Secondary control power (SCP) is an important component of control power in the power grid that helps balance medium-term imbalances between electricity generation and consumption and maintain grid stability.
Second line of defense after the primary reserve
Second ary control power responds more slowly than primary reserve, but faster than the tertiary reserveto fluctuations in the power grid. It is needed to compensate for medium-term imbalances between power generation and consumption and to stabilize the grid frequency. Typical applications include sudden changes in load or outages of power generation facilities.
Pumped-storage plants, gas turbines, and virtual power plants
The secondary reserve is provided by various entities, including power plants that are easily controllable and can be switched on and off fully automatically, as well as virtual power plants. Pumped-storage power plants can quickly switch between pumping and turbine operation, and gas turbines can be started up or shut down within a few minutes. Virtual power plants aggregate decentralized generation and storage facilities such as biogas plants, hydroelectric power plants, and electricity storage systems.
Registration and Access Through the Transmission System Operators
The provision and compensation for secondary control services are handled through auctions and activations by the transmission system operators (TSOs). Providers register their capacities on the relevant platforms. When needed, the facilities are activated and compensated accordingly, in accordance with the requirements of the respective control area.
Compensation for Availability and Actual Usage
The capacity fee is paid for the provision of secondary control power, while the energy fee is charged for the power actually supplied. The exact terms are determined during the auctions and may vary depending on market conditions.
Faster than TRL, slower than PRL
The SRL supplements the primary and tertiary reserves to maintain the stability of the power grid. Primary reserve (PRL) responds to sudden outages within a few seconds. Tertiary reserve is used for longer-term grid fluctuations. In the event of grid fluctuations lasting longer than 15 minutes, the secondary reserve is replaced by the tertiary reserve.
Conclusion: Central second line of defense
Secondary control power plays a crucial role in maintaining grid stability and ensuring a reliable power supply. The integration of secondary control into the overall balancing energy system is essential for ensuring a reliable energy supply within the control area.
Frequently Asked Questions (FAQ)
What is secondary control power (SRL)?
SRL balances medium-term imbalances between electricity generation and consumption, with response times measured in minutes.
How quickly does SRL respond to grid fluctuations?
SRL reacts more slowly than PRL (seconds), but faster than TRL (15 minutes)—that is, in the range of minutes.
Who can provide SRL?
Adjustable power plants, pumped-storage power plants, gas turbines, and virtual power plants consisting of biogas, hydroelectric, and storage facilities.
