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- 저자 : Yang Rongfeng (검색결과 6 건)
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A new cascaded multilevel converter topology with energy exchange unit for STATCOM application
Rongfeng Yang,Yinglin Zhang,Binbin Li,Rong xu,Yong yu,Dianguo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
The star-connected H-bridge cascaded converter has the disadvantage of capacitors unbalance especially when the unbalance occurs between phases. This paper analyzed one novel topology with energy exchange unit (EEU) to realize the phase capacitors voltage balance. After analyzing the converter structure and balance operation concept, this paper provided detailed modulation and capacitors balance control, including maintaining the EEU capacitor voltage stable, sharing the energy storage between phases and in same phase. The simulation results demonstrate the correction of the topology and control.
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Rongfeng Lin,Lei Yang,Shucai Li,Rangjie Li,Xiangchao Sheng,Guangxiao Song 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.4
This study investigates the influence of redispersible latex powder and hydroxy propyl methyl cellulose on the physical andmechanical properties of cement-sodium silicate grouts with a high W/B ratio. The rheological properties, setting time,compressive strength, autogenous shrinkage sulfate attack resistance and permeability of the grouts were assessed andcompared. The microstructures were investigated in terms of crack development. The results show that satisfactory propertiesand durability, such as an initial setting time extension of 20~55%, an autogenous shrinkage reduction of 0.332~1.21‰, anda permeability addition of 0.1–0.4 MPa, were obtained in cement-sodium silicate grouts with the addition of two polymers. Theflexural strength of cement-sodium silicate grouts with redispersible latex powder was improved after curing in water andsulfate attack by 3 wt% sodium sulfate. However, the addition of two polymers reduced the compressive strength of all groutsexcept for the redispersible latex powder content of 3%. These research results can provide a technical reference for groutingmaterial selection and mixing ratio adjustment.
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An Improved Modulation Scheme for Voltage Balancing in Modular Multilevel Converter
Sui, Shunke,Yang, Rongfeng,Xu, Dianguo The Korean Institute of Electrical Engineers 2014 The Journal of International Council on Electrical Vol.4 No.2
With the continuous development of power electronic technology toward the high voltage and high-power conversion, the Modular Multilevel Converter (MMC) has attracted research attention. Since a large number of capacitors, voltage balancing problem becomes one of the key technologies of the MMC. To resolve the voltage balancing problem, this paper presents a novel voltage balancing modulation scheme, which control the instantaneous power of each sub-module timely by adjusting carriers offset in PWM, and the respective capacitor voltage could be stabilized at a set value. Simulation results based on MATLAB / SIMULINK environment are provided to testify to the effectiveness of the proposed method.
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An IGBT Open-Circuit Fault Detection Method for Modular Multilevel Converters
Binbin Li,Yi Zhang,Rongfeng Yang,Gaolin Wang,Dianguo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Recently, the modular multilevel converter (MMC) has attracted increasing attentions due to its distinctive features, especially in the application of HVDC power transmission. One of the most significant characteristic of MMC is that it is composed of identical low-voltage submodules (SMs). As a result, the low-voltage IGBTs can be employed in each SM as the main power switch. However, since an MMC station usually contains hundreds of SMs, the IGBT becomes the most fragile component. In this paper, the failure characteristics of the IGBT open-circuit fault in a SM are firstly analyzed. Then, an observer-based IGBT open-circuit detection method is proposed, which can accurately detect the fault by comparing the estimated values with the actual sampled values. Finally, the validity and effectiveness of the proposed fault detection method are demonstrated by experimental results based on a single-phase MMC prototype in the laboratory.
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Analysis of the Operating Principle and Parameter Design for the Modular Multilevel DC/DC Converter
Binbin Li,Shaolei Shi,Yibo Zhang,Rongfeng Yang,Gaolin Wang,Dianguo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
The modular multilevel converter (MMC) has become more and more attractive in the field of high-voltage high-power dc/ac power conversions. In the very recent years, the dc/dc modular multilevel converter is proposed intended for high-voltage dc/dc applications, such as the solid-state transformers and future dc-grid networks, which is extended from the traditional MMC. However, it remains unknown how to optimize the operation of this dc/dc modular multilevel converter and how to dimension the parameters of the elements in it. In this paper, a detailed analysis is performed to indentify the operating principle of the dc/dc modular multilevel converter. Using these analyses, the selection rules and parameter design method of the components are given to maximize the utilization ratio, improve the power density, and increase efficiency. Finally, the validity and effectiveness of this paper are verified by simulation results.
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Improved Model Predictive Control for H-bridge Cascaded STATCOM
Xu Rong,Yu Yong,Wu Jian,Yang Rongfeng,Xu Dianguo,Chen He,Yu Yannan,Ni Ronggang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
H-bridge cascaded static synchronous compensator (STATCOM) is often used to compensate the harmonic and reactive current derived from non-linear load. In order to improve the performance of STATCOM, an improved model predictive control (MPC) method is put forward in this paper. In the proposed MPC, the difference equations which are derived from the transfer functions of controlling variables and controlled variables in STATCOM are used as the predictive control model, the error between the output of STATCOM and predictive model is used to design feedback correction controller and rolling optimization controller. Meanwhile, the introduced repetitive controller is used to eliminate the inherent steady error. The actual H-bridge cascaded STATCOM is constructed and a series of verification tests are executed. The experimental results prove that the output voltage and current of H-bridge cascaded STATCOM with the proposed MPC have smaller distortion and better sinusoidal shape than those of the traditional Proportion Integral (PI) control. Moreover, the performance of H-bridge cascaded STATCOM is great in high power experiment.
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