This paper presents the fault-ride through (FRT) validation and improvement of reactive power capability fully rated converter (Type-4) wind turbine (WT) during the transient grid disturbances. Typically, wind power plants must contribute to inject/absorb additional reactive current to the grid for supporting voltage stability according to the grid code requirements. First, the real and reactive power curves, current, and voltage harmonics are analyzed in detail at the different types of control modes under normal grid conditions. Furthermore, the wind farm's under-voltage-ride-through (UVRT) and over-voltage-ride-through (OVRT) behaviors and reactive power capability are presented. Based on the analysis, the capacitor bank is proposed and validated by simulation results for a grid-connected wind farm. The simulation is carried out under DIgSILENT Power Factory.