A method for controlling the power generation of a distributed power generation system including a plurality of small power plants, wherein said distributed power generation system produces power for a power supply system managed by a production control center, the method comprises the steps of at predetermined time intervals less than one minute, receiving measurement data relating to instantaneous power generated by the small power plants for the distributed power generation system, and at predetermined time intervals less than one minute, determining from said measurement data an aggregate instantaneous power of the distributed power generation system, from said production control center, receiving, at predetermined intervals, a plurality of control reference signal values specifying the power to be produced by the distributed power generation system for said power supply system as a function of the instantaneous load in the power supply system managed by said production control center, at predetermined time intervals less than one minute, determining a difference between the power specified by said production control center for the distributed power generation system and the aggregate instantaneous power of the distributed power generation system, and individually controlling the power of each small power plant within a predetermined time limit so that if the power specified for the distributed power generation system is greater than the aggregate instantaneous power of the distributed power generation system, then instructing at least one small power plant selected from the small power plants having free capacity to increase its power, if the power specified for the distributed power generation system is equal to the aggregate instantaneous power of the distributed power generation system, then keeping the aggregate power of the distributed power generation system unchanged, and if the power specified for the distributed power generation system is smaller than the aggregate instantaneous power of the distributed power generation system, then instructing at least one small power plant selected from said plurality of small power plants to decrease its power, characterized in that when the power of the distributed power generation system has reached the power specified by the production control center for it or has approximated the specified power with a predetermined error, the method further comprises the step of modifying the power of at least two small power plants, while keeping the aggregate power of distributed power generation system at the same level, in so manner that a) the individual powers of the selected small power plants are modified towards such power values that have the same relative deviation from the scheduled power values of the respective small power plants. if the power specified for the distributed power generation system is greater than the aggregate instantaneous power of the distributed power generation system, then instructing at least one small power plant selected from the small power plants having free capacity to increase its power, if the power specified for the distributed power generation system is equal to the aggregate instantaneous power of the distributed power generation system, then keeping the aggregate power of the distributed power generation system unchanged, and if the power specified for the distributed power generation system is smaller than the aggregate instantaneous power of the distributed power generation system, then instructing at least one small power plant selected from said plurality of small power plants to decrease its power, a) the individual powers of the selected small power plants are modified towards such power values that have the same relative deviation from the scheduled power values of the respective small power plants.