A method and system for locating a fault on a travelling wave

Abstract

The application relates to the technical field of power fault identification, and discloses a traveling wave fault positioning method and system. The method is used for positioning a traveling wave fault by screening two traveling wave collecting devices with opposite traveling wave directions and the closest distance, constructing a cubic B-spline wavelet as a wavelet base, performing wavelet decomposition on the traveling wave signals of the screened traveling wave collecting devices, obtaining the highest frequency harmonic component, simulating the harmonic component, determining the fault section in the direction of the first mutation point of the harmonic spectrum obtained through simulation at scale 1, obtaining the wavelet coefficient modulus maximum point at scale 4 of the harmonic spectrum and the corresponding modulus maximum value, calculating the fault time according to the modulus maximum value and the sampling frequency, and calculating the specific position of the fault point in the fault section by using the fault time, so that the fault positioning accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of power fault identification technology, and in particular to a traveling wave fault location method and system. Background Technology

[0002] In high-voltage direct current (HVDC) transmission, traveling wave ranging based on global GPS positioning is used to locate line faults. This method determines the fault location based on the propagation time of the fault's traveling wave within the line. However, in practical applications, factors such as sag size, wave velocity attenuation, waveform attenuation, and interference signals frequently affect the positioning accuracy.

[0003] Meanwhile, when locating faults, current transformers are usually used for power supply, and traveling wave fault location devices are installed on both sides of the line terminal. However, the fault type is not identified, and the influencing factors in traveling wave ranging are not comprehensively considered, resulting in a low fault location accuracy. Summary of the Invention

[0004] This invention provides a traveling wave fault location method and system, which solves the technical problem of low fault location accuracy.

[0005] In view of this, the first aspect of the present invention provides a method for locating traveling wave faults, comprising the following steps:

[0006] When a fault occurs, traveling wave signals and directions are acquired by multiple preset traveling wave acquisition devices. Based on the traveling wave direction of the traveling wave signal, two traveling wave acquisition devices with opposite traveling wave directions and the closest distance are selected. The multiple preset traveling wave acquisition devices have the same sampling frequency.

[0007] A cubic B-spline wavelet is constructed as a wavelet basis, and the traveling wave signal of the selected traveling wave acquisition device is decomposed by wavelet to obtain the highest frequency harmonic component.

[0008] The harmonic components are simulated to obtain the harmonic spectrum. The direction of the first abrupt change point of the harmonic spectrum at scale 1 is obtained. If the direction of the first abrupt change point is positive, it is determined that the fault section is located outside the installation point of the traveling wave acquisition device corresponding to the harmonic component and the midpoint of the line. If the direction of the first abrupt change point is negative, it is determined that the fault section is located between the installation point of the traveling wave acquisition device corresponding to the harmonic component and the midpoint of the line.

[0009] Obtain the wavelet coefficient modulus maxima and corresponding modulus maxima at scale 4 of the harmonic spectrum. Calculate the fault time based on the modulus maxima and the sampling frequency. Use the fault time to calculate the specific location of the fault point in the fault segment.

[0010] Preferably, after a fault occurs, traveling wave signals and arrival times are acquired from multiple preset traveling wave acquisition devices. Based on the traveling wave direction of the signals, two traveling wave acquisition devices with opposite directions and closest distances are selected. Prior to the step where the multiple preset traveling wave acquisition devices have the same sampling frequency, the following steps are included:

[0011] The length of the faulty line is obtained, and it is determined whether the length of the faulty line is greater than a preset length threshold. If the length of the faulty line is not greater than the preset length threshold, a traveling wave acquisition device is set up at the connection point of the substations at both ends of the line. If the length of the faulty line is greater than the preset length threshold, a traveling wave acquisition device is set up at the connection point of the substations at both ends of the line, and a traveling wave acquisition device is installed at a preset distance along the faulty line.

[0012] Determine whether the faulty line contains a T-junction section. If it is determined that the faulty line contains a T-junction section, then install a traveling wave acquisition device at the junction of the T-junctions.

[0013] Preferably, the steps of obtaining the wavelet coefficient modulus maxima points and corresponding modulus maxima at scale 4 of the harmonic spectrum, calculating the fault time based on the modulus maxima and the sampling frequency, and calculating the specific location of the fault point in the fault segment using the fault time specifically include:

[0014] Obtain the wavelet coefficient modulus maxima and their corresponding modulus maxima at scale 4 of the harmonic spectrum;

[0015] The fault time is obtained by multiplying the modulus maximum value by the sampling frequency.

