A method, system and device for locating a fault section of a distribution network overhead line

Abstract

The present invention discloses a method, system, and device for locating a fault section of a distribution network overhead line. The fault section locating method comprises: obtaining high-frequency transient current and voltage traveling wave signals from different monitoring nodes of the distribution network overhead line; analyzing the polarity differences of the high-frequency transient current and voltage traveling wave signals at each monitoring node to determine the transient fault source directions corresponding to the polarity differences at all monitoring nodes; and determining the fault section of the overhead line based on the transient fault source directions of all adjacent monitoring nodes. The present invention can locate high-resistance faults in addition to locating low-resistance faults on distribution network overhead lines.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network fault locating, and specifically to a method, system and device for locating a fault section of a distribution network overhead line. Background Art

[0002] As the last layer of the power system, distribution networks are frequently exposed to various faults, such as short circuits, ground faults, and overvoltage. These faults often lead to equipment damage, power outages, and even fires. Therefore, timely fault identification and rapid and accurate repair are fundamental to ensuring stable power supply. With the development of smart grids and the integration of large-scale renewable energy, distribution networks are becoming increasingly complex. Accurately identifying the fault point and its location is crucial for ensuring safe and reliable power system operation.

[0003] At present, the methods for identifying distribution network fault sections mainly include traditional inspection method, non-relay protection fault location method, fault indicator method, fault location method based on electromagnetic wave traveling wave principle and fault location method based on machine learning.

[0004] Traditional inspection methods typically rely on manual inspections, requiring workers to inspect individual components and wiring within the power system to determine the location and extent of faults. While this method offers advantages such as ease of operation and high real-time performance, it requires significant human and material resources and is incapable of servicing in inaccessible areas.

[0005] Non-relay protection fault location methods refer to the collection of voltage and current signals by measuring equipment in the distribution network, analysis and processing, and determining the location and range of the fault point based on the changes in the signals. For example, CN103927459A discloses a method for locating faults in a distribution network containing distributed power sources. The method is based on the voltage and current information measured by a synchronized phasor measurement device or fault recording device installed at the main power source and each distributed power source outlet. The fault location is then determined by comparing the error between the measured value and the calculated value of the voltage change at each power source before and after the fault. The asymmetry of the distributed power source, distribution transformer, and distribution line is taken into account in the process of calculating the voltage change. This method can not only accurately identify the fault point, but also further determine the type of fault that has occurred based on the collected data and process it. However, it requires high device precision and a large amount of calculation, and is susceptible to external interference. In addition, because it uses low-frequency (quasi-power frequency) current to achieve fault judgment, the power frequency overcurrent of high-resistance faults is too small to be detected by it. Therefore, it is basically ineffective for judging high-resistance faults.

[0006] A fault indicator is an electromagnetic induction device that can reflect the presence of a short-circuit current by displaying a fault sign (red sign). For example, CN104483601A discloses a distribution network fault location method based on a fault indicator. The method includes the following steps: constructing an association matrix, transmitting status information from the fault indicator to a master control center, generating a trigger vector, and locating the fault section. The association matrix construction unit generates the association matrix, the fault indicator transmits status information to the master control center via a Zigbee wireless network, and the fault location unit generates a trigger vector. A matrix operation is performed on the trigger vector and the association matrix to obtain a fault section vector, thereby analyzing and locating the fault section and diagnosing the fault information. This method installs fault indicators along the distribution line. Once a short-circuit fault occurs and the short-circuit current flows, the fault indicator activates, and a red fault sign appears. The fault point is then located by patrolling along the line. This method has a low implementation cost. However, this method uses power frequency overcurrent measurement to achieve fault section indication. The power frequency overcurrent of a high-resistance fault is too small to be detected, making this method essentially ineffective for high-resistance faults.

[0007] The fault location method based on the electromagnetic wave principle mainly determines the fault line and fault area by monitoring the electromagnetic wave signals generated by the fault line. For example, CN106505736A discloses a method for remotely monitoring and starting the real-time waveform of a fault recording device, including the following steps: S1, remotely start the fault recorder to monitor the fault waveform in the substation;

[0008] S2. Monitor the environment inside the substation through a mobile monitoring unit, and use VR equipment to replace staff to inspect the substation; S3. Send the waveform of the fault recorder and the environmental data inside the substation to the monitoring center. The monitoring center activates the ultra-high frequency omnidirectional sensor receiving and amplifying module of the mobile monitoring unit to receive the electromagnetic waves generated by the discharge of the power equipment defects in the substation, and determines the location of the fault by monitoring its direction and the movement of the mobile monitoring unit. It uses a small number of sensors to monitor the entire substation and equipment information, and cooperates with the fault recorder of the power grid line to achieve all-round monitoring of the substation and quickly find and locate the fault point in a timely manner. However, this method needs to capture the rising edge of the fault signal (a detailed waveform of a fault transient signal). Therefore, it is necessary to accurately collect the fault signal waveform. This requires the monitoring node to have a high-speed acquisition system of no less than 50MS / s, which is costly to implement.

