Tertiary control

Description of tertiary control (minute reserve)

If an imbalance in the control area lasts for longer than 15 minutes, the tertiary control system is activated. This is activated manually, and frees up the secondary control system to enable it to support the primary control system and restore the latter’s availability if the reserves are fully taken up.

In the APG control area, the reservation of tertiary control capacity also has the purpose of supporting the secondary control system to enable it to compensate for an outage of the largest generating unit in the control area without jeopardising network stability. Because of this, the positive tertiary control capacity is also referred to as an “outage reserve” and is charged on together with the secondary control energy. Call-offs of positive tertiary control energy are only allocated to the secondary control costs if they arise from power station outages. Otherwise, the call-off costs are fully covered by the balancing energy charges. Negative tertiary control energy call-offs are always allocated to the balancing energy charges.

The balancing energy price is derived from the cost and volume of the minute reserve.

Tender procedure

Since 1 January 2012 APG has organised the tertiary control energy market (market maker and day ahead tenders).

APCS is responsible for the clearing and settlement of tertiary control energy, and posts comprehensive information on the tenders (summary list of bids, bid call-offs, tender details, etc.) in the restricted area of the APCS clearing platform for the use of tertiary control energy suppliers that have registered with the site.