AEMO ELECTRICITY MARKET NOTICE.
Refer to Electricity Market Notices 59119 and 59120.
AEMO has observed that in certain circumstances the constraint violation penalty factors (CVP) applied for an AEMO Intervention Event may result in intervention pricing that is not reflective of dispatch prices had the Intervention Event not occurred. If this happens, AEMO will need to alter the relevant CVP for intervention pricing constraints.
For example, if a Directed generating unit gets trapped at the minimum or maximum enablement limits of its FCAS trapezium in the Intervention Pricing run, it can remain trapped in the Intervention Pricing run until either the FCAS enablement limits are amended or intervention pricing is revoked. This is because, after the first dispatch interval (DI), the Initial MW is based on the Target MW from the previous DI in the Intervention Pricing run. The NEM Dispatch Engine (NEMDE) is currently unable to un-trap the unit in the Intervention Pricing run.
To overcome this, AEMO would temporarily increase the CVP for the Direction and Intervention Pricing constraints from 55 and 50 respectively to a value above 70 (CVP for FCAS min/max enablement limits). This higher CVP for the Direction and Intervention Pricing constraints enables NEMDE to move the Directed unit outside the FCAS trapezium in the Intervention Pricing run. The change is not expected to affect the physical dispatch targets in the Outturn run. Once the issue is resolved, AEMO will revert the CVP of the Direction and Intervention Pricing constraints to the current CVP values (55 and 50) specified in the Schedule of CVP.
Further information will be provided at the NEMWCF on 11 October 2017.
For any queries, please contact: Ken Harper, Manager Electricity Market Monitoring at Ken.Harper@aemo.com.au or 02 8884 5623.