[0009] Machine learning-based fault location methods typically utilize machine learning algorithms, such as neural networks and support vector machines, to process collected data and identify patterns and features associated with the fault point. This method offers advantages such as high automation and accuracy, but it also requires significant computational and processing time, places high demands on training data and algorithm design, and carries a high implementation cost.

[0010] In view of this, how to achieve low-cost and high-resistance fault determination of distribution network overhead line fault sections is a problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0011] In response to the above-mentioned defects in the prior art, the present invention provides a method, system and device for locating the fault section of a distribution network overhead line. In addition to locating low-resistance faults on distribution network overhead lines, the method can also locate high-resistance faults.

[0012] In a first aspect, the present invention provides a method for locating a fault section of a distribution network overhead line, comprising:

[0013] Obtain high-frequency transient traveling wave signals of current and voltage at different monitoring nodes of distribution network overhead lines;

[0014] Determining a fault condition of the overhead line based on a preset current fault threshold and a voltage fault threshold;

[0015] Analyze the polarity differences of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at each monitoring node of the faulty overhead line, and provide the fault transient source direction corresponding to the polarity differences of all monitoring nodes;

[0016] The fault section of the overhead line is obtained according to the fault transient source direction of all adjacent monitoring nodes.

[0017] Furthermore, after obtaining the fault section of the overhead line according to the fault transient source directions of all adjacent monitoring nodes, the method further includes:

[0018] Match the corresponding overhead line node switch according to the fault section;

[0019] Control the overhead line node switch to cut off the fault section from the distribution network and restore power supply outside the fault section.

[0020] Furthermore, obtaining the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of different monitoring nodes of the distribution network overhead line includes:

[0021] A data acquisition unit is set up at each monitoring node of the overhead line;

[0022] The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node;

[0023] Acquire the current high-frequency transient traveling wave signals and voltage high-frequency transient traveling wave signals collected by the data acquisition units at all monitoring node locations.

[0024] Furthermore, the polarity differences of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of each monitoring node are analyzed, and the fault transient source direction corresponding to the polarity differences of all monitoring nodes is given, including:

[0025] Performing band-pass filtering within a predetermined frequency range on the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal;

[0026] According to the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal after bandpass filtering, the cross-power spectrum coefficients of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at different frequencies are obtained; the cross-power spectrum coefficients include:

[0027]

[0028] Where ψ(ω) is the cross-power spectrum coefficient, I(ω) is the Fourier transform result of the current high-frequency transient traveling wave signal after bandpass filtering, and U * (ω) is the complex conjugate of the Fourier transform result of the voltage high-frequency transient traveling wave signal after bandpass filtering, and ω is the angular frequency, which ranges from 0 to πf s , f s is the acquisition frequency;

[0029] The average value of the phase coefficient within a predetermined frequency range is obtained based on the cross power spectrum coefficient; the average value of the phase coefficient includes:

[0030]

[0031] Where P is the average value of the phase coefficient, ψ(·) is the cross power spectrum coefficient, ∠(·) is the phase coefficient, which is the angle between the real and imaginary parts of the cross power spectrum coefficient, Δω is the acquisition frequency interval, and f min is the minimum frequency boundary of the predetermined frequency range, i is the number of acquisitions, and K is the number of acquisition frequencies within the predetermined frequency range;

[0032] The source direction of the fault transient is obtained based on the average value of the phase coefficient.

[0033] Furthermore, the source direction of the fault transient is obtained based on the average value of the phase coefficient, including:

[0034] If the average value of the phase coefficient is positive, the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line; if the phase coefficient is negative, the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line;

[0035] After obtaining the source direction of the fault transient according to the average value of the phase coefficient, it also includes:

[0036] Identify the monitoring nodes according to the source direction of the fault transient; identification includes:

[0037]

[0038] Where D is the identification result, 1 means the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line, and 0 means the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line.

