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Single-phase-to-ground fault protection based on zero-sequence current ratio coefficient for low-resistance grounding distribution network 被引量:4
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作者 Jianrui Li Yongli Li +1 位作者 Yonghuan Wang Jinzhao Song 《Global Energy Interconnection》 EI CAS CSCD 2021年第6期564-575,共12页
Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to thei... Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to their high settings of the action value when a high-impedance grounding fault occurs.In this study,the relationship between the zero-sequence currents of each feeder and the neutral branch was analyzed.Then,a grounding protection method was proposed on the basis of the zero-sequence current ratio coefficient.It is defined as the ratio of the zero-sequence current of the feeder to that of the neutral branch.Nonetheless,both zero-sequence voltage and zero-sequence current are affected by the transition resistance,The influence of transition resistance can be eliminated by calculating this coefficient.Therefore,a method based on the zero-sequence current ratio coefficient was proposed considering the significant difference between the faulty feeder and healthy feeder.Furthermore,unbalanced current can be prevented by setting the starting current.PSCAD simulation results reveal that the proposed method shows high reliability and sensitivity when a high-resistance grounding fault occurs. 展开更多
关键词 low-resistance grounding system High-impedance grounding fault grounding protection Zero-sequence current ratio coefficient
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Seismic Reliability Assessment of Inelastic SDOF Systems Subjected to Near-Fault Ground Motions Considering Pulse Occurrence 被引量:2
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作者 Jilei Zhou Chuansong Sun +1 位作者 Xiangjun Dai Guohai Chen 《Structural Durability & Health Monitoring》 EI 2019年第4期361-378,共18页
The ground motions in the orientation corresponding to the strongest pulse energy impose more serious demand on structures than that of ordinary ground motions.Moreover,not all near-fault ground motion records present... The ground motions in the orientation corresponding to the strongest pulse energy impose more serious demand on structures than that of ordinary ground motions.Moreover,not all near-fault ground motion records present distinct pulses in the velocity time histories.In this paper,the parameterized stochastic model of near-fault ground motion with the strongest energy and pulse occurrence probability is suggested,and the Monte Carlo simulation(MSC)and subset simulation are utilized to calculate the first excursion probability of inelastic single-degree-of-freedom(SDOF)systems subjected to these types of near-fault ground motion models,respectively.Firstly,the influences of variation of stochastic pulse model parameters on structural dynamic reliability with different fundamental periods are explored.It is demonstrated that the variation of pulse period,peak ground velocity and pulse waveform number have significant effects on structural reliability and should not be ignored in reliability analysis.Then,subset simulation is verified to be unbiased and more efficient for computing small reliable probabilities of structures compared to MCS.Finally,the reliable probabilities of the SDOF systems with different fundamental periods subjected to impulsive,non-pulse ground motions and the ground motions with pulse occurrence probability are performed,separately.It is indicated that the ground motion model with the pulse occurrence probability can give a rational estimate on structural reliability.The impulsive and ordinary ground motion models may overestimate and underestimate the reliability of structures with fundamental period much less than the mean pulse period of earthquake ground motions. 展开更多
关键词 Near-fault ground motion strongest pulse energy pulse occurrence probability seismic reliability inelastic SDOF systems
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Ground States for a Class of Nonlinear Schrodinger-Poisson Systems with Positive Potential
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作者 Guoqing Zhang Xue Chen 《Applied Mathematics》 2015年第1期28-36,共9页
Based on Nehari manifold, Schwarz symmetric methods and critical point theory, we prove the existence of positive radial ground states for a class of Schrodinger-Poisson systems in , which doesn’t require any symmetr... Based on Nehari manifold, Schwarz symmetric methods and critical point theory, we prove the existence of positive radial ground states for a class of Schrodinger-Poisson systems in , which doesn’t require any symmetry assumptions on all potentials. In particular, the positive potential is interesting in physical applications. 展开更多
关键词 ground STATES Schrodinger-Poisson systems
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Triple One Wire System without Grounding
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作者 Michael Bank Vladimir Tsingaouz 《Engineering(科研)》 2023年第12期867-870,共4页
Today the entire globe is shrouded in an inefficient three-phase system. There is however an efficient single-wire system. To use the single wire method, three phase systems can be converted to triple one wire systems.
