High-Pass-Filter-Based Virtual Impedance Control for LCL-filtered Inverters Under Weak Grid

Wang, Jiangfeng,Xing, Yan,Zhang, Li,Hu, Haibing,Yang, Tianyu,Lu, Daorong The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

Voltage feed-forward control (VFFC) is widely used in LCL-type grid-tied inverters due to its advantages in terms of disturbance rejection performance and fast dynamic response. However, VFFC may worsen the stability of inverters under weak grid conditions. It is revealed in this paper that a large phase-lag in the low-frequency range is introduced by VFFC, which reduces the phase margin significantly and leads to instability. To address this problem, a novel virtual-impedance-based control, where a phase-lead is introduced into the low-frequency area to compensate for the phase lag caused by VFFC, is proposed to improve system stability. The proposed control is realized with a high-pass filter, without high-order-derivative components. It features easy implementation and good noise immunity. A detailed design procedure for the virtual impedance control is presented. Both theoretical analysis and experimental results verify the effectiveness of the control proposed.

A Concise Design for Irradiating U-10Zr Metallic Fuel at Very Low Burnup

Haibing Guo,Wei Zhou,Yong Sun,Dazhi Qian,Jimin Ma,Jun Leng,Heyong Huo,Shaohua Wang 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.4

In order to investigate the swelling behavior and fuelecladding interaction mechanism ofUe10Zr alloy metallic fuel at very low burnup, an irradiation experiment was conciselydesigned and conducted on the China Mianyang Research Reactor. Two types of irradiationsamples were designed for studying free swelling without restraint and the fuelecladdinginteraction mechanism. A new bonding material, namely, pure aluminum powder, wasused to fill the gap between the fuel slug and sample shell for reducing thermal resistanceand allowing the expansion of the fuel slug. In this paper, the concise irradiation rig designis introduced, and the neutronic and thermalehydraulic analyses, which were carried outmainly using MCNP (Monte Carlo N-Particle) and FLUENT codes, are presented. Out-of-piletests were conducted prior to irradiation to verify the manufacturing quality and hydraulicperformance of the rig. Nondestructive postirradiation examinations using cold neutronradiography technology were conducted to check fuel cladding integrity and swellingbehavior. The results of the preliminary examinations confirmed the safety and effectivenessof the design.

High-Pass-Filter-Based Virtual Impedance Control for LCL-filtered Inverters Under Weak Grid

Jiangfeng Wang,Yan Xing,Li Zhang,Haibing Hu,Tianyu Yang,Daorong Lu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

Voltage feed-forward control (VFFC) is widely used in LCL-type grid-tied inverters due to its advantages in terms of disturbance rejection performance and fast dynamic response. However, VFFC may worsen the stability of inverters under weak grid conditions. It is revealed in this paper that a large phase-lag in the low-frequency range is introduced by VFFC, which reduces the phase margin significantly and leads to instability. To address this problem, a novel virtual-impedance-based control, where a phase-lead is introduced into the low-frequency area to compensate for the phase lag caused by VFFC, is proposed to improve system stability. The proposed control is realized with a high-pass filter, without high-order-derivative components. It features easy implementation and good noise immunity. A detailed design procedure for the virtual impedance control is presented. Both theoretical analysis and experimental results verify the effectiveness of the control proposed.

Eu³⁺→Eu²⁺ unusual reduction and bond energy in MAlSi₂O₆:Eu (M = Li, Na, K, Rb, Cs)

Pan, Yu,Wang, Wenjun,Zhu, Yuhan,Xu, Haibing,Noh, Hyeon Mi,Jeong, Jung Hyun,Liu, Xiaoguang,Li, Ling Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.7