[0039] Furthermore, the fault section of the overhead line is obtained based on the fault transient source direction of all adjacent monitoring nodes, including:

[0040] Based on the upstream and downstream directions of the overhead line, the identification results of all adjacent monitoring nodes are compared;

[0041] Obtaining adjacent monitoring nodes with different identification results according to the comparison result;

[0042] The section between adjacent monitoring nodes with different identification results is identified as a fault section.

[0043] In a second aspect, the present invention further provides a fault section locating system using the above-mentioned fault section locating method, comprising:

[0044] A signal acquisition module is used to acquire high-frequency transient traveling wave signals of current and voltage at different monitoring nodes of the distribution network overhead line;

[0045] a fault determination module, configured to determine a fault condition of the overhead line based on a preset current fault threshold and a voltage fault threshold;

[0046] A signal analysis module is used to analyze the polarity differences of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at each monitoring node of the faulty overhead line, and provide the fault transient source direction corresponding to the polarity differences of all monitoring nodes;

[0047] The fault location module is used to obtain the fault section of the overhead line according to the fault transient source direction of all adjacent monitoring nodes.

[0048] Furthermore, the signal acquisition module is used to:

[0049] A data acquisition unit is set up at each monitoring node of the overhead line;

[0050] The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node;

[0051] Acquire the current high-frequency transient traveling wave signals and voltage high-frequency transient traveling wave signals collected by the data acquisition units at all monitoring node locations.

[0052] Furthermore, the signal analysis module is used to:

[0053] Performing band-pass filtering within a predetermined frequency range on the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal;

[0054] According to the bandpass filtered current high-frequency transient traveling wave signal and voltage high-frequency transient traveling wave signal, the cross-power spectrum coefficients of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at different frequencies are obtained;

[0055] obtaining an average value of a phase coefficient within a predetermined frequency range based on the cross-power spectrum coefficient;

[0056] The source direction of the fault transient is obtained based on the average value of the phase coefficient.

[0057] Furthermore, the signal analysis module is also used to:

[0058] If the average value of the phase coefficient is positive, the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line; if the phase coefficient is negative, the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line;

[0059] The monitoring nodes are identified according to the source direction of the fault transient.

[0060] Furthermore, the fault location module is used to:

[0061] Based on the upstream and downstream directions of the overhead line, the identification results of all adjacent monitoring nodes are compared;

[0062] Obtaining adjacent monitoring nodes with different identification results according to the comparison result;

[0063] The section between adjacent monitoring nodes with different identification results is identified as a fault section.

[0064] Furthermore, the fault section location system also includes a fault processing module, which is used to:

[0065] Match the corresponding overhead line node switch according to the fault section;

[0066] Control the overhead line node switch to cut off the fault section from the distribution network and restore power supply outside the fault section.

[0067] In a third aspect, the present invention further provides a device for locating a fault section of a distribution network overhead line, comprising: a data acquisition unit and a data acquisition and analysis unit connected to the data acquisition unit;

[0068] The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node;

[0069] The data acquisition and analysis unit applies the above-mentioned fault section location method.

[0070] Furthermore, the data acquisition unit includes an inductive coupler and a conditioning circuit. The inductive coupler is a ring-shaped magnetic core mounted on the overhead line, which converts the high-frequency transient traveling wave signal of the fault transient current on the overhead line into a voltage signal.

[0071] The conditioning circuit includes a voltage divider and a rectifier bridge. The voltage divider is composed of a high-voltage capacitor, a high-voltage inductor, a high-voltage resistor and a low-voltage resistor. The high-voltage capacitor and the high-voltage inductor are connected in series and then connected in parallel with the rectifier bridge to both ends of the inductive coupler. The high-voltage resistor and the low-voltage resistor are connected in series and then connected in parallel with the high-voltage inductor. Both ends of the low-voltage resistor output the converted current high-frequency transient traveling wave signal.

[0072] Furthermore, the data acquisition unit includes a bipolar plate coupler, and a high-frequency transient voltage traveling wave signal of a fault transient on the overhead line is obtained by detecting the voltage of an upper plate and a lower plate of the bipolar plate coupler.

[0073] Furthermore, the upper plate and the lower plate of the bipolar plate coupler form a first capacitor and a third capacitor with the overhead line and the earth respectively, and the upper plate and the lower plate of the bipolar plate coupler form a second capacitor between them;

[0074] The high-frequency transient traveling wave signal of the voltage during fault transient includes:

[0075]

[0076] Where V 极板 and V 故障 are respectively the high-frequency transient traveling wave signal of the fault transient voltage and the voltage of the bipolar plate coupler, C1, C2 and C3 are respectively the first capacitance formed by the overhead line and the upper plate, the second capacitance formed by the upper plate and the lower plate, and the third capacitance formed by the lower plate and the earth.