关键词 Three-Phase One-Wire system ZEROING groundING Nullifier
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The Calculation of Ground State Energies of Double-Electron Systems in an Uniform Magnetic Field below 10~9 G
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作者 Wu Liangkai Liu Lianjun Zhang Zhehua 《Wuhan University Journal of Natural Sciences》 CAS 1999年第1期51-55,共5页
Energies for the ground states of double electron systems in a uniform magnetic field B≤ 10 9 G are calculated by using the modified Slater basis and configuration interaction method, and the result for energy i... Energies for the ground states of double electron systems in a uniform magnetic field B≤ 10 9 G are calculated by using the modified Slater basis and configuration interaction method, and the result for energy in zero magnetic field is comparable with those obtained by different methods. 展开更多
关键词 double electron system MCI method magnetic field ground state energy
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Ground State Solutions for Schrdinger-Poisson Systems
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作者 XU Na 《Chinese Quarterly Journal of Mathematics》 2016年第1期9-18,共10页
This paper deals with a class of Schr¨odinger-Poisson systems. Under some conditions, we prove that there exists a ground state solution of the system. The proof is based on the compactness lemma for the system. ... This paper deals with a class of Schr¨odinger-Poisson systems. Under some conditions, we prove that there exists a ground state solution of the system. The proof is based on the compactness lemma for the system. Our results here improve some existing results in the literature. 展开更多
关键词 Schrdinger-Poisson system ground state solution COMPACTNESS
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A Novel Method for Vibration Mitigation of Complex Mechanical Systems 被引量:2
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作者 Cheng Hu 《Sound & Vibration》 2019年第5期199-206,共8页
Taking the complex mechanical systems as the research project,a theoretical multi-degree-of-freedom(MDOF)model was established.Based on the vibration characteristics analysis of this system,a novel method of vibration... Taking the complex mechanical systems as the research project,a theoretical multi-degree-of-freedom(MDOF)model was established.Based on the vibration characteristics analysis of this system,a novel method of vibration mitigation was proposed,which can be applied to most of the complex mechanical systems.Through this method,limited grounding stiffness was made use of and added to certain degree of freedom(DOF)discretely.Thus,the root-meansquare(RMS)of the systems amplitude can be reduced to ideal level.The MATLAB code based on this method was attached,which was tested on the theoretical model.Consider that complex mechanical systems are nonlinear and uncertain,theoretically the optimal solution of vibration mitigation is inaccessible.However,this method can always provide a relatively effective solution. 展开更多
关键词 ibration mitigation complex mechanical systems grounding stiffness MDOF MATLAB
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The HY-1 satellite and ground system in China 被引量:6
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作者 Liu Jianqiang , Jiang Xingwei, Lin Mingsen National Satellite Ocean Application Service of State Oceanic Administration, Beijing 100081, China, 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2003年第2期301-308,共8页
INTRODUCTIONWith the coming of the 21st century, we are faced the problems of the environment, re-sources and population. The ocean is regarded as supplier of resources such as food, minerals,energy and space, and pla... INTRODUCTIONWith the coming of the 21st century, we are faced the problems of the environment, re-sources and population. The ocean is regarded as supplier of resources such as food, minerals,energy and space, and plays an important role in sustainable economic development. At thesame time the ocean has a very important effect on the worldwide environmental changes. 展开更多
关键词 HY-1 satellite ground system China
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Investigation and Reduction on Conducted Electromagnetic Interference Noise Mechanism for Complex Power Electronics Systems 被引量:4
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作者 YAN Wei ZHAO Yang +4 位作者 WANG Ertrong ZHANG Yuhuan QIU Xiaohui SUN Hongyan CHEN Xueli 《中国电机工程学报》 EI CSCD 北大核心 2012年第30期I0022-I0022,24,共1页
针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导... 针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导噪声模型。同时,还设计了一种串扰扼流圈以有效抑制因串扰引起的传导EMI噪声。实验结果表明,采用文中方法,某型商用车载导航和刷卡器能够通过GB 9254标准测试,噪声抑制效果分别可达44.8和29.28 dB V,从而验证了方法的有效性。 展开更多
关键词 传导电磁干扰 电力电子系统 噪声机理 共模扼流圈 噪声分离 和差模 EMI 电容
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Quantification by allometric equations of carbon sequestered by Tectona grandis in different agroforestry systems 被引量:2
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作者 Avinash Jain S.A.Ansari 《Journal of Forestry Research》 SCIE CAS CSCD 2013年第4期699-702,共4页
