MVDC Application: Switching Processes AC-to-DC, DC -to- AC and Imbalance Mitigation through DC Mode

Oliveira, T. E. Castelo de; Overbeeke, F. van; Ćuk, V.; Jong, E.C.W. de

doi:10.1109/isgteurope.2019.8905558

Cited by 4 publications

(2 citation statements)

References 5 publications

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“…The operating modes (all four of the P-Q plane quadrants) are all available to the network operator, with continuous control of the set points, all whilst fixing the DC link voltage. Castelo De Oliveria et al in [178] experimentally tested the flexibility of AC-DC links and claimed that the main priority of DC operation is to provide the ancillary services that are required by the grid (as well as increasing power capacity). The paper concluded that the VSC controlled the DC link effectively and that it was capable of switching from power transmission to shunt FACTS.…”

Section: Dc-ac Converter Controlmentioning

confidence: 99%

Review of MVDC Applications, Technologies, and Future Prospects

Coffey

Timmers

et al. 2021

Energies

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This paper presents a complete review of MVDC applications and their required technologies. Four main MVDC applications were investigated: rail, shipboard systems, distribution grids, and offshore collection systems. For each application, the voltage and power levels, grid structures, converter topologies, and protection and control structure were reviewed. Case studies of the varying applications as well as the literature were analyzed to ascertain the common trends and to review suggested future topologies. For rail, ship, and distribution systems, the technology and ability to implement MVDC grids is available, and there are already a number of case studies. Offshore wind collection systems, however, are yet able to be implemented. Across the four applications, the MVDC voltages ranged from 5–50 kV DC and tens of MW, with some papers suggesting an upper limit of 100 kV DC and hundreds of MV for distribution networks and offshore wind farm applications. This enables the use of varying technologies at both the lower and high voltage ranges, giving flexibility in the choice of topology that is required required.

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Section: Dc-ac Converter Controlmentioning

confidence: 99%

Review of MVDC Applications, Technologies, and Future Prospects

Coffey

Timmers

et al. 2021

Energies

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“…Some discussion on the insulation performance under ac and dc voltages is provided empirically in [25]. The challenges associated with ac-to-dc and dc-to-ac switching processes on the system operation with the purpose of using the VSC based flexible ac-dc links to provide ancillary services to medium voltage distribution grids are explored experimentally in [26].…”

Section: A Ac-dc Reconfiguration Strategymentioning

confidence: 99%

Offline Reconfigurability Based Substation Converter Sizing for Hybrid AC–DC Distribution Links

Shekhar

Soeiro

Ramírez-Elizondo

et al. 2020

IEEE Trans. Power Delivery

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Hybrid ac-dc distribution systems with multiple parallel operating ac and dc links are being developed to maximize system capacity during (n-1) contingencies. This paper shows that offline reconfigurability between such ac and dc links post-fault clearance allows an additional design flexibility of reducing the required substation converter rating to maintain the same required capacity by maximizing the utilization of healthy infrastructure. The associated variation of system capacity with power rating and number of substation converters is determined for different types of component faults. It is discussed that while converter downsizing is possible, as a consequence the parallel ac-dc link system is forced to operate at a sub-optimal efficiency during normal conditions. Using case-studies, the economics of this trade-off is quantified for determining the optimal de-rating factor for varying grid voltage, link length and conductor area.

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A hybrid mixed‐cells DC‐DC modular multilevel converter with balanced arm energy and DC fault blocking capability for high voltage direct current systems

Farghly,

Elserougi,

Abdel‐khalik

et al. 2024

Circuit Theory & Apps

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SummaryDC‐DC converters play a vital role in the integration of renewable energy sources. Modular multilevel converter (MMC) has emerged as a highly promising option for high‐voltage high‐power applications, for DC‐AC and DC‐DC conversion, thanks to its distinctive characteristics. An inherent limitation of using traditional MMC in DC‐DC conversion is the occurrence of arm energy drift, leading to imbalanced voltages across capacitors of submodules (SMs). Many approaches have been presented in the literature to address the energy drift issue during DC‐DC conversion process. In this paper, a novel bidirectional hybrid modular multilevel DC‐DC converter with balanced arm energy has been proposed. The proposed converter consists of one high‐voltage valve and two legs. Each leg is equipped with half‐bridge submodules (HB‐SMs) in the upper arm and full‐bridge submodules (FB‐SMs) in the lower arm. The proposed architecture enables the parallel connection between series‐connected capacitors of the upper arm and series‐connected capacitors of the lower arm during the equalization period. The parallel connectivity enables the energy transfer between the upper and lower arms in the same leg, hence preventing energy drift issues. A detailed illustration of converter operational concept, mathematical analysis, design, and efficiency estimation are presented. The presented simulation and experimental results show the bidirectional power flow ability and the promising behavior of the proposed converter during normal operating conditions with balanced arm energy. Finally, a comparison between the proposed converter and other existing topologies has been made to show the superiority of the proposed converter over the other alternatives. The proposed converter has a lower count of insulated gate bipolar transistors (IGBTs) and eliminates the usage of isolating transformers when compared to the energy equalization modules approach. In addition, unlike the other alternatives, the proposed converter has a DC fault blocking capability.

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MVDC Application: Switching Processes AC-to-DC, DC -to- AC and Imbalance Mitigation through DC Mode

Cited by 4 publications

References 5 publications

Review of MVDC Applications, Technologies, and Future Prospects

Review of MVDC Applications, Technologies, and Future Prospects

Offline Reconfigurability Based Substation Converter Sizing for Hybrid AC–DC Distribution Links

A hybrid mixed‐cells DC‐DC modular multilevel converter with balanced arm energy and DC fault blocking capability for high voltage direct current systems

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