计及频率耦合和汇集网络的风电场序阻抗模型等值方法

近年来，中国河北沽源、新疆哈密等风电基地频繁发生电网振荡问题，呈现次、超同步频率振荡分量强耦合现象。频域小信号阻抗方法是建模和分析这类由电力电子并网装置引起的控制不稳定和振荡问题的有效方法。目前针对单个逆变器或风电机组频率耦合阻抗模型已有研究基础，文中基于此提出一种考虑频率耦合和汇集网络的风电场序阻抗模型等值方法，建立的风电场等值阻抗与单个逆变器或风电机组的模型定义和形式统一，能够用于分析次、超同步频率耦合的振荡问题。以直驱风电场并入弱电网系统为例，对所提出的模型应用于系统稳定性分析及振荡频率预测的准确性进行了仿真验证。

Equivalent Method for Sequence Impedance Model of Wind Farms Considering Frequency Coupling and Collecting Network

In recent years, power grid oscillation problems frequently occur in the wind generation bases of China, such as Guyuan in Hebei Province and Hami in Xinjiang Uygur Autonomous Region. These new oscillation problems often contain two closely coupled components at sub-synchronous and super-synchronous frequencies. Frequency-domain small-signal impedance is proven as an effective method for modeling and analyzing this kind of unstable and oscillation problems caused by the control of power electronic devices. Given that the frequency coupling impedance models for single inverter or wind turbines have been developed, an equivalent method for the sequence impedance model of wind farms is proposed considering both the frequency coupling and the collecting network. The definition and form of the developed equivalent impedance are consistent with the models of single inverter or wind turbines, and can be used to analyze the sub-synchronous and super-synchronous oscillations. Finally, case studies are presented with the PMSG-based wind farm integrated into weak power grid. The accuracy of the proposed model to analyze system stability and predict oscillation frequency is verified by simulation.