Secondary control

Description of secondary control

Secondary control energy is automatically activated to free up the primary control system so that it can return to fulfilling its network balancing function. Secondary control is activated when a system imbalance lasts for longer than 30 seconds or it is anticipated that this will be the case. For shorter periods of over- or undersupply, the system is balanced by primary control.

The quantity of secondary control energy required depends on the size of the control area and the availability of the generating capacity in it. The secondary control capacity must be sufficient to compensate for an outage of the largest generating unit in the control area. The APG control area is capable of dealing with the loss of the largest generating unit by calling on a combination of secondary and tertiary control energy.

Under the Systemnutzungsentgelte-Verordnung (SNE-VO) the cost of secondary control energy is payable by generators with an installed maximum capacity of over 5 MW. This component of the system charges is referred to as the “system services”. The text of the current SNE-VO can be downloaded from the website of the Austrian regulator, at

APCS passes on the cost of the secondary control services to the balance groups on a cost reflective basis, as a component of the overall balancing charges.

Tender procedure

Since 1 January 2012 APG has organised the secondary control energy market.

APCS is responsible for the clearing and settlement of secondary 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 secondary control energy suppliers that have registered with the site.