Reserves and balancing power
Electricity production must be equal to electricity consumption at all times. The balance between production and consumption is indicated by the frequency of the electricity grid which has a nominal value of 50.0 Hz. The market operators plan and balance their consumption and production in advance, but in practice there are deviations during each hour. To balance these deviations, Fingrid procures different kinds of reserves from reserve markets. Reserves are power plants and consumption resources which either increase or decrease their electric power according to the need of the power system.