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Template: AEMO System Strength Impact Assessment Guidelines (Appendix B)

Preview of template's gridmo Flow showing Nodes

Last updated: 17 Oct 2024

Country:

AU

Software required:

PSS®E
PSCAD™

Source: v2.2 (1 July 2024)

How to download: Add a new Flow in gridmo and select this template from the list.

This gridmo template:

  • Includes all required tests as per Appendix B of AEMO's System Strength Impact Assessment Guidelines (SSIAG) version 2.2 (1 July 2024).
  • Includes a "helper run" (an optional part of the template) to help identify the likely Withstand Short Circuit Ratio (SCRwithstand) of the generator being tested.

Configuration​

To use this template:

  • Configure your global and scenario variables by using gridmo's Model setup template.
  • Download this template using the download button above and load the template into the gridmo web-app.
  • Transfer your general tab data, global variables and scenario variables across using the 'Import' buttons in the gridmo web-app.
  • If you know your target Withstand SCR for your generating system:
    • Set the global variables g_min_scr and g_min_xr to the values corresponding to your target Withstand SCR.
    • Run all tests, except for the helper Run.
  • If you do not know your target Withstand SCR for your generating system:
    • Run the helper Run to identify the likely Withstand SCR of the generating system.
    • Set the global variables g_min_scr and g_min_xr to the SCR and X/R ratio you identified from the helper Run.
    • Run all tests, except for the helper Run.
  • If your X/R ratio at the connection point is not known:
    • For each Loop Start Node, disable all loop rows, then only enable those with X/R=3 or X/R=10 rows.
danger

Whilst the SSIAG document explains what is required as demonstration of the Withstand SCR, there is no clear guidance provided on how to identify the Withstand SCR for a particular project.

Our template includes a helper run which includes a fault and a series of active power steps for sequentially lower fault levels at the connection point.

If, based on your engineering judgement, a given generating system successfully rides through these tests for a given SCR, it does not confirm that it is stable under all modes for this SCR. However this may help early stage projects identify the likely range for the plant's withstand SCR.

Additional studies will likely be required to confirm this SCR is stable for your generating system, such as the AEMO Generator Performance Standards (GPS) template.

Assumptions​

  • This template helps with Appendix B studies but doesn't cover all SSIAG requirements like calculating '∆AFL' at the connection point.
  • The SSIAG is unclear if both PSS®E and PSCAD™ should be overlaid for the first two tables of tests in Appendix B. It is also unclear if error bands in compliance with AEMO's PSMG are also required. Both have been included for completeness.
  • The SSIAG does not state what generator output channels should be presented as part of Appendix B. We have used the same plot structure as our AEMO DMAT v2 template.
  • PSS®E does not natively support 3PHG faults. Hence for this template, we apply 3PH faults in PSS®E and 3PHG faults in PSCAD™.

Sources​

Template revision history​

  • 17 Oct 2024 (v1.4.17)
    • Updated to AEMO SSIAG v2.2 (1 July 2024) - note there were no changes to the tests required (Section 7.4.4 and Appendix B were not updated in this revision). Removed SSIAG version number from plot subtitles.
  • 9 Apr 2024 (v1.4.12)
    • Updated to new template structure, standardised template sticky notes.
    • Added low.scr.mode=yes to all PSS®E Static Nodes to improve low SCR convergence performance.
    • Expanded helper run to loop down to SCR of 1.2 (was previously minimum of 2.0).
    • Added additional Advanced Parameters to the helper run to help with low SCR convergence.
    • Disabled POC X/R 3 and X/R 10 tests by default in all Loop Start nodes.
  • 30 January 2024 (v1.4.9)
    • Fixed plot sub-titles overlapping customer logos when describing SCR and XR in some Plot Nodes.
  • 1 Aug 2023 (v1.3.4)
    • First release.