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Journal of Modern Power Systems and Clean Energy 2019年第6期7卷 1365-1384页

作者： Luka V.STREZOSKI Nikola R.VOJNOVIC Vladimir C.STREZOSKI Predrag M.VIDOVIC Marija D.PRICA Kenneth A.LOPARO Case School of Engineering Case Western Reserve UniversityClevelandUSA Faculty of Technical Sciences University of Novi SadNovi SadSerbia

We aim to systematically review challenges imposed by emerging distributed energy resources(DERs)to model in two basic distribution management system(DMS)online applications—power flow and short-circuit analysis,as well as to offer a systematic review of potential *** the last decade,electronically coupled DERs became increasingly *** can employ a wide range of control strategies for power,current,or voltage control,in both normal and faulted ***,DERs cannot be modeled with the traditional PQ(load or generator bus)or PV(generator bus)bus types used for modeling synchronous and induction machines in online power flow ***,since fault currents of DERs are limited to predefined maximal values,electronically coupled DERs cannot be represented with traditional voltage source behind impedance models for online short-circuit calculation(SCC).However,most of the DMS software packages still use the traditional models to represent all DER types,including those that are electronically *** paper shows that there will be large calculation errors in such practice,which make the system model an inadequate representation of the *** will lead to serious errors in the management,control,and operation of distribution ***,potential solutions to the challenges are systematically ***,the calculation results on a distribution test system with all DER types are used to prove the claim.

关键词： Distributed energy resources(DERs) Distribution management system(DMS) Power flow modeling short-circuit modeling

Application of thyristor controlled phase shifting transformer excitation impedance switching control to suppress short-circuit fault current level

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Journal of Modern Power Systems and Clean Energy 2018年第4期6卷 821-832页

作者： Jun LIU Xudong HAO Xu WANG Yefu CHEN Wanliang FANG Shuanbao NIU Shaanxi Key Laboratory of Smart Grid State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical Engineering Xi'an Jiaotong University Northwest Subsection of State Grid Corporation of China

short-circuit fault current suppression is a very important issue in modern large-interconnected power networks. Conventional short-circuit current limiters, such as superconducting fault current limiters, have to increase additional equipment investments. Fast power electronics controlled flexible AC transmission system(FACTS)devices have opened a new way for suppressing the fault current levels, while maintaining their normal functionalities for steady-state and transient power system operation and control. Thyristor controlled phase shifting transformer(TCPST) is a beneficial FACTS device in modern power systems, which is capable of regulating regional powerflow. The mathematical model for TCPST under different operation modes is firstly investigated in this study. Intuitively, the phase shifting angle control can adjust the equivalent impedance of TCPST, but the effect has been demonstrated to be weak. Therefore, a novel transformer excitation impedance switching(EIS) control method, is proposed for fault current suppressing, according to the impedance characteristics of TCPST. Simulation results on IEEE 14-bus system have shown considerable current limiting characteristic of the EIS control under various fault types. Also, analysis of the timing requirement during fault interruption, overvoltage phenomenon, and ancillary mechanical support issues during EIS control is discussed,so as to implement the proposed EIS control properly for fast fault current suppression.

关键词： Excitation impedance switching(EIS) control Interruption time sequence Phase shifting angle(PSA) control short-circuit fault current suppression Thyristorcontrolled phase shifting transformer(TCPST)

Allocation of synchronous condensers for restoration of system short-circuit power

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Journal of Modern Power Systems and Clean Energy 2018年第1期6卷 17-26页

作者： Emanuel MARRAZI Guangya YANG Peter WEINREICH-JENSEN Center for Electric Power and Energy Department of Electrical Engineering Technical University of Denmark Siemens A/S

Modern power systems,employing an increasing number of converter-based renewable energy sources(RES)and decreasing the usage of conventional power plants,are leading to lower levels of short-circuit power and rotational inertia.A solution to this is the employment of synchronous condensers in the grid,in order to provide sufficient short-circuit *** results in the increase of the short-circuit ratio(SCR)at transmission system busbars serving as points of interconnection(POI)to renewable *** of the required capacity and grid-location of the synchronous condensers,is inherently a mixed integer nonlinear optimization problem,which could not be done on manual basis considering each type of machine and all *** study therefore proposes a method of optimal allocation of synchronous condensers in a hypothetic future scenario of a transmission system fed by renewable *** cost of synchronous condenser installations in the system is minimized and the SCRs at the POIs of central renewable power plants are *** method has potential for application on larger grids,aiding grid-integration of RES.

关键词： short-circuit power short-circuit ratio Synchronous condenser

Numerical study on short-circuit current of single layer organic solar cells with Schottkey contacts

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Science China(Technological Sciences) 2010年第4期53卷 1023-1027页

作者： MA ChaoZhu1,MENG WeiMin2,PENG YingQuan1,2,WANG RunSheng1,LI RongHua1,XIE HongWei1,WANG Ying1 & YE ZaoChen1 1 Institute of Microelectronics of School of Physical Science and Technology,Lanzhou University,Lanzhou 730000,China 2 Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou University,Lanzhou 730000,China Institute of Microelectronics of School of Physical Science and Technology Lanzhou University Lanzhou China Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou University Lanzhou China

The influence of the cathode work function,carriers mobilities and temperature on the short-circuit current of single layer organic solar cells with Schottkey contacts was numerically studied,and the quantitative dependences of the short-circuit current on these quantities were *** results provide the theoretical foundation for experimental study of single layer organic solar cells with Schottkey contacts.

