Analysis and Modeling of a Hybrid MMC Coordinated With a Circuit Breaker Under DC Short-Circuit Fault Conditions

In recent years, hybrid modular multilevel converters (H-MMCs), which employ both half-bridge submodules (HB-SMs) and full-bridge submodules (FB-SMs) in each arm, have gained significant attention in high-voltage dc (HVdc) systems. This article thoroughly investigates the behavior of an H-MMC with an arbitrary ratio of FB-SMs per arm, coordinated with a dc circuit breaker (CB), during a pole-to-pole short-circuit (SC) fault. Upon detecting an SC fault, the CB is activated, and the H-MMC is temporarily blocked to reduce the peak fault current. The behavior of the H-MMC during this short interval is highly nonlinear, and this article aims to provide a precise model to analyze the H-MMC's behavior and calculate arm currents, dc fault current, and voltage increase in the FB-SMs. The model accounts for all nonlinear states during the blocking state, including arm current decay and the effect of arm inductors on current commutation, which becomes critical when fast CBs or short dc lines are considered in HVdc systems. A new index is also introduced to compare the power switch requirements for various MMC and CB combinations as a function of the FB-SM ratio and CB interruption times. Finally, the analytical model and mathematical equations are validated through simulations and experimental testing on a scaled-down prototype.

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Published in:
IEEE transactions on power electronics : PE ; a publ. of the Power Electronics Council / Institute of Electrical and Electronics Engineers
Publisher:
Institute of Electrical and Electronics Engineers (IEEE)
Publishing place:
New York, NY
Vol.:
40
No.:
9
ISSN:
0885-8993
ISSN:
1941-0107
Pages:
12566 - 12580
Date Issued:
2025
URN:
urn:nbn:de:gbv:8:3-2026-00831-1
DOI:
10.1109/tpel.2025.3563582
Language:
English
Type of Resource:
Text
Publisher:
Institute of Electrical and Electronics Engineers (IEEE)
Keywords:
Circuit faults; Circuit breakers; Analytical models; Inductors; Fault currents; HVDC transmission; Voltage; Stress; Voltage control; Integrated circuit modeling; Circuit Breaker; Short-circuit Fault; Modular Multilevel Converter; Hybrid Modular Multilevel Converter; DC Short-circuit; Short-circuit Fault Condition; Interrupted Time; Current Decay; Dc System; DC Line; Equivalent Circuit; Peak Current; Upper Arm; Maximum Stress; Conduction Loss; Maximum Voltage; Switching Mechanism; Voltage Waveforms; Current Waveforms; Current Stress; Voltage Stress; Dc Side; Lower Arm; Nominal Voltage; Kirchhoff’s Current Law; Kirchhoff's Voltage Law; Overvoltage; Flexible Parameters; Fault Scenarios; ARM Processor; DC circuit breaker (DCCB); dc short-circuit (SC) faults; high-voltage dc systems; hybrid modular multilevel converter (H-MMC); modeling
Classification:
Accepted version
DDC subject of DNB:
621.3 Electrical engineering, electronics
Hosting institution:
Faculties, Faculty of Engineering

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