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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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Zero-sequence Current Suppressing Strategy for Dual Three-phase Permanent Magnet Synchronous Machines Connected with Single Neutral Point 被引量:2
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作者 Zongwang Li Yuxuan Du +2 位作者 Jinghua Ji Tao Tao Wenxiang Zhao 《CES Transactions on Electrical Machines and Systems》 CSCD 2022年第4期465-472,共8页
Dual three-phase permanent-magnet synchronous machines(DTP-PMSM)connected with a single neutral point provide a loop for zero-sequence current(ZSC).This paper proposes a novel space vector pulse width modulation(SVPWM... Dual three-phase permanent-magnet synchronous machines(DTP-PMSM)connected with a single neutral point provide a loop for zero-sequence current(ZSC).This paper proposes a novel space vector pulse width modulation(SVPWM)strategy to suppress the ZSC.Five vectors are selected as basic voltage vectors in one switching period.The fundamental and harmonic planes and the zero-sequence plane are taken into consideration to synthesis the reference voltage vector.To suppress the ZSC,a non-zero zero-sequence voltage(ZSV)is generated to compensate the third harmonic back-EMF.Rather than triangular carrier modulation,the sawtooth carrier modulation strategy is used to generate asymmetric PWM signals.The modulation range is investigated to explore the variation of modulation range caused by considering the zero-sequence plane.With the proposed method,the ZSC can be considerably reduced.The simulated and experimental results are presented to validate the effectiveness of the proposed modulation strategy. 展开更多
关键词 zero-sequence current a single neutral point dual three-phase permanent-magnet synchronous machine third harmonic back-EMF
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Zero-Sequence Current Suppression Strategy for Open-End Winding Permanent Magnet Synchronous Motor Based on Model Predictive Control
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作者 LIU Huashan LI Jie YAO Fei 《Journal of Donghua University(English Edition)》 EI CAS 2020年第4期286-292,共7页
Compared with the traditional three-phase star connection winding,the open-end winding permanent magnet synchronous motor(OW-PMSM)system with a common direct current(DC)bus has a zero-sequence circuit,which makes the ... Compared with the traditional three-phase star connection winding,the open-end winding permanent magnet synchronous motor(OW-PMSM)system with a common direct current(DC)bus has a zero-sequence circuit,which makes the common-mode voltage and the back electromotive force(EMF)harmonic generated by the inverters produce the zero-sequence current in the zero-sequence circuit,and the zero-sequence current has great influence on the operation efficiency and stability of the motor control system.A zero-sequence current suppression strategy is presented based on model predictive current control for OW-PMSM.Through the mathematical model of OW-PMSM to establish the predictive model and the zero-sequence circuit model,the common-mode voltage under different voltage vector combinations is fully considered during vector selection and action time calculation.Then zero-sequence loop constraints are established,so as to suppress the zero-sequence current.In the end,the control strategy proposed in this paper is verified by simulation experiments. 展开更多
关键词 open-end winding permanent magnet synchronous motor(OW-PMSM) zero-sequence current HARMONIC model predictive current control common-mode voltage
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特高压同塔双回线路零序电流补偿系数整定对接地距离保护的影响研究 被引量:18
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作者 周春霞 余越 +2 位作者 赵寒 詹荣荣 王兴国 《电网技术》 EI CSCD 北大核心 2012年第12期106-111,共6页
为提高特高压同塔双回线路接地距离保护的动作性能,分析了特高压同塔双回线路在不同运行方式下,零序互感对接地距离保护零序电流补偿系数K和测量阻抗的影响,讨论了使用双K值及单K值整定方法的接地距离保护的有效保护范围。分析发现,由... 为提高特高压同塔双回线路接地距离保护的动作性能,分析了特高压同塔双回线路在不同运行方式下,零序互感对接地距离保护零序电流补偿系数K和测量阻抗的影响,讨论了使用双K值及单K值整定方法的接地距离保护的有效保护范围。分析发现,由于特高压同塔双回线路的互感系数较大,采用上述2种整定方法,大大减小了双回线正常运行方式下接地距离I段的动作范围,同时也给接地距离II(III)段的整定配合带来困难。为此提出了通过切换定值区的方式进行接地距离保护零序电流补偿系数整定的建议。建立了基于1 000 kV特高压同塔双回交流输电工程实际参数的动态模拟系统,对不同运行方式下接地距离保护的有效保护范围进行了试验验证,试验结果与理论分析一致。 展开更多
关键词 特高压交流 同塔双回 零序电流补偿系数 接地 距离保护
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Research on Fault-feeder Selection Dvice
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作者 Ziming Zhuo Haimeng Sun Haibin Ji 《Energy and Power Engineering》 2013年第4期937-940,共4页
The compensation current of the arc-suppressing coil makes the phase and amplitude of zero-sequence measurement current of the earthed fault feeder to vary. It is very hard to detect the fault feeder by using existing... The compensation current of the arc-suppressing coil makes the phase and amplitude of zero-sequence measurement current of the earthed fault feeder to vary. It is very hard to detect the fault feeder by using existing detectors based on single method. In this paper, integrative feeder selection strategy—zero sequence current increment method and the direction of transient current— is put forward. Based on the integrative feeder selection strategy, the design of fault-feeder selection device for one-phase-to ground fault on resonance grounding system is presented. For the purpose of testing and validating the operating principle of the device, the experiment of single-phase-to-ground fault has been carried out on the simulation of 1.2 kV power network. The results from many repeat experiments show that stability of the fault selection device is satisfactory. 展开更多
