Fast and accurate fault detection and localization are important topics in voltage source converter-based high-voltage direct current transmission (VSC-HVDC) grids in order to isolate the fault after the first milliseconds of occurrence. Common signal processing methods used for detecting fault traveling wave (TW) peaks like Fourier transform, S-transform and wavelet-based techniques transform the signal into the frequency domain, requiring complicated computations. In this paper, the application of mathematical morphology (MM)-based filters for detecting and locating faults in VSC-HVDC links is studied. MM-based methods analyze the signal in the time domain and detect the wave peaks accurately. Multiple MM-based filters resulted from basic MM operators are presented and used for TW-based fault study in VSC-HVDC grids. Several fault cases are applied to the CIGRE VSC-HVDC model in PSCAD, and the MM-based scripts are written in MATLAB. The impact of different sizes and types of the structuring elements on the accuracy of peak detection is analyzed. The results show the accuracy of MM filters for detecting and locating fault transient in VSC-HVDC links. The proposed method gives accurate results for both low-impedance and high-impedance faults.

中文翻译：

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用于 VSC-HVDC 链路单端故障定位的数学形态滤波器的分析和验证

快速准确的故障检测和定位是基于电压源换流器的高压直流输电 (VSC-HVDC) 电网中的重要课题，以便在故障发生的最初几毫秒后隔离故障。用于检测故障行波 (TW) 峰值的常用信号处理方法，如傅立叶变换、S 变换和基于小波的技术将信号转换到频域，需要复杂的计算。本文研究了基于数学形态学 (MM) 的滤波器在 VSC-HVDC 链路故障检测和定位中的应用。基于MM的方法在时域中分析信号并准确检测波峰。介绍了由基本 MM 算子产生的多个基于 MM 的滤波器，并将其用于 VSC-HVDC 电网中基于 TW 的故障研究。在PSCAD中将几个故障案例应用于CIGRE VSC-HVDC模型，并在MATLAB中编写基于MM的脚本。分析了不同尺寸和类型的结构元素对峰检测精度的影响。结果显示了 MM 滤波器在 VSC-HVDC 链路中检测和定位故障瞬变的准确性。所提出的方法为低阻抗和高阻抗故障都提供了准确的结果。