[0077] The present invention provides a method, system, and device for locating a fault section of a distribution network overhead line, which have at least the following beneficial effects:

[0078] (1) By measuring the high-frequency transient at the moment of fault occurrence, low-resistance faults and high-resistance faults in the distribution network overhead lines can be effectively located.

[0079] (2) Using the average value of the above phase coefficient to determine the direction of the fault source has the following advantages: First, it has good anti-noise interference capability. Because the average value of the phase coefficient utilizes the information of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal in the left and right frequency bands, even if interference occurs in certain frequency bands, it will not affect the final result. Second, it will not be affected by high-frequency oscillations caused by equipment such as transformers and reactors. When the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal propagate to the transformer or reactor, it may cause obvious high-frequency oscillations in the signal, and the conventional method of judging the polarity by the rising edge direction or the positive and negative peak value will fail. However, because this method uses the average value of the phase information of each frequency point, it is not affected by the frequency point amplitude and is therefore immune to this type of high-frequency oscillation.

[0080] (3) There is no need to use a high-speed acquisition device (sampling rate higher than 50MS / s), only a 5MS / s analog-to-digital converter is needed, which is low-cost and suitable for large-scale application in distribution networks.

[0081] (4) It can be integrated with the existing distribution network automation system and configured in the intelligent switch to achieve rapid identification and isolation of fault sections of the distribution network overhead lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 A flow chart of a method for locating a fault section of a distribution network overhead line provided by the present invention;

[0083] Figure 2 A flowchart showing the source direction of a transient fault in an embodiment of the present invention;

[0084] Figure 3 A schematic diagram of the principle and identification of the source direction of a transient fault according to an embodiment of the present invention;

[0085] Figure 4 A schematic diagram of a fault section locating system for a distribution network overhead line provided by the present invention;

[0086] Figure 5 A schematic diagram of a fault section locating device for a distribution network overhead line provided by the present invention;

[0087] Figure 6 A schematic diagram of the installation of a data acquisition unit according to an embodiment of the present invention;

[0088] Figure 7 A circuit diagram of an inductive coupler and a conditioning circuit according to an embodiment of the present invention;

[0089] Figure 8 An equivalent circuit diagram of a bipolar plate coupler according to an embodiment of the present invention;

[0090] Figure 9 This is a schematic diagram of the installation of the fault section locating device provided by the present invention.

[0091] Explanation of reference numerals: 10 - fault section locating device, 11 - inductive coupler, 12 - bipolar plate coupler, 13 - data acquisition and analysis unit, 14 - overhead line. DETAILED DESCRIPTION

[0092] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0093] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a," "an," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0094] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0095] like Figure 1 As shown, the present invention provides a method for locating a fault section of a distribution network overhead line, which may include:

[0096] Obtain high-frequency transient traveling wave signals of current and voltage at different monitoring nodes of distribution network overhead lines;

[0097] Determining a fault condition of the overhead line based on a preset current fault threshold and a voltage fault threshold;

[0098] Analyze the polarity differences of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at each monitoring node of the faulty overhead line, and provide the fault transient source direction corresponding to the polarity differences of all monitoring nodes;

[0099] The fault section of the overhead line is obtained according to the fault transient source direction of all adjacent monitoring nodes.

[0100] The method of determining the fault condition of the overhead line based on the preset current fault threshold and voltage fault threshold includes:

[0101] Comparing the obtained current high-frequency transient traveling wave signal and voltage high-frequency transient traveling wave signal with the preset current fault threshold and voltage fault threshold, respectively; wherein the preset current fault threshold and voltage fault threshold are 100A and 5kV, respectively;

[0102] Determining whether the acquired current high-frequency transient traveling wave signal and voltage high-frequency transient traveling wave signal both exceed a preset current fault threshold and a preset voltage fault threshold based on the comparison result;

[0103] If the acquired current high-frequency transient traveling wave signal and voltage high-frequency transient traveling wave signal both exceed the preset current fault threshold and voltage fault threshold, it is determined that the overhead line is faulty; otherwise, it is determined that the overhead line is not faulty.

[0104] Since both high-resistance faults and low-resistance faults will generate high-frequency transients, the present invention realizes fault monitoring and interval judgment through the high-frequency transients when the fault occurs, so that the fault section locating method of the present invention can realize effective judgment and positioning of low-resistance and high-resistance faults.

