Cong Zhao

Chinese Academy of Sciences

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i-10 index

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Zixin Li

University of Chinese Academy of Sciences

Fanqiang Gao

Institute of Electrical Engineering

Yaohua Li

Institute of Electrical Engineering

Fei Xu

Chinese Academy of Sciences

Yaohua Li

Nanyang Technological University

Ping Wang

Royal Netherlands Meteorological Institute

Hang Zhang

Institute of Electrical Engineering

Ming Lei

Tianjin University

Ping Wang

Shandong Academy of Chinese Medicine

Yaohua Li

Institute of Electrical Engineering

Cooperative Institutions

Chinese Academy of Sciences

University of Chinese Academy of Sciences

Institute of Electrical Engineering

University of Science and Technology of China

Tianjin Research Institute of Electric Science (China)

Wuyi University

Tianjin University

Shandong University

Huazhong University of Science and Technology

Tsinghua University

Author Statistics

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Coordinated Balancing Charging Strategy for Cascaded H-Bridge Inverter With Supercapacitor and DC–DC Stage

IEEE Transactions on Industrial Electronics (2023)

Ye Zhang Zixin Li Fanqiang Gao Cong Zhao Yaohua Li

This article presents a coordinated balancing charging strategy for the cascaded H-bridge inverter (CHBI) with supercapacitor (SC) and dc–dc stage by adopting multistage adjustment of the SCs' charging powers. The power distribution constraints among the submodules (SMs) are analyzed to prevent over-modulation of the H-bridges. The reactive power distribution is optimized to expand the stable operation range of the CHBI in case of significant disparity in the active power distribution among the SMs. The relationship among the charging powers of different SCs is also derived under the aforementioned constraints. Finally, the effectiveness of the presented strategy is verified through the experimental results on a 16-kW CHBI single-phase prototype with four SMs.

H bridge

10.1109/tie.2023.3301545

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Citations (2)

Characteristics analyses and rebalancing method of modular multilevel converter under submodule fault conditions

2022 IEEE 13th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) (2016)

Cong Zhao Yaohua Li Zixin Li Fei Xu Ping Wang

Modular multilevel converter (MMC) is a promising circuit topology in the field of high-voltage direct current transmission (HVDC) systems. To enhance the reliability of the MMC in this field, the popular method is the addition of redundant submodules (SMs). However, the MMC will become unbalanced when some SMs fails and the performance will be deteriorated, especially when the number of the failed SMs is high. This paper analyzes the impact of the SM fault on the performance of the MMC. Theoretical analyses show that fundamental frequency component appears in the dc side current when some SMs fails. Furthermore, the approximate expression of the fundamental frequency component is derived. Based on the analyses, the number of the redundant SM design criterion is proposed. In addition, a rebalancing method is proposed to eliminate the harmonic component in the dc side and arm currents under SM faults scenario. Simulation results verified the theoretical analyses and the proposed rebalancing method.

Component (thermodynamics)

Harmonic

Harmonic Analysis

10.1109/pedg.2016.7527048

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Citations (2)

Capacitor Voltage Ripples Reduction of Full-bridge MMC With Circulating Current Injection Under Single-Line-to-Ground Fault Conditions

IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society (2019)

Cong Zhao Fanqiang Gao Zixin Li Ping Wang Yaohua Li

Full-bridge submodule (FBSM) voltage ripples can achieve a significant reduction of FBSM-based modular multilevel converter (FB-MMC) with boosted ac voltages. However, the FBSM voltage ripples increase substantially when single-line-to-ground (SLG) faults occur, which may cause damage to the safe operation of FB-MMC. This paper analyzes the FBSM voltage ripples characterization of the FB-MMC under SLG faults conditions. It is found that the fundamental frequency component, which is minor in steady-state operations, becomes dominant in the event of SLG faults leading to a dramatic increase of FBSM voltage ripples. Based on these analyses, a circulating current injection (CCI) method is proposed in order to suppress the main components of the FBSM fundamental frequency fluctuations. Both of the presented analysis and the effectiveness of the proposed CCI method are verified by simulations on a ±200 kV FB-MMC system.

Line (geometry)

10.1109/iecon.2019.8926930

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Citations (2)

Optimized Design of Full-Bridge Modular Multilevel Converter With Low Energy Storage Requirements for HVdc Transmission System

IEEE Transactions on Power Electronics (2017)

Cong Zhao Yaohua Li Zixin Li Ping Wang Xun Ma

Modular multilevel converter (MMC) is a well-proved circuit topology in voltage-source converter-based high voltage direct current (VSC-HVdc) transmission systems. As is known, the conventional half-bridge submodule (HBSM)-based MMC-HVdc is not suitable for overhead line transmission applications. In addition, high energy storage requirements, i.e., large capacitance is inevitable. The conventional design of the full-bridge submodule (FBSM)-based MMC usually does not utilize the negative voltage state of FBSM in normal operation. Considering the same dc voltage as with the HBSM case and utilizing the negative voltage state of the FBSM, this paper presents the design method of the power transmission capability of a single FBSM. Meanwhile, an optimized energy storage capacitance design method of the FBSM is proposed. With this method, the capacitance of FBSM can be reduced significantly. The correctness and effectiveness of the proposed method is verified by the simulation of a ±160 kV VSC-HVdc MMC and the comparison results of the dc short fault blocking and ride through capability are also provided.

