The Equivalent Method for Wind Power Units Considering the Power Characteristic Differences of Units Under Low-Voltage Ride-Through

Considering the increasing penetration of doubly-fed wind farms, a simplification method is proposed for clustering the DFIG units in the stability analysis of the power system. Moreover, the low-voltage ride-through (LVRT) process is taken into account and the power characteristics of the units are considered as a basis for the clustering. First, the control strategy during LVRT is analyzed to achieve a mathematical representation of the output power characteristics of the DFIG units. Then, by examining the differences in dynamic power characteristics among the units, the ability to restore steady-state active power to pre-fault levels is used as the criterion for initial clustering. After that, the units are clustered for equivalence based on an improved D-K clustering method. Finally, power curves and error levels are compared between the proposed and alternative methods using five measured wind speed scenarios. Simulation and calculation results demonstrate that the proposed method can effectively improve the accuracy of the equivalent model.