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Effects of Wind Generation Uncertainty and Volatility on Power System Small Signal Stability
Shi, Li-Bao,Kang, Li,Yao, Liang-Zhong,Qin, Shi-Yao,Wang, Rui-Ming,Zhang, Jin-Ping The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.1
This paper discusses the impacts of large scale grid-connected wind farm equipped with permanent magnet synchronous generator (PMSG) on power system small signal stability (SSS) incorporating wind generation uncertainty and volatility. Firstly, a practical simplified PMSG model with rotor-flux-oriented control strategy applied is derived. In modeling PMSG generator side converter, the generator-voltage-oriented control strategy is utilized to implement the decoupled control of active and reactive power output. In modeling PMSG grid side converter, the grid-voltage-oriented control strategy is applied to realize the control of DC link voltage and the reactive power regulation. Based on the Weibull distribution of wind speed, the Monte Carlo simulation technique based is carried out on the IEEE 16-generator-68-bus test system as benchmark to study the impacts of wind generation uncertainty and volatility on small signal stability. Finally, some preliminary conclusions and comments are given.
Effects of Wind Generation Uncertainty and Volatility on Power System Small Signal Stability
Li-Bao Shi,Li Kang,Liang-Zhong Yao,Shi-Yao Qin,Rui-Ming Wang,Jin-Ping Zhang 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.1
This paper discusses the impacts of large scale grid-connected wind farm equipped with permanent magnet synchronous generator (PMSG) on power system small signal stability (SSS) incorporating wind generation uncertainty and volatility. Firstly, a practical simplified PMSG model with rotor-flux-oriented control strategy applied is derived. In modeling PMSG generator side converter, the generator-voltage-oriented control strategy is utilized to implement the decoupled control of active and reactive power output. In modeling PMSG grid side converter, the grid-voltageoriented control strategy is applied to realize the control of DC link voltage and the reactive power regulation. Based on the Weibull distribution of wind speed, the Monte Carlo simulation technique based is carried out on the IEEE 16-generator-68-bus test system as benchmark to study the impacts of wind generation uncertainty and volatility on small signal stability. Finally, some preliminary conclusions and comments are given.
Behavior of improved through-diaphragm connection to square tubular column under tensile loading
Qin, Ying,Zhang, Jing-Chen,Shi, Peng,Chen, Yi-Fu,Xu, Yao-Han,Shi, Zuo-Zheng 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.4
Square tubular columns are commonly used in moment resisting frames, while through-diaphragm connection is the most typical configuration detail to connect the H-shaped beam to the column. However, brittle fracture normally occurs at the complete joint penetration weld between the beam flange and the through-diaphragm due to the stress concentration caused by the geometrical discontinuity. Accordingly, three improved types of through-diaphragm are presented in this paper to provide smooth force flow path comparing to that of conventional connections. Tensile tests were conducted on four specimens and the results were analyzed in terms of failure modes, load-displacement response, yield and ultimate capacity, and initial stiffness. Furthermore, strain distributions on the through-diaphragm, the beam flange plate, and the column face were comprehensively evaluated and discussed. It was found that all the proposed three types of improved through-diaphragm connections were able to reduce the stress concentration in the welds between the beam flange and the through-diaphragm. Furthermore, the stress distribution in connection with longer tapered through-diaphragm was more uniform.
Further study on improvement on strain concentration in through-diaphragm connection
Ying Qin,Jing-Chen Zhang,Peng Shi,Yi-Fu Chen,Yao-Han Xu,Zuo-Zheng Shi 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.2
Hollow structural section (HSS) columns have been increasingly popular due to their structural and architectural merits. However, practical difficulty lies in developing proper connections. The through-diaphragm connections are considered as suitable connection type that is widely adopted in Asian countries. However, the stress concentration occurs at the location connecting through-diaphragm and steel beam. Furthermore, the actual load path from the beam flange is not uniformly transferred to the HSS column as conventionally assumed. In this paper, tensile tests were further conducted on three additional specimens with beam flange plate to evaluate the load versus displacement response. The load-displacement curves, yield and ultimate capacity, ductility ratio were obtained. Furthermore, the strain development at different loading levels was discussed comprehensively. It is shown that the studied connection configuration significantly reduces the stress concentration. Meanwhile, simplified trilinear load-displacement analytical model for specimen under tensile load was presented. Good agreement was found between the theoretical and experimental results.
