System Strength Impact Assessment Guidelines

The System Strength Impact Assessment Guidelines (SSIAG) are made under clause 4.6.6 of the National Electricity Rules (NER). The key function of the SSIAG is to prescribe how connecting Network Service Providers (NSPs) will assess the impact of a connection to system strength when processing connection enquiries, applications for connection or alterations to plant.

The SSIAG covers:

• Methodologies for undertaking system strength impact assessments, calculating a system strength locational factor (SSLF), available fault levels (AFLs) and system strength quantity (SSQ).
• A threshold below which a system strength impact may be disregarded (Materiality Threshold).
• A methodology for assessing the short circuit ratio (SCR) and guidance on information to demonstrate compliance with relevant performance standards.
• The criteria for classification of a load as an inverter-based load (IBL) and an inverter-based resource (IBR) as a large inverter-based resource (LIBR).
• How AEMO assesses adverse system strength impacts.
• Guidance on the methodology to be used when undertaking modelling to verify the stability of plant.

Additional information on system strength can be found at the following: