Calculation of DC Magnetic Flux Deviation in the Converter-Transformer of a Self-Commutated BTB System During Single-Line-to-Ground Faults

Hagiwara, Makoto; Pham, Phuong Viet; Akagi, Hirofumi

doi:10.1109/tpel.2007.915611

Cited by 16 publications

(13 citation statements)

References 27 publications

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“…However, comparison reveals that the two waveforms of v 0 are different in harmonic voltage. The reason is that the buffer 5 The dc capacitor of each chopper cell can be floated as in Fig. 7.…”

Section: B Operating Performance Under a Steady-state Conditionmentioning

confidence: 99%

“…The 80-MVA Static synchronous Compensator (STATCOM) commissioned in 2004 consists of 18 neutral-point-clamped (NPC) converter legs [4], where each of the ac sides is connected in series by the corresponding transformer. The use of line-frequency transformers, however, not only makes the converter heavy and bulky, but also induces the so-called dc magnetic flux deviation when a single-line-to-ground fault occurs [5].…”

Section: Introductionmentioning

confidence: 99%

“…7. Each dc side of positive and negative chopper-cells possesses a common dc capacitor, whereas its ac side is connected in parallel via two buffer inductors 5. …”

mentioning

confidence: 99%

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Control and Experiment of Pulsewidth-Modulated Modular Multilevel Converters

Hagiwara

Akagi

2009

IEEE Trans. Power Electron.

1,411

438

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A modular multilevel converter (MMC) is one of the next-generation multilevel converters intended for high-or medium-voltage power conversion without transformers. The MMC is based on cascade connection of multiple bidirectional chopper-cells per leg, thus requiring voltage-balancing control of the multiple floating dc capacitors. However, no paper has made an explicit discussion on voltage-balancing control with theoretical and experimental verifications. This paper deals with two types of pulsewidth-modulated modular multilevel converters (PWMMMCs) with focus on their circuit configurations and voltagebalancing control. Combination of averaging and balancing controls enables the PWM-MMCs to achieve voltage balancing without any external circuit. The viability of the PWM-MMCs, as well as the effectiveness of the voltage-balancing control, is confirmed by simulation and experiment.

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Section: B Operating Performance Under a Steady-state Conditionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Control and Experiment of Pulsewidth-Modulated Modular Multilevel Converters

Hagiwara

Akagi

2009

IEEE Trans. Power Electron.

1,411

438

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“…The magnetic flux deviation decays very slowly due to the lack of driving forces and the high efficiency nature of the transformer. This could easily cause the inrush current as the faulted grid voltages restore to the normal level [11], [12]. This inrush current and the associated unbalanced magnetomotive force (MMF)can exert significant axial forces on transformer windings and damage its insulation [13], thus compromise the long term reliability of the transformer.…”

Section: Introductionmentioning

confidence: 99%

An inrush current mitigation method for the grid-connected converters in the low-voltage ride-through operation

Chen

Cheng

2013

2013 IEEE Energy Conversion Congress and Exposition

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With more and more renewable and other distributed energy resources (DERs) being adopted, the utility requires these DERs systems have low voltage ride-through (LVRT) capability, which means the DERs converters must remain grid-connected and to provide reactive or active power for grid support during low voltage situations caused by faults. As such voltage sags occur, the deformed grid voltages often result in magnetic flux deviations in the grid-side transformer of the DERs converter. When the fault clears and the voltages restore to normal level, the flux deviation can easily result in inrush current of the transformer. This paper proposes an inrush current mitigation method for the grid-connected converters in the LVRT operation. The proposed method reduces the risk of inrush current by compensating the magnetic flux deviation during the LVRT operation. A pre-defined ampere constraint is imposed upon the LVRT and flux compensation to avoid burdening the power semiconductor devices. The proposed method can reduce the the stress of the converter and its grid-side transformer while performing the LVRT operation.

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“…In LVRT operation, the sudden reduction of grid voltages often lead to the magnetic flux deviation in the step-up transformer. The magnetic flux deviation decays very slowly due to high efficiency nature of the transformer, and it easily leads to inrush current in grid side of the step-up transformer as grid voltages restore to the normal level [11], [12]. This inrush current results in unbalanced magnetomotive force (MMF), which can exert significant axial forces on transformer windings and wreck its insulation [13].…”

mentioning

confidence: 99%