An improved single-ended frequency-domain-based fault detection scheme for MMC-HVDC transmission lines. (February 2021)

• Record Type: Journal Article
• Authors: Zhang, Yunqi; Cong, Wei
• Is Part Of: International journal of electrical power & energy systems. Volume 125(2021)
• Publication Date: 2021-02
• Subjects: Single-ended fault detection -- Modular multilevel converter (MMC) -- High voltage direct current (HVDC) grid -- Initial voltage traveling wave (IVTW) -- Frequency domain -- Attenuation rate; Electrical engineering -- Periodicals; Electric power systems -- Periodicals; Électrotechnique -- Périodiques; Réseaux électriques (Énergie) -- Périodiques; Electric power systems; Electrical engineering; Periodicals; 621.3
• DOI: 10.1016/j.ijepes.2020.106463
• Languages: English
• ISSNs: 0142-0615

Abstract

Highlights: This paper proposes an improved single-ended MMC-HVDC fault detection scheme based on the frequency-domain attenuation rate of the initial voltage traveling wave. The sensibility will not decrease significantly as the transition resistance increases. The fault detection time is not more than 2.36 ms after the fault, which satisfies the requirement of MMC-HVDC grids. When the DC inductor decreases in the range above 50mH, the sensibility is still high without needing to increase the sampling frequency. Abstract: Aiming at the problems currently existing in transmission line protection for modular multilevel converter (MMC) based high voltage direct current (HVDC) grids, this paper proposes an improved single-ended fault detection scheme for MMC-HVDC transmission lines. The proposed scheme is based on the frequency-domain attenuation rate of the initial voltage traveling wave (IVTW). Firstly, the values of the IVTWs generated by the internal and external faults are calculated respectively based on the equivalent model of the four-terminal MMC-HVDC grid. Due to the boundary effect of DC inductors installed on both ends of DC lines, the attenuation rates of IVTWs with the increase of the frequency under internal and external faults have different characteristics. The detail coefficients of the IVTW in different frequency bands are extracted by stationary wavelet transform at different scales, and the amplitudes of the IVTW in different frequency bands are quantified by wavelet transform modulus maximums (WTMMs) at corresponding scales. A criterion for identifying internal and external faults is constructed based on the square of the frequency-domain equivalent attenuation rate of the IVTW. Lastly, simulation results under diverse fault conditions verify the effectiveness of the proposed fault detection scheme.