682 results about "Cable fault location" patented technology

The invention relates to a cable-overhead joint line failure travelling wave range count method, particularly performing the effective fusion based on the failure range count method of the fundamental frequency and the travelling wave aiming at the particularity and the complexity of the cable joint line, belonging to the technical field of the power system relay protection. The invention judges the failure generating places firstly based on the cable-overhead junction derivated through the electric quantity at the two ends of the system attached with the negative sequence net after the failure, then performs the correct range count by the range count method of the single end; on the basis of considering the line zero modulus component couple, through comparing the performance of the current travelling wave line zero modulus component, the performance of each reflected wave is judged, to find out the fault point reflected wave, and then perform the correct range count.

The invention discloses a time-domain failure distance measuring method with two asynchronous ends of a direct-current power line and self-adaptive parameters, which comprises the following steps of: setting up an asynchronous time-domain failure observation equation of the direct-current line, which includes quantities of fault distance, distributed resistances of the line, transmission wave velocity, wave impedance, asynchronous time difference of data at the two ends and the like to be observed; taking the time of initial failure traveling waves which arrive at the two ends of the line respectively as reference time of data at each end; introducing a traveling wave characteristic equation; and eliminating the quantities to be observed of asynchronous time difference in the time-domain failure observing equation, thus obtaining a novel time-domain failure distance measuring method of the direct-current line so as to realize self-adaption of the line parameter self-adapting without synchronizing with a clock. The time-domain failure distance measuring method has higher transition resistance durability and can effectively improve the accuracy and reliability of failure distance measurement at the two ends of the direct-current line.

The invention discloses a fault positioning method for a transmission line and belongs to the technical field of power systems. The fault positioning method comprises the following steps: arranging a Rogowski coil-based broadband core-through traveling wave detection device on the high-voltage transmission line; acquiring a current traveling wave signal of a three-phase line; performing singular value detection by applying the phase mode conversion and wavelet mode maximum principle; accurately identifying the traveling wave line mode wave head, and accurately determining the wave head arrival time by using a GPS high-precision clock; and measuring the wave speed of real-time traveling wave mode on line according to different wave head time difference information to realize accurate fault positioning. The fault positioning method has the advantages of effectively avoiding two main factors influencing the traveling wave fault positioning precision, along with high positioning precision and accurate and reliable fault positioning result.

The invention relates to a distributed single-phase earth fault ranging system that is used for realizing ranging of a fault on a high tension transmission line between two transformer substations. The system comprises: at least two sets of fault current detection device sets, which are installed at preset test points of a high tension transmission line; a remote wireless communication module; and a remote monitoring master station. The remote monitoring master station is respectively connected with the fault current detection device sets by the remote wireless communication module as well as receives fault currents collected by the fault current detection device sets by the remote wireless communication module; and the remote monitoring master station carries out comparison and an analysis according to positional data of the preset test points and length data of the high tension transmission line, so that a final fault position is obtained. In addition, a ranging method of the distributed single-phase earth fault ranging system is also provided. Power frequency fault current information and fault current travelling wave energy information are utilized to determine fault intervals; and different positioning equations are selected according to different fault intervals as well as fault point positions are determined; therefore, a dead zone problem can be solved, wherein the problem occurs when there are faults at a head and an end of a line, that is, when a fault point approaches a bus.

The present invention relates to the relay protection method in the field of a power system. The present invention discloses a method for realizing two-terminal fault location in the power system through two terminal synchronism sampling current and voltage according to the method of equal voltages at two ends of a fault point and using a phase current and a phase voltage without zero sequence current and zero sequence voltage. The method comprises main steps as follows: a line protection device samples to a line side current sensor secondary current and voltage sensor secondary voltage to obtain a corresponding instantaneous value of the current and the voltage. The Fourier form of a three phase current and a three phase voltage on the side is worked out using a Fourier algorithm. The phasor form of phase current and phase voltage obtained by filtering to compute of protecting synchronism sampling on the other side is received through optical fiber network of communication. The distance from the protection arranging place to the fault point is obtained using the situation that the phase voltages on two sides of the fault point is equal with each other. The method is not affected by the power supply impedance and the transition resistance in the line operation method. Theory and practice prove that the method greatly improves the accuracy of transmission line fault location.

