The all-DC delivered offshore wind farm has great potential in power engineering application due to its advantages in large capacity and long distance delivery. Considering the cost and reliability, the all-DC wind farm can be connected to the onshore grid via the Line-Commuted Converter High Voltage Direct Current (LCC-HVDC) but more interaction may also occur in the form of sub-/super-synchronous oscillations. In order to analyze the stability issue of such offshore wind farm system, the DC-port impedance are firstly established for the aggregated wind farm based on permanent magnet synchronous generator (PMSG) and LCC-inverter by using the harmonic linearization method, where the power outer loop cascaded by the current inner loop of PMSG wind farm and the phase-lock loop (PLL) of the LCC inverter are taken into consideration. Furthermore, the interaction between these two subsystems is analyzed based on the stability criteria through their impedance characteristics. Finally, simulation results are conducted by reproducing the time-domain oscillation in order to evaluate the effectiveness of impedance model for the all-DC delivered offshore wind farm system.

中文翻译：

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全直流外送海上风电场阻抗建模与稳定性分析

全直流交付海上风电场凭借其大容量、远距离输送的优势，在电力工程应用中具有巨大潜力。考虑到成本和可靠性，全直流风电场可以通过换流器高压直流（LCC-HVDC）连接到陆上电网，但更多的交互也可能以次/超同步的形式发生振荡。为分析此类海上风电场系统的稳定性问题，首先采用谐波线性化方法，为基于永磁同步发电机（PMSG）和LCC逆变器的聚合风电场建立直流端口阻抗，其中功率PMSG风电场电流内环级联的外环和LCC逆变器的锁相环（PLL）被考虑在内。此外，这两个子系统之间的相互作用是基于稳定性标准通过它们的阻抗特性来分析的。最后，通过重现时域振荡来进行仿真结果，以评估阻抗模型对全直流交付海上风电场系统的有效性。