Abstract:
As modular multilevel converter (MMC)-based high-voltage direct current (HVDC) systems play an increasingly vital role in modern grids, fast and reliable fault detection remains challenging. This paper analyzes high-frequency transients at the point of common coupling (PCC) during AC faults, where disturbances excite internal resonances and generate localized high-frequency components. A protection scheme combining Variational Mode Decomposition (VMD) and the Hilbert Transform (HT) is proposed. VMD is used to extract the fault-related third intrinsic mode, while HT computes its instantaneous energy. An energy kurtosis index is then employed to quantify transient impulsiveness, enabling rapid fault detection and accurate phase selection. The method is validated in an RTDS platform using a ± 400 kV MMC-HVDC system. Results under various symmetrical and asymmetrical faults show that the proposed VMD-HT scheme achieves accurate identification with strong robustness, maintaining reliable performance even under high-resistance faults up to 300 Ω.
L. Liu et al., "Instantaneous Energy Kurtosis-Based Protection for MMC-HVDC System Using VMD-HT," 2026 IEEE Eighth International Conference on DC Microgrids (ICDCM), Xi'an, China, 2026, pp. 1-5, doi: 10.1109/ICDCM67837.2026.11594525.
KEYWORDS: MMC-HVDC, Protection, Fault Analysis, VMDHT, RTDS