The invention discloses a distributed fault location method for an overhead line-cable hybrid circuit. The method comprises the following steps: S1, arranging fault traveling wave detection devices at the joint of the hybrid circuit and a bus and the joints of different circuits in the hybrid circuit, judging a failed circuit according to the polarity of a first fault travelling wave head detected by each fault traveling wave detection device, wherein when fault current travelling wave heads detected by two adjacent fault travelling wave detecting devices are of opposite polarities, a circuit between the two adjacent fault travelling wave detection device is the failed circuit; and S2, judging the source of a second travelling wave head according to the arriving time of the fault travelling wave heads detected by the fault travelling wave detection devices at the two ends of the failed circuit, and selecting a proper fault location method for positioning. According to the distributed fault location method, online calculation of the travelling wave transmission speed of a power transmission line is realized, and the source of a second fault travelling wave of a detection point is judged according to the analysis of a travelling wave sequence; and the method has a good application prospect.

The invention provides a fault distance measuring method for a combined travelling wave of a power transmission line. The method comprises the following steps of: firstly, performing primary fault distance measurement with the single-end principle to obtain two possible fault positions; and then, comparing the time difference of the fault initial travelling wave arriving at the two sides of the line with the time difference of the fault travelling wave arriving at the two ends of the line after the possible fault points fail, so as to obtain the real fault point determined by the single-end travelling wave principle. The method has the advantages that: as the obtained distance measurement result is obtained by the single-end principle, the influence of the mixed line length error caused by the distance measurement adopting the double-end principle and the accurate time synchronization problem between the two sides of the line on the distance measurement accuracy is eliminated, thus the accuracy and reliability of the distance measurement are improved. Through the method, the fault distance measurement for the travelling wave of the power line is realized, and the reliability and accuracy of the travelling wave distance measurement are improved; and after the line fails, the fault point can be found without taking much time, the power supply reliability is improved, and the method has wide application prospects.

The invention relates to a single-end fault ranging method based on initial reversed-polarity directional traveling wave detection, which can effectively realize single-end traveling wave fault ranging and has high reliability and high accuracy. The method comprises the following steps: (1) when a traveling wave fault ranging device is started, testing the arriving time t1 of the line modular component of the initial traveling wave of a fault, and extracting traveling wave signals in the time interval [0, 2L/v], wherein L indicates the length of the line, and v indicates the wave speed of theline module component; (2) testing the initial reversed-polarity directional traveling wave in the time interval, calculating the difference of the arriving time of the line modular component of the initial reversed-polarity directional traveling wave and the arriving time of the line modular component of the initial traveling wave of the fault, determining whether the fault is a nearby fault or a remote fault with reference to Curve Chart 3, and accordingly determining the section with the fault point; (3) judging the properties of the second arriving wave head through the determined fault section; and (4) determining final ranging results through the initial traveling wave and the wave head of the second traveling wave of the fault.

The invention relates to a method for hybrid electric power circuit fault distance measurement of a power distribution network, in particular to a method for hybrid circuit combined distance measurement of the power distribution network based on single-ended fault information. The method for hybrid circuit combined distance measurement comprises the steps that firstly, high-frequency traveling wave components of a fault current signal and a fault voltage signal of a hybrid circuit are decomposed; secondly, the wave velocity of traveling waves transmitted in an overhead line and a cable is measured offline; thirdly, preliminary fault distance measurement is conducted according to a correlation coefficient analytical method; fourthly, final fault distance measurement is conducted according to a wave tip combining method; fifthly, a fault distance measurement result is verified. According to the method, only the fault information measured at one end of the circuit is used, initial wave tips and various reflecting wave tips of the traveling waves can be effectively extracted when a fault occurs, the method can be applied to the occasions without the double-ended traveling wave distance measurement function, accurate fault distance measurement is achieved, and the defects of fault distance measurement in the hybrid circuit of an existing power distribution network are overcome. According to the method, on the basis that fault distance measurement is achieved through the current traveling waves, a voltage traveling wave distance measurement result is comprehensively considered, and the reliability and the accuracy of distance measurement judgment are improved.