<P><B>Abstract</B></P> <P>Eu-doped MAlSi<SUB>2</SUB>O<SUB>6</SUB> (M = Li, Na, K, Rb, Cs) phosphors were synthesized by solid-state reaction in air. The crystal structure and optical properties of the phosphors were investigated by X-ray powder diffraction and photoluminescence. Their emission spectra are composed of some broad bands coming from the 5d-4f transition of Eu<SUP>2+</SUP> and some sharp emission peaks coming from the f-f transitions of Eu<SUP>3+</SUP>. The co-existence of Eu<SUP>3+</SUP> and Eu<SUP>2+</SUP> cations is detected in MAlSi<SUB>2</SUB>O<SUB>6</SUB>:2%Eu, which shows that the unusual Eu<SUP>3+</SUP>→Eu<SUP>2+</SUP> reduction process occurs in MAlSi<SUB>2</SUB>O<SUB>6</SUB>. The preferential occupancy of Eu<SUP>3+</SUP> or Eu<SUP>2+</SUP> in MAlSi<SUB>2</SUB>O<SUB>6</SUB> can be calculated to be M<SUP>+</SUP> sites by the bond-energy method. The deviation of the Eu<SUP>3+</SUP>–O<SUP>2-</SUP> bond energy is closed to that of the Eu<SUP>2+</SUP>–O<SUP>2-</SUP> bond energy, which means that Eu<SUP>3+</SUP> and Eu<SUP>2+</SUP> can coexist in air. The abnormal reduction of Eu<SUP>3+</SUP> to Eu<SUP>2+</SUP> can be explained by charge compensation model. The doped Eu<SUP>3+</SUP> was induced to M<SUP>+</SUP> and the vacancy (<I>V</I> <SUB> <I>M</I> </SUB>) may be formed. The vacancy(<I>V</I> <SUB> <I>M</I> </SUB>) acted as a donor of electrons, and the Eu M ∙ ∙ defect acted as an acceptor of electrons. The theoretical result is consistent with the experimental phenomenon.</P>

Linear sampling method for the heat equation with inclusions

Nakamura, Gen,Wang, Haibing Institute of Physics 2013 Inverse problems Vol.29 No.10

<P>We are concerned with the reconstruction of unknown inclusions inside a heat conductor from boundary measurements, which is modeled as an inverse boundary value problem for a parabolic equation. Taking the Neumann-to-Dirichlet map as measured data, we establish a linear sampling-type method to identify the inclusions. As in inverse scattering problems, the so-called forward interior transmission problem naturally arises in the linear sampling method for identifying inclusions. The unique solvability of the forward interior transmission problem for parabolic equations is also investigated.</P>

Sources and trace element geochemical characteristics of the coarse sediment in the Ningxia-Inner Mongolia reaches of the Yellow River

Xiaopeng Jia,Haibing Wang,Hongfang Wang 한국지질과학협의회 2014 Geosciences Journal Vol.18 No.2

Siltation of coarse sediment in the river channel isthe main cause of flooding and dike burst on China’s Yellow River,and the loess are thought as the coarse sediment sources of the lowerreach of the Yellow River. The Ningxia-Inner Mongolia reaches ofthe Yellow River flow through an extensive area of aeolian desert,with flood events occurring frequently in this region. In this paper,we investigate the trace element contents of the coarse sediment inthe Ningxia-Inner Mongolia reaches of the Yellow River. The mainchemical components of the coarse sediments consist of 28 traceelements. Correlation analysis and factor analysis of 21 of thesetrace elements indicates that Ti and Zr are stable indicators of thecoarse sediment sources. Comparing the spatial distribution of someof the main trace elements to major sources and riverbed sedimentof the main reaches of the Yellow River suggests that the coarsesediments deposited in the Ningxia-Inner Mongolia reaches aremostly controlled by the local sediment sources. The results of R-factoranalysis further proved that desert sand, riverbank material,and the Ten Tributaries are the primary sources of the coarse sedimentin the Ningxia-Inner Mongolia reaches of the Yellow River.

