柔性低频交流输电技术较工频输电技术具备输电能力强、控制柔性的优点，可应用于大规模陆上新能源广域汇集送出场景。为分析柔性低频交流输电系统的可用电压等级及范围，本文开展了架空线输送能力研究。首先，建立了以X/R为变量的电压电流函数，分析了不同电压、不同频率下架空线沿线电压、电流特性及静态电压稳定性，提出了低频系统送出能力的主要影响因素。其次，计算了10kV-1000kV典型架空线路的输送能力，其中220kV及以上的低频线路输电能力可提升2倍以上，输电半径扩大3倍以上。最后，在PSCAD/EMTDC中搭建了220kV/1000MW长距离架空线柔性低频交流送出系统，验证了远距离大容量新能源输送场景下柔性低频交流输电系统的有效性。

Flexible low-frequency AC transmission (FLFAC) technology has the advantages of strong transmission capacity and flexible control capability and can be applied in large-scale renewable energy wide area collection and transmission scenarios. The overhead line transmission capacity can directly reflect the available voltage level and range of the low-frequency system. Firstly, function with X/R as the variable was established and the voltage and current characteristics are analyzed under different voltages and frequencies, as well as the static voltage stability. The main influencing factors of the low-frequency system's capability were proposed. Then, a transmission capacity analysis method for the for renewable energy transmission was proposed, and the transmission capacity of 10kV-1000kV systems was carried out. The transmission capacity of low-frequency systems can be increased by more than 2.5 times and the power supply radius is about three times larger than the power frequency. Finally, low-frequency transmission system rated at 220kV/1000MW with 260km overhead lines was built in PSCAD/EMTDC to verify the stability of the low-frequency system in long-distance high-capacity transmission scenarios.