The invention provides a fault location method based on single-terminal location. The method is characterized by using a transmission line travelling wave fault location device to measure the power frequency quantity of a home terminal bus of a transmission line when short circuit happens to the transmission line, determining the fault point range by an impedance method and estimating the transition resistance; then analyzing the transient voltage/current travelling waves through wavelet transform and adopting a single-terminal travelling wave method combined with the length of line to directly compute the positions of the fault points if the faults are judged to be common short circuit faults; and adopting a transmission line single-terminal fault location method combining the impedance method and the travelling wave method to compute the positions of the fault points if the faults are judged to be special short circuit faults. The method has the following beneficial effects: the accuracy of fault location is ensured by utilizing the single-terminal travelling wave method, can be within 500m and is not affected by such factors as the length of line and the like; and the method can adapt to fault location under the condition of different fault types and is basically not affected by such factors as the transition resistance, the line structure, the system operation mode and the like.

The present invention discloses a failure distance-measuring method of uniform and non-uniform zero-sequence mutual inductance and multi-loop circuit with loops of different voltage levels arranged on the same rod or with the same electricity-transmitting corridor. Based on a distributed parameter model, the method samples the voltage and current synchronously at two ends. As for the parallel multi-loop circuit with the loops arranged on the same rod and with the same electricity-transmitting corridor, the influence of mutual inductance of the positive sequence and negative sequence between the loops can be ignored. When the power line has a single-line or over-line failure, the positive-sequence voltage and the negative-sequence voltage, which are respectively calculated from two sides of the fault point, should be equal to the sum of the positive-sequence voltage and the negative-sequence voltage, so as to solve the fault distance equation based on the positive-sequence component, negative-sequence component, or the positive-sequence and negative-sequence component. When the protection indicates that the line has an internal failure, the failure distance can be measured according to the fault distance equation. The mutual inductance between the lines which can be even or uneven has no influence on the distance measurement of the loops arranged on the same rod. The method can be used for precise distance measurement of the loops arranged on the same rod, which have various topological structures.

The present invention belongs to the field of power system, including four portions of topping machine, background machine, power system synchroclock and printer, in which the topping machine includes steady-state voltage and current collecting unit, transient voltage and current collecting unit, high-frequency collecting unit and GPS (global navigational satellite timing and distance-measuring system) time synchronization unit which can be used for providing accurate time mark and interfaced with power system synchroclock. The background machine adopts industrial control computer for fault data analysis and processing, the power system synchroclock is used for providing accurate time information and the printer can be used for printing fault record and fault distance-reasuring result.

The invention relates to a two-end distance measuring method of transmission line fault under a dynamic condition, comprising the following steps of: acquiring two-end voltage and current signals through two-end phasor measurement units of the transmission line; then acquiring dynamic positive sequence impedance, admittance, wave impedance and propagation coefficients according to line parameter estimation and a dynamic line parameter method; and finally solving a nonlinear equation related to a fault distance according to the fact that positive sequence voltages derived from two ends to a fault point are equal by applying a Newton iteration method so as to obtain a dynamic distance measuring result of the transmission line fault. The two-end distance measuring method can more effectivelysolve the problem of line parameter and fault distance estimation under the dynamic condition and has accurate and reliable fault distance measuring result.

The invention discloses a fault localization method suitable for a three-terminal T connection electric transmission line, comprising the following steps: firstly, judging the running state of the three-terminal electric transmission line: if the line is in a three-terminal running mode, firstly identifying a fault branch line, and calculating the fault distance according to the electric quantityof both ends of a T connection point and the endpoint of the fault branch line; if the line is in a two-terminal running mode or one side branch line is in a three-terminal running mode in a hot standby state, firstly determining if a fault point is at a switch cut-off branch line or not, if so, adopting a single-terminal localization method to calculate the distance from the T connection point tothe fault point, thereby obtaining the fault distance from the endpoint of the branch line to the fault point; but if the fault point is not at the switch cut-off branch line, respectively carrying out fault localization calculation under the two-terminal running mode or the three-terminal running mode. The invention provides a fault localization method before/after converting the running mode ofthe three-terminal electric transmission line and a fault localization method when the line is in the two-terminal running mode or one side branch line is in the three-terminal running mode under thehot standby condition.