Non destructive methods for quantification of carbon seques- tration in tropical trees are inadequately developed. We described a stan- dardized method for estimating carbon stock in teak (Tectona grandis Linn. F.).... Non destructive methods for quantification of carbon seques- tration in tropical trees are inadequately developed. We described a stan- dardized method for estimating carbon stock in teak (Tectona grandis Linn. F.). We developed linear allometric equations using girth at breast height (GBH), height and age to quantify above ground biomass (AGB). We used AGB to estimate carbon stock for teak trees of different age groups (1.5, 3.5, 7.5, 13.5, 18.5 and 23.5 years). The regression equation with GBH, y = 3.174x - 21.27, r2=0.898 (p 〈0.01), was found precise and convenient due to the difficulty in determination of height and age in dense natural forests of teak. The equation was evaluated in teak agroforestry systems that included Triticum aestivum (wheat), Cicer arietinum (gram), Withania somnifera (ashwagandha), 展开更多
关键词 Tectona grandis agroforestry system allometric equation carbon sequestration above ground biomass
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A GROUND STATE SOLUTION TO THE CHERN-SIMONS-SCHRODINGER SYSTEM
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作者 Jin DENG Benniao LI 《Acta Mathematica Scientia》 SCIE CSCD 2022年第5期1743-1764,共22页
In this paper,we consider the Chern-Simons-Schrodinger system{−Δu+[e^(2)|A|^(2)+(V(x)+2eA_(0))+2(1+κq/2)N]u+q|u|^(p−2)u=0,−ΔN+κ^(2)q^(2)N+q(1+κq2)u^(2)=0,κ(∂_(1)A_(2)−∂_(2)A_(1))=−eu^(2),∂_(1)A_(1)+∂_(2)A_(2)=0,... In this paper,we consider the Chern-Simons-Schrodinger system{−Δu+[e^(2)|A|^(2)+(V(x)+2eA_(0))+2(1+κq/2)N]u+q|u|^(p−2)u=0,−ΔN+κ^(2)q^(2)N+q(1+κq2)u^(2)=0,κ(∂_(1)A_(2)−∂_(2)A_(1))=−eu^(2),∂_(1)A_(1)+∂_(2)A_(2)=0,κ∂_(1)A_(0)=e^(2)A_(2)u^(2),κ∂_(2)A_(0)=−e^(2)A_(1)u^(2),where u∈H^(1)(R^(2)),p∈(2,4),Aα:R^(2)→R are the components of the gauge potential(α=0,1,2),N:R^(2)→R is a neutral scalar field,V(x)is a potential function,the parametersκ,q>0 represent the Chern-Simons coupling constant and the Maxwell coupling constant,respectively,and e>0 is the coupling constant.In this paper,the truncation function is used to deal with a neutral scalar field and a gauge field in the Chern-Simons-Schrödinger problem.The ground state solution of the problem(P)is obtained by using the variational method. 展开更多
关键词 Chern-Simons-Schrodinger systems ground state solution variational method
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Probabilistic analysis for the response of nonlinear base isolation system under the ground excitation induced by high dam flood discharge 被引量:2
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作者 Liang Chao Zhang Jinliang +2 位作者 Lian Jijian Liu Fang Li Xinyao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第4期841-857,共17页
According to theoretical analysis, a general characteristic of the ground vibration induced by high dam flood discharge is that the dominant frequency ranges over several narrow frequency bands, which is verified by o... According to theoretical analysis, a general characteristic of the ground vibration induced by high dam flood discharge is that the dominant frequency ranges over several narrow frequency bands, which is verified by observations from the Xiangjiaba Hydropower Station. Nonlinear base isolation is used to reduce the structure vibration under ground excitation and the advantage of the isolation application is that the low-frequency resonance problem does not need to be considered due to its excitation characteristics, which significantly facilitate the isolation design. In order to obtain the response probabilistic distribution of a nonlinear system, the state space split technique is modified. As only a few degrees of freedom are subjected to the random noise, the probabilistic distribution of the response without involving stochastic excitation is represented by the δ function. Then, the sampling property of the δ function is employed to reduce the dimension of the Fokker-Planck-Kolmogorov (FPK) equation and the low-dimensional FPK equation is solvable with existing methods. Numerical results indicate that the proposed approach is effective and accurate. Moreover, the response probabilistic distributions are more reasonable and scientific than the peak responses calculated by conventional time and frequency domain methods. 展开更多
关键词 ground vibration high dam flood discharge structural response nonlinear base isolation system probabilisticanalysis
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The Research on Grounding Protection for 110kV Resistance Grounding Distribution System 被引量:1
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作者 Shan Sun Guo Zeng +2 位作者 Xiaozang He Yanping Lv Xinyi Li 《Energy and Power Engineering》 2013年第4期877-880,共4页
Using the neutral grounding method by the resistance in 110?kV system, it can limit the voltage sag and short circuit current when one-phase grounding fault occurred, but it will change the sequence of the network str... Using the neutral grounding method by the resistance in 110?kV system, it can limit the voltage sag and short circuit current when one-phase grounding fault occurred, but it will change the sequence of the network structure and parameters. This paper analyzes the size and distribution of zero sequence voltage and current when one-phase grounding fault occurred in the 110 kV resistance grounding system, and puts forward the grounding protection configuration setting principle of this system combining the power supplying characteristics of 110?kV distribution network. In a reforming substation as an example, the grounding protection of 110 kV lines and transformer have been set and calculated. 展开更多
