In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line select...In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.展开更多
Based on the fuzzy expert system fault diagnosis theory, the knowledge base architecture and inference engine algorithm are put forward for avionic device fault diagnosis. The knowledge base is constructed by fault qu...Based on the fuzzy expert system fault diagnosis theory, the knowledge base architecture and inference engine algorithm are put forward for avionic device fault diagnosis. The knowledge base is constructed by fault query network, of which the basic ele- ment is the test-diagnosis fault unit. Every underlying fault cause＇s membership degree is calculated using fuzzy product inference algorithm, and the fault answer best selection algorithm is developed, to which the deep knowledge is applied. Using some examples the proposed algorithm is analyzed for its capability of synthesis diagnosis and its improvement compared to greater membership degree first principle.展开更多
When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is...When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.展开更多
Binary particle swarm optimization algorithm(BPSOA) has the excellent characters such as easy to implement and few set parameters.But it is tendentious to stick in the local optimal solutions and has slow convergence ...Binary particle swarm optimization algorithm(BPSOA) has the excellent characters such as easy to implement and few set parameters.But it is tendentious to stick in the local optimal solutions and has slow convergence rate when the problem is complex.Cultural algorithm(CA) can exploit knowledge extracted during the search to improve the performance of an evolutionary algorithm and show higher intelligence in treating complicated problems.So it is proposed that integrating binary particle swarm algorithm into cultural algorithm frame to develop a more efficient cultural binary particle swarm algorithm (CBPSOA) for fault feature selection.In CBPSOA,BPSOA is used as the population space of CA;the evolution of belief space adopts crossover,mutation and selection operations;the designs of acceptance function and influence function are improved according to the evolution character of BPSOA.The tests of optimizing functions show the proposed algorithm is valid and effective.Finally,CBPSOA is applied for fault feature selection.The simulations on Tennessee Eastman process (TEP) show the CBPSOA can perform better and more quickly converge than initial BPSOA.And with fault feature selection,more satisfied performance of fault diagnosis is obtained.展开更多
On October 7,2021,a magnitude 5.9 earthquake struck the Harnai(Baluchistan)region of Pakistan,causing several fatalities and injuries within the epicentral area.First-order tectonic deformation in this region is cause...On October 7,2021,a magnitude 5.9 earthquake struck the Harnai(Baluchistan)region of Pakistan,causing several fatalities and injuries within the epicentral area.First-order tectonic deformation in this region is caused by the convergence of the Indian Plate with respect to the Eurasian Plate.The Katwaz Block hinders the motion of the Indian Plate,resulting in the formation of strike-slip faults.In this study,the P-wave first-motion polarity technique was used to determine the mainshock faulting style.Cyclic scanning of the polarity solutions was applied to determine the most suitable focal mechanism solution among the available solutions generated by the FOCMEC(focal mechanism)software.The nodal planes correspond to different faulting styles(i.e.,thrust and strike-slip faulting).A nodal plane oriented in the NW-SE direction corresponded to a strike-slip mechanism,which was considered to be the fault plane.Tectonically,this earthquake was associated with the Harnai-Karahi strike-slip fault zone owing to the fault strike and direction of slip.The apparent stress drop,fault length,and moment magnitude of the Harnai earthquake were 35.4 bar,6.1 km,and 5.9,respectively.A lower b-value for the Gutenberg-Richter law was observed prior to the earthquake.Higherα-than b-values(α>b)indicate that this earthquake was governed by large events as opposed to small-magnitude events.The Harnai sequence had a decay exponent close to unity,lasted for 145 days,and produced few aftershocks.The study will help the future hazard mitigation in the region.展开更多
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
文摘In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.
基金The 11th Five-year National Defense Preliminary Research Projects (B0520060455)
文摘Based on the fuzzy expert system fault diagnosis theory, the knowledge base architecture and inference engine algorithm are put forward for avionic device fault diagnosis. The knowledge base is constructed by fault query network, of which the basic ele- ment is the test-diagnosis fault unit. Every underlying fault cause＇s membership degree is calculated using fuzzy product inference algorithm, and the fault answer best selection algorithm is developed, to which the deep knowledge is applied. Using some examples the proposed algorithm is analyzed for its capability of synthesis diagnosis and its improvement compared to greater membership degree first principle.
文摘When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.
基金National High Technology Research and Development Program of China(No.2007AA04Z171)
文摘Binary particle swarm optimization algorithm(BPSOA) has the excellent characters such as easy to implement and few set parameters.But it is tendentious to stick in the local optimal solutions and has slow convergence rate when the problem is complex.Cultural algorithm(CA) can exploit knowledge extracted during the search to improve the performance of an evolutionary algorithm and show higher intelligence in treating complicated problems.So it is proposed that integrating binary particle swarm algorithm into cultural algorithm frame to develop a more efficient cultural binary particle swarm algorithm (CBPSOA) for fault feature selection.In CBPSOA,BPSOA is used as the population space of CA;the evolution of belief space adopts crossover,mutation and selection operations;the designs of acceptance function and influence function are improved according to the evolution character of BPSOA.The tests of optimizing functions show the proposed algorithm is valid and effective.Finally,CBPSOA is applied for fault feature selection.The simulations on Tennessee Eastman process (TEP) show the CBPSOA can perform better and more quickly converge than initial BPSOA.And with fault feature selection,more satisfied performance of fault diagnosis is obtained.
文摘On October 7,2021,a magnitude 5.9 earthquake struck the Harnai(Baluchistan)region of Pakistan,causing several fatalities and injuries within the epicentral area.First-order tectonic deformation in this region is caused by the convergence of the Indian Plate with respect to the Eurasian Plate.The Katwaz Block hinders the motion of the Indian Plate,resulting in the formation of strike-slip faults.In this study,the P-wave first-motion polarity technique was used to determine the mainshock faulting style.Cyclic scanning of the polarity solutions was applied to determine the most suitable focal mechanism solution among the available solutions generated by the FOCMEC(focal mechanism)software.The nodal planes correspond to different faulting styles(i.e.,thrust and strike-slip faulting).A nodal plane oriented in the NW-SE direction corresponded to a strike-slip mechanism,which was considered to be the fault plane.Tectonically,this earthquake was associated with the Harnai-Karahi strike-slip fault zone owing to the fault strike and direction of slip.The apparent stress drop,fault length,and moment magnitude of the Harnai earthquake were 35.4 bar,6.1 km,and 5.9,respectively.A lower b-value for the Gutenberg-Richter law was observed prior to the earthquake.Higherα-than b-values(α>b)indicate that this earthquake was governed by large events as opposed to small-magnitude events.The Harnai sequence had a decay exponent close to unity,lasted for 145 days,and produced few aftershocks.The study will help the future hazard mitigation in the region.
基金This work was supported in part by the National Natural Science Foundation of China(No.51177039)in part by the Fundamental Research Funds for the Central Universities(2018B06314)the 111 Intelligence project(B14022).
文摘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.