[0105] The present invention obtains the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of different monitoring nodes of the distribution network overhead line, which may include:

[0106] A data acquisition unit is set up at each monitoring node of the overhead line;

[0107] The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node;

[0108] Acquire the current high-frequency transient traveling wave signals and voltage high-frequency transient traveling wave signals collected by the data acquisition units at all monitoring node locations.

[0109] The configuration of monitoring nodes in the present invention can be selected based on the results of overhead line fault analysis. For example, monitoring nodes can be densely distributed in areas where overhead line faults frequently occur. Furthermore, the configuration of monitoring nodes can be integrated with the overhead line's distribution network automation system. For example, monitoring nodes can be deployed at locations where intelligent switches are installed on the overhead line. This allows the system to quickly and accurately remove the faulty section when a fault is detected at that location, ensuring continuous power supply to the overhead line.

[0110] like Figure 2 and Figure 3 As shown in the figure, the polarity differences of the current high-frequency transient traveling wave signals and the voltage high-frequency transient traveling wave signals at different monitoring nodes are analyzed, and the fault transient source directions corresponding to the polarity differences at different monitoring nodes are given, including:

[0111] Performing bandpass filtering on the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal within a predetermined frequency range; preferably, the predetermined frequency range is 10 kHz-1 MHz;

[0112] According to the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal after bandpass filtering, the cross-power spectrum coefficients of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at different frequencies are obtained; the cross-power spectrum coefficients include:

[0113]

[0114] Where ψ(ω) is the cross-power spectrum coefficient, I(ω) is the high-frequency transient traveling wave signal of the current after bandpass filtering, and U * (ω) is the complex conjugate of the voltage high-frequency transient traveling wave signal after bandpass filtering, and ω is the frequency coefficient;

[0115] The average value of the phase coefficient within a predetermined frequency range is obtained based on the cross power spectrum coefficient; the average value of the phase coefficient includes:

[0116]

[0117] Where P is the average value of the phase coefficient, ψ(·) is the cross power spectrum coefficient, ∠(·) is the phase coefficient (phase angle), which is the angle between the real and imaginary parts of the cross power spectrum coefficient, Δω is the acquisition frequency interval, and f min is the minimum frequency boundary of the predetermined frequency range, i is the number of acquisitions, and K is the number of acquisition frequencies within the predetermined frequency range;

[0118] The source direction of the fault transient is obtained based on the average value of the phase coefficient, which may include:

[0119] If the average value of the phase coefficient is positive, the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line (reference direction); if the phase coefficient is negative, the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line.

[0120] After obtaining the source direction of the fault transient according to the average value of the phase coefficient, the following steps may also be performed:

[0121] The monitoring nodes are identified using binary method according to the source direction of the fault transient; Figure 3 As shown, the identification results include:

[0122]

[0123] Where D is the identification result, 1 means the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line, and 0 means the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line.

[0124] The present invention calculates the polarity of voltage high-frequency transient traveling wave signals and current high-frequency transient traveling wave signals by using cross-power spectrum coefficients, and determines the direction of the fault source based on the polarity difference of adjacent monitoring nodes, thereby having the characteristics of good anti-noise ability and high accuracy.

[0125] The fault section of the overhead line is obtained based on the fault transient source direction of all adjacent monitoring nodes, including:

[0126] Based on the upstream and downstream directions of the overhead line, the identification results of all adjacent monitoring nodes are compared;

[0127] Obtaining adjacent monitoring nodes with different identification results according to the comparison result;

[0128] The section between adjacent monitoring nodes with different identification results is identified as a fault section.

[0129] After obtaining the fault section of the overhead line based on the fault transient source direction of all adjacent monitoring nodes, the following steps are also included:

[0130] Match the corresponding overhead line node switch according to the fault section;

[0131] Control the overhead line node switch to cut off the fault section from the distribution network and restore power supply outside the fault section.

[0132] When disconnecting the faulty section from the distribution network, the present invention transmits the faulty section to the distribution network automation system. The distribution network automation system controls the intelligent switch corresponding to the faulty section based on the received faulty section, thereby removing the section from the distribution network and ultimately quickly restoring power to non-faulty sections. Furthermore, in practical applications, a single fault in a distribution network overhead line can cause the entire distribution network to be grounded. In this case, the positioning method of the present invention can quickly locate and remove the faulty section, enabling continuous monitoring and positioning of overhead line faults.

