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Jingyun Liu

Bio: Jingyun Liu is an academic researcher from Beijing Union University. The author has contributed to research in topics: Modular design & Power rating. The author has an hindex of 1, co-authored 1 publications receiving 92 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a diode-clamped modular multilevel converter (DCM2C) topology is proposed and a power feedback control method is developed, which enables the capacitor voltages to be clamped by low power rating clamping diodes.
Abstract: Voltage balance issue of dc-link capacitors is very important for applications of a cascade multilevel converter or a modular multilevel converter. In this paper, a novel diode-clamped modular multilevel converter (DCM2C) topology is proposed and a power feedback control method is developed. With the developed control strategy, the proposed diode-clamped circuit becomes a controllable closed loop which enables the capacitor voltages to be clamped by low power rating clamping diodes. The proposed topology and control strategy has quicker response and requires much fewer voltage sensors than the normally used traditional method; therefore, the system performance improvement and cost reduction are expected. Based on the proposed DCM2C, a novel N +1-level cascade multilevel topology is proposed for a cascade active power filter (CS-APF). The simulation and experimental results from the CS-APF have demonstrated and verified the effectiveness of the proposed novel topology and control method.

101 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, an improved electromagnetic transient (EMT) simulation model for the half and full-bridge modular multilevel converters (MMCs) that can be used for full-scale simulation of multi-level high-voltage dc (HVDC) transmission systems, with hundreds of cells per arm.
Abstract: This paper presents an improved electromagnetic transient (EMT) simulation model for the half- and full-bridge modular multilevel converters (MMCs) that can be used for full-scale simulation of multilevel high-voltage dc (HVDC) transmission systems, with hundreds of cells per arm. The presented models employ minimum software overhead within their EMT parts to correctly represent MMCs behavior during dc network faults when converter switching devices are blocked. The validity and scalabilities of the presented models are demonstrated using open-loop simulations of the half- and full-bridge MMCs, and closed-loop simulation of a full-scale HVDC link, with 201 cells per arm that equipped with basic HVDC controllers, including that for suppression of the second harmonic currents in the converter arms. The results obtained from both demonstrations have shown that the presented models are able to accurately simulate the typical behavior of the MMC during normal, and ac and dc network faults.

119 citations

Journal ArticleDOI
TL;DR: In this article, an emerging hybrid cascaded converter that offers the dc side short circuit proof feature at reduced loss and footprint compared to the existing multilevel and other hybrid converters is considered.
Abstract: Hybrid multilevel converters are contemplated in an attempt to optimize the performance of voltage source converters in terms of magnitude of semiconductor losses and converter footprint, and to achieve additional features such as dc short circuit proof, which is essential for a high integrity multiterminal HVDC grid. Therefore, this paper considers an emerging hybrid cascaded converter that offers the dc side short circuit proof feature at reduced loss and footprint compared to the existing multilevel and other hybrid converters. Its operating principle, modulation, and capacitor voltage balancing strategies are described in detail. Furthermore, hybrid converter scalability to high voltage applications is investigated. The validity of the modulation and capacitor voltage strategy presented are confirmed using simulation and experimentation. The hybrid cascaded converter is extendable to a large number of cells, making it applicable to high voltage applications, and operation is independent of modulation index and power factor. On these ground, the converter is expected to be applicable for both real and reactive power applications.

114 citations

Journal ArticleDOI
Fujin Deng1, Zhe Chen1
TL;DR: A voltage-balancing control method is proposed for the MMC under phase-shifted carrier-based pulsewidth modulation that uses the linearization method for pulse sorting without arm current measurement and reduces the computational intensity and burden.
Abstract: The modular multilevel converter (MMC) becomes attractive for medium- or high-power applications because of the advantages of high modularity, availability, and power quality. One of the technical challenges associated with an MMC is the balancing of the capacitors' voltages. In this paper, a voltage-balancing control method is proposed for the MMC under phase-shifted carrier-based pulsewidth modulation. The proposed voltage-balancing method uses the linearization method for pulse sorting without arm current measurement, which can control the capacitor charge transfer to balance the capacitor voltage in the MMC. In the proposed method, the voltagebalancing algorithm is implemented in each carrier wave period, which reduces the computational intensity and burden. In addition, the arm current can also be improved with the proposed method. The simulation studies with the professional tool PSCAD/EMTDC are conducted, and a downscale MMC prototype is also tested with the proposed method. The study results show the effectiveness of the proposed voltage-balancing method.

107 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present an innovative submodule selection method for the sub-module capacitor's voltage balancing within one arm of an MMC, which shows very fast response, high reliability, and its implementation suits a large number of implemented submodules as for highvoltage dc applications.
Abstract: The modular multilevel converter (MMC) is attracting more and more interest in high-power and high-voltage applications. Highly redundant, each arm of the converter is made of a large number of identical submodules with inner storage capability allowing to reach very high voltage without dc-link capacitor. The control of such a converter represents a challenge when it comes to the implementation of an MMC with a large number of submodules, namely in distributing the control tasks and handling the communicated values in-between controllers and submodules. This paper presents the details of an innovative submodule selection method for the submodule capacitor's voltage balancing within one arm of an MMC. “The Tortoise and the Hare” sorting method shows very fast response, high reliability, and its implementation suits a large number of implemented submodules as for high-voltage dc applications. The proposed submodule capacitor's balancing method is validated on a three-phase 10-kVA prototype with five submodules per arm.

103 citations

Journal ArticleDOI
Fujin Deng1, Zhe Chen1
TL;DR: A voltage-balancing method is proposed for the MMC switched at grid frequency with reduced losses and does not rely on the arm current, and the results confirm the effectiveness of the proposed capacitor voltage- Balancing method.
Abstract: The modular multilevel converter (MMC) becomes attractive for high-voltage and high-power applications due to its high modularity, availability, and power quality. The voltage balance issue of capacitors is very important in the MMC, and balancing of the capacitor voltage is increasingly difficult as the switching frequency is reduced. In this paper, a voltage-balancing method is proposed for the MMC switched at grid frequency with reduced losses and does not rely on the arm current. By assigning the low-frequency pulses with different pulsewidths, the capacitor charge transfer in the MMC can be controlled for keeping the capacitor voltage balancing in the MMC. Simulations and experimental studies of the MMC are conducted, and the results confirm the effectiveness of the proposed capacitor voltage-balancing method.

98 citations