Power Losses Control for Modular Multilevel Converters Under Capacitor Deterioration

Deng, Fujin; Qian, Heng; Liu, Chengkai; Wang, Qingsong; Zhu, Rongwu; Cai, Xu; Chen, Zhe

doi:10.1109/jestpe.2019.2922445

Cited by 41 publications

(16 citation statements)

References 28 publications

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“…When i au < 0 and S i = 1, the i au flows through T 1 and the T 1 's current is i T 1 = − i au , which produces conduction loss P con_T 1 . When i au < 0 and S i = 0, the i au flows through D 2 and the D 2 's current is i D 2 = − i au , which produces conduction loss P con_D 2 22 …”

Section: Power Losses Of Mmcsmentioning

confidence: 99%

Power losses minimization for modular multilevel converter s with second‐order and fourth‐order harmonic circulating current injection

Zhao

Deng

Liu

et al. 2021

Int Trans Electr Energ Syst

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Summary Modular multilevel converters (MMCs) are regarded as promising topologies in medium/high‐voltage and high‐power applications. The reduction of power losses is an important issue for MMCs. This paper proposes a power loss minimization control (PLMC) by injecting optimal second‐ and fourth‐order harmonic circulating current into the arm current of MMCs. The proposed control can further reduce the power loss in comparison with the conventional control by only injecting the second‐order harmonic circulating current. In addition, the proposed control not only reduces the peak value of the arm current, but also improves the reliability of MMCs. Simulation with the PSCAD/EMTDC and experiment with 1‐kW MMC prototype are also conducted and their results confirm the validity of the proposed PLMC for MMCs.

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Section: Power Losses Of Mmcsmentioning

confidence: 99%

Power losses minimization for modular multilevel converter s with second‐order and fourth‐order harmonic circulating current injection

Zhao

Deng

Liu

et al. 2021

Int Trans Electr Energ Syst

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“…When Saui equals 0, the SM is at "OFF" state. Here, the capacitor is bypassed and the capacitor voltage remains unchanged [28]. As a result, the capacitor current icaui of the i-th SM is caui aui au i S i = .…”

Section: Operation Principles Of Mmcsmentioning

confidence: 99%

Capacitor ESR and C Monitoring in Modular Multilevel Converters

Deng

Qian

Liu

et al. 2020

IEEE Trans. Power Electron.

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The capacitor is one of the weakest components in the module multilevel converter (MMC). The rise of equivalent series resistance (ESR) is a prominent character to monitor the lapsed capacitor, but current researches only focus on capacitance and neglect ESR of capacitors in the MMC. This paper proposed a sorting-based monitoring strategy for capacitors in the MMC, which monitors not only the capacitance but also the ESR of capacitor. This paper reveals the relationship among the capacitor's ESR, capacitance, current and energy. Based on the relationship, the ESRs and capacitances of submodule (SM) capacitors in the arm are indirectly sorted, respectively, and only the capacitor with biggest ESR and the capacitor with smallest capacitance in the arm are monitored. The proposed strategy not only realizes both ESR and capacitance monitoring in the MMC, but also proposes a simplified monitoring algorithm for MMCs with large number of capacitors. The simulation and experimental results confirm the effectiveness of the proposed monitoring strategy for MMCs. 1

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“…e s = n p ω r ψ f (10) where P G denotes electromagnetic power generated by the PMSG, T e denotes electromagnetic torque, J denotes rotational inertia, e s denotes the excitation electromotive force, n p denotes pole pairs, and ψ f denotes the flux linkage.…”

Section: Mathematical Modelmentioning

confidence: 99%

A Modular Multiple DC Transformer Based DC Transmission System for PMSG Based Offshore Wind Farm Integration

Yin

2020

IEEE Access

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In this paper, a modular multiple DC (MMDC) transformer based DC transmission system, which is used for permanent magnetic synchronous generator (PMSG) based offshore wind farm grid connection, is proposed. The MMDC transformer is composed of input-parallel output-series (IPOS) DC/DC submodule groups, each of which consists of several input-series output-series (ISOS) LLC resonant converters (i.e., submodules). In the offshore wind farm, the electrical power generated by PMSG is converted to DC power by diode rectifier. Compared with the existing offshore wind farm grid-connection schemes, the proposed system has advantages of fewer conversion stages, higher efficiency and lower cost. The mathematical relationship of the system is studied, and then one kind of control strategy is proposed. Furthermore, a detailed DC transmission system simulation model containing a 160 submodules (LLC resonant converters) based MMDC transformer is built in PSCAD/EMTDC. Finally, a down-scaled experimental prototype of the DC system, which includes 9 submodules, is presented. Both simulation and experimental results validate the feasibility of the proposed DC system and effectiveness of the control strategy. INDEX TERMS Offshore DC wind farm, modular multiple DC transformer, HVDC, input-parallel outputseries, input-series output-series.

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Power Losses Control for Modular Multilevel Converters Under Capacitor Deterioration

Cited by 41 publications

References 28 publications

Power losses minimization for modular multilevel converter s with second‐order and fourth‐order harmonic circulating current injection

Power losses minimization for modular multilevel converter s with second‐order and fourth‐order harmonic circulating current injection

Capacitor ESR and C Monitoring in Modular Multilevel Converters

A Modular Multiple DC Transformer Based DC Transmission System for PMSG Based Offshore Wind Farm Integration

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