To ensure stable operation of the grid, injections to and withdrawals from the grid must be kept in balance at all times. The transmission system/control area operator is responsible for maintaining such balance by carrying out load frequency control (in accordance with Section 7(60) of the 2010 Electricity Industry and Organisation Act (ElWOG 2010)). If load demand fluctuates in the control area, the appropriate power reserves (primary control reserve, secondary control reserve or tertiary control reserve) are activated or deactivated in order to continuously balance the energy load. “Control power” refers to the energy quantities released when the power reserves are activated. “Balancing energy” refers to the energy needed to compensate for deviations in the forecasts (generation schedules) of balancing groups.