【摘要】 在海上风电直流汇集-直流送出系统中，基于单相模块化多电平换流器的面对面型(modularmultilevel converter based front-to-front, MMC-FTF)高压大功率DC/DC变换器是连接中压汇聚线与高压直流输电(high voltage directcurrent,HVDC)线路的关键接口设备。然而，针对MMC-FTF变换器的阻抗建模鲜有报道，且含MMC-FTF变换器的HVDC系统的小信号稳定性问题尚不明确。针对此问题，该文首先根据频率耦合效应提出共差模提取矩阵，实现了多谐波线性化方法下单相及三相MMC交直流侧阻抗模型的统一，并建立了MMC-FTF变换器的直流侧阻抗模型。其次，利用阻抗稳定性判据揭示了MMC-FTF变换器与岸上三相MMC换流站互联时存在的振荡风险。接着，根据相角灵敏度指标定量评估了不同控制器参数对系统稳定性的影响，并提出用于提升系统稳定性的调参准则。最后，基于MATLAB/Simulink仿真和硬件在环实验验证了结果的正确性。更多还原

【Abstract】 In the DC collection and transmission of offshore wind power system, the single-phase modular multilevel converter-based front-to-front(MMC-FTF) converter is the key interface device that connects the medium-voltage convergence line with the high voltage direct current(HVDC) line. However, the impedance modeling for MMC-FTF is rarely reported, and the small signal stability of HVDC systems containing MMC-FTF is still unclear. To address this problem, this paper firstly realizes the unification of the ac and DC impedance models of the single-phase and three-phase MMC under the multi-harmonic linearization method based on the frequency coupling effect and the proposed common mode and differential mode extraction matrix, and establishes the DC impedance models of MMC-FTF. Secondly, the impedance criterion is utilized to reveal the oscillation risk when the MMC-FTF is interconnected with the onshore three-phase MMC converter station. Then, the effects of different controller parameters on system stability are quantitatively evaluated based on the phase angle sensitivity index, and the corresponding parameter-tuning criteria are proposed to improve the stability of the system. Finally, the correctness of the results is verified through comprehensive simulation results and hardware-in-the-loop(HIL) experiments.更多还原