Fig.7 Simulation of the current fault component waveform when an external fault occurs
From Fig.7, it can be seen that: when a fault occurs beyond the DC line, the fault components of positive and negative current at 4 and 5 stations on both sides are positive or negative, and the current fault component waveforms collected by the corresponding poles are negatively correlated, with low similarity and large waveform distance.
In order to explore the sensitivity of line end protection, simulation verifications are carried out for different fault locations and fault types, and the comprehensive distance DallP and DallN of current fault waveform are calculated, and D1 value could be obtained after comparison. Simulation verification results is shown in Table 4.
Table 4 Identification results of metal short circuit of internal and external fault