Analysis of Single-Phase-to-Ground Faults at the Valve-Side of HB-MMCs in HVDC Systems

Although the probability of occurrence of station internal ac grounding faults in modular multilevel converter (MMC)-based high-voltage direct-current systems is low, they may lead to severe consequences that should be considered when designing protection systems. This paper analyzes the characteris...

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Bibliographic Details
Published in:IEEE transactions on industrial electronics (1982) 2019-03, Vol.66 (3), p.2444-2453
Main Authors: Li, Gen, Liang, Jun, Ma, Fan, Ugalde-Loo, Carlos E., Liang, Haifeng
Format: Article
Language:English
Subjects:
Alternating current
Capacitors
Circuit breakers
Circuit faults
Circuits
Configurations
Converters
Current zero behaviour
Fault currents
Fault tolerance
Faults
ground faults
Grounding
half-bridge modular multilevel converter
High voltages
high-voltage direct-current systems
HVDC transmission
Metal matrix composites
Protection systems
station internal fault
Topology
Voltage control
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Summary:Although the probability of occurrence of station internal ac grounding faults in modular multilevel converter (MMC)-based high-voltage direct-current systems is low, they may lead to severe consequences that should be considered when designing protection systems. This paper analyzes the characteristics of valve-side single-phase-to-ground (SPG) faults in three configurations of MMC systems. Fault responses for symmetrical monopole MMCs are first studied. Upper arm overvoltages and ac-side nonzero-crossing currents arising from SPG faults in asymmetrical and bipolar configurations are then investigated. DC grounding using an LR parallel circuit is employed to create current zero-crossings, which will enable the operation of grid-side ac circuit breakers. The theoretical analysis is verified through simulations performed in PSCAD/EMTDC, with simulation results and the theoretical analysis showing a good agreement. The studies in this paper will be valuable for the design of protection systems for station internal ac grounding faults.
ISSN:0278-0046
1557-9948
DOI:10.1109/TIE.2018.2829666