Protection of direct current (DC) transmission lines is one of the key difficulties to be urgently solved in the construction of the future voltage-sourced converter (VSC)-based DC grids. In this… Click to show full abstract
Protection of direct current (DC) transmission lines is one of the key difficulties to be urgently solved in the construction of the future voltage-sourced converter (VSC)-based DC grids. In this paper, a novel ultra-high-speed traveling-wave (TW) protection principle for DC transmission lines is proposed which is based on characteristics of modulus voltage TWs. First, the absolute value of the change in amplitude of the 1-mode voltage TW is used to construct the protection starting-up element. Then, the dyadic wavelet transform is utilized to extract the wavelet-transform modulus maxima (WTMM) of 1-mode and 0-mode initial reverse voltage TWs separately, which are used for fault section identification and selection of fault line successively. A four-terminal annular VSC-based DC grid electromagnetic transient model is established in PSCAD/EMTDC, and performance of the proposed novel ultra-high-speed TW protection principle is evaluated. Extensive simulation results under different fault conditions show that the proposed ultra-high-speed TW protection principle is excellent in rapidity, reliability and robustness. Therefore, the proposed novel ultra-high-speed TW protection principle in this paper can be adopted as an outstanding main protection for VSC-based DC grids.
               
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