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- 저자 : Beihai Chen (검색결과 5 건)
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Phase Shift Control for Series Active Voltage Quality Regulators
Xiao, Guochun,Teng, Guofei,Chen, Beihai,Zhang, Jixu The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
A phase shift algorithm based on the closed-loop control of dc-link voltage implemented on a series active voltage quality regulator (AVQR) is proposed in this paper. To avoid pumping-up the dc-link voltage, a general phase shift compensation strategy is applied. The relationships among the operation variables are discussed in detail, which is very important for guiding the design of both the main circuit and the control system. Then on the basis of an investigation of the dc-link voltage pumping-up from viewpoint of the active power flow, a novel phase shift control method based on the closed-loop of the dc-link voltage is proposed. This method can adjust the phase of the output voltage gradually and automatically according to the dc-link voltage variation without introducing a phase jump. The effectiveness of the proposed strategy is verified through simulations of a single-phase 5kVA prototype and laboratory experiments on both a single-phase 5kVA and a three-phase 15kVA prototype.
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Phase Shift Control for Series Active Voltage Quality Regulators
Guochun Xiao,Guofei Teng,Beihai Chen,Jixu Zhang 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
A phase shift algorithm based on the closed-loop control of dc-link voltage implemented on a series active voltage quality regulator (A VQR) is proposed in this paper. To avoid pumping-up the dc-link voltage, a general phase shift compensation strategy is applied. The relationships among the operation variables are discussed in detail, which is very important for guiding the design of both the main circuit and the control system. Then on the basis of an investigation of the dc-link voltage pumping-up from viewpoint of the active power flow, a novel phase shift control method based on the closed-loop of the dc-link voltage is proposed. This method can adjust the phase of the output voltage gradually and automatically according to the dc-link voltage variation without introducing a phase jump. The effectiveness of the proposed strategy is verified through simulations of a single-phase SkV A prototype and laboratory experiments on both a single-phase SkV A and a three-phase ISkV A prototype.
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Shaona Wang,Kang Du,Rongfang Yuan,Huilun Chen,Fei Wang,Beihai Zhou 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.1
The effects of four types of sulfonamide antibiotics (SAs), including sulfaquinoxaline, sulfamethoxazole, sulfamethoxydiazine and sulfathiazole, on the digestion performance during anaerobic digestion process were studied using a lab-scale anaerobic sequencing batch reactor, and the changes of the community structure in the presence of SAs were investigated with the help of high throughput sequencing. The results indicated that when SAs were added, the hydrolytic acidification process was inhibited, and the accumulation of volatile fatty acids (VFAs) was induced, resulting in the suppression of methane production. However, the inhibition mechanism of different SAs was quite different. The inhibitory effect of high concentration of SAs on the hydrolysis of solid particulate matter into dissolved organic matter followed the order of sulfaquinoxaline > sulfamethoxydiazine > sulfathiazole > sulfamethoxazole. SAs have obvious inhibitory effects on acidification and methanation of dissolved organic matter, especially sulfathiazole. The richness and the community composition of the microorganism including bacteria and archaea in the digestion system were affected by SAs. Under the effect of SAs, the relative abundance of many microorganisms is negatively correlated with methane production, among which Methanobrevibacter, a kind of Archaea, had the greatest influence on methane production.
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Hao Wang,Jiangyue Dai,Huilun Chen,Fei Wang,Yangchen Zhu,Jia Liu,Beihai Zhou,Rongfang Yuan 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.2
In this study, Mg/Fe-doped biochar (MFDB) was prepared using the impregnation pyrolysis method, and its preparation was optimized using response surface methodology (RSM). The competitive adsorption between dissolved organic matter (DOM) and phosphorus was also investigated. The best adsorption capacity was obtained with an ㎎ impregnation ratio of 3.17:1 (Mg: biomass, g:g), Fe impregnation ratio of 1.3:1 (Fe: biomass, g:g), and pyrolysis temperature of 491℃. The adsorption capacity of MFDB for phosphorus was 179.21 ㎎/g at 40℃, an initial phosphate concentration of 50 ㎎/g and pH 4. The phosphate adsorption by MFDB conformed to a pseudo-primary and secondary adsorption kinetic model, proving the coexistence of physical and chemical adsorption. The adsorption mechanisms, including ligand exchange, electrostatic interaction, and complexation reaction were revealed. As the pH increased, it weakened the electrostatic interaction of phosphate by MFDB and the ligand exchange between phosphate and OH⁻. When the pH was less than 3, the metal oxide dissolved. For pH values exceeding, OH⁻ competed with phosphate for adsorptio, which also weakened the complexation of phosphate and MFDB. The DOM in domestic wastewater had a slight effect on the phosphorus adsorption. The phosphorus removal rates were closely related to lignin-like humic acid and tryptophan.
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The mechanisms of conventional pollutants adsorption by modified granular steel slag
Shaona Wang,Sijian Yao,Kang Du,Rongfang Yuan,Huilun Chen,Fei Wang,Beihai Zhou 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.1
This study was performed to investigate the removal of phosphorus, nitrogen, ammonia and dissolved organic matter (DOM) from domestic wastewater using modified granular steel slag (GSS) as adsorbent. The modification methods include acid modification, alkalinity modification and thermal modification. The GSS modified at 800°C for 1 h was easier to hydrolyze Ca<SUP>2+</SUP>, which could promote the precipitation of phosphates and the ion exchange process of ammonia. Therefore, the adsorptive capacity of GSS for phosphates and ammonia could be significantly improved by the thermal treatment. The acid-modified GSS promoted the adsorption capacity of nitrates by increasing surface protonation, specific surface area and pore size. The highest nitrates adsorption capacity was obtained when GSS was immersed in 1 mol/L HCl solution for 24 h. The presence of nitrates inhibited the adsorption of phosphates by GSS because the adsorption of nitrates and phosphates by GSS depended largely on electrostatic attraction and intermolecular force, and the competition between them reduced the adsorption capacity. Ammonia can promote the hydrolysis of metal ions on the surface of GSS, increase the concentration of metal ions in solution and promote the formation of phosphate precipitation, but ammonia also competed with phosphate for active sites on the surface of GSS. The effect of ammonia nitrogen on phosphate adsorption was the result of the interaction of the two mechanisms. For domestic wastewater, the thermally modified GSS showed the best adsorption rate of total phosphorus and total nitrogen, and the acid-modified GSS had better adsorption capacity for organic matter. The thermally modified GSS had a good application effect in laboratory subsurface flow constructed wetlands.
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