In this section
In this section
Connection Applicants are required to submit a model package, that represents the structure and performance of their generating plant, to AEMO and the connecting Network Service Provider (NSP). Some parts of this package, such as the model source code, will only be submitted to AEMO and will be treated as confidential information – see clauses S5.2.4 and 3.13.3 (l) of the National Electricity Rules (Rules).
AEMO requires modelling information to represent the physical arrangement of the generating system and its connection to the network. We also require that simulation models are sufficiently accurate to demonstrate the performance of the generating plant under all expected operating conditions. AEMO uses the modelling data and simulation models to assess the Generator Performance Standards (GPS) that might apply to the generating system, and to determine the impact of the new or modified generating plant on power system security. Models are verified against physical tests that are completed during the commissioning process, and events that occur on the network.
At the conclusion of the commissioning process, verified simulation models and their supporting data are integrated into AEMO’s Operations and Planning Data Management System (OPDMS). Registered Participants are entitled to certain network data under clause 3.13.3(k) of the Rules, and AEMO provides this data from the OPDMS.
Once a plant is operational, AEMO relies on the modelled performance being accurate for undertaking its market and system operator functions.
AEMO uses PSS®E software as its primary simulation tool for connection studies – Connection Applicants are encouraged to confirm model compatibility with AEMO before submitting a model as part of an application to connect. AEMO will accept simulation models in other software formats where accompanied by the model source code in an unencrypted form. Such a model must be converted into PSS®E format prior to AEMO assessing the model, and it will incur conversion fees.
The items listed below are to be included in the model package. AEMO may request other types of model and data, depending on the strength of the proposed connection point.
To be included in the model package:
- Generating System Design and Setting Datasheets – as required by clause S5.5.7 of the Rules (template provided in Related Documents below).
- Releasable User Guide (RUG) – as required by clause S5.4.2 of the Rules. It should include:
- Table of all simulation model STATEs, VARs, CONS, ICONs, their values as implemented in the dynamic data files, and a description of the function.
- Sufficient information to allow other Registered Participants to perform system studies without any prior knowledge of the plant.
- Single Machine Infinite Bus (SMIB) PSS®E model representing the generating system and its connection to the network as defined in the RUG, including all reticulation networks represented as equivalent impedances.
- Source code of the simulation model, including all elements of the generating system that affect its dynamic response, such as:
- Generating units.
- Central park level controller.
- Dynamic reactive support plant.
- Coordination of multiple reactive support devices.
- The compiled version of the above source code (dynamic-link library .DLL file).
- Dynamic data files (PSS®E .DYR files) – containing dynamic simulation model settings relevant to the generating system.
- Functional block diagrams as required by clause S5.2.4 of the National Electricity Rules (Rules):
- A set of functional block diagrams, with all functions between feedback signals and generating system output.
- The parameters of each functional block, with all settings, gains, time constants, delays, deadbands, and limits.
- The characteristics of non-linear elements.
The model package submitted by a Connection Applicant must be revised periodically throughout a connection project, reflecting the stage of the process. The final (registered) data packages as defined under clause S5.5.2 of the Rules are:
- R1 model package – must be submitted at least three months before commissioning as specified under Clause S5.2.4 of the Rules,
- R2 model package – is the validated data, and must be submitted, along with an R2 model verification report, within three months of the final commissioning tests being completed.
Generating systems connecting to networks with low short circuit ratio (SCR)
In the course of performing power system security analysis in some regions, AEMO has become aware of a potential network issue, primarily driven by a reduction in the number of online synchronous generating systems, which may impact both existing and prospective solar and wind farm connections.
All practical power electronic-based generating systems are designed such that they require a minimum fault current or SCR at their terminals for stable operation. Should the SCR drop below the minimum design value, it could give rise to adverse impacts, including voltage instability during steady-state conditions and inverter or generating unit tripping.
The critical SCR level at which this can occur will vary for different technologies, however, in general, SCRs less than 2 should be avoided.
AEMO suggests that connection applicants seek information to understand whether their proposed technology can reliably operate at low SCRs, and that they request the following:
- Confirmation from the inverter manufacturer of the minimum SCR at which plant can reliably operate.
- Confirmation from the inverter manufacturer of the minimum SCR at which PSS®E model is valid.
Depending on the outcome of AEMO’s first stage of studies and confirmation from connection applicants regarding these two points, an electromagnetic transient-type simulation model compatible with simulation software such as PSCAD/EMTDC might be required to allow AEMO to conduct an accurate stability and security assessment of the impact of low fault levels in the relevant region. AEMO would be agreeable to receiving a model as developed by the original equipment manufacturers (OEMs), or if unavailable, to work closely with the OEMs to develop the necessary models.
For more details on software requirements see the following documents:
- Dynamic Model Acceptance Guideline – explaining how AEMO tests dynamic models that are provided to it for assessment.
- R2 Testing Guideline – providing guidance for preparing test programs intended to validate models and derive data.
- Generating System Model Guidelines – description of the Rules’ modelling requirements.
- Generating System Design and Setting Datasheets Template – spreadsheet template outlining the design of the major plant elements and relevant settings.
- Generating System Design and Setting Datasheets – explaining each element and requirement for the Generating System Design and Setting Datasheet Template.
- Turbine Governor Testing and Model Validation Guideline – providing Generators with test guidelines suitable for demonstrating compliance with agreed performance standards, as well as deriving validated turbine-governor model data.
- Data and model requirements for generating systems less than 30 MW – detailing AEMO’s preferred approach for meeting the model and data requirements for generating systems with a combined nameplate rating of less than 30 MW.