In accordance with clause 2.13.6D of the Wholesale Electricity Market (WEM) Rules, System Management may determine the Tolerance Range to apply to Facilities for the purpose of System Management's Dispatch Instruction compliance monitoring obligations under clauses 2.13.9 and 7.10 of the WEM Rules.
Since 1 July 2012, System Management has applied a Tolerance Range to Scheduled Generators derived from monitoring methodologies present in the National Electricity Market (NEM). There has been no change to the Tolerance Range since it was first applied.
When determining the appropriate Tolerance Range to apply for all Market Participants, System Management must consult with Rule Participants before setting the Tolerance Range. Details of the initial consultation process can be found here.
System Management is required to conduct an annual review of the Tolerance Range. Details of the 2015 annual review can be found here.
Tolerance Ranges to Apply from 1 July 2016
The result of the 2016 Review of the Tolerance Range is set out in the document: Outcome of 2016 Annual Review of the Tolerance Range.
System Management has determined that the Tolerance Ranges to apply to Scheduled Generators from 1 July 2016 will continue to be calculated with the following formula:
Tolerance Range = (+/-) MAX (6, MIN [5% NPC, 4*ROC])
NPC: Name plate capacity of the generator, expressed in MW (Market Rules Appendix 1(b)(ii))
ROC: Rate of Change or Ramp Rate of a Unit per minute (Market Rules Appendix 1(b)(v))
The Tolerance Range is next required to be reviewed by System Management by 1 July 2017 [clause 2.13.6G of the Market Rules].