The static var compensator will affect the sub synchronous oscillation characteristics of the wind power system and need further analysis. For this purpose

for the DFIG via series compensation transmission system

shunt reactor and shunt capacitor are mounted at the power grid side. The impedance scanning method is adopted to measure the total equivalent impedance of grid side and DFIG. The influence mechanism of position and capacity magnitude of static reactive power compensation device to sub-synchronous oscillation characteristic of the system from the point of view of impedance. It is shown by the analysis result that the bigger the compensation capacity of the shunt reactor is

the bigger to the equivalent impedance is. The resonant frequency can be reduced and the resistance at the resonance point can be improved when the installation position is close to the fan

and the absolute value of resonant frequency and the resistance at the resonance point will be increased when the installation position is far from the fan. However

the influence of shunt capacitor on the system impedance is very small. Finally

the correctness of theoretical analysis is verified by the time domain simulation.