关键词 Resonance GROUNDING System Earthed FAULT FEEDER Detection zero-sequence current INCREMENT Method zero-sequence Transient currents
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High-impedance Fault Section Location for Distribution Networks Based on t-distributed Stochastic Neighbor Embedding and Variable Mode Decomposition
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作者 Zhihua Yin Yuping Zheng +3 位作者 Zhinong Wei Guoqiang Sun Sheng Chen Haixiang Zang 《Journal of Modern Power Systems and Clean Energy》 SCIE EI CSCD 2024年第5期1495-1505,共11页
When high-impedance faults(HIFs)occur in resonant grounded distribution networks,the current that flows is extremely weak,and the noise interference caused by the distribution network operation and the sampling error ... When high-impedance faults(HIFs)occur in resonant grounded distribution networks,the current that flows is extremely weak,and the noise interference caused by the distribution network operation and the sampling error of the measurement devices further masks the fault characteristics.Consequently,locating a fault section with high sensitivity is difficult.Unlike existing technologies,this study presents a novel fault feature identification framework that addresses this issue.The framework includes three key steps:(1)utilizing the variable mode decomposition(VMD)method to denoise the fault transient zero-sequence current(TZSC);(2)employing a manifold learning algorithm based on t-distributed stochastic neighbor embedding(t-SNE)to further reduce the redundant information of the TZSC after denoising and to visualize fault information in high-dimensional 2D space;and(3)classifying the signal of each measurement point based on the fuzzy clustering method and combining the network topology structure to determine the fault section location.Numerical simulations and field testing confirm that the proposed method accurately detects the fault location,even under the influence of strong noise interference. 展开更多
关键词 High-impedance fault noise interference fault section location t-distributed stochastic neighbor embedding(t-SNE) transient zero-sequence current
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Arc flash fault detection in wind farm collection feeders based on current waveform analysis 被引量:6
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作者 Bin WANG Jiang NI +2 位作者 Jianzhao GENG Yuanyuan LU Xinzhou DONG 《Journal of Modern Power Systems and Clean Energy》 SCIE EI 2017年第2期211-219,共9页
High impedance faults(HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse d... High impedance faults(HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse due to the limited fault current values and the situation is worse in wind farms. The mostly adopted HIF detection algorithms are based on the 3rd harmonic characteristic of the fault zero-sequence currents, whereas these 3rd harmonics are very easy to be polluted by wind power back-to-back converters. In response to this problem, the typical harmonic characteristic of HIF arc flash based on Mayr’s arc model is first analyzed, and the typical fault waveforms of HIF in wind farm are presented. Then the performance of the harmonic based HIF detection algorithm is discussed,and a novel detection algorithm is proposed from the viewpoint of time domain, focusing on the convex and concave characteristic of zero-sequence current at zerocrossing points. A HIFs detection(HIFD) prototype implementing the proposed algorithm has been developed.The sensitivity and security of the algorithm are proved byfield data and RTDS experiments. 展开更多
关键词 Wind farm High impedance fault Arc flash zero-sequence current Convex and concave characteristic
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Evaluation of overhead line current unbalance in meshed grids and its reduction
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作者 Jakub EHRENBERGER Jan ?VEC 《Journal of Modern Power Systems and Clean Energy》 SCIE EI 2018年第6期1204-1212,共9页
This paper describes new methodology in the current unbalance calculations in meshed grids. The meshed grids, mainly the transmission ones, consist of more parts connected together which are formed using different con... This paper describes new methodology in the current unbalance calculations in meshed grids. The meshed grids, mainly the transmission ones, consist of more parts connected together which are formed using different conductor types, phase sequence arrangements,tower constructions, and various number of lines on the same tower. Therefore several computational challenges arise in comparison with the widely discussed point-topoint configuration. The methodology divides the grid into a number of impedance matrices respecting all the self and mutual impedances among all conductors and all parallel lines. Another challenging issue for the line impedancedescription is changing the number of shield wires along the line if the line is composed of several sections with different tower configurations. For the current unbalance calculation, shield wires must also be included in the algorithms, and matrices of various dimensions can be obtained. For the overall matrix description to be used,dimensions of all matrices in final equations must be equal,and therefore the virtual shield wires are created. To compare more conductor transposition cases with each other, the line loadings caused by voltage sources should be equal. This is necessary mainly in case of meshed grids where the supplying sources on different lines can have strong mutual couplings. This can be achieved by an appropriately designed optimization of the connected voltage sources. 展开更多
