This study presents a dq impedance-decoupled network modelling method of offshore wind power plant (OWPP) for stability analysis. DQ impedance frequency responses of grid-connected inverters (GCIs) and long transmission cables (LTCs) are first measured by frequency scanning method, which are fitted as transfer function matrices using matrix fitting algorithm. Then, the GCIs are modelled as Norton equivalent circuits. In addition, per-unit-length electrical parameters of the LTCs are extracted from the measured dq impedance frequency responses of a specific LTC, based on which dq impedance-decoupled two port network models of the LTCs are established. DQ impedance-decoupled network model of the whole OWPP is then established based on connection relationships of these GCIs and LTCs. Finally, generalised Nyquist criterion (GNC) is performed in all the dq impedance-decoupled subsystems, and the subsystems where the GNC is not satisfied are identified as instability sources. Compared with conventional impedance-based stability analysis methods of OWPP, the proposed dq impedance-decoupled modelling method is able to facilitate the application of GNC and further instability source identification based on partitioning the whole OWPP into several decoupled subsystems. The effectiveness of the network modelling method is validated based on time-domain simulation results in Matlab/Simulink and real-time verification results in OPAL-RT.

中文翻译：

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DQ 电网条件下海上风电厂基于阻抗解耦网络模型的稳定性分析

这项研究提出了 dq 用于稳定分析的海上风电厂阻抗分离网络建模方法。 DQ首先通过频率扫描法测量并网逆变器（GCI）和长传输电缆（LTC）的阻抗频率响应，然后使用矩阵拟合算法将它们拟合为传递函数矩阵。然后，将GCI建模为诺顿等效电路。另外，从测量的值中提取LTC的每单位长度的电参数dq 特定LTC的阻抗频率响应，基于 dq 建立了LTC的阻抗解耦的两个端口网络模型。 DQ然后，基于这些GCI和LTC的连接关系，建立了整个OWPP的阻抗解耦网络模型。最后，在所有条件下执行广义奈奎斯特准则（GNC）dq阻抗去耦子系统和不满足GNC的子系统被标识为不稳定源。与传统的基于阻抗的OWPP稳定性分析方法相比，该提议dq通过将整个OWPP划分为几个解耦子系统，阻抗解耦建模方法能够促进GNC的应用和进一步的不稳定源识别。基于Matlab / Simulink中的时域仿真结果和OPAL-RT中的实时验证结果，验证了网络建模方法的有效性。