Fault classification of power distribution cables is essential for tripping relays, pinpointing fault location, and repairing failures of a distribution network in the power system. However, existing fault-classification techniques are not totally satisfactory because they may: 1) require the precalibration of responding threshold for each network; 2) fail to identify the three-phase short-circuit faults. since some electrical parameters (e.g., phase angle) are still symmetrical even in abnormal status; and 3) be invulnerable of electromagnetic interferences. In this paper, a fault-classification technique by detecting decaying dc components of currents in faulted phases through magnetic sensing is proposed to overcome the shortcomings mentioned above. First, the three-phase currents are reconstructed by magnetic sensing with a stochastic optimization algorithm, which avoids the waveform distortion in the measurement by current transformers that incurred by the dc bias. Then, the dc component is extracted by mathematical morphology (MM) in phase currents to identify the fault type together with the polarity of dc components. This method was verified successfully for various fault types on a 22-kV power distribution cable in simulation and also a scaled power distribution network experimentally. The proposed method can enhance the reliability of the power distribution network and contribute to smart grid development.

中文翻译：

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通过磁感应检测衰减直流分量对配电电缆进行故障分类

配电电缆的故障分类对于跳闸继电器、确定故障位置和修复电力系统配电网络故障至关重要。然而，现有的故障分类技术并不完全令人满意，因为它们可能：1）需要对每个网络的响应阈值进行预校准；2）未能识别三相短路故障。由于某些电气参数（如相位角）即使在异常状态下仍然是对称的；3) 不受电磁干扰。在本文中，提出了一种通过磁感应检测故障相中电流衰减直流分量的故障分类技术，以克服上述缺点。第一的，三相电流通过磁感应和随机优化算法重建，避免了由直流偏置引起的电流互感器测量中的波形失真。然后，通过相电流中的数学形态学 (MM) 提取直流分量，以识别故障类型以及直流分量的极性。该方法在22 kV配电电缆上的各种故障类型的仿真中得到了成功验证，在规模化配电网络中也得到了实验验证。所提出的方法可以提高配电网的可靠性，有助于智能电网的发展。通过相电流中的数学形态学 (MM) 提取直流分量，以识别故障类型以及直流分量的极性。该方法在22 kV配电电缆上的各种故障类型的仿真中得到了成功验证，在规模化配电网络中也得到了实验验证。所提出的方法可以提高配电网的可靠性，有助于智能电网的发展。通过相电流中的数学形态学 (MM) 提取直流分量，以识别故障类型以及直流分量的极性。该方法在22 kV配电电缆上的各种故障类型的仿真中得到了成功验证，在规模化配电网络中也得到了实验验证。所提出的方法可以提高配电网的可靠性，有助于智能电网的发展。