DC fault detection in hybrid MTDC systems using transient average of DC reactor voltage. (August 2023)

• Record Type: Journal Article
• Authors: Li, Jiapeng; Li, Yujun; Wang, Minghao; Xu, Zhao; Song, Guobing
• Is Part Of: International journal of electrical power & energy systems. Volume 150(2023)
• Publication Date: 2023-08
• Subjects: Short-circuit current calculation -- Hybrid MTDC system -- Fault detection -- Transient average voltage; 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.2023.109093
• Languages: English
• ISSNs: 0142-0615

Abstract

Highlights: A reduced LCC model for DC fault analysis is proposed based Taylor expression, where the LCC-based rectifier with control effects is regarded as an equivalent RLC circuit. By reserving only the high-frequency components of the Laplace fault circuit, the hybrid MTDC network is significantly reduced, and analytical expressions of the initial short-circuit current are derived. A single-terminal DC fault detection scheme is designed for hybrid MTDC systems using the transient average of DC reactor voltage, which is steady and robust. Abstract: The existence of various types of converters makes the fault characteristics of the hybrid multi-terminal DC (MTDC) system more complicated than the voltage source converter-based (VSC-based) MTDC system. A reduced line commutated converter (LCC) model for DC fault analysis is first proposed in this paper, where the LCC-based rectifier with control effects is regarded as an equivalent RLC circuit. By neglecting the resistive and capacitive components in the high-frequency domain, the original network analysis is significantly simplified to derive concise time-domain expressions of the initial DC fault current. On top of this, a single-terminal DC fault detection scheme using the transient average of DC reactor voltage is designed for the hybrid MTDC system. The thresholds for detecting faults on the LCC-connected and VSC-connected lines are calculated based on the derived fault current expressions, respectively. Simulation studies based on PSCAD/EMTDC have validated the proposed fault analysis model is accurate within the initial period after fault, while the proposed fault detection scheme for hybrid MTDC systems is fast, sensitive, and tolerant to high fault resistances.