[0133] like Figure 4 As shown, the present invention also provides a fault section locating system using the above-mentioned fault section locating method, comprising:

[0134] A signal acquisition module is used to acquire high-frequency transient traveling wave signals of current and voltage at different monitoring nodes of the distribution network overhead line;

[0135] a fault determination module, configured to determine a fault condition of the overhead line based on a preset current fault threshold and a voltage fault threshold;

[0136] A signal analysis module is used to analyze the polarity differences of the current high-frequency transient traveling wave signals and the voltage high-frequency transient traveling wave signals at different monitoring nodes of the faulty overhead line, and provide the fault transient source direction corresponding to the polarity differences at different monitoring nodes;

[0137] The fault location module is used to obtain the fault section of the overhead line according to the fault transient source direction of all adjacent monitoring nodes.

[0138] The signal acquisition module is used to:

[0139] A data acquisition unit is set up at each monitoring node of the overhead line;

[0140] The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node;

[0141] Acquire the current high-frequency transient traveling wave signals and voltage high-frequency transient traveling wave signals collected by the data acquisition units at all monitoring node locations.

[0142] The signal analysis module is used to:

[0143] Performing band-pass filtering within a predetermined frequency range on the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal;

[0144] According to the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal after bandpass filtering, the cross-power spectrum coefficients of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at different frequencies are obtained;

[0145] obtaining an average value of a phase coefficient within a predetermined frequency range based on the cross-power spectrum coefficient;

[0146] The source direction of the fault transient is obtained based on the average value of the phase coefficient.

[0147] The signal analysis module is also used to:

[0148] If the average value of the phase coefficient is positive, the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line; if the phase coefficient is negative, the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line;

[0149] The monitoring nodes are identified according to the source direction of the fault transient.

[0150] The fault location module is used to:

[0151] Based on the upstream and downstream directions of the overhead line, the identification results of all adjacent monitoring nodes are compared;

[0152] Obtaining adjacent monitoring nodes with different identification results according to the comparison result;

[0153] The section between adjacent monitoring nodes with different identification results is identified as a fault section.

[0154] The fault section location system also includes a fault processing module, which is used to:

[0155] Match the corresponding overhead line node switch according to the fault section;

[0156] Control the overhead line node switch to cut off the fault section from the distribution network and restore power supply outside the fault section.

[0157] like Figure 5 As shown, the present invention also provides a fault section locating device 10 for a distribution network overhead line, comprising: a data acquisition unit and a data acquisition and analysis unit 13 connected to the data acquisition unit;

[0158] The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node;

[0159] The data acquisition and analysis unit applies the above-mentioned fault section location system.

[0160] like Figure 6 As shown, the data acquisition unit captures the fault transient current high-frequency transient traveling wave signal and voltage high-frequency transient traveling wave signal through the inductive coupler 11 and the bipolar plate coupler 12. In actual application scenarios, Figure 7 As shown, the data acquisition unit may include an inductive coupler and a conditioning circuit, wherein the inductive coupler utilizes a non-intrusive broadband transformer. Specifically, the inductive coupler is a toroidal magnetic core made of closed permalloy and mounted on the overhead line 14. The toroidal magnetic core converts the high-frequency transient traveling wave signal of the current of the high-frequency fault transient on the overhead line 14 into a voltage signal. The non-intrusive broadband transformer can sense the power frequency current signal and detect the high-frequency current. Preferably, the outer and inner diameters of the toroidal magnetic core are 6 cm and 4 cm, respectively, and the number of winding turns is set to 700-1200 turns. The inductive coupler monitors the high-frequency transient traveling wave signal of the current of the fault transient. However, since the analog-to-digital conversion device can only collect voltage signals, the toroidal magnetic core converts the high-frequency transient traveling wave signal of the current of the fault transient into a voltage signal so that the data acquisition unit can collect and analyze it.

[0161] The conditioning circuit can include a voltage divider and a rectifier bridge. The voltage divider is connected by a high-voltage capacitor C, a high-voltage inductor L, and a high-voltage resistor R. H and low voltage resistor R LThe high-voltage capacitor and the high-voltage inductor are connected in series and then connected in parallel with the rectifier bridge at both ends of the inductive coupler. The high-voltage resistor and the low-voltage resistor are connected in series and then connected in parallel with the high-voltage inductor. The two ends of the low-voltage resistor output the converted current high-frequency transient traveling wave signal. The conditioning circuit can realize the separation of the power frequency voltage and the high-frequency fault transient current high-frequency transient traveling wave signal. The power frequency voltage obtained by separation can be used to generate power frequency current, and the high-frequency fault transient current high-frequency transient traveling wave signal obtained by separation is used for fault diagnosis. Preferably, the high-voltage capacitor C is 1uF, the high-voltage inductor L is 1mH, and the high-voltage resistor R H 200kΩ, low voltage resistor R L The rectifier bridge includes four fully controlled MOS switches (K1, K2, K3, and K4), model PJQ4464AP-AU, which rectify the power frequency current induced by the inductive coupler into DC for use by the data acquisition unit. Specifically, the circuits and chips in the data acquisition unit are all powered by DC.

