Large-scale integration of wind turbines(WTs)results in the reduction of the power system inertia and weakens the system's frequency regulation capability. Therefore

the virtual inertia control has been applied in the permanent magnet synchronous generator(PMSG)based wind turbines for grid frequency support

which introduces the frequency signal into the WT's power or torque control. In the virtual inertia control

a phase locked-loop(PLL)is commonly needed to realize grid synchronization of the WTs. However

when connected to weak grids

the dynamics of the PLL can be deteriorated

which may even cause instability of the WTs. To deal with this problem

a virtual inertia coordinated control scheme is proposed for PMSG-based WTs

which utilizes the dynamics of the DC-link capacitor to realize self-synchronization instead of the PLL. Thus

it can ensure the desired stability of PMSG-based WTs when integrated into weak grids. Besides

based on the proposed control scheme

the WTs can release the stored kinetic energy in the rotating mass to supply inertia support under frequency disturbances. Corresponding grid connected self-synchronization and inertia simulation mechanisms are discussed in detail and simulations by MATLAB/Simulink verify effectiveness of the proposed coordinated control scheme.