Power system model development

Power system models for DER and load

AEMO is improving power system models to better represent the behaviour of DER and load during power system disturbances.

PSS®E models for load and distributed PV in the NEM

In collaboration with Network Service Providers (NSPs), AEMO has developed dynamic models to represent the aggregate behaviour of distributed PV and composite load during NEM power system disturbances. The development of these models, and their validation against historical disturbances is documented in this report:

The models have been calibrated against fifteen different historical disturbances occurring in QLD, NSW, SA and VIC during 2018 to 2021, and are designed to represent distributed PV shake-off in response to voltage disturbances, achieving an uncertainty margin of ±30%.  

The intention is for the models to be used by Transmission Network Service Providers to review network stability limits in periods with high levels of distributed PV generation, so that the possibility of distributed PV shake-off can be incorporated into those limits. This will allow limits to be updated to consider the increasing role of distributed PV in determining the operating envelope of the power system. 

These models represent a first version, and continuing refinement and improvement is expected.

PSCAD models for load and distributed PV in the NEM

AEMO commissioned Manitoba Hydro International Ltd.(MHI) to develop and validate dynamic models to represent the bulk aggregate changes in active and reactive power observed at each transmission bus due to changes in load and distributed PV. These models were designed as a replica of the PSS®E models, with the addition of fractional four-stage voltage phase-angle jump tripping. This behaviour cannot be accurately represented in an RMS-based simulation platform such as PSS®E.  They are “performance” models that have been developed with a focus on representing the aggregate net load/DPV shake-off observed at the transmission bus.  They have not been designed to represent the complex control systems and internal workings of individual inverters.  

When tested against seven different historical voltage disturbances occurring in various NEM regions during 2018 to 2021, the models generally capture 63-112% of the observed load shake-off, and 65-157% of the observed DPV shake-off.

AEMO has made these models available to Transmission Network Service Providers (TNSPs) so they can be used to review power system limits in periods with high levels of distributed PV generation, and the possibility of distributed PV and load shake-off can be incorporated into those limits. TNSPs are responsible for ensuring that any models applied are fit for purpose.

Further supporting materials

Materials prepared to support the parameters and development of these models include:

These reports may be useful to those stakeholders utilising AEMO’s models. For further information regarding these reports and the models being developed by AEMO, contact DERProgram@aemo.com.au.

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