关键词： cathode work function carrier mobility temperature short-circuit current

Practical Equivalent Method of Power Network Based on PSASP short-circuit Calculation Program

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Energy and Power Engineering 2017年第4期9卷 683-692页

作者： Haini Qu Mingnian Li Xiu Yang Pengfei Zhang State Grid Electric Power Research Institute SMEPC Shanghai China Shanghai University of Electric power School of Electrical Engineering Shanghai China

When using the ATP-EMTP software to simulate the electromagnetic transient of local line or nearby line for a large area power grid, it is necessary to divide the area grid into internal network and external network so as to make the external network simple for the restriction of the simulation calculation scale of software. Based on the existing equivalence method, in this paper we proposed a practical equivalent method using the short-circuit calculation program of PSASP. In this way, we completed the equivalence of northwest power grid operating at the large mode of summer 2016. By comparing the power flow and the characteristics of short-circuit in the system before and after the equivalence, this equivalent method is proved to be correct.

关键词： PSASP short-circuit Calculation Practical Equivalence

Research on Numerical Simulation of 3D Leakage Magnetic Field and short-circuit Impedance of Axial Dual-low-voltage Split-winding Transformer

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Energy and Power Engineering 2013年第4期5卷 1093-1096页

作者： Yan Li Longnv Li Yongteng Jing Fangxu Han Research Institute of Special Electrical Machines Shenyang University of Technology Shenyang China

It is difficult to accurately calculate the short-circuit impedance, due to the complexity of axial dual-low-voltage split-winding transformer winding structure. In this paper, firstly, the leakage magnetic field and short-circuit impedance model of axial dual-low-voltage split-winding transformer is established, and then the 2D and 3D leakage magnetic field are analyzed. Secondly, the short-circuit impedance and split parallel branch current distribution in different working conditions are calculated, which is based on field-circuit coupled method. At last, effectiveness and feasibility of the proposed model is verified by comparison between experiment, analysis and simulation. The results showed that the 3D analysis method is a better approach to calculate the short-circuit impedance, since its analytical value is more closer to the experimental value compared with the 2D analysis results, the finite element method calculation error is less than 2%, while the leakage flux method maximum error is 7.2%.

关键词： Split-winding Transformer short-circuit Impedance Field-circuit Coupled Current Distribution

Calculation of Eddy Current Loss and short-circuit Force in SSZ11-50000/110 Power Transformer

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Energy and Power Engineering 2013年第4期5卷 1105-1108页

作者： Yan Li Bo Zhang Longnv Li Tongxun Yang Ning Wang Power Transmission Technology Research Institution Shenyang University of Technology Shenyang TBEA Shenyang Transformer Group Co. Ltd. Shenyang

The ?method is used in this paper to calculate the leakage magnetic field of SSZ11-50000/110 Power transformer, and by which the structures’ influences to the main leakage flux are analyzed. Through the combination of the product and TEAM Problem 21B, the surface impedance method shows its great advantage in the calculation of eddy current loss.

关键词： Power Transformer Finite Element short-circuit Force Eddy Current Loss Surface Impedance Method

Field validation of generic wind park models using fault records

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Journal of Modern Power Systems and Clean Energy 2019年第4期7卷 826-836页

作者： Aboutaleb HADDADI Ilhan KOCAR Thomas KAUFFMANN Ulas KARAAGAC Evangelos FARANTATOS Jean MAHSEREDJIAN Polytechnique Montreal MontréalCanada The Hong Kong Polytechnic University Hong KongChina Electric Power Research Institute(EPRI) Palo AltoUSA

A challenge faced by protection and planning engineers is the development and validation of accurate wind turbine generator(WTG)models to study the impact of increasing wind integration on system *** is on the experimental validation of a generic electromagnetic transient-type(EMT-type)model of aggregated WTGs or wind parks suitable for transient *** phasor domain equivalent of the generic model,suitable for protection tools based on steady-state solvers,is also *** model has been validated using two sets of actual relay records for the fault response of two wind parks consisting of Type-III WTGs and connected to115 kV and 230 kV transmission *** objective is to show that the generic model can reproduce the actual fault response in simulations,and protection engineers can obtain accurate models of wind parks using fault records.A distinctive characteristic of a WTG is its substantially different negative sequence fault current contribution compared to a synchronous *** paper shows that the generic model provides enough options to reproduce the negative sequence behavior and hence is suitable for fault studies involving negative sequence-based protection.