Transmission system

HVDC converter station

10.1109/tpel.2017.2660532

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Citations (89)

Coordinated capacitor voltage balancing method for cascaded H-bridge inverter with supercapacitor and DC-DC stage

CES Transactions on Electrical Machines and Systems (2024)

Ye Zhang Zixin Li Fanqiang Gao Cong Zhao Yaohua Li

Cascaded H-bridge inverter (CHBI) with supercapacitors (SCs) and dc-dc stage shows significant promise for medium to high voltage energy storage applications. This paper investigates the voltage balance of capacitors within the CHBI, including both the dc-link capacitors and SCs. Balance control over the dc-link capacitor voltages is realized by the dc- dc stage in each submodule (SM), while a hybrid modulation strategy (HMS) is implemented in the H-bridge to balance the SC voltages among the SMs. Meanwhile, the dc-link voltage fluctuations are analyzed under the HMS. A virtual voltage variable is introduced to coordinate the balancing of dc-link capacitor voltages and SC voltages. Compared to the balancing method that solely considers the SC voltages, the presented method reduces the dc-link voltage fluctuations without affecting the voltage balance of SCs. Finally, both simulation and experimental results verify the effectiveness of the presented method.

H bridge

10.30941/cestems.2024.00019

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Citations (0)

Visual Simulation for LCD Display Controller Using Matlab

Chinese Journal of Liquid Crystals and Displays (2005)

Cong Zhao

This paper describes how to simulate visual picture using matlab software in 256 K color LCD controller.This hardware designed by VerilogHDL language,can generate some data by simulation of NC tools.Matlab reads the data and generates a picture for verification of common and segment address mapping or grayscale arithmetic.

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Study of Black Startup Strategy of The Turn-off Device Based Current Source HVDC Converter

Kedong Luan Yaohua Li Zixin Li Bing Xia Cong Zhao

The turn-off device based current source converter (TOD-CSC) is a promising circuit topology in high voltage direct current (HVDC) transmission systems. Compared with the conventional line-commutated converters (LCCs) the controllability of TOD-CSC is dramatically enhanced, while the cost and complexity are reduced compared with voltage-source converters (VSCs). However, for many applications, such as renewable energy generation systems, the black startup of TOD-CSC is a big challenge. In this paper, the mechanism of the black startup of TOD-CSC for passive networks are analyzed first. A segmented black startup strategy is proposed for TOD-CSC. Simulation results on a TOD-CSC based 120 kV/240 MW back-to-back HVDC transmission system in PSCAD/EMTDC environment show the correctness of the proposed black startup strategy.

High-voltage direct current

Transmission system

10.1109/ifeec47410.2019.9014978

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Citations (1)

Evaluation of Waterborne Coating for Controlled-Release Fertilizer Using Wurster Fluidized Bed

Industrial & Engineering Chemistry Research (2010)

Cong Zhao Yazhen Shen Changwen Du Jianmin Zhou Huoyan Wang

Coating through polymer film to control nutrient release can reduce the nutrient losses and minimize environmental contamination. In this research, the waterborne acrylate latex and additive (cross-linker aziridine) were used to develop coated controlled-release fertilizers by Wurster-type fluidized bed, and the influences of different cross-linker percentage on the coating properties and the nutrient-release profiles were investigated. The results indicated that the waterborne coating coupled with the 2 wt % of cross-linker could effectively decrease the swelling capacity of the membrane to 5.54 ± 0.32% while obtaining a suitable Tg (6.13 °C); the cumulative nutrient-release percentage was significantly improved to around 40% in 9 days at 40 °C. This organic solvent-free coating provided a promising option for the development of coated controlled-release fertilizer.

10.1021/ie101239m

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Citations (59)

A Novel Multilevel Current Source Actively Commuted Converter For High Voltage DC Transmission

Hang Zhang Zixin Li Cong Zhao Fanqiang Gao Fei Xu

High Voltage

10.1109/ipemc-ecceasia60879.2024.10567159

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Study on the controlled release performance of modified polyacrylate coated controlled release fertilizers.

Acta Pedologica Sinica (2017)

Cong Zhao Yazhen Shen Changwen Du Jianmin Zhou

Sodium polyacrylate

Immediate release

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