Abstract Microgrids (MGs) are very attractive for electrical power generation/consumption owing to increased reliability and resiliency, however, protection against different short-circuit faults is a major challenge in implementation. This paper proposes a simple algorithm for on-line estimation of apparent resistance per-phase of a three-phase ac power line. The idea is to compare the estimated apparent resistance with the real resistance per-phase of the power line. Then, any reasonable difference between the two resistances will indicate a short-circuit fault occurrence along the line; hence, the line has to be tripped immediately. This pilot-based unit protection scheme presents salient advantages when applied to protect the power lines in the meshed MGs. Effectiveness of the proposed protection scheme is verified by simulation in the MATLAB/SIMULINK environment using a test MG with inverter-based distributed generations. The results confirm reasonable performance of the protection scheme for the meshed MGs with various topologies under both the grid-connected and islanded modes of operation and with different faults including the symmetrical/asymmetrical short-circuit faults, high impedance short-circuit faults, and close-in-internal short-circuit faults.

中文翻译：

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基于视在电阻估计的网状微电网的基于试点的单元保护方案

摘要 微电网（MG）由于提高了可靠性和弹性而对发电/消费非常有吸引力，然而，针对不同短路故障的保护是实施中的主要挑战。本文提出了一种用于在线估计三相交流电力线每相视在电阻的简单算法。这个想法是将估计的表观电阻与电力线每相的实际电阻进行比较。然后，两个电阻之间的任何合理差异都将表明沿线发生了短路故障；因此，线路必须立即跳闸。这种基于试点的单元保护方案在应用于保护网状 MG 中的电力线时具有显着优势。所提出的保护方案的有效性通过在 MATLAB/SIMULINK 环境中使用基于逆变器分布式发电的测试 MG 进行仿真来验证。结果证实了在并网和孤岛运行模式下以及具有不同故障（包括对称/非对称短路故障、高阻抗短路故障和闭合故障）的各种拓扑的网状MG的保护方案的合理性能。 - 内部短路故障。