关键词： Renewable generation Wind turbine generator Doubly-fed induction generator short-circuit analysis Electromagnetic transient-type model Phasor domain model

Regulating effect of Tong Xie-Yao Fang on colonic epithelial secretion via Cl- and HCO3- channel

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World Journal of Gastroenterology 2016年第48期22卷 10584-10591页

作者： Cheng Yang Ying Xiong Sheng-Sheng Zhang Fang-Mei An Jing Sun Qing-Lin Zhang Qiang Zhan Department of Gastroenterology Wuxi People’s HospitalNanjing Medical UniversityWuxi 214023Jiangsu ProvinceChina Community Health Service Center of Jinkui Street Wuxi 214023Jiangsu ProvinceChina Digestive Disease Diagnosis and Treatment Center Beijing Chinese Medicine HospitalCapital Medical UniversityBeijing 100010China

AIM To investigate the pharmacological effect of Tong XieYao Fang(TXYF) formula, a Chinese herbal formula, on Diarrhea-predominant irritable bowel syndrome(D-IBS) *** In a neonatal maternal separation plus restraint stress(NMS + RS) model of D-IBS, male Sprague Dawley rats were randomly divided into two groups(NMS + RS group and TXYF-formula group) with no handlings were used as controls(NH group). Starting from postnatalday 60, rats in TXYF-formula group were administered TXYF-formula(4.92 g/100 g bodyweight) orally twice a day for 14 consecutive days while NH group and NMS + RS group were given distilled water. Using short-circuit current technology, we observed 5-HT-induced changes of current across ion channels, such as cystic fibrosis transmembrane conductance regulator(CFTR) Clchannel, epithelial Na+ channel(ENaC), Ca2+-dependent Cl- channel(CACC), Na+-K+-2Cl- co-transporter(NKCC), and Na+-HCO-3 co-transporter(NBC), in the colonic epithelium of three groups after exposure to drugs and specific blockers with a Power Lab System(AD Instruments International).RESULTS Under basal conditions, the changes of short-circuit current(?Isc, μA/cm2) induced by 5-HT were similar in NH group and TXYF-formula group, and both higher than NMS + RS group(70.86 μA/cm2 ± 12.32 μA/cm2, 67.67 μA/cm2 ± 11.68 μA/cm2 vs 38.8 μA/cm2 ± 7.25 μA/cm2, P < 0.01, respectively). When CACC was blocked by 4,4′-diisothiocyanato-stilbene-2,2′-disulfonic acid, 5-HT-induced ?Isc was smaller in NMS + RS group than in NH group and TXYF-formula group, respectively(48.41 μA/cm2 ± 13.15 μA/cm2 vs 74.62 μA/cm2 ± 10.73 μA/cm2, 69.22 μA/cm2 ± 11.7 μA/cm2, P < 0.05, respectively). The similar result could be obtained when ENaC was blocked by Amiloride(44.69 μA/cm2 ± 12.58 μA/cm2 vs 62.05 μA/cm2 ± 11.26 μA/cm2, 62.11 μA/cm2 ± 12.01 μA/cm2, P < 0.05, respectively). However, when CFTR Cl- channel was blocked by 1,1-dimethyl piperidinium chloride(DPC), 5-HT-induced ?Isc did not significantly differ in t

关键词： Ion channel Diarrhea-predominant irritable bowel syndrome Colonic mucosa short-circuit current TongX ie-YaoF ang formula

Overvoltage Condition Assessment of a Microgrid Due to Faults Occurring in the Islanded Mode of Operation

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Energy and Power Engineering 2015年第11期7卷 525-534页

作者： Ricardo Leon Vasquez-Arnez Dorel Soares Ramos Tesoro Elena Del Carpio Huayllas Foundation for the Technological Development of the Engineering Sciences (FDTE) S&atilde o Paulo Brazil Department of Electric Power and Automation Engineering University of S&atilde o Paulo S&atilde o Paulo Brazil

This paper presents the results of the simulations and their respective analyses corresponding to the power frequency overvoltages resulting from various fault types occurring inside a microgrid. During the islanded mode of operation, the analysed microgrid can be simultaneously fed by a diesel generator, a 1 MW wind power turbine, a small solar system and a 1 MW hydroelectric scheme. The operating voltage of the microgrid is 2.4 kV. During a fault in the system, the overvoltages normally occur in two remarkable instants. The first one occurs at the beginning of the fault itself. The second one occurs at the instant when the fault is cleared. The major concern here is the overvoltage during the fault period. Due to the travelling wave effect along cables and overhead lines composing the microgrid system, these overvoltages can be amplified, thus jeopardizing the insulation level of the microgrid transmission system and related equipment. Much of the work available now is dedicated to overvoltages present in high-voltage systems leaving a gap for the study and behaviour on low voltage microgrid systems. The overvoltage stress is characterized by the maximum low-frequency, short-duration (crest value) of the overvoltage. Both cables and overhead lines that constitute the microgrid transmission system are characterized by their R-L-C parameters. The simulations of the microgrid system are conducted using the ATP program. According to the international ANSI and IEEE standards, the minimum BIL (Basic Impulse Insulation Level) and BSL (Basic Impulse Switching Level) for the 2.4 kV voltage level are 20 kV and 10 kV, respectively;thus, care should be taken so that the healthy phases upon which commonly appear such overvoltages are not exceeded in their insulation level.

关键词： Islanded Mode Microgrids Overvoltage short-circuit