• Title, Summary, Keyword: Modular multilevel converter

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A Design Methodology of Digital Controller Considering Time Delay Effect for a Modular Multilevel Converter VSC HVDC System (모듈형 멀티레벨 전압형 HVDC 시스템을 위한 시간 지연을 고려한 디지털 제어기의 설계)

  • Song, Ji-Wan;Ku, Nam-Joon;Kim, Rae-Young
    • The Transactions of the Korean Institute of Power Electronics
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    • v.21 no.1
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    • pp.49-57
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    • 2016
  • A modular multilevel converter is widely adapted for a high-voltage direct current power transmission system. This study proposes a design methodology for a novel digital control that mitigates the negative effects caused by time delay, including communication transport delay for a modular multilevel converter. The modeling and negative effect of time delay are analyzed theoretically in a frequency domain, and its compensation methodology based on an inverse model is described fully with practical considerations. The proposed methodology is verified through several simulation results using a modular 21-level converter system.

An Isolated Bidirectional Modular Multilevel DC/DC Converter for Power Electronic Transformer Applications

  • Wang, Zhaohui;Zhang, Junming;Sheng, Kuang
    • Journal of Power Electronics
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    • v.16 no.3
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    • pp.861-871
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    • 2016
  • With high penetration of renewable energies, power electronic transformers (PETs) will be one of the most important infrastructures in the future power delivery and management system. In this study, an isolated bidirectional modular multilevel DC/DC converter is proposed for PET applications. A modular multilevel structure is adopted as switching valves to sustain medium voltages to achieve modular design and high reliability. Only one high-frequency transformer is used in the proposed converter, which significantly simplifies the circuit and galvanic insulation design. A dual-phase-shift modulation strategy is proposed to regulate the output power and achieve a simple voltage balancing control. A down-scaled (2 kW/20 kHz) prototype is constructed to demonstrate the proposed converter and verify the control strategy. The experimental results comply with the theoretical analysis well, with the highest power efficiency reaching 97.6%.

Enhancement of Cell Voltage Balancing Control by Zero Sequence Current Injection in a Modular Multilevel Converter (Modular Multilevel Converter에서 영상분 전류주입에 의한 셀간 전압평형화 제어의 향상)

  • Kim, Tae-Hyeong;Kwon, Byung-Ki
    • Proceedings of the KIPE Conference
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    • pp.159-160
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    • 2014
  • 본 논문에서는 ${\Delta}$결선으로 구성된 Modular Multilevel Converter(MMC)에서 흐르는 전류가 매우 적은 경우 계통에 영향이 없이 셀 직류전압의 불평형을 제어할 수 있도록 영상분전류를 주입하는 방법을 제안하였고, 시뮬레이션을 통해 검증하였다.

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Mathematical Analysis and Experiment Validation of Modular Multilevel Converters

  • Zhang, Yushu;Adam, Grain Philip;Lim, Tee-Chong;Finney, Stephen J.;Williams, Barry W.
    • Journal of Power Electronics
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    • v.12 no.1
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    • pp.33-39
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    • 2012
  • This paper describes operating and capacitor voltage balancing of the modular multilevel converter. The paper focuses on sizing of the cell capacitor and establishes approximate expressions for the capacitor voltage. Simulations and experiments results obtained from three-level modular converter are used to demonstrate its viability in medium voltage applications. It is shown that the modular converter can operate over the full modulation index linear range independent of load power factor.

Module Multilevel-Clamped Composited Multilevel Converter (M-MC2) with Dual T-Type Modules and One Diode Module

  • Luo, Haoze;Dong, Yufei;Li, Wuhua;He, Xiangning
    • Journal of Power Electronics
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    • v.14 no.6
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    • pp.1189-1196
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    • 2014
  • A modular multilevel-clamped composited multilevel converter ($M-MC^2$) is proposed. $M-MC^2$ enables topology reconfiguration, power device reuse, and composited clamping. An advanced five-level converter ($5L-M-MC^2$) is derived from the concept of $M-MC^2$. $5L-M-MC^2$ integrates dual three-level T-type modules and one three-level neutral point clamped module. This converter can also integrate dual three-level T-type modules and one passive diode module by utilizing the device reuse scheme. The operation principle and SPWM modulation are discussed to highlight converter performance. The proposed $M-MC^2$ is comprehensively compared with state-of-the-art five-level converters. Finally, simulations and experimental results are presented to validate the effectiveness of the main contributions of this study.