[0016] The specific location of the fault point in the fault section is calculated using the following formula based on the fault time:

[0017]

[0018]

[0019] In the formula, L M L represents the distance from the fault point to the installation point of the Mth traveling wave acquisition device, L is the total length between the installation points of the Mth and Nth traveling wave acquisition devices, v represents the traveling wave velocity, and t represents the traveling wave velocity. M t represents the fault time corresponding to the Mth traveling wave acquisition device. N L represents the fault time corresponding to the Nth traveling wave acquisition device. N This represents the distance from the fault point to the installation point of the Nth traveling wave acquisition device, where the installation points of the Mth and Nth traveling wave acquisition devices are two adjacent installation points.

[0020] Preferably, the method further includes:

[0021] Based on a preset sampling frequency, the fault current of the faulty line within a preset time period is acquired, and a fault current sequence is constructed, denoted as I1, I2, I3, ..., I... n , among which, I n This represents the fault current of the nth fault.

[0022] The rate of change of current is calculated using the following formula:

[0023]

[0024] In the formula, ΔI represents the rate of change of current, and t n This represents the nth time point;

[0025] The current change rate is compared with a preset current change rate threshold. If the current change rate is greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a lightning strike fault. If the current change rate is not greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a non-lightning strike fault.

[0026] Secondly, the present invention provides a traveling wave fault location system, comprising:

[0027] The device screening module is used to, when a fault occurs, acquire traveling wave signals and traveling wave directions from multiple preset traveling wave acquisition devices, and screen out two traveling wave acquisition devices with opposite traveling wave directions and the closest distance based on the traveling wave direction of the traveling wave signal, wherein the multiple preset traveling wave acquisition devices have the same sampling frequency.

[0028] The wavelet decomposition module is used to construct a cubic B-spline wavelet as a wavelet basis to perform wavelet decomposition on the traveling wave signal of the selected traveling wave acquisition device to obtain the highest frequency harmonic component.

[0029] The fault section judgment module is used to simulate the harmonic components, obtain the harmonic spectrum, and obtain the direction of the first abrupt change point of the harmonic spectrum at scale 1. If the direction of the first abrupt change point is positive, it is determined that the fault section is located outside the installation point of the traveling wave acquisition device corresponding to the harmonic component and the line midpoint. If the direction of the first abrupt change point is negative, it is determined that the fault section is located between the installation point of the traveling wave acquisition device corresponding to the harmonic component and the line midpoint.

[0030] The fault location module is used to obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4, calculate the fault time based on the modulus maxima and the sampling frequency, and use the fault time to calculate the specific location of the fault point in the fault section.

[0031] Preferably, the system further includes:

[0032] The first device deployment module is used to obtain the length of the faulty line and determine whether the length of the faulty line is greater than a preset length threshold. If the length of the faulty line is not greater than the preset length threshold, a traveling wave acquisition device is deployed at the connection point of the substations at both ends of the line. If the length of the faulty line is greater than the preset length threshold, a traveling wave acquisition device is deployed at the connection point of the substations at both ends of the line, and a traveling wave acquisition device is installed at a preset distance along the faulty line.

[0033] The second device deployment module is used to determine whether the faulty line contains a T-connection section. If the faulty line is determined to contain a T-connection section, a traveling wave acquisition device is installed at the intersection of the T-connections.

[0034] Preferably, the fault location module specifically includes:

[0035] The first calculation module is used to obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4.

[0036] The second calculation module is used to perform a product operation based on the modulus maximum value and the sampling frequency to obtain the fault time.

[0037] The third calculation module is used to calculate the specific location of the fault point in the fault section using the following formula based on the fault time.

[0038]

[0039]

[0040] In the formula, L M L represents the distance from the fault point to the installation point of the Mth traveling wave acquisition device, L is the total length between the installation points of the Mth and Nth traveling wave acquisition devices, v represents the traveling wave velocity, and t represents the traveling wave velocity. M t represents the fault time corresponding to the Mth traveling wave acquisition device. N L represents the fault time corresponding to the Nth traveling wave acquisition device. N This represents the distance from the fault point to the installation point of the Nth traveling wave acquisition device, where the installation points of the Mth and Nth traveling wave acquisition devices are two adjacent installation points.

