as one of the common faults in Modular Multilevel Converters (MMC) affects the safe and stable operation of the system. To detect faulty SMs in a timely manner
this paper proposes an MMC open-circuit fault diagnosis strategy based on the variation of arm voltages variation. By using the abnormal arm voltage increment of the arm within two sampling periods
the faulty arm is identified. The average SM capacitor voltage within the faulty arm is then calculated and compared with each individual SM capacitor voltage. When the difference exceeds a set threshold
the faulty SM is located
and the average value is updated to continue detecting any remaining faulty SMs
this allows for the detection of both single and multiple SMs faults. Furthermore
a method for setting the threshold is provided based on theoretical analysis.This strategy features simple steps
fast detection speed
and low computational complexity
enabling the detection of both single and multiple SM faults. The feasibility and effectiveness of the proposed method have been validated through MATLAB/Simulink simulation analysis and hardware-in-the-loop (HIL) system experiments.
HAREDASHT M R, BARAKATI S M, DARMIAN S Y, et al.Open-circuit fault diagnosis strategy for modular multilevel converter semiconductor power switches[C]//2022 13th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC). Tehran, Iran, Islamic Republic of, 2022: 150-154.
BI K T, AN Q T, DUAN J D, et al.Fast diagnostic method of open circuit fault for modular multilevel DC/DC converter applied in energy storage system[J]. IEEE transactions on power electronics, 2017, 32(5): 3292-3296.
WANG J, MA H, BAI Z H.A submodule fault ride-through strategy for modular multilevel converters with nearest level modulation[J]. IEEE transactions on power electronics, 2018, 33(2): 1597-1608.
ZHANG J Z, HU X, XU S, et al.Fault diagnosis and monitoring of modular multilevel converter with fast response of voltage sensors[J]. IEEE transactions on industrial electronics, 2020, 67(6): 5071-5080.
CHEN X X, LIU J J, DENG Z F, et al.A diagnosis strategy for multiple IGBT open-circuit faults of modular multilevel converters[J]. IEEE transactions on power electronics, 2021, 36(1): 191-203.
LIU C K, DENG F J, CAI X, et al.Submodule open-circuit fault detection for modular multilevel converters under light load condition with rearranged bleeding resistor circuit[J]. IEEE transactions on power electronics, 2022, 37(4): 4600-4613.
HU X, JIA H F, ZHANG Y D, et al.An open-circuit faults diagnosis method for MMC based on extreme gradient boosting[J]. IEEE transactions on industrial electronics, 2023, 70(6): 6239-6249.
AN Y, SUN X D, REN B Y, et al.Open-circuit fault diagnosis for a modular multilevel converter based on hybrid machine learning[J]. IEEE access, 2024, 12: 61529-61541.
ZHOU D H, QIU H, YANG S F, et al.Submodule voltage similarity-based open-circuit fault diagnosis for modular multilevel converters[J]. IEEE transactions on power electronics, 2019, 34(8): 8008-8016.
JIN Y, XIAO Q, JIA H J, et al.A novel detection and localization approach of open-circuit switch fault for the grid-connected modular multilevel converter[J]. IEEE transactions on industrial electronics, 2023, 70(1): 112-124.
JIA H F, DENG Y, HU X, et al.A concurrent diagnosis method of IGBT open-circuit faults in modular multilevel converters[J]. IEEE journal of emerging and selected topics in power electronics, 2023, 11(1): 1021-1034.
WANG H R, LI Y, WIJESEKERA A, et al.Switch open-circuit fault detection and localization for modular multilevel converters based on signal synthesis[J]. IEEE journal of emerging and selected topics in power electronics, 2023, 11(5): 5391-5404.
LIU Z H, XIAO L, CAO X, et al.A faulty submodule mathematical model-based localization strategy for switch open-circuit fault of module multilevel converter[J]. IEEE transactions on power electronics, 2023, 38(3): 3899-3916.
GENG Z, HAN M X.Fault localization strategy for modular multilevel converters in rectifier mode under submodule switch open-circuit failure[J]. IEEE Transactions on Circuits and Systems II: Express Briefs, 2020, 67(12): 3222-3226.
LIU C K, DENG F J, HENG Q, et al.Fault localization strategy for modular multilevel converters under submodule lower switch open-circuit fault[J]. IEEE transactions on power electronics, 2020, 35(5): 5190-5204.
LYU Y L, ZI Y S, LI X W.Improved control of capacitor voltage balancing in modular multilevel converter submodules[J]. IEEE access, 2024, 12: 19510-19519.