The line-commutated converter-based high-voltage direct-current (LCC-HVDC) transmission has become one of the main forms to deliver wind power in China. However, due to the connections of a large number of power electronic devices (PEDs), there emerges a risk of sub/super-synchronous oscillations in the DFIG-based wind power base with LCC-HVDC transmission. The existing multi-node system analysis methods have ignored the frequency coupling characteristic (FCC) of PEDs, unable to obtain accurate oscillation characteristics. Besides, the relationship between the oscillation and multi-level factors has not been revealed yet. Therefore, this paper proposes an improved quantitative analysis method of oscillation mode which considers the FCC on the basis of the system admittance network model. Firstly, the impedance model of the system considering the FCC is established. Then, the improved quantitative analysis method of the oscillation mode considering the FCC is proposed and its steps are as follows. 1) To establish the system transfer function matrix considering the FCC, and determine the system stability accurately by the dominant oscillation mode; 2) To define the node oscillation participation factor, considering the effect of the coupling frequency, and quantify the participation degree of each node and identify the origin and weak point of oscillation; 3) To carry out multi-level oscillation mode sensitivity analysis. Finally, the oscillation characteristics and laws of the DFIG-based wind power base with LCC-HVDC transmission are studied, and the time-domain simulations in MATLAB/Simulink validate the analytical results.

中文翻译：

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考虑频率耦合特性的双馈风电基地LCC-HVDC输电振荡模态改进量化分析方法

基于线换流器的高压直流（LCC-HVDC）输电已成为我国风电输送的主要形式之一。然而，由于接入大量电力电子设备（PED），双馈风电基地LCC-HVDC输电存在亚/超同步振荡风险。现有的多节点系统分析方法忽略了PED的频率耦合特性（FCC），无法获得准确的振荡特性。此外，振荡与多级因素之间的关系尚未揭示。为此，本文在系统导纳网络模型的基础上，提出了一种考虑FCC的改进振荡模态定量分析方法。首先，建立了考虑FCC的系统阻抗模型。然后，提出了考虑FCC的振荡模式的改进定量分析方法，其步骤如下。1) 建立考虑FCC的系统传递函数矩阵，通过主振荡模式准确判断系统稳定性；2) 定义节点振荡参与因子，考虑耦合频率的影响，量化各节点参与程度，识别振荡源点和弱点；3) 进行多级振荡模态灵敏度分析。最后，研究了LCC-HVDC输电双馈风电基础的振荡特性和规律，并在MATLAB/Simulink中进行时域仿真验证了分析结果。