The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-bran...The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-branch fault location algorithm makes it difficult to meet the demands of high-precision fault localization in the multi-branch distribution network system.In this paper,the multi-branch mainline is decomposed into single branch lines,transforming the complex multi-branch fault location problem into a double-ended fault location problem.Based on the different transmission characteristics of the fault-traveling wave in fault lines and non-fault lines,the endpoint reference time difference matrix S and the fault time difference matrix G were established.The time variation rule of the fault-traveling wave arriving at each endpoint before and after a fault was comprehensively utilized.To realize the fault segment location,the least square method was introduced.It was used to find the first-order fitting relation that satisfies the matching relationship between the corresponding row vector and the first-order function in the two matrices,to realize the fault segment location.Then,the time difference matrix is used to determine the traveling wave velocity,which,combined with the double-ended traveling wave location,enables accurate fault location.展开更多
Radio-frequency(RF)breakdown analysis and location are critical for successful development of high-gradient traveling-wave(TW)accelerators,especially those expected to generate high-intensity,high-power beams.Compared...Radio-frequency(RF)breakdown analysis and location are critical for successful development of high-gradient traveling-wave(TW)accelerators,especially those expected to generate high-intensity,high-power beams.Compared with commonly used schemes involving dedicated devices or complicated techniques,a convenient approach for breakdown locating based on transmission line(TL)theory offers advantages in the typical constant-gradient TW-accelerating structure.To deliver such an approach,an equivalent TL model has been constructed to equate the TW-accelerating structure based on the fun-damental theory of the TL transient response in the time domain.An equivalence relationship between the TW-accelerating structure and the TL model has been established via analytical derivations associated with grid charts and verified by TL circuit simulations.Furthermore,to validate the proposed fault-locating method in practical applications,an elaborate analysis via such a method has been conducted for the recoverable RF-breakdown phenomena observed at an existing prototype of a TW-accelerating-structure-based beam injector constructed at the Huazhong University of Science and Technology.In addition,further considerations and discussion for extending the applications of the proposed method have been given.This breakdown-locating approach involving the transient response in the framework of TL theory can be a conceivable supple-ment to existing methods,facilitating solution to construction problems at an affordable cost.展开更多
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
A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in this paper.A special d...A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in this paper.A special diagnostic signal current is injected into the fault distribution system,and then it is detected at the outlet terminals to identify the fault line and at the sectionalizing or branching point along the fault line to locate the fault section.The method has been put into application in actual distribution network and field experience shows that it can identify the fault line and locate the fault section correctly and effectively.展开更多
A novel numerical algorithm of fault location estimation for double line to ground fault involving different phases from each of two parallel lines is presented in this paper.It is based on the one terminal voltag...A novel numerical algorithm of fault location estimation for double line to ground fault involving different phases from each of two parallel lines is presented in this paper.It is based on the one terminal voltage and current data.The loop and nodal equations comparing faulted phase with non faulted phase of two parallel lines are introduced in the fault location estimation models,in which the source impedance of a remote end is not involved.The effects of load flow and fault resistance on the accuracy of fault location are effectively eliminated,therefore precise algorithms of locating fault are derived.The algorithm is demonstrated by digital computer simulations.展开更多
The modern travelling wave based fault location principles for transmission lines are analyzed.In order to apply the travelling wave principles to HVDC transmission lines,the special technical problems are studied.Bas...The modern travelling wave based fault location principles for transmission lines are analyzed.In order to apply the travelling wave principles to HVDC transmission lines,the special technical problems are studied.Based on this,a fault locating system for HVDC transmission lines is developed.The system can support modern double ended and single ended travelling wave princi- ples simultaneously,and it is composed of three different parts:travelling wave data acquisition and processing system,communication network and PC based master station.In the system,the fault generated transients are induced from the ground leads of the over-voltage suppression capacitors of an HVDC line through specially developed travelling wave couplers.The system was applied to 500 kV Gezhouba-Nanqiao(Shanghai)HVDC transmission line in China.Some field operation experiences are summarized,showing that the system has very high reliability and accuracy,and the maximum location error is about 3 km(not more than 0.3%of the total line length). Obviously,the application of the system is successful,and the fault location problem has finally been solved completely since the line operation.展开更多
