provide system strength when they generate. System strength can also be provided by machines called synchronous condensers.

Asynchronous generators – like wind and solar – do not provide system strength and require system strength from another source.

While a system strength shortfall is very unlikely to impact the ongoing supply of electricity to customers in Queensland, it may limit an asynchronous generator's capability to export power to the grid. Queensland has a broad mix of generation types located across various regions in the state which can be accessed through our transmission network in the unlikely event that supply is impacted.

The Australian Energy Market Operator (AEMO) is responsible for setting the minimum required level of system strength throughout the National Electricity Market (NEM). When a region is identified as not having the required system strength, AEMO declares a shortfall.

As with other Market Notices, it is simply designed to send a signal to the market that a response is required.

AEMO periodically re-evaluates the required minimum fault levels throughout the NEM to minimise the risk of a sudden, widespread loss of supply due to an unforeseen event that impacts system strength.

AEMO has conducted electromagnetic transient (EMT) studies of the Queensland power system using the PSCAD product. This modelling includes detailed models of synchronous generators from major coal-fired, gas-fired and hydro power stations in Queensland. Only inverter-based plants not subject to the system strength remediation requirements were considered in this requirement determination.