The influence research of large-scale wind power on out-of-step oscillation of the Northwest China Power Grid

Based on theoretical research of the influence of Doubly Fed Induction Generator (DFIG) on equivalent system, it is offered that the oscillation is affected by the characteristic of wind turbine. The qualitative analysis shows that the influence of reactive power voltage control mode and protection mode of wind turbine to oscillation mode are unignorable. It is studied that the influence of DFIG active power output to oscillation splitting strategies. Grid simulation result shows that the wind turbine is likely to drop out from the grid if the wind turbines without Low Voltage Ride Through (LVRT) feature. As a result, oscillation will become more obvious, or even new out-of-step oscillation will emerge after wind turbines generator tripping. Reactive power and voltage control has little effect on the oscillation. It is found that the splitting strategies will be affected by the variation of DFIG active power output during a relative long time period compared to the transient oscillation process. The reason behind is that the power flow distribution and voltage level of the system will change due to the variation of DFIG active power output which will finally influence the splitting strategies in some extent.