Connecting to the SWIS: the Western Power transmission connection process, explained.

Five stages, one long modelling thread

Western Power runs transmission connections on the South West Interconnected System (SWIS) through five stages: Enquiry → Initiation → Scoping → Planning → Execution. Western Power publishes the customer deliverables for each stage on its customer deliverables and considerations page - this guide explains what each deliverable is in engineering terms, and why it exists.

Read the deliverables list closely and one pattern emerges: the process is a modelling thread that runs end to end. A steady-state PowerFactory model at application. A dynamic model for the GPS or load model assessment. A PSCAD model for EMT studies in Execution. Each model arrives with a model user guide, and each major resubmission updates the connection application. Keep that thread coherent - same plant, same parameters, models that agree with each other - and the process moves. Let the models drift apart and every stage gets harder.

APD Global works this process from the proponent's side: power system studies in the tools Western Power's engineers use, grid connection engineering across the WEM and NEM, and the substation and terminal design the connection ultimately needs. 15 GW+ of connection studies delivered.

Stage 1 - Enquiry

The entry point is deliberately light: a submitted enquiry form, an executed contract with payment, and evidence against Western Power's critical project criteria. That buys the connection options assessment - Western Power's early look at how and where your facility could connect.

Light does not mean unimportant. The connection option assessed here is the one you confirm later, and the option you pick shapes every study that follows. Arriving with a clear single line diagram concept, realistic plant parameters and an honest view of your project's criticality makes the assessment work for you rather than around you.

Stage 2 - Initiation

Initiation is where the engineering starts in earnest. The connection application assessment requires the connection application form, a PowerFactory model of your facility (steady state), a model user guide, a single line diagram, equipment data sheets and the application fee.

In plain terms: the steady-state model tells Western Power what your plant looks like to the network under normal and contingency conditions - load flow and fault level behaviour. The single line diagram is the plant's electrical anatomy on one page. The equipment data sheets pin the model to real hardware. And the model user guide is what lets Western Power's engineers run your model without you in the room - structure, controls, initialisation, limitations.

The GPS track deserves emphasis. The Generator Performance Standards are the negotiated technical promises your plant makes at the connection point - and the dynamic PowerFactory model is the evidence. R0 validation checks that evidence at the design stage; R1 and R2 assessment submissions arrive later, in Execution, as staged proof through commissioning that the plant performs the way the model said it would. Getting the dynamic model right at R0 is the cheapest schedule protection in the whole process - APD has taken plant from new-build batteries to a fifty-year-old alumina refinery through GPS compliance on Western Power's SWIS. The GPS case →

Initiation also carries the non-electrical groundwork: the grid input package, community engagement and environmental desktop assessment, and scope definition - each progressed on payment, and each feeding the stage that follows.

Stage 3 - Scoping

Project scoping turns the confirmed option into a concept design and estimate. Your side of the table: site location and line route confirmed; environmental, planning and heritage due diligence provided; community engagement conducted; and a land access in-principle agreement in hand.

This is where the connection stops being an abstraction and becomes a site, a route and a terminal arrangement - which is why concept-stage substation and line thinking matters. A route or terminal concept that ignores constructability gets re-scoped later, at Execution prices. Substation design →

Stage 4 - Planning

Planning is short to describe and unforgiving to satisfy: Western Power prepares the access offer, and it needs your final third-party approvals - environmental, planning, heritage and land access - locked in. Everything provisional up to now must become final here.

Stage 5 - Execution

Execution opens when the access offer contracts - the IWC and ETAC - are executed and payments or securities received. Then the deep modelling returns:

Dynamic studies - Western Power's network-level dynamic work, enabled by the executed contracts.

EMT studies, stages 1 and 2 - electromagnetic transient studies in PSCAD, requiring a PSCAD model of your facility, an updated connection application and a model user guide. RMS-scale dynamic models can't resolve fast inverter control interactions; EMT can, which is why the SWIS process demands it - and why the PSCAD model must genuinely represent the delivered control system, not a generic template. Power system studies →

Detailed design - the primary and secondary design of the works themselves.

Construction and commissioning - the final gate, with all IWC deliverables satisfied: final studies and designs, financial close, land access agreements and easements, environmental, planning and heritage approvals, and third-party approvals (gas, water, railway, telecommunications). For market participant generators, a commissioning test plan must be approved by AEMO before any testing - and the GPS R1 and R2 assessment submissions (generation only) close the modelling thread that opened at Initiation: measured plant behaviour against the registered model.

Where the effort concentrates

Across the five stages, the recurring customer deliverables are models, model documentation and studies - PowerFactory steady state and dynamic, then PSCAD - plus the approvals trail. That is why proponents mid-process tend to need a partner who runs the same tools the network's assessors run. APD Global delivers in DIgSILENT PowerFactory for steady-state work where networks require it, PSS®E for RMS and PSCAD for EMT, with GPS registration experience across the WEM and NEM. Connecting a battery? BESS connections carry their own study load - see BESS grid connection & studies.

SWIS connection FAQ

What models does Western Power require?
PowerFactory steady state (with the application), PowerFactory dynamic (for GPS or load model assessment), PSCAD (for EMT studies in Execution) - each with a model user guide.

GPS R0 vs R1 vs R2?
R0 validates the GPS submission and dynamic model at design stage; R1 and R2 are the staged Execution submissions proving the built plant matches the model. Generation only.

Do loads follow the same track?
Same five stages, different modelling track: load model assessment instead of GPS, and no R1/R2. The AEMO-approved commissioning test plan applies to market participant generators.

What is a model user guide?
The document that lets Western Power's engineers run your model without you - structure, controls, settings, initialisation, limitations. It accompanies every model submission.

When do EMT studies happen?
In Execution, stages 1 and 2, after the IWC and ETAC are executed - on a PSCAD model with an updated connection application.

What unlocks Execution?
The access offer: prepared in Planning once final third-party approvals are in, and executed as the IWC and ETAC contracts with payment or securities received.