A balance between generation and consumption is essential at all times to guarantee a stable grid frequency. Deviations from this balance, which could for example be caused by power plant failures or unexpected changes, must permanently be compensated through the activation of power plant capacity. Activation must be possible in both directions (increased/reduced generation). In its role as control area manager, APG is responsible for the procurement and activation of the required power plant capacity in the APG control area. (A control area is a grid area in which the balance between generation and consumption is coordinated.)
Control energy market
Since 2012, the control power required in the APG control area will be procured uniformly by APG by way of regular tenders. Each market participant, who meets specific technical and contractual conditions, can participate in these tenders.
For technical and economic reasons, a distinction is made between three types of control energy. Further details relating to the respective tenders can be found on the individual pages (direct links in the right-hand column). In the event of further queries, please use the corresponding contact (also listed in the right-hand column).
Primary control
Primary control is needed to automatically compensate an imbalance between generation and consumption within a few seconds through corresponding activation (control) thus leading to the stabilisation of the frequency. Primary control power in the amount of +/-3000 MW is continuously available in the Continental European Grid. All control areas make a contribution on the basis of their annual generation. The volume of primary control power that must be provided by the APG control area lies at approximately +/-70 to 80 MW.
The primary control energy is registered as unintentional deviation between the control areas and compensated.
Secondary control
Secondary control is automatically activated to relieve primary control so that it can resume its function of balancing the system. Secondary control is activated when the system is affected for longer than 30 seconds or it is assumed that the system will be affected for a period longer than 30 seconds. Prior to this, a surplus or deficit in the grid is only balanced using primary control.
The required volume of secondary control depends on the size of the control area and the availability of power plants in the control area. Secondary control must be capable of compensating for the failure of the largest power plant block in the control area. In the APG control area, the largest power plant block is covered by secondary control in combination with tertiary control. Up to the end of 2011, the secondary control band in the APG control area amounts to +/-195 MW, whereby the secondary control band can be temporarily increased up to +425 MW. This power is continuously available. VERBUND Trading AG is the supplier up to the end of 2011.
In the case of electricity producers with an installed congestion capacity of more than 5 MW, the power price of secondary control is settled in accordance with the System Utilization Tariff Directive [Systemnutzungstarife-Verordnung (SNT-VO)]. This tariff component is referred to as a system service. The current System Utilization Tariff Directive 2010 can be accessed on the website of the Austrian regulator www.e-control.at.
The costs for the secondary control power provided are passed on to the respective balance groups as a part component of the total balancing energy by APCS, the independent clearing agency in the APG control area.
Tertiary control (minutes reserve)
Tertiary control is activated in cases where the deviation in the control area lasts more than 15 minutes. (This is also referred to as "minutes reserve".) Tertiary control is used to relieve secondary control so that this is once again free to support or restore the availability of primary control should this be necessary. Tertiary control can be activated automatically or manually. In the APG control area, tertiary control is activated manually. In the APG control area, tertiary control is also used to support secondary control to ensure that the largest power plant block can be compensated in the event of a failure without endangering grid stability.
Due to the stipulations in the market rules for the balancing energy market, the balancing energy price calculated from costs and volumes of the minutes reserve is not published until the following month. It can be found under www.apcs.at.
Details relating to the minutes reserve called are also promptly published (indicative values) on the APG website Control Area Imbalance.
Legal framework for balancing
- The Electricity Industry and Organisation Act [Elektrizitätswirtschafts- und -organisationsgesetz (ElWOG)]
- Technical and Organisational Rules for System Operators and Users (TOR)
- ENTSO-E Operation Handbook, Policy 1 and Appendix 1 relating to Load-Frequency Control and Performance
Links to the legal framework are provided under Legal Matters.