The invention discloses an improved additional frequency control method suitable for a double-fed wind-driven generator set to participate in
system frequency adjustment in a short-circuit fault in the field of
new energy technology. In view of the conventional additional frequency control of a DFIG unit is only suitable for frequency fluctuation caused by a sudden load change and makes it difficult to satisfy the frequency adjustment in the whole process from the occurrence of the short-circuit fault to the
elimination of the fault, the wind-driven generator set uses MPPT control when the
power grid is in normal operation, and uses the conventional additional frequency control in response to a
system frequency change, and improves the transient stability of the
system frequency when the system has a load fluctuation. When a
transmission line has a fault, according to the change law of the system frequency in the whole process from the occurrence of the short-circuit fault to the
elimination of the fault, the parameters in the conventional additional frequency control of the DFIG unit are corrected, so that the output of the DFIG unit is quickly adjusted according to the system frequency change, thereby maintaining the effective
inertia damping characteristics of the DFIG unit in the whole process and improving the dynamic
response characteristics of the system frequency.