An unbalanced current protection relay (60C, 51NC) cannot operate fast enough to avoid catastrophic failure against high system fault currents within capacitor units because a traditional unbalanced current protection relay is not capable of classifying the transient fault current and switching inrush current. This article proposes a new algorithm for the detection and classification of these transient current signals. Simulations are performed using PSCAD/EMTDC programs. The outputs of the current signals are used as inputs for the discrete wavelet transform (DWT) process. The wavelet-based fault and inrush current detection and classification unit receive the captured transient current signals and use DWT to detect and analyze these signals. Actual inrush current signals from an experimental setup and shunt capacitor banks of 115 kV, 22 kV, and 6.6 kV are used to verify the proposed algorithm. The results show that the proposed algorithm provides good performance and accuracy in identifying faults and inrush currents.

中文翻译：

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使用离散小波变换提取并联电容器组中的瞬态涌流和故障电流信号进行检测和分类

不平衡电流保护继电器 (60C, 51NC) 的运行速度不够快，无法避免因电容器单元内的高系统故障电流而发生灾难性故障，因为传统的不平衡电流保护继电器无法对瞬态故障电流和开关浪涌电流进行分类。本文提出了一种新的算法来检测和分类这些瞬态电流信号。使用 PSCAD/EMTDC 程序进行模拟。电流信号的输出用作离散小波变换 (DWT) 过程的输入。基于小波的故障和涌流检测和分类单元接收捕获的瞬态电流信号，并使用 DWT 对这些信号进行检测和分析。来自实验装置和 115 kV、22 kV 并联电容器组的实际浪涌电流信号 和 6.6 kV 用于验证所提出的算法。结果表明，所提出的算法在识别故障和浪涌电流方面具有良好的性能和准确性。