This paper introduced correlation method to locate transmission line fault.First it described the principle of transmission line fault location based on traveling waves.The principle of correlation analysis is introdu...This paper introduced correlation method to locate transmission line fault.First it described the principle of transmission line fault location based on traveling waves.The principle of correlation analysis is introduced,then the method using correlation analysis in fault location is given.Transmission line model is established with EMTP-ATP.Basing on the model,some kinds of fault are simulated.The feasibility of this algorithm is proved based on simulation results.By comparing with the classical wavelet analysis,this paper gave the advantages of this algorithm in two cases:noise influence suppression and accuracy of near distance fault location.Experiment is established to simulate transmission line grounding fault.The experiment result showed the correlation algorithm's validity.All the analysis result indicated that the correlation algorithm have a high precision.展开更多
:A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system(TPTLS)as influenced by the mutual effect to determine the fault location is discussed in this work.The distance rela...:A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system(TPTLS)as influenced by the mutual effect to determine the fault location is discussed in this work.The distance relay measures the impedance to the fault location which is the positive-sequence.The principle of summation the positive-,negative-,and zero-sequence voltages which equal zero is used to determine the fault location on the TPTLS.Also,the impedance of the transmission line to the fault location is determined.These algorithms are applied to single-line-to-ground(SLG)and double-line-to-ground(DLG)faults.To detect the fault location along the transmission line,its impedance as seen by the distance relay is determined to indicate if the fault is within the relay’s reach area.TPTLS under study are fed from one-and both-ends.A schematic diagrams are obtained for the impedance relays to determine the fault location with high accuracy.展开更多
An accurate numerical algorithm for three-line fault involving different phases from each of two-parallel lines is presented. It is based on one-terminal voltage and current data. The loop and nodel equations comparin...An accurate numerical algorithm for three-line fault involving different phases from each of two-parallel lines is presented. It is based on one-terminal voltage and current data. The loop and nodel equations comparing faulted phase to non-faulted phase of two-parallel lines are introduced in the fault location estimation modal, in which the faulted impedance of remote end is not involved. The effect of load flow and fault resistance on the accuracy of fault location are effectively eliminated, therefore an accurate algorithm of locating fault is derived. The algorithm is demonstrated by digital computer simulations and the results show that errors in locating fault are less than 1%.展开更多
A novel numerical algorithm of fault location estimation for four-line fault without ground connection involving phases from each of the parallel lines is presented in this paper. It is based on one-terminal voltage a...A novel numerical algorithm of fault location estimation for four-line fault without ground connection involving phases from each of the parallel lines is presented in this paper. It is based on one-terminal voltage and current data. The loop and nodal equations comparing faulted phase to non-faulted phase of two-parallel lines are introduced in the fault location estimation model, in which the source impedance of a remote end is not involved. The effects of load flow and fault resistance on the accuracy of fault location are effectively eliminated, therefore a precise algorithm of locating fault is derived. The algorithm is demonstrated by digital computer simulations.展开更多
With proper phase module transformation,parallel lines can be decomposed to the same directional net and the reverse directional net. The propagation characteristics of traveling waves in the reverse directional net w...With proper phase module transformation,parallel lines can be decomposed to the same directional net and the reverse directional net. The propagation characteristics of traveling waves in the reverse directional net were analyzed,and the refraction coefficient at the fault point for a single phase fault was derived. In addition,the module selection was discussed. Simulation results show that satisfying accuracy can be achieved with the proposed method. Moreover,it is immune to fault types,fault resistances,and outside system parameters.展开更多
