Consultation on initial version of Reserve Level Declaration Guidelines

New System to Go-Live

As advised in January , there has been delay in the implementation of the new reserve Level Declaration Guidelines in order to allow changes to the systems to be made to address the issues described below. These changes have now been implemented and system is expected to go live in mid-February 2018

In the report on the outcomes of the Consultation on the Reserve Level Declaration Guidelines published in December 2017, AEMO advised the initial reasonability limits that would be adopted for the forecast uncertainty measure ( FUM) which is used as an input for the determination of forecast LOR1 and LOR2 level in the Pre-Dispatch PASA and Short Term PASA.

However final reviews prior to implementation have shown that revised reasonability limits are required. This is because the pre-production trial has shown at times

1. excessively large values being output from the BBN during extreme events.
2. Large transient movements in the output values from the BBN

Under the Guidelines , AEMO may alter the reasonability limits used in the BBN application at any time if necessary to ensure correct operation.

Accordingly AEMO has

• revised the initial upper and lower reasonability limits for the FUM values
• introduced limits on the amount of change in the FUM values between successive runs ( “delta reasonability limits”)

These changes are set  in the document below . A more fundamental solution for this issue will be implemented  when the BBN is retrained after this Summer.

Delay in Implementation of Reserve Declaration Guidelines

The Reserve Declaration Guidelines were due to be implemented on Tuesday 16 January 2018. However a final readiness review of the system which calculates the forecast uncertainty measure (FUM), a key input to the process, has identified periods of excessive volatility of the measure and the system is not considered ready for on- line operational service. The implementation thus needs to be deferred to allow changes to the application to address this issue (the changes required have been identified).

These changes will involve introduction of additional reasonability limits. These limits will be on the changes in the FUM values between successive half-hourly runs  of the system which calculates these values.

It is expected that the Reserve Declaration Guidelines will be ready for implementation by mid-February 2018.  A specific implementation date will be advised later.

In the meantime the system which calculates the FUM will remain in service in an off-line mode. AEMO may consider reasonable forecast uncertainty data to help inform its operational decision making when prudent to do so.

If you have any enquiries please contact op.forecasting@aemo.com.au

AEMO has consulted on the development of the initial Reserve Level Declaration Guidelines (Guidelines), which AEMO is required to publish by 9 January 2018 under clause 11.103.2 of the NER.

No consultation requirements are specified in the NER for the first version of the Guidelines. However, AEMO released a draft of the initial Guidelines for consultation and invited submissions from interested stakeholders. Those submissions have been considered and AEMO’s responses are set out in this report.

Two submissions, which are included below, were received. In response to these submissions AEMO has:

• Altered the proposed formula used to calculate the LOR1 level in the Guidelines.
• Provided additional information in the Guidelines on the operation of the Bayesian Belief Network and assumptions used in the inputs to this process
• Provided additional information in this report on error distributions for AEMO’s demand and intermittent generation forecasting and forecasts of aggregate scheduled generating unit availability.
• Agreed to consider ongoing publication of the forecast uncertainty measure (FUM) values.
• Set out in the Guidelines principles for the selection of appropriate confidence levels to be used in the determination of FUM.
• Established a process in the Guidelines to provide information to Participants on changes to credible contingency events considered relevant to the setting of the lack of reserve (LOR) levels.
• Set out in the Guidelines the conditions under which AEMO would exercise discretion regarding the declaration of LOR conditions
• Undertaken to conduct a review of the performance of this process after summer 2017-18.

This report also sets out:  

• The process used to select the initial appropriate confidence levels used in the determination of
  the FUM.
• The initial reasonability limits for FUM values.
• Indicative values of FUM for a range of scenarios.

Having considered the matters raised in submissions and the additional matters described in this report, AEMO’s determination is to make the initial version of the Reserve Level Declaration Guidelines in accordance with clause 11.103.2 of the NER in the form published with this report. An associated initial Lack of Reserve Credible Contingency List has also been determined and is published alongside the Guidelines.