A Calculation Method for the Nonlinear Crowbar Circuit of DFIG Wind Generation based on Frequency Domain Analysis

Luo, Hao,Lin, Mingyao,Cao, Yang,Guo, Wei,Hao, Li,Wang, Peng The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

The ride-through control of a doubly-fed induction generator (DFIG) for the voltage sags on wind farms utilizing crowbar circuits by which the rotor side converter (RSC) is disabled has being reported in many literatures. An analysis and calculation of the transient current when the RSC is switched off are of significance for carrying out the low voltage ride through (LVRT) of a DFIG. The mathematical derivation is highlighted in this paper. The zero-state and zero-input responses of the transient current in the frequency domain through a Laplace transformation are investigated, and the transient components in the time domain are achieved. With the characteristics worked out from the linear resolving without modeling simplification, the selection of the resistance in the linear crowbar circuit and the value conversion from a linear circuit to a nonlinear one is proposed to setup the attenuation rate. In terms of grid code requirements, the theoretical analysis for the time constant of the transient components attenuation insures the controllability when the excitation of the RSC is resumed and it guarantees the reserved time for the response of the reactive power compensation. Simulations are executed in MATLAB/SIMPOWER and experiments are carried out to validate the theoretical analysis. They indicate that the calculation method is effective for selection of the resistance in a crowbar circuit for LVRT operations.

A Calculation Method for the Nonlinear Crowbar Circuit of DFIG Wind Generation based on Frequency Domain Analysis

Hao Luo,Mingyao Lin,Yang Cao,Wei Guo,Li Hao,Peng Wang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

The ride-through control of a doubly-fed induction generator (DFIG) for the voltage sags on wind farms utilizing crowbar circuits by which the rotor side converter (RSC) is disabled has being reported in many literatures. An analysis and calculation of the transient current when the RSC is switched off are of significance for carrying out the low voltage ride through (LVRT) of a DFIG. The mathematical derivation is highlighted in this paper. The zero-state and zero-input responses of the transient current in the frequency domain through a Laplace transformation are investigated, and the transient components in the time domain are achieved. With the characteristics worked out from the linear resolving without modeling simplification, the selection of the resistance in the linear crowbar circuit and the value conversion from a linear circuit to a nonlinear one is proposed to setup the attenuation rate. In terms of grid code requirements, the theoretical analysis for the time constant of the transient components attenuation insures the controllability when the excitation of the RSC is resumed and it guarantees the reserved time for the response of the reactive power compensation. Simulations are executed in MATLAB/SIMPOWER and experiments are carried out to validate the theoretical analysis. They indicate that the calculation method is effective for selection of the resistance in a crowbar circuit for LVRT operations.

Combining different forms of statistical energy analysis to predict vibrations in a steel box girder comprising periodic stiffening ribs

Hao Luo,Zhiyang Cao,Xun Zhang,Cong Li,Derui Kong 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.1

Due to the complexity of the structure and the limits of classical SEA, a combined SEA approach is employed, with angle-dependent SEA in the low- and mid-frequency ranges and advanced SEA (ASEA) considering indirect coupling in the high-frequency range. As an important component of the steel box girder, the dynamic response of an L-junction periodic ribbed plate is calculated first by the combined SEA and validated by the impact hammer test and finite element method (FEM). Results show that the indirect coupling due to the periodicity of stiffened plate is significant at high frequencies and may cause the error to reach 38.4 dB. Hence, the incident bending wave angle cannot be ignored in comparison to classical SEA. The combined SEA is then extended to investigate the vibration properties of the steel box girder. The bending wave transmission study is likewise carried out to gain further physical insight into indirect coupling. By comparison with FEM and classical SEA, this approach yields good accuracy for calculating the dynamic responses of the steel box girder made of periodic ribbed plates in a wide frequency range. Furthermore, the influences of some important parameters are discussed, and suggestions for vibration and noise control are provided.