An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system is presented. The algorithm, which employs the faulted phase network and zero-sequence netwo...An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system is presented. The algorithm, which employs the faulted phase network and zero-sequence network as fault-location model in which the source impedance at the remote end is not involved, ef-fectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The algorithm achieves accurate location by measuring only one local end data and is used in a procedure that provides automatic determination of faulted types and phases, and does not require the engineer to specify them. Simulation results showed the effectiveness of the algorithm under the condition of double phase-to-earth fault.展开更多
The results of T-Line Traveling Wave Fault Location is easily influenced by the wave arrival time and traveling wave propagation velocity;it proposes that the traveling wave uses wavelet transform to extract the modul...The results of T-Line Traveling Wave Fault Location is easily influenced by the wave arrival time and traveling wave propagation velocity;it proposes that the traveling wave uses wavelet transform to extract the modulus maxima of breakdown voltage, to confirm the time of the traveling wave reaching the three-terminal line. The speed of the traveling wave reaching three terminals is confirmed by the structural parameters of the transmission line. We apply the arrival time and propagation velocity to the T-type traveling wave fault location algorithm. Different transmission line distance select the corresponding algorithm, excluding the impact of fault branches and in some cases ranging accuracy, the failure dead zone will not appear. After MATLAB simulation analysis, the algorithm analysis is clear;the range accuracy is high, so that it can meet the requirements of fault location.展开更多
In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location,a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in th...In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location,a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in this paper.Firstly,the 3-terminal synchronous fundamental positive sequence voltage and current phasors are extracted and substituted into the fault branch distance function to realize the selection of fault branch when the fault occurs;Secondly,use the condition of the fundamental positive sequence voltage phasor at the fault point is equal to calculate all roots(including real root and virtual roots);Finally,the phase-angle jump check function is used for checking calculation,and then the only real root can be determined as the actual fault distance,thereby achieving the purpose of high-precision fault location.MATLAB simulation results show that the proposed new algorithm is feasible and effective with high fault location accuracy and good versatility.展开更多
Fault location and distance protection are essential smart grid technologies ensuring reliability of the power system. This paper describes an accurate algorithm for locating faults on double-circuit transmission line...Fault location and distance protection are essential smart grid technologies ensuring reliability of the power system. This paper describes an accurate algorithm for locating faults on double-circuit transmission lines. The proposed approach is capable of identifying the faulted circuit of a parallel transmission line by checking the estimated fault location and fault resistance. Voltage and current measurements from only one of the terminals of the faulty line are used. No pre-fault data are required for the estimation. The lumped parameter line model considering shunt capacitance is utilized for the derivation of the algorithm. It’s assumed that line parameters are known and transmission lines are fully transposed. The method is applicable to all types of faults. It’s evinced by evaluation studies that the proposed algorithm can correctly determine the faulted circuit in most cases. For exceptional cases, the current waveforms during the fault can be used to help identify the faulted circuit. The proposed algorithm generates quite accurate fault location estimates, and may be suitable for distance relaying.展开更多
An accurate fault location algorithm for double-circuit series compensated lines is presented.Use of two-end unsynchronized measurements of current and voltage signals is considered.The algorithm applies two subroutin...An accurate fault location algorithm for double-circuit series compensated lines is presented.Use of two-end unsynchronized measurements of current and voltage signals is considered.The algorithm applies two subroutines,designated for locating faults on particular line sections,and additionally the procedure for selecting the valid subroutine.The subroutines are formulated with use of the generalized fault loop model and the distributed parameter line model is applied.Performed ATP-EMTP based evaluation has shown the validity of the derived fault location algorithm and its high accuracy.展开更多
Anewfault location algorithmfor double-circuit transmissionlines is described inthis paper.Theproposed method uses data extractedfromtwo ends of the transmissionlines andthus eliminates the effects ofthe source impeda...Anewfault location algorithmfor double-circuit transmissionlines is described inthis paper.Theproposed method uses data extractedfromtwo ends of the transmissionlines andthus eliminates the effects ofthe source impedance andthe fault resistance.The distributed parameter model and the modal transformationare also employed.Depending on modal transformation,the coupled equations of the lines are converted intodecoupled ones.Inthis way,the mutual coupling effects between adjacent circuits of the lines are eliminatedandtherefore an accurate fault location can be achieved.The proposed methodis tested via digital simulationusing EMTP in conjunction with MATLAB.The test results corroborate the high accuracy of the proposedmethod.展开更多