关键词 NEUTRAL groundING system by Resistance One-phase groundING Fault ZERO SEQUENCE Voltage ZERO SEQUENCE Current PROTECTION Setting
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A New Compact Omni-Directional Quasi-Self-Complementary Antenna for Wireless Communication Systems
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作者 Aliakbar Dastranj 《Open Journal of Antennas and Propagation》 2016年第2期24-33,共10页
This article describes a new miniaturized omni-directional antenna with quasi-self-complementary structure for wireless communication applications. A novel ground structure composed of five rectangular plates is propo... This article describes a new miniaturized omni-directional antenna with quasi-self-complementary structure for wireless communication applications. A novel ground structure composed of five rectangular plates is proposed to enhance the impedance bandwidth and reduce the antenna size. The proposed antenna is comprised of two patches surrounded by the ground structure. Two metal patches of the antenna are located on two opposite sides of the dielectric substrate. The feed patch is used to excite the radiation patch. This unique design is realized by properly choosing the suitable feed patch shape, selecting similar slot shape on the radiation patch, and tuning their dimensions. The proposed antenna with an extremely small size of 6 mm × 9 mm has an operating impedance bandwidth ranging from 4.5 to 6.1 GHz for S<sub>11</sub> < -10 dB, which also covers the two IEEE 802.11a wireless local area network bands (5.15 - 5.35 GHz and 5.725 - 5.825 GHz). In addition to be very small in size, the antenna exhibits omni-directional radiation patterns in the entire operating bandwidth and low cross polarization. The distortionless time domain performance of the antenna is confirmed by investigation of the phase response and group delay. The obtained results in both frequency and time domain show that the proposed antenna is suitable for use in wireless communication systems. 展开更多
关键词 ground Structure OMNI-DIRECTIONAL Quasi-Self-Complementary Antenna QSCA Wireless Communication systems WLAN
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GROUND STATE SOLUTIONS FOR THE CRITICAL KLEIN-GORDON-MAXWELL SYSTEM 被引量:1
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作者 Lixia WANG Xiaoming WANG Luyu ZHANG 《Acta Mathematica Scientia》 SCIE CSCD 2019年第5期1451-1460,共10页
In this article,we study the following Klein-Gordon-Maxwell system involving critical exponent■where λ and w are two positive constants.We found the existence of positive ground state solutions(that is,for solutions... In this article,we study the following Klein-Gordon-Maxwell system involving critical exponent■where λ and w are two positive constants.We found the existence of positive ground state solutions(that is,for solutions which minimizes the action functional among all the solutions)of(KGM) which improves some previous existence result in Carriao et al.(2012) [8]. 展开更多
关键词 ground state solution Klein-Gordon-Maxwell system Ekeland's VARIATIONAL principle MOUNTAIN PASS theorem
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Application of Atomic Sparse Decomposition to Feature Extraction of the Fault Signal in Small Current Grounding System 被引量:1
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作者 Nanhua Yu Rui Li +1 位作者 Jun Yang Bei Dong 《Energy and Power Engineering》 2013年第4期603-607,共5页
Applying the atomic sparse decomposition in the distribution network with harmonics and small current grounding to decompose the transient zero sequence current that appears after the single phase to ground fault occu... Applying the atomic sparse decomposition in the distribution network with harmonics and small current grounding to decompose the transient zero sequence current that appears after the single phase to ground fault occurred. Based on dictionary of Gabor atoms and matching pursuit algorithm, the method extracts the atomic components iteratively from the feature signals and translated them to damped sinusoidal components. Then we can obtain the parametrical and analytical representation of atomic components. The termination condition of decomposing iteration is determined by the threshold of the initial residual energy with the purpose of extract the features more effectively. Accordingly, the proposed method can extract the starting and ending moment of disturbances precisely as well as their magnitudes, frequencies and other features. The numerical examples demonstrate its effectiveness. 展开更多
关键词 Small Current groundING system Fault Line Selection ATOMIC SPARSE Decomposition Matching PURSUIT DAMPED SINUSOIDS
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Finite Element Modeling of Unbounded Grounding System Considering Soil Ionization Characteristic 被引量:1
