With the expansion and increasing complexity of data center networks(DCNs),network fault-tolerance has become increasingly important.RRect is a server-centered DCN with a good interconnection structure.In this paper,w...With the expansion and increasing complexity of data center networks(DCNs),network fault-tolerance has become increasingly important.RRect is a server-centered DCN with a good interconnection structure.In this paper,we propose a fault-tolerant routing algorithm RRFP under a conditional fault pattern of RRect,which can find a fault-free path between any two fault-free vertices.Firstly,we study a fault pattern of RRect in the case of restricted faulty vertex sets,{1,2}-restricted connectivity.It is about{2,3}times RRect’s traditional connectivity,indicating that{1,2}-restricted connectivity better evaluates the fault-tolerant capability.Secondly,we design an effective fault-tolerant routing algorithm RRFP under the conditional fault pattern of RRect,and RRFP can accommodate more faulty vertices.Finally,we conduct experiments on RRFP to evaluate its performance.The experimental results show that in terms of the running time,as parameters n and k change,RRFP outperforms Dijkstra’s algorithm by 64%–84%and Breadth-First-Search(BFS)by 56%–71%.The running time of all the three algorithms is very short as parameter m changes.In terms of the constructing path length,as parameters change,RRFP outperforms BFS by 12%–19%.Moreover,the path constructed by RRFP approaches the shortest path of Dijkstra’s algorithm.Moreover,RRFP still maintains a low transmission failure rate(TFR)and high reliability even with an increase in the number of fault elements.展开更多
A new algorithm was developed to correctly identify fault conditions and accurately monitor fault development in a mine hoist. The new method is based on the Wavelet Packet Transform (WPT) and kernel PCA (Kernel Princ...A new algorithm was developed to correctly identify fault conditions and accurately monitor fault development in a mine hoist. The new method is based on the Wavelet Packet Transform (WPT) and kernel PCA (Kernel Principal Compo- nent Analysis, KPCA). For non-linear monitoring systems the key to fault detection is the extracting of main features. The wavelet packet transform is a novel technique of signal processing that possesses excellent characteristics of time-frequency localization. It is suitable for analysing time-varying or transient signals. KPCA maps the original input features into a higher dimension feature space through a non-linear mapping. The principal components are then found in the higher dimen- sion feature space. The KPCA transformation was applied to extracting the main nonlinear features from experimental fault feature data after wavelet packet transformation. The results show that the proposed method affords credible fault detection and identification.展开更多
Medium voltage distribution networks usually suffer from single-ground arcing fault,especially high impedance arcing fault.Moreover,induced intermittent arcing faults can severely endanger the reliability and safety o...Medium voltage distribution networks usually suffer from single-ground arcing fault,especially high impedance arcing fault.Moreover,induced intermittent arcing faults can severely endanger the reliability and safety of power systems.The arc model is important for high impedance arcing fault suppression and detection to effectively eliminate the single-ground arcing fault.This paper proposes an improved arc model,which is concise and explicit,based on a single-ground arcing fault conducted on a 10 kV experimental platform under different fault conditions.Characteristic parameters of single-ground arcing faults are obtained based on test results.Furthermore,characteristic parameters under different fault conditions of the improved arc model are presented.Finally,verification of the improved arc model is supported by PSCAD-EMTDC.Comparisons of the proposed arc model between three typical black-box arc models indicate that the proposed model has better performance and higher accuracy than that of the three typical arc models as fault resistance is in a range of 0.1 kΩto 2.4 kΩ.Thus,its accuracy is acceptable and it is helpful to the simulation and suppression of arc fault overvoltage.展开更多
Selected milestones in the development and use of electrical tomography in powder conveying, slurry processing and multi-phase flow are highlighted. The ability to map concentration in opaque mixtures under process-re...Selected milestones in the development and use of electrical tomography in powder conveying, slurry processing and multi-phase flow are highlighted. The ability to map concentration in opaque mixtures under process-realistic conditions was a major innovation for the method and has had far reaching implications. Subsequent developments have enabled velocity information to be abstracted resulting in the ability to measure component flux and motion.展开更多
