双馈风电场内部多模式谐振引发电力系统次同步振荡的机理研究

Mechanism Investigation of Sub-synchronous Oscillations in Power Systems as Caused by Multi-modal Resonance Within DFIG-based Wind Farm

该文研究风电场内部不同风电机群间多模式谐振引发电力系统次同步振荡和振荡模式频率漂移的作用机理。首先,提出多模式谐振理论,当风电场中N个风电机群的开环次同步振荡模式在复平面上相近时,N个风电机群之间发生的多模式谐振使得对应的两类闭环次同步振荡模式在复平面上分布于开环次同步振荡模式两侧相对的位置,当模式阻尼减弱的闭环次同步振荡模式位于复平面上的不稳定区域时,会引发系统失稳。其次,基于多模式谐振理论研究双馈风电场内部风电机群间动态交互引发电力系统次同步振荡的机理和次同步振荡的频率漂移现象,为风电场接入引发电力系统次同步振荡的研究提供新的视角。最后,通过算例分析验证理论分析和相关结论的正确性和有效性。

The paper investigated the mechanism of the occurrence of sub-synchronous oscillations(SSOs) and frequency drift in power systems with DFIG-based wind farm as caused by multi-modal resonance(MMR) among different wind clusters within the wind farm. Firstly, the paper proposed the MMR theory. It is found that when the open-loop SSO modes of N wind clusters within the wind farm are close to each other on the complex plane, two types of closed-loop SSO modes will be located at the opposite positions with respect to those of the open-loop SSO modes on the complex plane due to the MMR among N wind clusters. In addition, if the closed-loop SSO mode with damping degradation enters the right half-plane, the power system will be destabilized. Secondly, based on the MMR theory, the mechanism of SSOs in power systems caused by dynamic interactions among wind clusters within the DFIG-based wind farm and the frequency drift of SSOs were investigated. This paper provided a new prospective for the research on SSOs in power systems caused by the integration of wind farms. Finally, case studies were conducted to validate the correctness and effectiveness of the theoretical analysis and corresponding conclusions.