Abstract: In view of the impact of the year-by-year growing grid-connected capacity of wind farms on the stability of the power system, and the voltage stability problems brought by the connecting of large-scale wind farms to local grid, the electromagnetic transient equivalent model of permanent magnet direct-drive (PMD) wind farms connected to the AC grid is established, and the effects of short-circuit ratio (SCR) and the ratio of equivalent resistance and reactance of contact line (X_L/R_L) on the voltage stability of the grid connection point are analyzed respectively from static and dynamic perspectives, and the combined reactive power compensation is carried out by shunt capacitor STATCOM at the grid connection point. The time domain simulation results show that the compensation method can effectively improve the transient stability of the parallel network voltage.