Abstract: Renewable generators are often connected to the UHVAC/DC power transmission system. The power grid with plenty renewable generators usually has fewer thermal power plants, which makes the strength of the power grid is weak. Transient voltage instability problems often occur after DC blocking or severe AC short circuit faults, which may lead the wind turbines with off-gird problem. Based on the typical voltage ride-through strategy, this paper established a mutil-pole permanent magnet synchronous generator (PMSG)- based wind generator grid-connected model. The PMSG transient characteristics were studied when short fault appears on the remote transmission line in a weak power grid. The PMSG active/reactive control coupling and control error at the time of fault occurrence were revealed. The influences from PMSG control strategy and parameters on the unit power characteristics and terminal transient voltage were analyzed. The results show that the voltage phase of the PMSG terminal generally jumps backwards at the time of the remote short-circuit fault clearing, which makes the phase-locked loop result bigger than the actual phase. As a result, the PMSG active/reactive power control is not decoupled, and the current control produces errors. The control error caused by the phase-locking result will inhibit the rapid rise of the PMSG terminal voltage.