Behavior of improved through-diaphragm connection to square tubular column under tensile loading
Ying Qin,Jing-Chen Zhang,Peng Shi,Yi-Fu Chen,Yao-Han Xu,Zuo-Zheng Shi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.4
Square tubular columns are commonly used in moment resisting frames, while through-diaphragm connection is the most typical configuration detail to connect the H-shaped beam to the column. However, brittle fracture normally occurs at the complete joint penetration weld between the beam flange and the through-diaphragm due to the stress concentration caused by the geometrical discontinuity. Accordingly, three improved types of through-diaphragm are presented in this paper to provide smooth force flow path comparing to that of conventional connections. Tensile tests were conducted on four specimens and the results were analyzed in terms of failure modes, load-displacement response, yield and ultimate capacity, and initial stiffness. Furthermore, strain distributions on the through-diaphragm, the beam flange plate, and the column face were comprehensively evaluated and discussed. It was found that all the proposed three types of improved through-diaphragm connections were able to reduce the stress concentration in the welds between the beam flange and the through-diaphragm. Furthermore, the stress distribution in connection with longer tapered through-diaphragm was more uniform.
Junqiang Song,Qin Yao,Ting Wu,Xun Shi,Lidong Chen 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.6
In the present study, p-type BixSb2-xTe3 thermoelectric thin films with various chemical compositions were fabricated by a magnetron co-sputtering process. The influence of Bi content (x) on the microstructures and thermoelectric properties of BixSb2-xTe3 films was investigated. It was found that the grain size of nanocrystalline BixSb2-xTe3 films decreased when increasing the Bi content from x = 0 to x = 0.57, which resulted in a concurrent decrease in the carrier mobility. Similarly, carrier concentration decreased with increasing Bi content,which caused an increase in the Seebeck coefficient. The largest room-temperature power factor reached 31.3 μWK−2cm−1 for the film with x = 0.45.
An Analytical Solution for Voltage Stability Studies Incorporating Wind Power
Lin, Yu-Zhang,Shi, Li-Bao,Yao, Liang-Zhong,Ni, Yi-Xin,Qin, Shi-Yao,Wang, Rui-Ming,Zhang, Jin-Ping The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3
Voltage stability is one of the most critical security issues which has not yet been well resolved to date. In this paper, an analytical method called PQ plane analysis with consideration of the reactive power capability of wind turbine generator and the wake effect of wind farm is proposed for voltage stability study. Two voltage stability indices based on the proposed PQ plane analysis method incorporating the uncertainties of load-increasing direction and wind generation are designed and implemented. Cases studies are conducted to investigate the impacts of wind power incorporation with different control modes. Simulation results demonstrate that the constant voltage control based on reactive power capability significantly enhances voltage stability in comparison of the conventional constant power factor control. Some meaningful conclusions are obtained.
Daoyou Guo,Xinyuan Qin,Ming Lv,Haoze Shi,Yuanli Su,Guosheng Yao,Shunli Wang,Chaorong Li,Peigang Li,Weihua Tang 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.6
Highly (201) oriented Zn-doped β-Ga2O3 thin films with differentdopant concentrations were grown on (0001) sapphire substrates byradio frequency magnetron sputtering. With the increase of Zn dopantconcentration, the crystal lattice expands, the energy band gap shrinks,and the oxygen vacancy concentration decreases. Both the metalsemiconductor metal (MSM) structure photodetectors based on thepure and Zn-doped β-Ga2O3 thin films exhibit solar blind UVphotoelectric property. Compared to the pure β-Ga2O3 photodetector,the Zn-doped one exhibits a lower dark current, a higher photo/darkcurrent ratio, a faster photoresponse speed, which can be attributed tothe decreases of oxygen vacancy concentration.
An Analytical Solution for Voltage Stability Studies Incorporating Wind Power
Yu-Zhang Lin,Li-Bao Shi,Liang-Zhong Yao,Yi-Xin Ni,Shi-Yao Qin,Rui-Ming Wang,Jin-Ping Zhang 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.3
Voltage stability is one of the most critical security issues which has not yet been well resolved to date. In this paper, an analytical method called PQ plane analysis with consideration of the reactive power capability of wind turbine generator and the wake effect of wind farm is proposed for voltage stability study. Two voltage stability indices based on the proposed PQ plane analysis method incorporating the uncertainties of load-increasing direction and wind generation are designed and implemented. Cases studies are conducted to investigate the impacts of wind power incorporation with different control modes. Simulation results demonstrate that the constant voltage control based on reactive power capability significantly enhances voltage stability in comparison of the conventional constant power factor control. Some meaningful conclusions are obtained.