The invention discloses a single-pole grounding fault line
selection method for a multi-terminal small-current grounding flexible direct-current
system, and relates to the field of
relay protection ofmulti-terminal flexible direct-current systems. Aiming at the problem of difficulty in single-pole grounding fault line selection of a direct-current power distribution network in a low-current grounding mode, the single-pole grounding fault line
selection method comprises the following specific steps of: firstly, reading
voltage and current data, iteratively recording the current data of 256 sampling points, then determining a starting criterion and
electrode selection judgment, judging whether a fault exists or not according to the starting criterion, if so, judging whether a positive
electrode fault or a negative
electrode fault exists according to the electrode selection judgment, after selecting the positive / negative electrode fault, carrying out
noise reduction
processing on currentwaveforms of the positive and negative electrode lines by utilizing
wavelet transformation, representing the difference of fault currents of the positive and negative electrode lines by utilizing a ratio of residual absolute values after
noise reduction, comparing the difference with a threshold value, determining a faulty line, and sending out a fault
signal. According to the single-pole grounding fault line
selection method, the problem of difficult threshold setting caused by
noise interference and
current amplitude change is avoided, and the reliability of a line selection scheme is improved.