This paper constructs a model of the internal cross-sectional temperature field of power cables based on the multiphysics coupling simulation software,Comsol,to conduct an in-depth analysis of internal defects in powe...This paper constructs a model of the internal cross-sectional temperature field of power cables based on the multiphysics coupling simulation software,Comsol,to conduct an in-depth analysis of internal defects in power cables.First,a temperature field coupling model for power cables was built,and the accuracy of the simulation model was verified through mesh and boundary condition analysis.Subsequently,the distribution patterns of the internal temperature field of power cables were investigated under normal operating conditions and typical fault conditions(eccentric defects,internal water tree defects).The simulation results reveal that the presence of faults affects the insulation capability of the cable’s insulation layer,causing an imbalance in internal heat conduction and thus impacting the temperature distribution within the power cable.Additionally,this paper compares the internal temperature field distribution of power cables under different conditions(changing coil current and heat transfer coefficient)during normal operation.The results indicate that the temperature rise of power cables is closely related to the current carrying capacity and the heat transfer coefficient.Through an in-depth study of the temperature field distribution in power cables,this research provides a more precise,efficient,and economical reference solution for fault detection and repair in power systems,thereby enhancing the stability and safety of power cables and promoting the sustainable development of power cable technology.展开更多
With the growing interest in monitoring and diagnostic techniques for assessing transformer condition,dissolved gas analysis(DGA)stands out as a crucial diagnostic tool to detect electrical and thermal faults in liqui...With the growing interest in monitoring and diagnostic techniques for assessing transformer condition,dissolved gas analysis(DGA)stands out as a crucial diagnostic tool to detect electrical and thermal faults in liquid-immersed transformers.Laboratory-based DGA studies have primarily focused on detecting gas concentrations and patterns under simulated fault conditions in different types of insulating liquids.To understand the significance of dissolved gas values it is invaluable to establish the quantitative relationship between the gas generation amount and the electrical energy associated with the fault.This study aims to systematically investigate the correlation between gas generation characteristics and the electrical energy associated with either partial discharges(PD)or breakdown sparks(BD)in a mineral oil(MO)and a synthetic ester(SE).An inhouse designed experimental setup was developed,and various influencing factors were explored.The results of DGA-PD tests indicated that PD magnitude influences the fault gas volume per unit energy(GVPUE,μL/J)generated in both liquids.The GVPUE in MO was found to be higher than that in SE for the same PD magnitude.The results of DGA-BD tests showed that larger breakdown gap distances lead to a higher GVPUE and a lower H_(2)/C_(2)H_(2) gas ratio.The findings bring new insights on fault gas generation mechanisms in transformer liquids.展开更多
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China under Grant No.62125203the National Natural Science Foundation of China under Grant Nos.61932013,62102196,62372248,and 62302235+1 种基金the Natural Science Fund for Colleges and Universities in Jiangsu Province of China under Grant No.24KJA520006the Postgraduate Research and Practice Innovation Program of Jiangsu Province of China under Grant No.SJCX23_0275.
文摘With the expansion and increasing complexity of data center networks(DCNs),network fault-tolerance has become increasingly important.RRect is a server-centered DCN with a good interconnection structure.In this paper,we propose a fault-tolerant routing algorithm RRFP under a conditional fault pattern of RRect,which can find a fault-free path between any two fault-free vertices.Firstly,we study a fault pattern of RRect in the case of restricted faulty vertex sets,{1,2}-restricted connectivity.It is about{2,3}times RRect’s traditional connectivity,indicating that{1,2}-restricted connectivity better evaluates the fault-tolerant capability.Secondly,we design an effective fault-tolerant routing algorithm RRFP under the conditional fault pattern of RRect,and RRFP can accommodate more faulty vertices.Finally,we conduct experiments on RRFP to evaluate its performance.The experimental results show that in terms of the running time,as parameters n and k change,RRFP outperforms Dijkstra’s algorithm by 64%–84%and Breadth-First-Search(BFS)by 56%–71%.The running time of all the three algorithms is very short as parameter m changes.In terms of the constructing path length,as parameters change,RRFP outperforms BFS by 12%–19%.Moreover,the path constructed by RRFP approaches the shortest path of Dijkstra’s algorithm.Moreover,RRFP still maintains a low transmission failure rate(TFR)and high reliability even with an increase in the number of fault elements.
