风电接入弱送端柔直系统次同步振荡主导模式及参与因子分析

Dominant mode and participation factor analysis of sub-synchronous oscillation of wind power connected to weak transmission end of the flexible HVDC system

风电接入弱送端柔直系统的场景下,电力电子设备间的相互作用有可能造成次同步振荡。文中围绕风电接入弱送端柔性直流输电系统的小信号建模和稳定性分析,开展以下工作:建立了双馈风机接入弱送端柔直系统的直流电压时间尺度模型,充分体现次同步频段内设备之间的耦合作用;研究不同物理场景下该系统次同步振荡主导模式以及各控制环路的参与因子,分析各控制环路在主导模式中的影响权重,揭示控制环路带宽对系统次同步振荡的影响规律;在MATLAB中建立时域仿真模型,对以上稳定性分析结果进行验证。研究结果表明,系统次同步振荡的主导模式与送端电网强度、运行点、控制环路带宽密切相关。

In the scenario where wind power is connected to the weak transmission end of flexible HVDC system,the interaction between power electronic equipments may cause sub-synchronous oscillation.This paper focuses on the small-signal modeling and stability analysis of wind power connected to the weak-end flexible HVDC transmission system,and carries out the following work:the DC voltage time scale model of the double-fed wind turbine connected to the weak-end flexible HVDC transmission system is established,which fully reflects the sub-synchronization coupling between devices in the frequency band;study the dominant mode of sub-synchronous oscillation of the system and the participation factors of each control loop in different physical scenarios,and analyze the influence weight of each control loop in the dominant mode,reveal the influence rule of control loop bandwidth on system sub-synchronous oscillation;the time-domain simulation model is established in MATLAB,and the above stability analysis results are verified.The research results show that the dominant mode of the system sub-synchronous oscillation is closely related to the strength of the sending end grid,the operating point and the control loop bandwidth.