关键词 current UNBALANCE Phase SEQUENCE arrangement SHIELD wire UNBALANCE FACTOR zero-sequence SET
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Single-phase-to-ground Fault Detection with Distributed Parameters Analysis in Non-direct Grounded Systems 被引量:19
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作者 Baowen Liu Hongzhong Ma +1 位作者 Honghua Xu Ping Ju 《CSEE Journal of Power and Energy Systems》 SCIE CSCD 2019年第1期139-147,共9页
The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were pr... The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems.At first,novel generating mechanisms of zero-sequence voltage and residual current were proposed.Then the compositions of residue parameters,including residual current and residual admittances,were decomposed in detail.After that,an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed,and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection.Furthermore,the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder,which cannot be affected by the asymmetry of the network.Theoretical analysis and the MATALB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms. 展开更多
关键词 Fault resistance calculation fault feeder selection non-direct grounded system residual parameters residual current zero-sequence voltage
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Analysis of unbalanced clustered voltage and control strategy of clustered voltage balancing for cascaded H-bridge STATCOM 被引量:1
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作者 Yu JIN Jianze WANG +2 位作者 Yiqi LIU Xinagyu SAI Yanchao JI 《Journal of Modern Power Systems and Clean Energy》 SCIE EI CSCD 2019年第6期1697-1708,共12页
To explore the clustered voltage balancing mechanism of the cascaded H-bridge static synchronous compensator(STATCOM),this paper analyzes the causes of unbalanced clustered voltage.The negative-sequence current caused... To explore the clustered voltage balancing mechanism of the cascaded H-bridge static synchronous compensator(STATCOM),this paper analyzes the causes of unbalanced clustered voltage.The negative-sequence current caused by the compensation of unbalanced reactive power or detection and control errors and the zero-sequence voltage caused by voltage drift of the STATCOM neutral point contribute to unbalanced clustered voltage.On this basis,this paper proposes a control strategy to inject negative-sequence current and zero-sequence voltage simultaneously.The injection of negative-sequence current may cause current asymmetry in the grid,and the zerosequence injection has a relatively limited balancing ability in the clustered voltages.The proposed control strategy can not only generate a faster balancing response than the traditional zero-sequence voltage injection method,but also lower the extent of current asymmetry compared with the traditional negative-sequence current injection method.Then,the negative-sequence current and zero-sequence voltage injection are further transformed into the dq frame to establish a unified frame.The effectiveness of the proposed control strategy is verified by the simulation and experimental results. 展开更多
关键词 Cascaded static SYNCHRONOUS compensator(STATCOM) Clustered VOLTAGE Control STRATEGY Negative-sequence current zero-sequence VOLTAGE
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Fault Feeder Identification in Non-effectively Grounded Distribution Network with Secondary Earth Fault 被引量:1
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作者 Shu Zhang Tianlei Zang +1 位作者 Wenhai Zhang Xianyong Xiao 《Journal of Modern Power Systems and Clean Energy》 SCIE EI CSCD 2021年第5期1137-1148,共12页
Secondary earth faults occur frequently in power distribution networks under harsh weather conditions.Owing to its characteristics,a secondary earth fault is typically hidden within the transient of the first fault.Th... Secondary earth faults occur frequently in power distribution networks under harsh weather conditions.Owing to its characteristics,a secondary earth fault is typically hidden within the transient of the first fault.Therefore,most researchers tend to focus on a feeder with single fault while disregarding secondary faults.This paper presents a fault feeder identification method that considers secondary earth faults in a non-effectively grounded distribution network.First,the wavelet singular entropy method is used to detect a secondary fault event.This method can identify the moment at which a secondary fault occurs.The zero-sequence current data can be categorized into two fault stages.The first and second fault stages correspond to the first and secondary faults,respectively.Subsequently,a similarity matrix containing the time-frequency transient information of the zero-sequence current at the two fault stages is defined to identify the fault feeders.Finally,to confirm the effectiveness and reliability of the proposed method,we conduct simulation experiments and an adaptability analysis based on an electromagnetic transient program. 展开更多
关键词 Secondary earth fault non-effectively grounded distribution network wavelet singular entropy similarity matrix zero-sequence current
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