In modem protection relays, the accurate and fast fault location is an essential task for transmission line protection from the point of service restoration and reliability. The applications of neural networks based f...In modem protection relays, the accurate and fast fault location is an essential task for transmission line protection from the point of service restoration and reliability. The applications of neural networks based fault location techniques to transmission line are available in many papers. However, almost all the studies have so far employed the FNN (feed-forward neural network) trained with back-propagation algorithm (BPNN) which has a better structure and been widely used. But there are still many drawbacks if we simply use feed-forward neural network, such as slow training rate, easy to trap into local minimum point, and bad ability on global search. In this paper, feed-forward neural network trained by PSO (particle swarm optimization) algorithm is proposed for fault location scheme in 500 kV transmission system with distributed parameters presentation, The purpose is to simulate distance protection relay. The algorithm acts as classifier which requires phasor measurements data from one end of the transmission line and DFT (discrete Fourier transform). Extensive simulation studies carried out using MATLAB show that the proposed scheme has the ability to give a good estimation of fault location under various fault conditions.展开更多
Precise fault location plays an important role in the reliability of modern power systems.With the in-creasing penetration of renewable energy sources,the power system experiences a decrease in system inertia and alte...Precise fault location plays an important role in the reliability of modern power systems.With the in-creasing penetration of renewable energy sources,the power system experiences a decrease in system inertia and alterations in steady-state characteristics following a fault occurrence.Most existing single-ended phasor domain methods assume a certain impedance of the remote-end system or consistent current phases at both ends.These problems present challenges to the applicability of con-ventional phasor-domain location methods.This paper presents a novel single-ended time domain fault location method for single-phase-to-ground faults,one which fully considers the distributed parameters of the line model.The fitting of transient signals in the time domain is real-ized to extract the instantaneous amplitude and phase.Then,to eliminate the error caused by assumptions of lumped series resistance in the Bergeron model,an im-proved numerical derivation is presented for the distrib-uted parameter line model.The instantaneous symmet-rical components are extracted for decoupling and inverse transformation of three-phase recording data.Based on the above,the equation of instantaneous phase constraint is established to effectively identify the fault location.The proposed location method reduces the negative effects of fault resistance and the uncertainty of remote end pa-rameters when relying on one-terminal data for localiza-tion.Additionally,the proposed fault analysis methods have the ability to adapt to transient processes in power systems.Through comparisons with existing methods in three different systems,the fault position is correctly identified within an error of 1%.Also,the results are not affected by sampling rates,data windows,fault inception angles,and load conditions. Index Terms—Fault location,distributed parameter line model,transient signal,renewable energy,instantaneous phase.展开更多
基金This work was funded by the project of State Grid Hunan Electric Power Research Institute(No.SGHNDK00PWJS2210033).
文摘The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-branch fault location algorithm makes it difficult to meet the demands of high-precision fault localization in the multi-branch distribution network system.In this paper,the multi-branch mainline is decomposed into single branch lines,transforming the complex multi-branch fault location problem into a double-ended fault location problem.Based on the different transmission characteristics of the fault-traveling wave in fault lines and non-fault lines,the endpoint reference time difference matrix S and the fault time difference matrix G were established.The time variation rule of the fault-traveling wave arriving at each endpoint before and after a fault was comprehensively utilized.To realize the fault segment location,the least square method was introduced.It was used to find the first-order fitting relation that satisfies the matching relationship between the corresponding row vector and the first-order function in the two matrices,to realize the fault segment location.Then,the time difference matrix is used to determine the traveling wave velocity,which,combined with the double-ended traveling wave location,enables accurate fault location.
基金supported by the National Natural Science Foundation of China(No.11905074).
