A Common-Grounded Single-Phase AC/Bipolar DC Hybrid Microgrid With a Four-Leg Interlinking Converter

Naghizadeh, Mohadeseh; Hojabri, Hossein; Muljadi, Eduard

doi:10.1109/jestpe.2023.3312210

Cited by 5 publications

(3 citation statements)

References 31 publications

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“…8 [21]. The single phase-to-ground fault current is calculated in (6) and the double phase-to-ground current is calculated in (7):…”

Section: ) Transformer Designmentioning

confidence: 99%

“…In the actual MG field implementation, there are still challenges, one of which is MG grounding. In recent years, MG grounding has attracted numerous research attentions, which mainly focus on future MGs such as dc MGs [5][6] and hybrid MGs [7], or grounding impacts on power electronics equipment [8][9]. However, in ac MG applications, there are also practical issues, which have not been well addressed.…”

Section: Introductionmentioning

confidence: 99%

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A Controllable Distributed Energy Resource Transformer-Based Grounding Scheme for Microgrids

Li,

Ma,

et al. 2024

IEEE Open J. Power Energy

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A microgrid (MG) may lose its grounding provided by the main distribution grid in islanded mode, which could cause equipment insulation damage, hazards to personnel, and protection malfunction. Existing MG grounding schemes include the grounding transformer-based scheme and distributed energy resource (DER) transformer-based scheme. However, the grounding transformer-based scheme will increase MG's cost, and the DER transformer approach will affect the main grid in the grid-connected mode. Moreover, future MGs may have multiple source locations. In each source location, the source and critical load can potentially operate as a sub-MG, requiring a grounding when it stands alone. In this scenario, the drawbacks of existing grounding schemes will be further magnified. In this paper, a novel controllable DER transformer-based grounding scheme is proposed, where a controllable switch is added to the neutral wire of the transformer. The proposed scheme can disable grounding capability in the grid-connected mode and enable it in the islanded mode by changing the transformer connection. The proposed approach can avoid impacts on the main distribution grid and eliminate the need for additional transformers. The design methodology of the proposed grounding scheme is provided. Simulation verification is conducted on a realistic MG model and experimental verification is conducted.

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“…8 [21]. The single phase-to-ground fault current is calculated in (6) and the double phase-to-ground current is calculated in (7):…”

Section: ) Transformer Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Controllable Distributed Energy Resource Transformer-Based Grounding Scheme for Microgrids

Li,

Ma,

et al. 2024

IEEE Open J. Power Energy

View full text Add to dashboard Cite

show abstract

“…One study [14] has analyzed the transient processes of pole-to-pole short circuits and single-pole grounding faults in DC cable lines and proposed methods for locating grounding faults, while others [15][16][17] presented models for calculating the short-circuit current between poles in DC distribution networks but did not consider the impact of DC faults on AC lines and converters. In [18], the diodes inside the converter were replaced with controllable electronic tubes, thus achieving isolation of DC faults using the converter, but at the cost of high investment and increased control complexity.…”

Section: Introductionmentioning

confidence: 99%

Propagation Mechanism and Suppression Strategy of DC Faults in AC/DC Hybrid Microgrid

Xiao,

Ren,

Cao

et al. 2024

Processes

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Due to their efficient renewable energy consumption performance, AC/DC hybrid microgrids have become an important development form for future power grids. However, the fault response will be more complex due to the interconnected structure of AC/DC hybrid microgrids, which may have a serious influence on the safe operation of the system. Based on an AC/DC hybrid microgrid with an integrated bidirectional power converter, research on the interaction impact of faults was carried out with the purpose of enhancing the safe operation capability of the microgrid. The typical fault types of the DC sub-grid were selected to analyze the transient processes of fault circuits. Then, AC current expressions under the consideration of system interconnection structure were derived and, on this basis, we obtained the response results of non-fault subnets under the fault process, in order to reveal the mechanism of DC fault propagation. Subsequently, a current limitation control strategy based on virtual impedance control is proposed to address the rapid increase in the DC fault current. On the basis of constant DC voltage control in AC/DC hybrid microgrids, a virtual impedance control link was added. The proposed control strategy only needs to activate the control based on the change rate of the DC current, without additional fault detection systems. During normal operations, virtual impedance has a relatively small impact on the steady-state characteristics of the system. In the case of a fault, the virtual impedance resistance value is automatically adjusted to limit the change rate and amplitude of the fault current. Finally, a DC fault model of the AC/DC hybrid microgrid was built on the RTDS platform. The simulation and experimental results show that the control strategy proposed in this paper can reduce the instantaneous change rate of the fault state current from 19.1 kA/s to 2.73 kA/s, and the error between the calculated results of equivalent modeling and simulation results was within 5%. The obtained results verify the accuracy of the mathematical equivalent model and the effectiveness of the proposed current limitation control strategy.

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An inherent fault current blocking modular series multilevel converter using half-bridge sub-modules for grid integration

Sarkar,

Chaudhury,

Das

2024

e-Prime - Advances in Electrical Engineering, Electronics and E

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A Common-Grounded Single-Phase AC/Bipolar DC Hybrid Microgrid With a Four-Leg Interlinking Converter

Cited by 5 publications

References 31 publications

A Controllable Distributed Energy Resource Transformer-Based Grounding Scheme for Microgrids

A Controllable Distributed Energy Resource Transformer-Based Grounding Scheme for Microgrids

Propagation Mechanism and Suppression Strategy of DC Faults in AC/DC Hybrid Microgrid

An inherent fault current blocking modular series multilevel converter using half-bridge sub-modules for grid integration

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