By using the decoupled double synchronous coordinate system software phase locked loop ( DDSRF-SPLL) ，it can detect the
unbalanced grid voltage of positive sequence component and negative sequence component，and put forward the coordinate transformation
of the mathematical to establish the grid side of directly-driven permanent wind generator's mathematical model，which includes
network side PWM inverter control and Voltage phase locked loop． A kind of current decoupling control strategy is proposed． It uses the
space vector pulse width modulation ( SVPWM) on AC output current control． This method can independently control the output current
of the active and reactive component，and can make the output current waveform of sine and grid voltage in phase with the same frequency．
Thus it can greatly reduce the harmonic pollution． It can eliminate the influence of unbalance voltage，and to achieve a precise
phase-locked output current and gird voltage three-phase grid voltage amplitude imbalance． In this paper，using Matlab /Simulink software
platform，the simulation proves the validity and feasibility of the control system when the grid stays in balance and unbalance． This
system improves reliability of wind power grid connection．