文摘Radio-frequency(RF)breakdown analysis and location are critical for successful development of high-gradient traveling-wave(TW)accelerators,especially those expected to generate high-intensity,high-power beams.Compared with commonly used schemes involving dedicated devices or complicated techniques,a convenient approach for breakdown locating based on transmission line(TL)theory offers advantages in the typical constant-gradient TW-accelerating structure.To deliver such an approach,an equivalent TL model has been constructed to equate the TW-accelerating structure based on the fun-damental theory of the TL transient response in the time domain.An equivalence relationship between the TW-accelerating structure and the TL model has been established via analytical derivations associated with grid charts and verified by TL circuit simulations.Furthermore,to validate the proposed fault-locating method in practical applications,an elaborate analysis via such a method has been conducted for the recoverable RF-breakdown phenomena observed at an existing prototype of a TW-accelerating-structure-based beam injector constructed at the Huazhong University of Science and Technology.In addition,further considerations and discussion for extending the applications of the proposed method have been given.This breakdown-locating approach involving the transient response in the framework of TL theory can be a conceivable supple-ment to existing methods,facilitating solution to construction problems at an affordable cost.
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Postdoctoral Foundation of China(No.20070410755)PAN Zhencun,born in 1962,male,postdoctor researcher.
文摘A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in this paper.A special diagnostic signal current is injected into the fault distribution system,and then it is detected at the outlet terminals to identify the fault line and at the sectionalizing or branching point along the fault line to locate the fault section.The method has been put into application in actual distribution network and field experience shows that it can identify the fault line and locate the fault section correctly and effectively.
基金Supported by Science Foundation of Guangdong(No.990 577)
文摘A novel numerical algorithm of fault location estimation for double line to ground fault involving different phases from each of two parallel lines is presented in this paper.It is based on the one terminal voltage and current data.The loop and nodal equations comparing faulted phase with non faulted phase of two parallel lines are introduced in the fault location estimation models,in which the source impedance of a remote end is not involved.The effects of load flow and fault resistance on the accuracy of fault location are effectively eliminated,therefore precise algorithms of locating fault are derived.The algorithm is demonstrated by digital computer simulations.
文摘The modern travelling wave based fault location principles for transmission lines are analyzed.In order to apply the travelling wave principles to HVDC transmission lines,the special technical problems are studied.Based on this,a fault locating system for HVDC transmission lines is developed.The system can support modern double ended and single ended travelling wave princi- ples simultaneously,and it is composed of three different parts:travelling wave data acquisition and processing system,communication network and PC based master station.In the system,the fault generated transients are induced from the ground leads of the over-voltage suppression capacitors of an HVDC line through specially developed travelling wave couplers.The system was applied to 500 kV Gezhouba-Nanqiao(Shanghai)HVDC transmission line in China.Some field operation experiences are summarized,showing that the system has very high reliability and accuracy,and the maximum location error is about 3 km(not more than 0.3%of the total line length). Obviously,the application of the system is successful,and the fault location problem has finally been solved completely since the line operation.
基金Project Supported by Chongqing Science and Technology Committee(2005AA600)
文摘This paper introduced correlation method to locate transmission line fault.First it described the principle of transmission line fault location based on traveling waves.The principle of correlation analysis is introduced,then the method using correlation analysis in fault location is given.Transmission line model is established with EMTP-ATP.Basing on the model,some kinds of fault are simulated.The feasibility of this algorithm is proved based on simulation results.By comparing with the classical wavelet analysis,this paper gave the advantages of this algorithm in two cases:noise influence suppression and accuracy of near distance fault location.Experiment is established to simulate transmission line grounding fault.The experiment result showed the correlation algorithm's validity.All the analysis result indicated that the correlation algorithm have a high precision.
文摘:A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system(TPTLS)as influenced by the mutual effect to determine the fault location is discussed in this work.The distance relay measures the impedance to the fault location which is the positive-sequence.The principle of summation the positive-,negative-,and zero-sequence voltages which equal zero is used to determine the fault location on the TPTLS.Also,the impedance of the transmission line to the fault location is determined.These algorithms are applied to single-line-to-ground(SLG)and double-line-to-ground(DLG)faults.To detect the fault location along the transmission line,its impedance as seen by the distance relay is determined to indicate if the fault is within the relay’s reach area.TPTLS under study are fed from one-and both-ends.A schematic diagrams are obtained for the impedance relays to determine the fault location with high accuracy.
