直驱风电机组频率耦合阻抗模型的辨识

Identification of Frequency-coupled Impedance Model for Direct-drive Wind Turbine

大规模风力发电并网可能会引发严重的稳定性问题,例如与直驱风电机组有关的新型次同步振荡(subsynchronous oscillation,SSO)。这种新型SSO发生时通常伴随着显著的频率耦合效应,且该耦合现象在分析系统稳定性时有重要影响。为此,文章首先提出采用频率耦合阻抗模型(frequency-coupled impedance model,FCIM)分析直驱风电机组的频率耦合特性,之后建立了频率耦合阻抗模型测试平台,提出了频率耦合阻抗模型的辨识方法。然后基于平台和辨识方法得到了直驱风电机组的频率耦合阻抗模型,并根据所提方法拟合得到了阻抗模型传递函数。最后分析了直驱风电机组的频率耦合特性,可为电力系统振荡研究的模型选择提供参考。

The increasing integration of large-scale wind turbine generators(WTGs) into the power grid maycause severe stability issues, one of which is the subsynchronous oscillation(SSO) associated with the direct-drive full-scale converter-based WTGs. This emerging SSO usually involves significant frequency-coupling effects which is critical for the system stability analysis. The frequency-coupled impedance model(FCIM) is firstly introduced in this paper to elaborate the frequency coupling characteristics. Then, a test platform, as well as an identification procedure, is established to obtain the FCIMs of WTGs at different frequencypoints. Next, the point-by-point FCIMs are converted into transfer functions using the curve-fitting technique. Finally, the frequency-coupled characteristics of direct-drive WTG are investigated, and suggestions are given for the proper selection of models for the studies of power system oscillations.