Unexpected fluctuations between inflows and outflows of electricity from the grid are quickly compensated by positive or negative balancing power, so as to maintain the frequency of the electricity network exactly at 50 Hertz. For this purpose, the four transmission system operators (TSOs) in Germany ask for positive and negative balancing power that can differ according to primary balancing power, secondary balancing power and minute reserve modes, depending on the required activation time.
If there is an imminent danger of a surplus of supplied energy and consequently an over-frequency in the network, the responsible TSO asks for negative balancing power; energy producers are therefore down-regulated or electrical consumers (e.g. pumps, compressors, refrigerated warehouses, power-to-gas plants) will be connected. The power held available by the TSO will be put out to tender on the balancing energy market.
Controllable, renewable energy and CHP plants are perfectly suited to offering minute reserve power and secondary balancing power. Power plant operators receive compensation for the mere provision of flexibility. In addition, the energy price offered individually will be paid by the power network operator, if required.