RSC扰动分量与转差频率耦合引起的DFIG定子间谐波电流解析模型

Analytical Model for DFIG Stator Interharmonic Current Induced by Coupling of RSC Disturbance Components and Slip Frequency

研究双馈风机(double fed induction generator,DFIG)的间谐波产生机理和传变规律对于分析风电的次同步振荡和电能质量问题兼具理论必要性和工程迫切性。为此,文章考虑转子侧变流器(rotor side converter,RSC)在逆变侧产生的扰动电压分量,根据双馈风机的稳态电压方程和磁链方程,构建了DFIG间谐波等效电路数学模型;通过坐标变换将转子与定子电气量统一于同步速dq旋转坐标系中;然后经推导和坐标反变换建立了RSC扰动分量与转差频率耦合引起的DFIG定子间谐波电流解析模型。在PSCAD平台上搭建双馈风机并网算例,仿真结果验证了该模型的准确性。最后利用该模型进行定量计算,分析了RSC扰动分量在DFIG中的传变规律和感应出的定子间谐波电流随风速变化的时变特性,从而为DFIG中定子间谐波电流的抑制奠定了基础。

Research on generating mechanism and propagation rule of interharmonics in double fed induction generator（DFIG） has theoretical necessity and engineering urgency for analyzing subsynchronous oscillation and power quality issues of wind power. In this paper, considering rotor side converter（RSC） disturbing voltage generated at inverter side, according to steady-state voltage equation and flux equation of DFIG, mathematical model of DFIG interharmonic equivalent circuit is built. Rotor and stator electrical parameters are unified in dq synchronous speed rotating coordinate system through coordinate conversion. Then analytical model of DFIG stator interharmonic current caused by coupling of RSC disturbing component and slip frequency is established through coordinate inverse conversion and derivation. In PSCAD platform, simulation examples verify accuracy of the established model. Finally, on basis of quantitative calculation with this model, propagation rule of RSC disturbing component in DFIG and time-varying characteristics of induced stator interharmonic current with wind speed variation are analyzed, thus laying foundation for suppressing DFIG stator interharmonic current.