Settlements Reform

As part of the introduction of the changes under the WEM Reform there were significant changes to the settlement calculations defined in the WEM Rules and a transition to weekly settlement for all market segments. Accordingly, the settlement systems and processes were updated to reflect new settlement formulas and timelines. This project also considered an archival strategy for historic settlement data and catered for the settlement adjustments for the previous market rules for the first 12 months post go-live.

For Market Participants this means:

• Updated formulas for all settlement amounts, to be represented in an update WEM Metering, Settlement & Prudential Calculations formulation document.
• STEM and NSTEM settlement combined into a single timeline with a single statement and weekly invoice.
• Prudential amendments aligned with updated formulas and settlement timeframes.
• Updated APIs for the provision of settlement data and settlement files.
• Changes to Reserve Capacity Mechanism settlement related processes such as Capacity Credit Allocations and Individual Reserve Capacity Requirements.
• Updated WEM Procedures – Meter Data Submission, Settlements, Capacity Credit Allocations, Individual Reserve Capacity Requirements, Intermitted Load Refunds, Prudential Requirements, and IT Interface Requirements.

Settlements Enhancements
In preparation for Settlements Reform, a new WEM Prudential and Settlement Service (WEM PaSS) was successfully deployed to the WEMS Production environment on 29 July 2021.
This inaugural release included changes required to replace AEMO’s previous settlement solution.  The new settlement solution extends the prudential calculation engine developed and certified under the Reduction of Prudential Exposure project to deliver prudential and settlement functionality, services to interface with the existing invoicing and billing systems, and undertake WEM settlement.
The system changes included in this release are effective for all NSTEM and STEM Settlement Statements and Invoices issued on or after 1 August 2021.
Please refer to the WEM PaSS 1.7, WEMS 3.41 and RCM 1.21 Release Notes for details of the new functionality.