Experimental Investigation of R(ω), T(ω) and L(ω) for Multi-Layer SRRs and Wires Metamaterials

Hao Luo,Xian Wang,Zhangqi Liao,Tao Wang,Rongzhou Gong 한국전자파학회JEES 2010 Journal of Electromagnetic Engineering and Science Vol.10 No.3

Reflection(R(ω)), transmission(T(ω)) and loss(L(ω)) characteristics of multi-layer metamaterials are investigated experimentally in free space with the incident EM waves perpendicular to the substrate plane. The sample is made of split-ring resonators(SRRs) and wires which are the typical model of metamaterials. The R(ω) and T(ω) of multi-layer metamaterials have been calculated from the measured S-parameters. In this paper, we got the impedancematched result according to the curves of R(ω), meanwhile the T(ω) decreased with increasing number of layers. At last, we attained the result that the L(ω) gets to nearly 98% around 8 ㎓, with R(ω)=T(ω)=0. The design presented in this paper achieves experimented loss near unity.

G-protein Coupled Estrogen Receptor 1 Expression in Primary Breast Cancers and Its Correlation with Clinicopathological Variables

Hao-jun Luo,Ping Luo,Guang-lun Yang,Qiong-le Peng,Man-ran Liu,Gang Tu 한국유방암학회 2011 Journal of breast cancer Vol.14 No.3

Purpose: G-protein coupled estrogen receptor 1 (GPER) probably play important roles in the progression of breast cancer including endocrine therapeutic resistance. We evaluated GPER in primary breast cancers. Methods: Immunohistochemistry was used to detect GPER in paraffin-embedded tissues of primary breast cancers from 423 patients and GPER expression was correlated with clinicopathological factors. Results: GPER was expressed in 63.8% of specimens, coexpressed with estrogen receptor alpha (ERα) in 36.6% of tumors and was positive in 62.5% of the ERα-negative tumors. The expression of GPER had no relationship with the status of ERα, progesterone receptor and HER2. Although the expression of GPER was significantly inversely related with nodal status (p=0.045), no correlation between GPER expression and other clinicopathological variables (age, menstruation status, tumor size, stage, histologic grade, Nottingham Prognostic Index or pathological type) was found. Conclusion: GPER and ERα exhibited independent expression pattern of distribution in primary breast cancers. A long-term follow-up and a more definite molecular phenotype for ER are necessary in confirming studies.

A Hybrid Self-Powered System Based on Wind Energy Harvesting for Low-Power Sensors on Canyon Bridges

Hao Cao,Xiaoping Wu,Hao Wu,Yajia Pan,Dabing Luo,Ali Azam,Zutao Zhang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.1

Canyon cross wind has great potential to be transformed into electricity to power for low-power sensors of the health monitoring devices in bridge field. In this paper, a hybrid wind energy harvesting system (WEHS), integrating piezoelectric and electromagnetic mechanisms, is proposed to supply power for low-power sensors on canyon bridges. Firstly, the S-rotor embedded with a one-way bearing converts wind energy into rotational mechanical energy. Then, the piezoelectric cantilever beam and coils simultaneously convert mechanical energy into electricity under the excitation of the rotational magnet array. For the piezoelectric transducer, the symmetrical poles arrangement of tip magnet reduces the starting wind speed and resistance torque during energy harvesting. In addition, the relationship between different number of excitation magnets and the output of the piezoelectric transducer is explored. Finally, the output electricity is stored in the capacitors to supply power for low power sensors. The experimental results showed that the symmetrical poles arrangement of tip magnet could effectively reduce the starting resistance torque and improve the output power at low wind speeds. Given a wind speed of 6.5 m/s, the maximum output power of the WEHS can reach 19.24 mW with corresponding electrical energy of 75.714 mJ in one sweep period (6 s). The field test results demonstrated that the WEHS could effectively charge for the capacitors and power for a hundred LEDs. Furthermore, the mechanical durability and stability of the WEHS are verified by introducing a self-powered low power sensor system.