[0162] The data acquisition unit includes a non-contact bipolar plate coupler for capturing the high-frequency transient traveling wave signal of the fault transient voltage. The upper and lower plates of the bipolar plate coupler form a first capacitor and a second capacitor with the overhead line and the earth respectively. The upper and lower plates of the bipolar plate coupler form a third capacitor, that is, the overhead line, the bipolar plate coupler and the earth form a three-capacitor voltage divider circuit, as shown in the attached figure. Figure 8 As shown, therefore, by detecting the voltage across the upper and lower plates, a high-frequency transient traveling wave signal of the voltage of the fault transient on the overhead line is obtained. Preferably, both the upper and lower plates are copper plates, and the principle diagram is as shown in FIG. Figure 8 As shown, the measurement of the high-frequency transient traveling wave signal of the voltage of the fault transient is achieved through the capacitance formed between the two plates, wherein the upper plate and the lower plate of the bipolar plate coupler respectively form a first capacitor and a third capacitor with the overhead line and the ground, and the upper plate and the lower plate of the bipolar plate coupler form a second capacitor between them;

[0163] The high-frequency transient traveling wave signal of the voltage during fault transient includes:

[0164]

[0165] Where V 极板 and V 故障They are respectively the voltage high-frequency transient traveling wave signal of the fault transient and the voltage of the bipolar plate coupler, C1, C2 and C3 are respectively the first capacitor formed by the overhead line and the upper plate, the second capacitor formed by the upper plate and the lower plate, and the third capacitor formed by the lower plate and the earth. More specifically, the size of each plate is 2cm×3cm×1mm, and the distance between the plates is 1cm. The data acquisition and analysis unit is a microprocessor STM32L476 with an integrated 5MS / s sampling rate, and its power consumption is less than 50mW. The present invention realizes the fault interval positioning through the polarity of the voltage high-frequency transient traveling wave signal and the current high-frequency transient traveling wave signal (a rough fault transient waveform feature), so there is no need to collect the waveform details of the fault transient. Therefore, a high sampling rate is not required to complete the fault monitoring and positioning of the overhead line.

[0166] The fault section locating device also includes a power management unit connected to the data acquisition and analysis units, enabling self-powered operation without the need for an additional power source. The power management unit consists of a DC-to-DC converter with an input voltage range of 5-30V and output voltages of 3.3 and 5V. It provides power to the data acquisition and analysis unit and its microprocessor and conditioning circuitry. The fault section locating device also includes a communication unit connected to the data acquisition and analysis unit. This unit transmits the unit's judgment results to a centralized processing platform for fault monitoring, display, alarms, and fault task scheduling.

[0167] Figure 9 This article illustrates an embodiment of the present invention's fault section locating device in a distribution network overhead line. The device can be distributed throughout the distribution network overhead line. For example, monitoring nodes can be placed at locations with intelligent switches, allowing integration with the distribution network automation system. Secondly, when a fault occurs, the deployed monitoring nodes can determine whether the fault originates from the upstream or downstream line. When two adjacent monitoring nodes produce opposite results, the fault is determined to be located between the two monitoring nodes. Finally, when a fault is determined in a section of overhead line, this information is uploaded to the distribution network automation system, and the intelligent switches are instructed to remove the section from the network system, allowing power to be quickly restored to the non-faulty section.

[0168] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such changes and modifications as fall within the scope of the claims and their equivalents.

Claims

1. A method for locating a fault section of a distribution network overhead line, characterized in that: include: Obtain high-frequency transient traveling wave signals of current and voltage at different monitoring nodes of distribution network overhead lines; Determining a fault condition of the overhead line based on a preset current fault threshold and a voltage fault threshold; Analyze the polarity differences of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at each monitoring node of the faulty overhead line, and provide the fault transient source direction corresponding to the polarity differences of all monitoring nodes, including: band-pass filtering the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal within a predetermined frequency range; obtain the cross-power spectrum coefficients of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at different frequencies based on the band-pass filtered current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal; obtain the average value of the phase coefficient within the predetermined frequency range based on the cross-power spectrum coefficient; and obtain the source direction of the fault transient based on the average value of the phase coefficient; The fault section of the overhead line is obtained according to the fault transient source direction of all adjacent monitoring nodes; The cross power spectrum coefficients include: Where ψ(ω) is the cross-power spectrum coefficient, I(ω) is the high-frequency transient traveling wave signal of the current after bandpass filtering, and U * (ω) is the complex conjugate of the voltage high-frequency transient traveling wave signal after bandpass filtering, and ω is the frequency coefficient; The average value of the phase coefficient includes: Where P is the average value of the phase coefficient, ψ(·) is the cross-power spectrum coefficient, ∠(·) is the phase coefficient, Δω is the acquisition frequency interval, and f min is the minimum frequency boundary of the predetermined frequency range, i is the number of acquisitions, and K is the number of acquisition frequencies within the predetermined frequency range.

