Flexible DC distribution networks are a key technology for supporting low-carbon energy transition and the integration of high-penetration distributed energy resources. However
their low inertia and weak damping characteristics lead to rapid increases in fault currents
imposing extremely high demands on the speed and reliability of protection. To address the edge effect issue of the dynamic time warping (DTW) algorithm in fault protection
this paper proposes a fault protection method based on Improved Fast-DTW (IF-DTW). Firstly
this method utilizes the whale optimization algorithm (WOA) to adaptively optimize the mode number and penalty factor of variational mode decomposition (VMD)
enabling precise extraction of high-frequency components from fault transients and effectively suppressing mode mixing and noise interference. Secondly
a fault initiation criterion is constructed using a third-order compact difference scheme of voltage signals to enhance noise immunity and numerical stability
ensuring rapid initiation within 0.15 ms. Subsequently
by calculating the IF-DTW distance between current signals at both ends of the line
waveform differences are quantified to achieve accurate identification of internal and external faults and fault pole selection. IF-DTW theoretically avoids edge effects through subsequence matching and a dynamic radius adjustment strategy
while significantly reducing computational complexity. Simulation results show that this method can complete fault isolation within 1.61 ms and maintains accurate discrimination even under harsh conditions of low signal-to-noise ratio (5 dB) and high transition resistance (300 Ω)
MEGHWANI A,SRIVASTAVA S C,CHAKRABARTI S. A non-unit protection scheme for DC microgrid based on local measurements [J ] . IEEE Transactions on Power Delivery,2017,32(5):2567-2577.
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Related Author
MA Xinmei
LI Xiaolu
LIU Jinsong
LIN Shunfu
SHEN Yunwei
YIN Dong
WANG Jian
CHEN Tewei
Related Institution
College of Electrical Engineering,Shanghai University of Electric Power
State Grid Shanghai Electric Power Research Institute
1. State Key Laboratory of Power Transmission Equipment Technology,Chongqing University
Modern Smart Distribution Grid Technology R&D and Application Laboratory (State Grid Chongqing Electric Power Company Shinan Power Supply Branch),,)