Systematic Evaluation and Meta-Analysis of the Effect of Gynostemma pentaphyllum on Clinical Indexes of Hyperlipidemia

Hao-Tian Luo,Man-Yu Xiao,Wen-Jing Pei,Kang-Le Bi,Peng Xie,Yu-Long Gu,Xiang-Lan Piao 한국생약학회 2023 Natural Product Sciences Vol.29 No.4

Single Nucleotide Polymorphisms of DNA Base-excision Repair Genes (APE1, OGG1 and XRCC1) Associated with Breast Cancer Risk in a Chinese Population

Luo, Hao,Li, Zheng,Qing, Yi,Zhang, Shi-Heng,Peng, Yu,Li, Qing,Wang, Dong Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.3

Altered DNA repair capacity can result in increased susceptibility to cancer. The base excision repair (BER) pathway effectively removes DNA damage caused by ionizing radiation and reactive oxidative species (ROS). In the current study, we analyzed the possible relation of polymorphisms in BER genes, including 8-oxoguanine DNA glycosylase (OGG1), apurinic/apyrimidinic endonuclease 1 (APE1), and X-ray repair cross-complementing group 1 protein (XRCC1), with breast cancer risk in Chinese Han women. This case-control study examined 194 patients with breast cancer and 245 cancer-free hospitalized control subjects. Single nucleotide polymorphisms (SNPs) of OGG1 (Ser326Cys), XRCC1 (Arg399Gln), and APE1 (Asp148Glu and -141T/G) were genotyped and analyzed for their association with breast cancer risk using multivariate logistic regression models. We found that XRCC1 Arg399Gln was significantly associated with an increased risk of breast cancer. Similarly, the XRCC1 Gln allele was significantly associated with an elevated risk in postmenopausal women and women with a high BMI (${\geq}24kg/m^2$). The OGG1 Cys allele provided a significant protective effect against developing cancer in women with a low BMI (< $24kg/m^2$). When analyzing the combined effects of these alleles on the risk of breast cancer, we found that individuals with ${\geq}2$ adverse genotypes (XRCC1 399Gln, APE1 148Asp, and OGG1 326Ser) were at a 2.18-fold increased risk of breast cancer (P = 0.027). In conclusion, our data indicate that Chinese women with the 399Gln allele of XRCC1 have an increased risk of breast cancer, and the combined effects of polymorphisms of BER genes may contribute to tumorigenesis.

A Framework for NFC-based Context-aware Applications

Jianchao Luo,Hao Feng 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.1

Near Field Communication (NFC) is an emerging technology that facilitates data exchange between two devices wirelessly within close proximity. As integrated into more and more mobile phones, the NFC technology enables the users to interact with the intelligent environments in a natural and intuitive manner and thus changes the way people perform many routine daily activities like mobile payment, business card exchange, etc. Although NFC has bridged the physical and virtual worlds, context-aware technology is needed to sense and use NFC context actively in order to provide users with more intelligent and personalized services. In this paper, we propose an ontology-based framework for developing NFC-based context-aware applications, which can perceive user context and offer appropriate context-aware services to the user by combining the NFC technology with context-aware technology. With the proposed framework, application providers are enabled to develop NFC-based context-aware applications in a simple way. Meanwhile, the framework provides security service for protecting data integrity of the NFC context. This paper presents the framework's design, implementation and a real use case scenario that shows the validation of the approach.

Green production of PVC from laboratory to industrialization: State-of-the-art review of heterogeneous non-mercury catalysts for acetylene hydrochlorination

Hao Xu,GUOHUA LUO 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-

This review gives a summary on heterogeneous non-mercury catalysts for acetylene hydrochlorination process. First, various catalysts are classified and their performances are compared. Next, studies on catalytic performance by theoretical characterizations and molecule level simulations are introduced. Then, efforts for industrial scaling up and corresponding long-term plant trial results are presented to show enormous potential of state-of-the-art catalysts. Finally, the crucial engineering issues for future industrialization process including kinetic study, reactor design & simulation and material recycling process are proposed. Based on promising achievements, we believe that extensive industrial application of non-mercury catalysts for acetylene hydrochlorination will soon become reality.