2. The fault section locating method according to claim 1, characterized in that: After obtaining the fault section of the overhead line based on the fault transient source direction of all adjacent monitoring nodes, the following steps are also included: Match the corresponding overhead line node switch according to the fault section; Control the overhead line node switch to cut off the fault section from the distribution network and restore power supply outside the fault section.

3. The fault section locating method according to claim 1, characterized in that: Obtain high-frequency transient traveling wave signals of current and voltage at different monitoring nodes of distribution network overhead lines, including: A data acquisition unit is set up at each monitoring node of the overhead line; The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node; Acquire the current high-frequency transient traveling wave signals and voltage high-frequency transient traveling wave signals collected by the data acquisition units at all monitoring node locations.

4. The fault section locating method according to claim 1, characterized in that: The source direction of the fault transient is obtained based on the average value of the phase coefficient, including: If the average value of the phase coefficient is positive, the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line; if the phase coefficient is negative, the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line; After obtaining the source direction of the fault transient according to the average value of the phase coefficient, it also includes: Identify the monitoring nodes according to the source direction of the fault transient; identification includes: Where D is the identification result, 1 means the source direction of the fault transient is the same as the upstream and downstream directions of the overhead line, and 0 means the source direction of the fault transient is opposite to the upstream and downstream directions of the overhead line.

5. The fault section locating method according to claim 4, characterized in that: The fault section of the overhead line is obtained based on the fault transient source direction of all adjacent monitoring nodes, including: Based on the upstream and downstream directions of the overhead line, the identification results of all adjacent monitoring nodes are compared; Obtaining adjacent monitoring nodes with different identification results according to the comparison result; The section between adjacent monitoring nodes with different identification results is identified as a fault section.

6. A fault section locating system using the fault section locating method according to any one of claims 1 to 5, characterized in that: include: A signal acquisition module is used to acquire high-frequency transient traveling wave signals of current and voltage at different monitoring nodes of the distribution network overhead line; a fault determination module, configured to determine a fault condition of the overhead line based on a preset current fault threshold and a voltage fault threshold; A signal analysis module is used to analyze the polarity differences of the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal at each monitoring node of the faulty overhead line, and provide the fault transient source direction corresponding to the polarity differences of all monitoring nodes; The fault location module is used to obtain the fault section of the overhead line according to the fault transient source direction of all adjacent monitoring nodes.

7. A fault section locating device for a distribution network overhead line, characterized in that: include: A data acquisition unit and a data acquisition and analysis unit connected to the data acquisition unit; The data acquisition unit collects the current high-frequency transient traveling wave signal and the voltage high-frequency transient traveling wave signal of the monitoring node; The data acquisition and analysis unit adopts the fault section positioning system as described in claim 6.

8. The fault section locating device according to claim 7, characterized in that: The data acquisition unit includes an inductive coupler and a conditioning circuit; The inductive coupler is a toroidal magnetic core mounted on the overhead line, which converts the high-frequency transient traveling wave signal of the fault transient current on the overhead line into a voltage signal; The conditioning circuit includes a voltage divider and a rectifier bridge. The voltage divider includes a high-voltage capacitor, a high-voltage inductor, a high-voltage resistor and a low-voltage resistor. The high-voltage capacitor and the high-voltage inductor are connected in series and then connected in parallel with the rectifier bridge to both ends of the inductive coupler. The high-voltage resistor and the low-voltage resistor are connected in series and then connected in parallel with the high-voltage inductor. The outputs at both ends of the low-voltage resistor are converted into current high-frequency transient traveling wave signals of voltage signals.

9. The fault section locating device according to claim 7, characterized in that: The data acquisition unit also includes a bipolar plate coupler, which obtains a high-frequency transient voltage traveling wave signal of a fault transient on the overhead line by detecting the voltage of the upper plate and the lower plate of the bipolar plate coupler.

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