As System Operator we monitor available generation capacity and potential peak demand from around six months ahead until the week ahead when we change to monitoring the market schedules up until real-time. This is because the market schedules have more accurate demand forecasts and reflect offers in the market. We provide a series of information and notifications from six months out to real-time.
The overview below describes the notices we send ahead of a potential deficit or shortfall.
(For potential shortfalls, low residuals, forecast deficits, or real-time deficits)
- Process for managing planned outages in response to a low residual situation
What is a low residual situation?
Residual represents the remaining generation to meet demand and maintain n-1 security on the power system. A Low Residual Situation typically occurs when Island Residual Generation is less than 200 MW. This situation is notified to industry by the System Operator via a Low Residual Situation Customer Advice Notice (CAN), Warning Notice (WRN), Grid Emergency Notice (GEN) depending on timeframe and extent of the level of residual. The notices issued typically include a request for participants to make changes to offers to help alleviate the situation. This generally involves reducing demand through load bids or increasing generation through additional offers.
Why rescheduling outages helps
Generation is often unable to offer due to outages on generation or transmission assets. By delaying, recalling, or cancelling outages, more generation capacity can often be made available, helping to alleviate the low residual situation.
Why engage the Asset Owner’s to reschedule outages during a low residual situation?
Generators may have a financial incentive to reschedule outages during low residual situations due to the increased system security risk to avoid exposure to scarcity prices or to increase revenue due to high prices. The System Operator will review generator outages and engage with them directly to explore viable rescheduling options during forward-looking security risk assessments.
The Grid Owner, who operates the high voltage transmission grid, does not have a financial incentive to reschedule outages. The System Operator engages with Grid Owner during these situations of increased system security risk and the Grid Owner have a regulatory obligation under the outage protocol to consider rescheduling outages if the System Operator raises concerns.
The flow diagram below outlines the process the System Operator’s Operations Planning follows to formally engage the Grid Owner in rescheduling its transmission outages under clause 6 of the Outage
Protocol document included in the Electricity Industry Participation Code.Process for engaging the Grid Owner
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Contact for more information
We encourage any industry participants who have questions around of our communications and processes to contact us via system.operator@transpower.co.nz