A power distribution network one-phase grounding fault location method based on a zero sequence voltage belongs to a power distribution network grounding fault location method. The fault location method starts from an overall zero sequence parameter of a single-end radial medium voltage power distribution network, analyzes a one-phase grounding fault while taking a distributed parameter model influence into consideration, measures a steady-state zero sequence voltage value and a zero sequence current of each feeder line at a bus position and at a tail end of each outlet line, and finds zero sequence voltage variation characteristics of a fault feeder line and non-fault feeder line. According to the invention, a large number of existing devices are used, the data sampling requirement is low in terms of being real-time, and the method of the invention is easy to realize; the simulation model analysis is established according to the actual parameters, so that the fault location can be realized in the system in which the neutral point is not grounded or the neutral point is grounded through an arc suppression coil; the precision is quite high; and the location method of the invention can be applied to the medium and low voltage power distribution network.

The invention provides a combined traveling wave fault location method of a high-voltage overhead line and cable hybrid line. The method comprises the following steps of: firstly, carrying out fault section selection by using a double-ended principle according to time difference generated when a fault initial traveling wave of the hybrid line arrives at two ends, then carrying out initial fault location by using a single-ended principle, and finally working out an accurate result via the single-ended principle by combining with the time difference generated when the fault initial traveling wave arrives at two sides of the line. The method has the advantages that: the obtained fault location result is the result of the single-ended fault location principle, and the effects of hybrid line length error and accurate time synchronization problem of two sides of the line to the fault location accuracy are eliminated in the fault location by using the double-ended principle so that the accuracy and reliability of the fault location are improved. Therefore, the traveling wave fault location of the high-voltage overhead line and cable hybrid line is realized by using the method, the problem on how to accurately search a fault point position after the hybrid line is in the fault can be reliably solved and the traveling wave fault location method has a good application prospect.

The invention discloses a distribution network communication optical cable fault location method and device and belongs to the technical field of electric power telecommunication. The distribution network communication optical cable fault location method includes building a geographic space model of distribution network communication optical cables; displaying a route distribution diagram of the distribution network communication optical cables on a Geographic Information System (GIS) map according to the geographic space model; after acquiring optical cable fault information, calculating the geographical location information of fault points of the optical cables according to the route distribution diagram and a preset fault point location algorithm; marking the fault points of the optical cables on the GIS map according to the geographical location information. By adopting the distribution network communication optical cable fault location method and device, the ground position of the fault points of the distribution network communication optical cables can be visually and quickly located, thus the staff can be guided to fast carry out dispatching repair, maintenance cost of the distribution network communication optical cables can be effectively reduced, and satisfaction of ultimate users can be improved.

The invention belongs to the field of electrical engineering and particularly relates to a fault distance measuring method for a non-parallel-state uplink and downlink traction network where partitions are located in a high-speed rail power supply traction network. The method is used for judging fault types and directions in the state and accurately positioning fault points. According to the method, an uplink and downlink current ratio is defined, fault distance determining is performed according to the uplink and downlink current ratio fault distance measuring principle and the reactance method, and therefore the problem that distance measuring of the non-parallel-state uplink and downlink traction network where the partitions are located cannot be performed by an existing fault distance measuring system is solved. Meanwhile, uplink and downlink faults and the fault types cannot be accurately judged, correct fault distances are given out, the fault points can be fast found out, and fast power supply restoration of the high-speed rail power supply traction network can be guaranteed.

The invention relates to a fault location method using three primary colours to represent travel waves of single-phase earth fault current of an AC transmission line. In the method, the travel waves in the direction of the fault current of the AC transmission line are represented by the three primary colours so as to realize single end fault location under the three primary colour mode and to achieve more intuitive fault location at the same time of ensuring the accuracy of the fault location. The method is carried out as follows: utilizing the travel waves in the construction direction of the current aerial model component in the case of single phase earth fault, mapping the travel waves in the fault current direction and zero model component of the fault current to the three primary colour mode, selecting former two mutation positions in which a red (R) channel and a green (G) channel have consistent colour mutation directions so as to correspond to former two wave heads coming from a fault point, and comparing the mutation direction at the second colour mutation positions of the red (R) channel and the green (G) channel; if the mutation directions are the same, the second colour mutation positions correspond to reflection waves of the fault point, otherwise, the second colour mutation positions correspond to reflection waves of an end bus. Through the method, single end fault location is finally realized.