[0041] Preferably, the system further includes:

[0042] The current acquisition module is used to acquire the fault current of the faulty line within a preset time period based on a preset acquisition frequency, and construct a fault current sequence, denoted as I1, I2, I3, ..., I n , among which, I n This represents the fault current of the nth fault.

[0043] The rate of change calculation module is used to calculate the rate of change of current using the following formula:

[0044]

[0045] In the formula, ΔI represents the rate of change of current, and t n This represents the nth time point;

[0046] The comparison module is used to compare the current change rate with a preset current change rate threshold. If the current change rate is greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a lightning strike fault. If the current change rate is not greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a non-lightning strike fault.

[0047] As can be seen from the above technical solutions, the present invention has the following advantages:

[0048] This invention locates traveling wave faults by selecting two traveling wave acquisition devices with opposite traveling wave directions and the closest distance. A cubic B-spline wavelet is constructed as a wavelet basis. The traveling wave signal from the selected acquisition devices is decomposed using wavelets to obtain the highest frequency harmonic component. The harmonic component is then simulated, and the direction of the first abrupt change point in the harmonic spectrum at scale 1 is used to determine the fault segment. Furthermore, the wavelet coefficient modulus maxima at scale 4 and their corresponding modulus maxima are obtained. The fault time is calculated based on the modulus maxima and the sampling frequency. The fault time is then used to calculate the specific location of the fault point within the fault segment, thereby improving the accuracy of fault location. Attached Figure Description

[0049] Figure 1 A flowchart of a traveling wave fault location method provided in an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a traveling wave in a faulty line containing a T-contact, provided in an embodiment of the present invention;

[0051] Figure 3 A waveform diagram of the harmonic spectrum at scale 1 provided for an embodiment of the present invention;

[0052] Figure 4 Another waveform diagram of the harmonic spectrum at scale 1 provided for an embodiment of the present invention;

[0053] Figure 5 This is a schematic diagram of a traveling wave fault location system provided in an embodiment of the present invention. Detailed Implementation

[0054] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] For easier understanding, please refer to Figure 1 The present invention provides a traveling wave fault location method, comprising the following steps:

[0056] S1. When a fault occurs, the traveling wave signal and direction are acquired by multiple preset traveling wave acquisition devices. Based on the traveling wave direction of the traveling wave signal, the two traveling wave acquisition devices with opposite traveling wave directions and the closest distance are selected. The sampling frequency of the multiple preset traveling wave acquisition devices is the same.

[0057] It should be noted that when a fault occurs, the traveling wave signal at the fault point will change. If the traveling wave signals acquired by the traveling wave acquisition devices are in the same direction, it means that the fault point is in the same direction. Therefore, it is necessary to find two traveling wave acquisition devices with opposite traveling wave directions and the closest distance to each other in order to narrow down the fault point location range and improve the location efficiency.

[0058] Among them, the traveling wave acquisition device can use an ultra-low power high-precision GPS / BeiDou timing module with a timing error of less than 100ns.

[0059] S2. Construct a cubic B-spline wavelet as a wavelet basis, and perform wavelet decomposition on the traveling wave signal of the selected traveling wave acquisition device to obtain the highest frequency harmonic component.

[0060] It should be noted that B-spline wavelets have the characteristics of linear correlation (the modulus maxima correspond to the abrupt change point without time delay), tight support wavelets (the smaller the support interval, the better for the detection of singular points), and first-order vanishing moments (too high vanishing moments will lead to an increase in modulus maxima, which is not conducive to determining the accurate arrival time of the traveling wave). Selecting B-cubic spline wavelets for the identification of traveling wave fronts can improve the identification accuracy.

[0061] S3. Simulate the harmonic components to obtain the harmonic spectrum. Obtain the direction of the first abrupt change point of the harmonic spectrum at scale 1. If the direction of the first abrupt change point is positive, it is determined that the fault section is located outside the installation point of the traveling wave acquisition device corresponding to the harmonic component and the midpoint of the line. If the direction of the first abrupt change point is negative, it is determined that the fault section is located between the installation point of the traveling wave acquisition device corresponding to the harmonic component and the midpoint of the line.

