中文摘要：

低压直流微网凭借其较大的优势,获得了越来越多的关注。但是,目前低压直流微网的保护技术仍不能满足其快速、准确切除故障的需求。鉴于此,首先对低压双极性直流微网中的各类故障进行分析,在此基础上通过对比暂态故障电流变化率的绝对值以区分不同类型、不同位置的故障。针对低压双极性直流微网中的馈线故障提出了基于暂态故障电流变化率绝对值的反时限保护方案,通过理论分析：该保护方案在并网和孤岛2种运行方式下均可以快速、准确地切除馈线上各种故障,有利于提高低压双极性直流微网供电的持续性与可靠性。PSCAD/EMTDC仿真实验验证了该保护方案的有效性。

英文摘要：

LV DC microgrid attracts research interest with its great advantages. However, LV DC microgridprotection still cannot isolate faults rapidly and accurately. In this paper, faults in LV bipolar DC microgrid are analyzed in detail, and then different types and different locations of the faultare distinguished by comparing absolute value of transient fault current derivative. An inverse-time protection method based on absolute value of transient fault current derivative is proposed for cable faults. This method will improve reliable operation of LVbipolar DC microgrid by isolating cable faults rapidly and accurately in all operational conditions. Finally, the protection method is verified with PSCAD/EMTDC simulation.