文摘An accurate numerical algorithm for three-line fault involving different phases from each of two-parallel lines is presented. It is based on one-terminal voltage and current data. The loop and nodel equations comparing faulted phase to non-faulted phase of two-parallel lines are introduced in the fault location estimation modal, in which the faulted impedance of remote end is not involved. The effect of load flow and fault resistance on the accuracy of fault location are effectively eliminated, therefore an accurate algorithm of locating fault is derived. The algorithm is demonstrated by digital computer simulations and the results show that errors in locating fault are less than 1%.
文摘A novel numerical algorithm of fault location estimation for four-line fault without ground connection involving phases from each of the parallel lines is presented in this paper. It is based on one-terminal voltage and current data. The loop and nodal equations comparing faulted phase to non-faulted phase of two-parallel lines are introduced in the fault location estimation model, in which the source impedance of a remote end is not involved. The effects of load flow and fault resistance on the accuracy of fault location are effectively eliminated, therefore a precise algorithm of locating fault is derived. The algorithm is demonstrated by digital computer simulations.
基金Sponsored by the Ph.D. Programs Foundation of Ministry of Education of China(Grant No.20070286047)the Scientific Innovation Foundation forYoungster of CSEE
文摘With proper phase module transformation,parallel lines can be decomposed to the same directional net and the reverse directional net. The propagation characteristics of traveling waves in the reverse directional net were analyzed,and the refraction coefficient at the fault point for a single phase fault was derived. In addition,the module selection was discussed. Simulation results show that satisfying accuracy can be achieved with the proposed method. Moreover,it is immune to fault types,fault resistances,and outside system parameters.
文摘An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system is presented. The algorithm, which employs the faulted phase network and zero-sequence network as fault-location model in which the source impedance at the remote end is not involved, ef-fectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The algorithm achieves accurate location by measuring only one local end data and is used in a procedure that provides automatic determination of faulted types and phases, and does not require the engineer to specify them. Simulation results showed the effectiveness of the algorithm under the condition of double phase-to-earth fault.
文摘The results of T-Line Traveling Wave Fault Location is easily influenced by the wave arrival time and traveling wave propagation velocity;it proposes that the traveling wave uses wavelet transform to extract the modulus maxima of breakdown voltage, to confirm the time of the traveling wave reaching the three-terminal line. The speed of the traveling wave reaching three terminals is confirmed by the structural parameters of the transmission line. We apply the arrival time and propagation velocity to the T-type traveling wave fault location algorithm. Different transmission line distance select the corresponding algorithm, excluding the impact of fault branches and in some cases ranging accuracy, the failure dead zone will not appear. After MATLAB simulation analysis, the algorithm analysis is clear;the range accuracy is high, so that it can meet the requirements of fault location.
基金supported by National Nature Science Foundation of China(51507031).
文摘In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location,a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in this paper.Firstly,the 3-terminal synchronous fundamental positive sequence voltage and current phasors are extracted and substituted into the fault branch distance function to realize the selection of fault branch when the fault occurs;Secondly,use the condition of the fundamental positive sequence voltage phasor at the fault point is equal to calculate all roots(including real root and virtual roots);Finally,the phase-angle jump check function is used for checking calculation,and then the only real root can be determined as the actual fault distance,thereby achieving the purpose of high-precision fault location.MATLAB simulation results show that the proposed new algorithm is feasible and effective with high fault location accuracy and good versatility.
