The primary control ensures restoration of the balance between production imbalance and consumption within seconds. The frequency is stabilized within the range of the permissible limit values. The activation takes place directly in the power plants by means of turbine controllers. The network frequency is monitored and in case of deviations immediately the necessary primary control power is activated. All transmission system operators represented in the UCTE must comply with the UCTE regulations in their country: the amount of primary control power to be maintained at any time is adjusted annually in accordance with ENTSO-E specifications.

The secondary control is intended for balancing intentional energy exchange of control area with the remaining UCTE alliance with simultaneously integral support of the frequency at 50 Hz. In case of an imbalance between energy production and energy consumption, the secondary control device will automatically take over the network regulation at connected power plants. These power plants should be operational, but should not create the maximum or minimum possible rated power to be able to fulfil the requests from the central network control at any time. The secondary control is activated after few seconds and is usually terminated after 15 minutes. If the reason of deviation is not removed after 15 minutes, the secondary control is replaced with the tertiary control.

Tertiary reserve is used for replacement of secondary control reserve and with it for restoration of sufficient secondary control band. Tertiary reserve is primarily necessary to compensate larger and longer continuous system deviations, particularly at production losses or unforeseen long-term loads. The activation is performed by Slovenian transmission system operator with special electronic signal announcements sent to aggregators. These have to ensure the delivery of additional tertiary energy within 15 minutes, regardless of the momentary timing of production.