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
It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of sing...It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of single-phase earth fault current distribution and case verification were accomplished by using the loop method.Influences of some factors,such as single-phase earth fault location and ground resistance of poles,on short-circuit current distribution were discussed.Results show that:1) results of the loop method conform to those of double sided elimination method;2) the fault location hardly influences macro-distribution of short-circuit current.However,current near fault location is evidently influenced;and 3) the short-circuit current distribution is not so sensitive to the ground resistance of poles.展开更多
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
Intrusions in the Zhangbaling uplift zone and the eastern margin of the Dabie orogenic belt belong to the syntectonic intrusions developed during the strike-slip stage in the southern segment of the Tan-Lu fault zone....Intrusions in the Zhangbaling uplift zone and the eastern margin of the Dabie orogenic belt belong to the syntectonic intrusions developed during the strike-slip stage in the southern segment of the Tan-Lu fault zone. However, characteristics of rare earth elements show that intrusions in the Zhangbaling uplift zone have the characteristics of mantle source type and those in the eastern margin of Dabie belt are the typical crust source type. Therefore, Au-deposits related to the intrusions in the Zhangbaling uplift zone are developed better than those in the eastern margin of the Dabieshan. The research results of the rare earth elements coincide with the studies of geophysics, tectonic setting and stable isotope. It is further indicated that the rare earth elements offer effective approach to tracing the material sources of magmatic rocks.展开更多
The relation between the local mean lunar time τ of earthquake occurrence and their fault trends is studied in this paper. The local mean lunar times τ of 53 earthquakes in 24 groups are calculated. Because ...The relation between the local mean lunar time τ of earthquake occurrence and their fault trends is studied in this paper. The local mean lunar times τ of 53 earthquakes in 24 groups are calculated. Because the tidal generation force arisen by the moon is a cyclic function of about 12 hours 25 minutes in the main, the two tidal generation forces anywhere in the earth arising by the moon are equal in general when the moon lies to the two sites of 180° interval of local mean lunar time. Based on this phenomenon the values Δ τ of τ 1- τ 2 or τ 1-τ 2±180° of two earthquakes occurring repetitiously in the same place are also calculated. The calculated results show that if the fault trends of the two earthquakes in the same place is near, the Δ τ is usually smaller and if the fault trends of the two ones is not near, the Δ τ is usually larger and the distribution of the local mean lunar time τ of earthquakes in different places is dispersive even if fault trends of these earthquakes are near, and the τ does not concentrate on the lower and upper transit of the moon. The above phenomena clear up that the triggering earthquake of earth solid tide arisen by the moon is relative with the fault trends of earthquakes and we ought to think over the difference of environmental conditions of earthquake preparation of each seismogenic zone and can not make statistics to earthquakes in different places when we study the relation between the solid earth tide arisen by the moon and earthquakes.展开更多
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It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of single-phase earth fault current distribution and case verification were accomplished by using the loop method.Influences of some factors,such as single-phase earth fault location and ground resistance of poles,on short-circuit current distribution were discussed.Results show that:1) results of the loop method conform to those of double sided elimination method;2) the fault location hardly influences macro-distribution of short-circuit current.However,current near fault location is evidently influenced;and 3) the short-circuit current distribution is not so sensitive to the ground resistance of poles.
基金This work was supported in part by National Science Foundation of China(No.51907097)National Key R&D Program of China(No.2020YFF0305800)+1 种基金the Full-time Postdoc Research and Development Fund of Sichuan University in China(No.2019SCU12003)the Applied Basic Research of Sichuan Province(No.2020YJ0012).
文摘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.
基金Project supported by the National Natural Science Foundation of China (40272094)
文摘Intrusions in the Zhangbaling uplift zone and the eastern margin of the Dabie orogenic belt belong to the syntectonic intrusions developed during the strike-slip stage in the southern segment of the Tan-Lu fault zone. However, characteristics of rare earth elements show that intrusions in the Zhangbaling uplift zone have the characteristics of mantle source type and those in the eastern margin of Dabie belt are the typical crust source type. Therefore, Au-deposits related to the intrusions in the Zhangbaling uplift zone are developed better than those in the eastern margin of the Dabieshan. The research results of the rare earth elements coincide with the studies of geophysics, tectonic setting and stable isotope. It is further indicated that the rare earth elements offer effective approach to tracing the material sources of magmatic rocks.
文摘The relation between the local mean lunar time τ of earthquake occurrence and their fault trends is studied in this paper. The local mean lunar times τ of 53 earthquakes in 24 groups are calculated. Because the tidal generation force arisen by the moon is a cyclic function of about 12 hours 25 minutes in the main, the two tidal generation forces anywhere in the earth arising by the moon are equal in general when the moon lies to the two sites of 180° interval of local mean lunar time. Based on this phenomenon the values Δ τ of τ 1- τ 2 or τ 1-τ 2±180° of two earthquakes occurring repetitiously in the same place are also calculated. The calculated results show that if the fault trends of the two earthquakes in the same place is near, the Δ τ is usually smaller and if the fault trends of the two ones is not near, the Δ τ is usually larger and the distribution of the local mean lunar time τ of earthquakes in different places is dispersive even if fault trends of these earthquakes are near, and the τ does not concentrate on the lower and upper transit of the moon. The above phenomena clear up that the triggering earthquake of earth solid tide arisen by the moon is relative with the fault trends of earthquakes and we ought to think over the difference of environmental conditions of earthquake preparation of each seismogenic zone and can not make statistics to earthquakes in different places when we study the relation between the solid earth tide arisen by the moon and earthquakes.
