Prototyping of 500 kVA Medium Frequency Transformer for Offshore Direct-Current Collection Grid

Hatakeyama, Tomoyuki; Kurita, Naoyuki; Kimura, Mamoru

doi:10.23919/ipec.2018.8507912

Cited by 3 publications

(1 citation statement)

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“…However, it would not account for an increase in the size and weight of the magnetic core that results from increased area product, due to extra insulation requirements needed to accommodate interwinding dc voltage stresses. This core volume increase would cause the core losses to go up for the same power rating [47]. Therefore, to estimate the total magnetics losses for the HVdc-AT and F2F-MMC, (24) is modified as follows:…”

Section: Converter Lossesmentioning

confidence: 99%

The Modular Multilevel DC Converter With Inherent Minimization of Arm Current Stresses

Kish

2020

IEEE Trans. Power Electron.

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The modular multilevel dc converter (M2dc) is a partial power processing dc-dc converter that is gaining popularity for medium-voltage and high-voltage dc (HVdc) grid applications. However, internal ac current stresses go up as the step-down dc voltage ratio increases, leading to increased cost and losses, and ultimately renders the M2dc impractical for some applications. The HVdc autotransformer (AT) (HVdc-AT) is another class of the partial power processing dc-dc converter that circumvents this issue by using a transformer for interarm ac voltage matching, although the core must tolerate a very large dc voltage stress between windings that leads to increased magnetics size and weight. Interestingly, the M2dc does not suffer from interwinding dc voltage stresses. This article presents a new class of the partial power processing dc-dc converter that uses an integrated center-tapped transformer to merge the best traits of the M2dc and HVdc-AT. Comparative analysis reveals the proposed converter can minimize ac current stresses at all operating points while also achieving a significant reduction in transformer area product relative to the HVdc-AT. A dynamic controller is proposed that regulates dc power transfer while ensuring balanced capacitor voltages. The converter operation and dynamic controls are validated by simulation and experiment. Index Terms-DC-DC power conversion, HVdc converters, HVdc transmission. NOMENCLATURE CCL Circulating current loop. F2F-MMC Front-to-front modular multilevel converter. HVdc High-voltage dc. HVdc-AT High-voltage dc autotransformer. MMC Modular multilevel converter. MVdc Medium-voltage dc. M2dc Modular multilevel dc converter. M2dc-CT Modular multilevel dc converter with integrated center-tapped transformer. P3T Partial power processing transformer. SM Submodule. I. INTRODUCTION D C POWER transmission and distribution technology has been garnering increased attention over the last several Manuscript

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Section: Converter Lossesmentioning

confidence: 99%