基金Projects 50674086 supported by the National Natural Science Foundation of ChinaBS2006002 by the Society Development Science and Technology Planof Jiangsu Province20060290508 by the Doctoral Foundation of Ministry of Education of China
文摘A new algorithm was developed to correctly identify fault conditions and accurately monitor fault development in a mine hoist. The new method is based on the Wavelet Packet Transform (WPT) and kernel PCA (Kernel Principal Compo- nent Analysis, KPCA). For non-linear monitoring systems the key to fault detection is the extracting of main features. The wavelet packet transform is a novel technique of signal processing that possesses excellent characteristics of time-frequency localization. It is suitable for analysing time-varying or transient signals. KPCA maps the original input features into a higher dimension feature space through a non-linear mapping. The principal components are then found in the higher dimen- sion feature space. The KPCA transformation was applied to extracting the main nonlinear features from experimental fault feature data after wavelet packet transformation. The results show that the proposed method affords credible fault detection and identification.
基金supported by National Natural Science Foundation of China under Grant No.51477018 and No.52077019。
文摘Medium voltage distribution networks usually suffer from single-ground arcing fault,especially high impedance arcing fault.Moreover,induced intermittent arcing faults can severely endanger the reliability and safety of power systems.The arc model is important for high impedance arcing fault suppression and detection to effectively eliminate the single-ground arcing fault.This paper proposes an improved arc model,which is concise and explicit,based on a single-ground arcing fault conducted on a 10 kV experimental platform under different fault conditions.Characteristic parameters of single-ground arcing faults are obtained based on test results.Furthermore,characteristic parameters under different fault conditions of the improved arc model are presented.Finally,verification of the improved arc model is supported by PSCAD-EMTDC.Comparisons of the proposed arc model between three typical black-box arc models indicate that the proposed model has better performance and higher accuracy than that of the three typical arc models as fault resistance is in a range of 0.1 kΩto 2.4 kΩ.Thus,its accuracy is acceptable and it is helpful to the simulation and suppression of arc fault overvoltage.
基金support of co-workers in the tomography groups at University of Leeds and the University of Manchester with funding to enable us to develop the frontiers of tomography provided by EPSRC (EP/D031257/1)
文摘Selected milestones in the development and use of electrical tomography in powder conveying, slurry processing and multi-phase flow are highlighted. The ability to map concentration in opaque mixtures under process-realistic conditions was a major innovation for the method and has had far reaching implications. Subsequent developments have enabled velocity information to be abstracted resulting in the ability to measure component flux and motion.
文摘This paper constructs a model of the internal cross-sectional temperature field of power cables based on the multiphysics coupling simulation software,Comsol,to conduct an in-depth analysis of internal defects in power cables.First,a temperature field coupling model for power cables was built,and the accuracy of the simulation model was verified through mesh and boundary condition analysis.Subsequently,the distribution patterns of the internal temperature field of power cables were investigated under normal operating conditions and typical fault conditions(eccentric defects,internal water tree defects).The simulation results reveal that the presence of faults affects the insulation capability of the cable’s insulation layer,causing an imbalance in internal heat conduction and thus impacting the temperature distribution within the power cable.Additionally,this paper compares the internal temperature field distribution of power cables under different conditions(changing coil current and heat transfer coefficient)during normal operation.The results indicate that the temperature rise of power cables is closely related to the current carrying capacity and the heat transfer coefficient.Through an in-depth study of the temperature field distribution in power cables,this research provides a more precise,efficient,and economical reference solution for fault detection and repair in power systems,thereby enhancing the stability and safety of power cables and promoting the sustainable development of power cable technology.
文摘With the growing interest in monitoring and diagnostic techniques for assessing transformer condition,dissolved gas analysis(DGA)stands out as a crucial diagnostic tool to detect electrical and thermal faults in liquid-immersed transformers.Laboratory-based DGA studies have primarily focused on detecting gas concentrations and patterns under simulated fault conditions in different types of insulating liquids.To understand the significance of dissolved gas values it is invaluable to establish the quantitative relationship between the gas generation amount and the electrical energy associated with the fault.This study aims to systematically investigate the correlation between gas generation characteristics and the electrical energy associated with either partial discharges(PD)or breakdown sparks(BD)in a mineral oil(MO)and a synthetic ester(SE).An inhouse designed experimental setup was developed,and various influencing factors were explored.The results of DGA-PD tests indicated that PD magnitude influences the fault gas volume per unit energy(GVPUE,μL/J)generated in both liquids.The GVPUE in MO was found to be higher than that in SE for the same PD magnitude.The results of DGA-BD tests showed that larger breakdown gap distances lead to a higher GVPUE and a lower H_(2)/C_(2)H_(2) gas ratio.The findings bring new insights on fault gas generation mechanisms in transformer liquids.
