Operating Wind Power Plants Under Weak Grid Conditions Considering Voltage Stability Constraints

This article analyzes the power transfer limit (<italic>P<sub>max</sub></italic>) of wind power plants (WPPs) under the weak grid condition. It is pointed out that the impact of different grid parameters and grid configurations on <italic>P<sub>max</sub></italic> cannot be fully reflected by the short-circuit ratio (SCR), but can be readily captured by voltage sensitivity (∂<italic>Q</italic>/∂<italic>V</italic>). Hence, ∂<italic>Q</italic>/∂<italic>V</italic> turns out to be a more appropriate metric for the assessment of <italic>P<sub>max</sub></italic> compared with the SCR. Based on this insight, the voltage control of the WPP is suggested to be implemented at the bus with the highest ∂<italic>Q</italic>/∂<italic>V</italic> to maximize the power transfer capability. Moreover, a dynamic voltage control is further added at the turbine level to improve the disturbance rejection capability of the WPP as well as its dynamic robustness against grid strength variations. Finally, simulation and field test results are given to demonstrate the theoretical analysis and the effectiveness of the proposed control method.