Influence of different electrical boundary conditions on the elasticity solutions of piezoelectric plane beam

Zhang Lang,Li Xuewu,Wang Yuping,Wang Qiang,Shi Haibing 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12

Influence of different electrical boundary conditions (BCs) on the elasticity solutions of piezoelectric plane beam (PPB) is investigated using analytical technique. The first case is considering electrical displacement of the two longitudinal sides of PPB. The second case is electrical potential. Firstly, the unified equations to obtain the elasticity solutions of PPB corresponding to these two cases are given briefly. Secondly, two examples are given to verify the correctness of the theoretical formulations presented in this paper. Finally, the responses of PPB acted by the same mechanical loads but with different electrical BCs are compared.

Tunable magnetoresistance behavior in suspended graphitic multilayers through ion implantation

Diaz-Pinto, Carlos,Wang, Xuemei,Lee, Sungbae,Hadjiev, Viktor G.,De, Debtanu,Chu, Wei-Kan,Peng, Haibing American Physical Society 2011 Physical review. B, Condensed matter and materials Vol.83 No.23

Gene Expression of Heart and Adipocyte Fatty Acid-binding Protein in Chickens by FQ-RT-PCR

Tu, Yunjie,Su, Yijun,Wang, Kehua,Zhang, Xueyu,Tong, Haibing,Gao, Yushi Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.8

This study was to detect the expression of heart fatty acid-binding protein (H-FABP) and adipocyte fatty acid-binding protein (A-FABP) gene mRNA in different tissues of Rugao and Luyuan chickens at 56 d and 120 d by real-time fluorescence quantitative reverse transcription polymerase-chain reaction (FQ-RT-PCR). The primers were designed according to the sequences of HFABP, A-FABP and GAPDH genes in Gallus gallus, which were used as target genes and internal reference gene, respectively. The levels of H-FABP and A-FABP gene expression were detected by SYBR Green I FQ-RT-PCR. The relative H-FABP and A-FABP gene mRNA expression level was calculated with 2-$^{{\Delta}Ct}$. Melting curve analysis showed a single peak of three genes. Intramuscular fat (IMF) content in breast muscle and leg muscle of the two chicken breeds at 120 d was higher than at 56 d. IMF content in breast muscle and leg muscle at 56 d and 120 d in Luyuan was significantly higher than in Rugao, however, abdominal fat of Luyuan was significantly lower than that of Rugao. The relative H-FABP gene mRNA expression level in cardiac muscle was the highest in both chicken breeds. The relative H-FABP and A-FABP gene expression of different tissues in Luyuan was higher than in Rugao. H-FABP gene mRNA expression had a negative effect on IMF of leg and breast muscles, and was significantly negatively correlated with IMF content. The relative A-FABP gene mRNA level in abdominal fat was higher than in liver. The A-FABP gene mRNA was not expressed in leg, breast and cardiac muscles. A-FABP gene mRNA expression level was significantly positively correlated with abdominal fat and had a significant effect on abdominal fat but not IMF content.

Polymerized Ionic Liquid for the Regulation of Phase Structure of PLA/PCL Blends

Yiyang Zhou,Qiuyue Meng,Ping Wang,Haibing Wei,Pei Xu,Yunsheng Ding 한국고분자학회 2022 Macromolecular Research Vol.30 No.9

Polymerized ionic liquid containing block structure (PIL) has been used as regulator for the phase structure of poly(lactide) (PLA)/poly(ε-caprolactone) (PCL) blends. The phase structure, crystallization, rheology behavior and mechanical properties of PLA/PCL and PLA/PCL/PIL blends were systematically investigated. PIL could be located in PCL phase or at the PLA/PCL interface, enhancing the interaction between polymer components. The crystallization ability of PLA and PCL was simultaneously enhanced with the addition of PIL, since the plasticization effect of ionic moiety and PEO segments in PIL as well as the nucleation effect of PIL-formed ionic cluster. When PIL content was 0.5 wt%, the PLA/PCL/0.5PIL blend system exhibited much better mechanical properties than additivefree PLA/PCL blend. But as PIL contents increased, the significantly change in viscosity ratio between PLA and PCL would lead to obviously change in phase structure of PLA/PCL blend, thus the mechanical properties of the blends would be degraded.