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作者 CHEN Lin LI Jingli +2 位作者 YANG Qing SIMA Wenxia SUN Caixin 《高电压技术》 EI CAS CSCD 北大核心 2012年第8期2104-2111,共8页
关键词 局部放电 射频信号 放电量 高电压技术
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Alternative Solutions to Mitigate Problems due to Neutral Conductors Theft in MV (Medium Voltage) Power Distribution Systems
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作者 Fabio Romero Alden Uehara Antunes +5 位作者 Fernando Locks Lange Dario Takahata Andre Meffe Carlos Cesar Barioni de Oliveira Hamilton Bueno de Souza 《Journal of Energy and Power Engineering》 2014年第12期2074-2079,共6页
This paper aims at analyzing the impact of the neutral conductor absence at specific sections over the performance of the power distribution lines, and proposing alternative solutions to mitigate the problems caused b... This paper aims at analyzing the impact of the neutral conductor absence at specific sections over the performance of the power distribution lines, and proposing alternative solutions to mitigate the problems caused by the neutral conductor theft. Simulations are made by the software lnterplan and show that the absence of neutral conductor at specific sections of power distribution lines may increase the neutral-to-ground voltages, which compromises the system's safety. The solution developed keeps the technical performance of the power distribution system at satisfactory levels, regarding the voltage profile, or, at least, close to the level before the neutral conductor's theft. 展开更多
关键词 Power distribution systems conductor theft system safety neutral-to-ground voltages grounding.
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Grounding Impedance Measurement of High Speed Railway Integrated Grounding System
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作者 Zhang Yi Jianguo Wang +2 位作者 Yadong Fan Mi Zhou Li Cai 《Journal of Power and Energy Engineering》 2015年第4期194-199,共6页
The high-speed railway integrated grounding system is the basic guarantee for the safe and stable operation of the railway. It is the world’s largest long-distance horizontally elongated joint grounding system, which... The high-speed railway integrated grounding system is the basic guarantee for the safe and stable operation of the railway. It is the world’s largest long-distance horizontally elongated joint grounding system, which stretches the length of hundreds to thousands of kilometers, and its structure is not only different from power station and substation grounding system, but also different from the transmission line tower, lightning rod and other small grounding devices. There is little research information on the grounding impedance of high-speed railway integrated grounding system. This paper adopted 0.618 compensation method and reverse away method respectively, measured a section of high-speed railway integrated grounding system grounding impedance by JD16 and CA6425. Measurement results are in good agreement using those two type instrument. By using 0.618 compensation method, the measurement result will be gradually converged at 0.3 Ω with the increasing of current electrode distance, which is the real grounding impedance of integrated grounding system. By using reverse away method, the maximum measurement result difference is less than 0.024 Ω with the lead of current electrode distance increasing. The measurement results will be rapidly converged 0.25 Ω. The results showed that the reverse away method is helpful to shorten the length of current electrode wiring. The measurement error will be small when the current electrode wiring is longer. 展开更多
关键词 HIGH-SPEED RAILWAY INTEGRATED groundING system groundING IMPEDANCE
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The Research of Voltage Sag and Power Frequency Overvoltage on 110kV Resistance Grounding System
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作者 Guo Zeng Guangliang Feng +1 位作者 Yanping Lv Shan Sun 《Energy and Power Engineering》 2013年第4期873-876,共4页
This paper researches the voltage transfer characteristics when one-phase ground fault occurred in the resistance grounding system, by using the theory of the asymmetric variable characteristics and the sequence netwo... This paper researches the voltage transfer characteristics when one-phase ground fault occurred in the resistance grounding system, by using the theory of the asymmetric variable characteristics and the sequence network analysis of the -11 transformer, and concludes the scope of voltage sag and swell and the degree of power frequency overvoltage and their influencing factors in the 110 kV resistance grounding system. Accordingly this paper puts forward the resistance choosing principle: the resistance grounding coefficient must be equal to or greater than 10. So it can not only wipe out the voltage sag and voltage swell but also make sure the overvoltage is limited to electrical equipment allowing range. The method mentioned above is verified by simulation results of a 110 kV power system in ATP. 展开更多
关键词 NEUTRAL groundING system by RESISTANCE One-phase groundING FAULT Power Frequency OVERVOLTAGE
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