Relevance of this field of application
A secure power supply is the backbone of all industrial nations. Alongside competitiveness and sustainability, security of power supply is one of the three core objectives of European energy policy.1 The expansion of renewable energies increases the volatility of electricity generation, as the sun does not always shine and the wind does not always blow. Therefore, supply or demand surpluses occur more and more frequently. The task of control energy is to reduce excess demand by reducing electricity consumption or to satisfy it by connecting additional generation plants (positive control energy) and to reduce excess supply by reducing electricity production or to remove it from the grid by connecting technical consumers (negative control energy). The forced disconnection of generation plants in the course of feed-in management is not one of the instruments of negative control energy.2
Electricity producers, electricity consumers and electricity storage facilities are involved in the provision of balancing power. The regulation differentiates according to the time of the first provision: The frequency containment reserves (FCR) must be available within 30 seconds after the occurrence of the balancing event, the automatic frequency restoration reserves (aFRR) within 5 minutes and the manual frequency restoration reserves (mFRR) after 15 minutes. Remuneration is based on performance prices, which remunerate the mere provision of the reserve power, and on working prices, which remunerate the actual delivery of balancing energy. In the special case of FCR, the commodity price does not apply, since in the case of demand, the amount of electricity injected or withdrawn is balanced out again at short notice and there is no price differentiation between injection and withdrawal. Tendering and processing of the balancing power is carried out by the transmission system operators both at national and international interconnection level and only concerns the period of the first 60 minutes after the occurrence of the control event. All balancing measures beyond this ("hourly reserves") are no longer the responsibility of the transmission system operators, but at the subordinate grid levels and must be covered by power plant control, intraday trading or over-the-counter trading by the balancing group managers concerned themselves.2
In Germany alone, a total of 6.8 GW of balancing power was tendered for frequency stabilisation in 2019, of which around 0.6 GW was FCR, 1.8 GW negative aFRR, 1.9 GW positive aFRR and 1.0 GW negative mFRR and 1.4 GW positive mFRR.2
1 Europäische Kommission (2010): Energie 2020. Eine Strategie für wettbewerbsfähige, nachhaltige und sichere Energie. Mitteilung der Kommission an das Europäische Parlament, den Rat, den Europäischen Wirtschafts- und Sozialausschuss und den Ausschuss der Regionen. SEK(2010) 1346. Brüssel, 10.11.2010.
Link ↗ (accessed 26.02.2021).
2 Next Kraftwerke (2021): Was ist Regelenergie?
Link ↗ (accessed 26.02.2021).