Method for performing frequency modulation on power grid, device and system

The invention discloses a method and system for performing frequency modulation on a power grid. The method includes the following steps that: demand electric load data are obtained; an upper limit value and a lower limit value are set for the adjustable rate of a power generation load on the basis of the demand electric load data; the deviation of the demand electric load data of a current powergrid for a power plant from the real-time power generation amount of the power plant is calculated according to the upper limit value and the lower limit value set for the adjustable rate of the powergeneration load; and whether the deviation is equal to a preset deviation value is judged; if the deviation is not equal to the preset deviation value, it is determined that the power plant needs toadjust the power generation load; and an adjustment strategy for adjusting the power generation load is selected according to the comparison result of the deviation and the preset deviation value, andthe selected adjustment str