文摘Fault location and distance protection are essential smart grid technologies ensuring reliability of the power system. This paper describes an accurate algorithm for locating faults on double-circuit transmission lines. The proposed approach is capable of identifying the faulted circuit of a parallel transmission line by checking the estimated fault location and fault resistance. Voltage and current measurements from only one of the terminals of the faulty line are used. No pre-fault data are required for the estimation. The lumped parameter line model considering shunt capacitance is utilized for the derivation of the algorithm. It’s assumed that line parameters are known and transmission lines are fully transposed. The method is applicable to all types of faults. It’s evinced by evaluation studies that the proposed algorithm can correctly determine the faulted circuit in most cases. For exceptional cases, the current waveforms during the fault can be used to help identify the faulted circuit. The proposed algorithm generates quite accurate fault location estimates, and may be suitable for distance relaying.
文摘An accurate fault location algorithm for double-circuit series compensated lines is presented.Use of two-end unsynchronized measurements of current and voltage signals is considered.The algorithm applies two subroutines,designated for locating faults on particular line sections,and additionally the procedure for selecting the valid subroutine.The subroutines are formulated with use of the generalized fault loop model and the distributed parameter line model is applied.Performed ATP-EMTP based evaluation has shown the validity of the derived fault location algorithm and its high accuracy.
文摘Anewfault location algorithmfor double-circuit transmissionlines is described inthis paper.Theproposed method uses data extractedfromtwo ends of the transmissionlines andthus eliminates the effects ofthe source impedance andthe fault resistance.The distributed parameter model and the modal transformationare also employed.Depending on modal transformation,the coupled equations of the lines are converted intodecoupled ones.Inthis way,the mutual coupling effects between adjacent circuits of the lines are eliminatedandtherefore an accurate fault location can be achieved.The proposed methodis tested via digital simulationusing EMTP in conjunction with MATLAB.The test results corroborate the high accuracy of the proposedmethod.
文摘In modem protection relays, the accurate and fast fault location is an essential task for transmission line protection from the point of service restoration and reliability. The applications of neural networks based fault location techniques to transmission line are available in many papers. However, almost all the studies have so far employed the FNN (feed-forward neural network) trained with back-propagation algorithm (BPNN) which has a better structure and been widely used. But there are still many drawbacks if we simply use feed-forward neural network, such as slow training rate, easy to trap into local minimum point, and bad ability on global search. In this paper, feed-forward neural network trained by PSO (particle swarm optimization) algorithm is proposed for fault location scheme in 500 kV transmission system with distributed parameters presentation, The purpose is to simulate distance protection relay. The algorithm acts as classifier which requires phasor measurements data from one end of the transmission line and DFT (discrete Fourier transform). Extensive simulation studies carried out using MATLAB show that the proposed scheme has the ability to give a good estimation of fault location under various fault conditions.
文摘Precise fault location plays an important role in the reliability of modern power systems.With the in-creasing penetration of renewable energy sources,the power system experiences a decrease in system inertia and alterations in steady-state characteristics following a fault occurrence.Most existing single-ended phasor domain methods assume a certain impedance of the remote-end system or consistent current phases at both ends.These problems present challenges to the applicability of con-ventional phasor-domain location methods.This paper presents a novel single-ended time domain fault location method for single-phase-to-ground faults,one which fully considers the distributed parameters of the line model.The fitting of transient signals in the time domain is real-ized to extract the instantaneous amplitude and phase.Then,to eliminate the error caused by assumptions of lumped series resistance in the Bergeron model,an im-proved numerical derivation is presented for the distrib-uted parameter line model.The instantaneous symmet-rical components are extracted for decoupling and inverse transformation of three-phase recording data.Based on the above,the equation of instantaneous phase constraint is established to effectively identify the fault location.The proposed location method reduces the negative effects of fault resistance and the uncertainty of remote end pa-rameters when relying on one-terminal data for localiza-tion.Additionally,the proposed fault analysis methods have the ability to adapt to transient processes in power systems.Through comparisons with existing methods in three different systems,the fault position is correctly identified within an error of 1%.Also,the results are not affected by sampling rates,data windows,fault inception angles,and load conditions. Index Terms—Fault location,distributed parameter line model,transient signal,renewable energy,instantaneous phase.