The invention relates to an earth fault distance measurement method based on traveling wave modulus time difference, belonging to the field of power electronic technology. The invention utilizes traveling wave detection devices installed at detections points along the line to ensures an effective detection point closer to a fault point to accurately distinguish a zero mode and a line mode initial wave head, and uploads the time difference between the zero mode and the line mode initial wave head into a monitor station. The monitor station is used for sequencing all the collected modulus time difference from big to small, firstly judges the detection point which is closed to the fault point for a first step, and then completing accurate fault distance measurement according to the primary locating result. The invention does not need a time synchronous system, has low communication traffic, is not influenced by line tap points, is easy for project implementation, and has higher reliability and distance measurement accuracy.

The invention discloses a distributed fault location method for a T-circuit. At least two fault current detectors are installed on each branch of the T-circuit. Each fault current detector is connected with a monitoring master station through a remote wireless communication module. The monitoring master station analyzes fault current information according to stored algorithm, judges a faulted branch according to travelling wave energy, and further analyzes to judge fault section according to arrival time series of fault current travelling energy detected by the two fault current detectors on the faulted branch, and calculates the fault location according to a positioning equation. The method solves the problem that a dead zone occurs when a fault point is close to a T node and is high in positioning precision.

The invention discloses a method and device for locating a fault on a direct current grounding electrode circuit. The method for locating the fault comprises the steps that a plurality of voltage sampling values and a plurality of current sampling values , corresponding to a plurality of preset sampling times, of the direct current grounding electrode circuit are obtained from the measuring points of the direct current grounding electrode circuit; a forward voltage traveling wave function and a backward voltage traveling wave function are obtained in a calculating mode; mathematical morphology gradient transformation is carried out to obtain a forward traveling wave gradient function and a backward traveling wave gradient function; the reflected wave of a fault point is confirmed through the forward traveling wave gradient function and the backward traveling wave gradient function; the time corresponding to the reflected wave of the fault point is used as fault time, and a fault distance is confirmed according to the fault time. The upper edge or the lower edge or the signal saltation point of transient signals can be extracted well, and therefore the reflected wave of the fault point can be distinguished accurately. Therefore, the accurate fault time can be obtained, and the accuracy of the fault distance can be greatly improved.

A transmission line single-phase grounding fault single-end ranging method belongs to the field of power system protection and control. According to the method of the invention, positive, negative and zero sequence voltage and current phasors of a line during the time section between the occurrence of a single phase grounding fault and single phase tripping and the time section between single phase tripping and reclosing are measured at a substation protection installation site and are used as input. The initial value of fault distance is set from 0 to the overall length of the line with delta1 as the step length, and the initial value of transition resistance starts from 1 ohm and increases to 1000 ohms with 1 ohm as the step length. For each combination of the values of fault distance and transition resistance, the equivalent electromotive force values of a system at the opposite end of the line during the time section between the occurrence of the single phase grounding fault and single phase tripping and the time section after single phase tripping are respectively calculated, the sum of absolute errors of the equivalent electromotive force values is calculated, and the fault distance value corresponding to the minimum value of the sum of absolute errors is selected as the fault ranging distance. The method is high in precision, is not affected by distributed capacitive current, transition resistance, load and system impedance and has very high practical values.

The invention discloses a traction power supply system fault location method applied to multiple operation modes. The method comprises the following steps: 1, reclosing is carried out when a traction network line fails, and if reclosing fails, a reactance method ranging principle is adopted for ranging, and if reclosing succeeds, the second step is carried out; 2, the operation mode of the traction network line is judged according to switch position signals, fault uplink and fault downlink are determined according to the specific operation mode, faults can be determined to be T-type faults, F-type faults or TF-type faults, and then according to the fault type of the specific operation mode, adopting of a suction current ratio principle, a reactance method ranging principle, an uplink downlink current ratio ranging principle or a transverse line current ratio ranging principle is determined to calculate the fault distance. When the method of the invention is adopted for traction network line fault location, the fault position can be quickly and accurately positioned, and thus, the fault clearing efficiency can be enhanced, normal power supply can be quickly recovered, and safe operation of the railway can be ensured.