【摘要】 随着交直流混联电网建设的发展，交直流线路同塔输电的情况日益增多。交直流跨线故障作为其特有的故障类型，发生概率也会逐渐增加。以交直流跨线不接地故障为研究对象，分析其故障特征及交流线路距离保护在跨线故障时的适应性。研究结果表明，故障发生后，故障相测量阻抗在复平面上位于第四象限，呈现容性特征，且数值大于线路全长阻抗，使得距离保护动作的灵敏度降低，存在拒动风险。提出基于交流三相电流波形差异度的故障选相判据，并基于测量阻抗性质给出交直流跨线故障的判定方法，实现了故障选相及故障判别。此外，还在PSCAD/EMTDC仿真平台上搭建了交直流同塔输电线路模型并进行了大量仿真实验，仿真结果验证了所提故障判别方法的有效性。更多还原

【Abstract】 With the continued development of hybrid AC/DC power grids, the practice of having AC and DC transmission lines on the same tower has become increasingly common. Consequently, AC/DC cross-line faults, which are unique to this configuration, are expected to occur more frequently. Focusing on ungrounded AC/DC cross-line faults, this paper analyzes their fault characteristics and investigates the adaptability of AC line distance protection under such conditions. The results indicate that after the fault occurs, the measured impedance of the faulted phase lies in the fourth quadrant of the complex plane, exhibiting capacitive characteristics and having a magnitude larger than the total line impedance. This causes a reduction in the sensitivity of the distance protection, leading to a risk of protection failure to trip. A fault phase selection criterion based on the difference in the three-phase AC current waveforms is proposed. Furthermore, a method for determining AC/DC cross-line faults based on measured impedance properties is developed, achieving both fault phase selection and fault discrimination. In addition, a same tower AC/DC transmission line model is built on the PSCAD/EMTDC simulation platform, and extensive simulation experiments verify the effectiveness of the proposed fault discrimination method.更多还原