Analysis and validation of mathematical morphology filters for single-ended fault localization in VSC-HVDC links

Abstract

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, 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 are 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 VSCHVDC grids. Several fault cases are applied to the CIGRE VSC-HVDC model in PSCAD and the MMbased scripts are written in MATLAB. The impact of different size and type of the Structuring Element (SE) 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.