构网型变流器模式切换下暂态同步-过电压的耦合分析和控制OA

After being subjected to a large disturbance,the grid-forming converter(GFM)will switch from the voltage source mode to the current limiting mode,which poses a risk of being unable to exit the current limiting mode after the disturbance is cleared and experiencing power-frequency overvoltage during the recovery period.Currently,research on the transient synchronization and power-frequency overvoltage coupling stability mechanisms of GFM is still insufficient.Therefore,first,by using power characteristic curves combined with the phasor method,the phase angle evolution and voltage boundary violation of the GFM operating point after a large disturbance are analyzed.A mode switching rule based on the output phase angle of the GFM is proposed.On this basis,the transient recovery process of the GFM is further investigated,and a power-frequency overvoltage criterion during the recovery period is analytically derived.Then,based on the mode switching rule and the power-frequency overvoltage criterion,the concept of the optimal fault-clearing phase interval is proposed,which balances synchronization stability and overvoltage limitation.Finally,an improved strategy considering both transient synchronization and power-frequency overvoltage coupling stability is proposed,and its effectiveness is verified through PSCAD/EMTDC simulation.