Abstract Field experiences have shown that sub-synchronous oscillation (SSO) can occur in direct-drive wind farms with VSC-HVDC systems. Due to the complexity of the detailed wind farm model, a dynamic equivalent model, with a reasonable order reduction of the detailed model and still reflecting inside-wind-farm and wind-farm-grid SSO characteristics is essential. In this paper, based on the principle that similar matrices have identical eigenvalues, the SSO analysis of an N-machine wind farm with VSC-HVDC system is conducted by simplifying it into two single-machine systems. The modeling method of the two single-machine systems is presented. Four case studies are presented to verify the effectiveness of the proposed model when compared with the detailed model in various scenarios. The proposed model is also benchmarked with the output multiplication-based equivalent model (OMM). Comparison results show that although the system order is reduced significantly, the proposed simplified equivalent model can still reflect inside-wind-farm and wind-farm-grid SSO modes in various scenarios. Meanwhile, the rationality of the OMM in terms of the wind-farm-grid SSO analysis is verified theoretically.

中文翻译：

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具有 VSC-HVDC 系统的直驱风电场次同步振荡分析的等效模型

摘要 现场经验表明，在采用 VSC-HVDC 系统的直接驱动风电场中可能发生次同步振荡 (SSO)。由于详细风电场模型的复杂性，一个动态等效模型，对详细模型进行了合理的降阶，同时仍能反映风电场内部和风电场电网的 SSO 特性。本文基于相似矩阵具有相同特征值的原理，将具有VSC-HVDC系统的N机风电场简化为两个单机系统进行SSO分析。给出了两种单机系统的建模方法。提出了四个案例研究，以验证所提出模型在各种情况下与详细模型的有效性。所提出的模型还与基于输出乘法的等效模型 (OMM) 进行了基准测试。对比结果表明，虽然系统阶数显着降低，但所提出的简化等效模型仍然可以反映各种场景下的风电场内部和风电场并网SSO模式。同时，从理论上验证了OMM在风-网-电网SSO分析方面的合理性。