Protection scheme of multi-terminal hybrid HVDC transmission line based on traveling wave theory and improved Hausdorff distance
Multi-terminal hybrid high-voltage direct current(HVDC)transmission systems have large transmission capacity,complex topology structure,and the characteristics of"multiple sending points and multiple receiving ends".The line is prone to faults,and the influence range after the fault is wide,so the reliability of protection is extremely high.To ensure the safe and stable operation of the multi-terminal hybrid DC transmission system,a protection scheme based on traveling wave theory and improved Hausdorff distance is proposed in this paper.The line mode component and ground mode component are calculated according to the traveling wave theory,and the Bergeron model of the transmission line is applied to deduce the line mode current of the opposite side of the line from the line mode component of the line.The improved Hausdorff distance algorithm is introduced to quantify the difference between the deduced value and the real value and to construct the criterion to identify the fault line.At the same time,the fault pole is determined based on the size and change rate of the ground mode wave,and the fault location is calculated according to the traveling wave detection time to achieve an accurate fault location.This paper adopts the Wudongde three-terminal hybrid DC transmission engineering model and conducts simulation through PSCAD/EMTDC.The results show that the proposed protection scheme can identify faults in the whole line within 5 ms,withstand transition resistance and noise interference,and has reliability,selectivity,quickness and sensitivity.
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