DC Fault Analysis in MMC Based HVDC Systems along with Proposing a Modified MMC Protective Topology for Grid Stability

Saleki, Araz; Pordanjani, Bahram Jahanbakhshi; Bina, Mohammad Tavakoli

doi:10.1109/epdc53015.2021.9610803

Cited by 5 publications

(3 citation statements)

References 16 publications

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“…Equation ( 9) can be expressed as: (10) Similarly, assuming i dc (t 1 ) =I 0 , i dc (t) can be expressed as (11) where the time constant For the AC side, the current of the AC side almost flows into the bypass arm (so only the bypass arm is considered). The three-phase bridge arm is equivalent to forming a threephase short circuit, as shown in Fig.…”

Section: Fig 7 DC Equivalent Circuit Diagrammentioning

confidence: 99%

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Bypass arm based DC fault isolation scheme for MMC-HVDC systems

et al. 2023

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High voltage direct current transmission based on a modular multilevel converter (MMC-HVDC) is an effective method to solve the grid connection of the new energy. A DC fault is an issue that must be solved for MMC-HVDC. This paper proposes a protection scheme for HVDC converters to quickly suppress DC fault current without increasing the operation loss. By employing a bypass arm in conjunction with a switch-type zero-loss current limiter (SZCL), most of the DC current in the bridge arm flows through the bypass arm so the fault current of the power devices is reduced. There are a number of main advantages of this scheme. The fault isolation time can be greatly shortened, the cost of the system is effectively reduced, the steady-state operation loss of the system does not increase, the operation of the AC-grid can be maintained stably when a DC fault occurs, and the overcurrent impulse to the AC-grid is reduced. The proposed scheme is applicable to two-terminal systems and the DC grid, especially for faults at the converter outlet of the DC grid. Simulation results using PSCAD/EMTDC show the superiority of the proposed scheme when compared with other schemes and a comparison of the costs shows the feasibility of the proposed scheme in practical applications.

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Section: Fig 7 DC Equivalent Circuit Diagrammentioning

confidence: 99%

“…For two-terminal systems, a DC fault can be cleared by tripping an AC circuit breaker (ACCB). However, ACCBs take a long time to isolate DC faults [10,11]. Another scheme for the DC fault isolation uses modified MMC topologies, such as the full-bridge sub-module (FBSM), the clamp double sub-module (CDSM), etc.…”

Section: Introductionmentioning

confidence: 99%

Bypass arm based DC fault isolation scheme for MMC-HVDC systems

et al. 2023

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“…In 54 – 56 the authors implemented an ANN-based technique to remove the unbalancing in capacitor voltage. The proposed approach reduces ripple from capacitor voltage and quickly finds circulating current without analytical computations.…”

Section: Fault Diagnosis and Control Techniques For MMCmentioning

confidence: 99%

A comprehensive review of fault diagnosis and fault-tolerant control techniques for modular multi-level converters

et al. 2022

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Background Many faults occur in the modular multi-level converters (MMCs), including unbalancing capacitor voltage, lower and upper arm unbalancing, the line to line voltage unbalancing, sensors and actuators fault, system fault, and sub-modules fault in high as well as medium voltage applications. Introduction Several fault-tolerant approaches are presented to overcome these problems, such as active fault-tolerant control system (AFTCS), passive fault-tolerant control system (PFTCS), hybrid fault-tolerant control system (HFTCS), redundant system technique, special power circuit with the controller, and zero sequence voltage methods, which we will explain extensively in this article. Methodology This review emphasizes the types of faults in the MMCs and discusses the protection methods under failure conditions. The MMC is more popular in high voltage applications because it not only improves the quality of the grid but also has good harmonic performance in high power transmission. There is no need for any isolated dc sources to operate it. When faults are removed, the efficiency and reliability of the system will be increased. Results This extensive explanation of the current literature on MMC fault diagnosis and control techniques will conclude which methods provide a more valuable solution. Finally, this paper discusses the best approach to reduce MMC faults and provides a future research direction to the readers.

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