The Valve Redundancy Determination for HVDC Converter based on Modular Multilevel Converter (MMC기반의 전압형 HVDC 밸브의 여유율 결정)

  • Kim, Chan-Ki;Choi, Soon-Ho;Kang, Ji-Won;Yoon, Yong-Bum
    • The Transactions of the Korean Institute of Power Electronics
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    • v.21 no.4
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    • pp.328-334
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    • 2016
  • This paper examines the reliability of a VSC-HVDC valve based on a modular multilevel converter (MMC) HVDC system. The main objective of this paper is to determine the redundancy of the MMC valve. Several prediction methods are introduced, but the binomial failure method is selected to be used. To determine the availability and reliability prediction of MMC valve, which comprises a DC/DC converter, a gate driver, a capacitor, and an IGBT, the failure data of the MMC module are used as the tracking data according to the experimental result. This method uses a simplified equation to find the valve redundancy by transforming the binomial function to De Moivre's formula. This method is the first to be used to find the valve margin.

A kind of Improvement Simulation Method for Multilevel Module Converter (Multilevel Modular Converter의 개선된 시뮬레이션 방법)

  • Yuan, Zhen;Sastrowijoyo, Fajar;Lee, Hyeyeon;Jo, Jinsang;Jang, Suhyeong
    • Proceedings of the KIPE Conference
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    • pp.151-152
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    • 2013
  • Multilevel Voltage Source Converter HVDC presents a new method for the energy transmission, The multilevel requires the converter bridge includes more than 100 converter modules, for the EMT simulation file, the simulation time increases to several hours; it can depress the research process. In the paper, author describes a method to simulate the multilevel arm based on time-varying equivalent. The result shows the extremely calculation time reduced with almost the same accuracy.

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Modulation, Harmonic Analysis, and Balancing Control for a New Modular Multilevel Converter

  • Li, Binbin;Zhang, Yi;Wang, Gaolin;Xu, Dianguo
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.163-172
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    • 2016
  • The modular multilevel converter (MMC) has been receiving increased attentions in recent years. The new modular multilevel converter is a derivative topology from the traditional MMC in which the number of sub-modules (SMs) necessitated by each phase can be reduced by one. This paper presents a phase-shifted carrier pulse-width modulation (PSC-PWM) for the new MMC with an optimal phase-shifted angle to suppress the harmonics of the output voltage. Further, the harmonic features when the capacitor voltage of the middle SM is selected as two different values are also investigated. Moreover, in order to avoid introducing an unnecessary dc offset current at the ac terminals of the new MMC, a novel capacitor voltage balancing scheme is proposed by adjusting the amplitude of the reference signals rather than the offset. Finally, the validity and effectiveness of the proposed modulation and balancing schemes have been verified by experimental results based on a three-phase prototype of the new MMC.

Harmonic Analysis of a Modular Multilevel Converter Using Double Fourier Series

  • Quach, Ngoc-Thinh;Chae, Sang Heon;Ahn, Jin Hong;Kim, Eel-Hwan
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.298-306
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    • 2018
  • This paper presents a harmonic analysis of the modular multilevel converter (MMC) using a double Fourier series (DFS) algorithm. First, the application of DFS for harmonic calculation in the MMC is made by considering the effect of arm inductor. The analytical results are then confirmed by comparing with the simulation results of using the fast Fourier transform (FFT) algorithm. Finally, distribution of harmonics and total harmonic distortion (THD) in the MMC will be analyzed in three cases: harmonics versus number of levels of MMC, harmonics versus total switching frequency and harmonics versus modulation index. The simulation results are performed in the PSCAD/EMTDC simulation program in order to verify the analytical results obtained by Matlab programming.

PSCAD/EMTDC Simulation for Modular Multilevel Converter System (Modular Multilevel Converter 시스템을 위한 PSCAD/EMTDC 시뮬레이션)

  • Son, G.T.;Lee, H.J.;Beak, S.T.;Lee, U.H.;Chung, Y.H.;Hur, K.;Park, J.W.
    • Proceedings of the KIEE Conference
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    • pp.1214-1215
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    • 2011
  • 현재 HVDC 및 FACTS와 같은 전력전자소자 기반 전력기기의 최신 개발은 능동형 스위치소자의 발전 및 설치 환경의 변화로 인하여 VSC Topology로 이동되고 있다. 하지만 VSC Toplolgy의 스위칭 손실등의 문제로 대용량 전력기기의 경우 MMC(Modular Multilevel Converter) 적용이 가속화되고 있다. 이에 본 논문에서는 MMC Topology의 특징, 구동 원리, 시뮬레이션 과정을 소개한다. Modulation 및 Quantization 그리고 Sorting Algorithm을 통해 7-level, 151-level 삼상 MMC Topology을 시뮬레이션을 수행하였다.

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