Ancillary servicesBalancing power
Grid operators always call on balancing power when the supply and demand in the electricity grid are out of balance. There are three types of balancing power: Primary and secondary control reserve and minutes reserve. The difference: They require different lengths of time until the grid operators can use them fully. The quickest is the primary control reserve. It must be able to replace the instantaneous reserve – i.e. the rotating masses – after 30 seconds at the latest and be fully available. After five minutes the secondary control reserve supports the grid. In grids with few rotating masses, the primary control reserve must be available much earlier.