[0062] It should be noted that, as Figure 2 As shown, this diagram illustrates the traveling wave of a faulty line containing a T-junction. Fault point A is located at the T-junction. Traveling wave acquisition devices are installed at substations 1, 2, and 3. The arrival times of the traveling wave from fault point A to substations 1 and 2 are approximately the same. Therefore, comparing the arrival times may not be sufficient to distinguish the faulty section. However, assuming a fault occurs in the line between fault point A and substation 1, the traveling wave will contain both reflected and refracted waves. Conversely, the traveling wave between fault point A and substation 3 will only contain reflected waves, without refraction. Using this, harmonic components are simulated, and the harmonic spectrum is obtained. It is found that... Figure 3 As shown, if a refracted wave signal appears, the direction of the first abrupt change point in the harmonic spectrum is negative, that is, a downward abrupt change; as... Figure 4 As shown, if no refracted wave signal appears, the direction of the first abrupt change point in the harmonic spectrum is positive, that is, an upward abrupt change. Therefore, the direction of the first abrupt change point in the harmonic spectrum at scale 1 can be used to determine the fault section.

[0063] Meanwhile, since the rise time of a traveling wave front is typically several to tens of microseconds, it may contain frequency components ranging from low frequencies to hundreds of kilohertz. When using wavelet analysis to analyze traveling wave signals, the wavelet transform of the signal at each scale is equivalent to processing a wave group with a known center frequency. As the analysis scale changes, the frequency band range of the analyzed traveling wave also changes. The smaller the scale, the more accurate the correspondence between the modulus maxima and abrupt change points of the wavelet coefficients. Therefore, simulations show that scale 1 is the most accurate.

[0064] S4. Obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4. Calculate the fault time based on the modulus maxima and the sampling frequency. Use the fault time to calculate the specific location of the fault point in the fault section.

[0065] It's important to note that the modulus maxima in wavelet transform are closely related to the scale (i.e., frequency). The distribution of modulus maxima differs at different scales; a modulus maxima present at one scale may not appear at another. Theoretically, the smaller the scale, the more accurate the correspondence between the modulus maxima and abrupt change points of the wavelet coefficients. However, at small scales, wavelet coefficients are highly susceptible to noise, resulting in many spurious extrema, making it difficult to pinpoint the location of abrupt change points by considering only one scale. If the scale parameter is chosen too large, the signal characteristics become unclear.

[0066] Meanwhile, when using higher-scale wavelet transform, the extracted traveling wave front bandwidth is narrower, and the occurrence time of the modulus maxima may have a certain delay from the actual abrupt change of the traveling wave front. Therefore, by working backward from and comparing the maxima points on a larger scale, the location of the abrupt change point is found, and the time when the traveling wave arrives at the detection point is finally determined, thereby calculating the fault distance. For this purpose, this embodiment uses the modulus maxima corresponding to the larger scale 4 for calculation.

[0067] It should be noted that this embodiment provides a traveling wave fault location method. By selecting two traveling wave acquisition devices with opposite traveling wave directions and the closest distance for traveling wave fault location, a cubic B-spline wavelet is constructed as a wavelet basis. The traveling wave signal from the selected traveling wave acquisition devices is decomposed into wavelet components to obtain the highest frequency harmonic components. The harmonic components are also simulated. The direction of the first abrupt change point of the harmonic spectrum obtained from the simulation is used to determine the fault segment. The wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4 are also obtained. The fault time is calculated based on the modulus maxima and the sampling frequency. The specific location of the fault point in the fault segment is calculated using the fault time, thereby improving the fault location accuracy.

[0068] In one specific embodiment, the steps preceding step S1 include:

[0069] S10. Obtain the length of the faulty line and determine whether the length of the faulty line is greater than a preset length threshold. If the length of the faulty line is not greater than the preset length threshold, then a traveling wave acquisition device is installed at the connection point of the substations at both ends of the line. If the length of the faulty line is greater than the preset length threshold, then a traveling wave acquisition device is installed at the connection point of the substations at both ends of the line, and a traveling wave acquisition device is installed at a preset distance along the faulty line.

[0070] In one example, the preset length threshold can be set to 50 km. If the line length is less than 50 km, two traveling wave acquisition devices can be installed, one at each of the first towers exiting from the two substations. If the line length is more than 50 km but between 50 and 80 km, three traveling wave acquisition devices can be installed, one at each of the first towers exiting from the two substations. Then, one traveling wave acquisition device is installed in the middle of the line. It is important to note that after the traveling wave acquisition device in the middle of the line divides the line into two segments, the two segments cannot be of equal length. For lines longer than 80 km, after installing one traveling wave acquisition device at each of the first towers exiting from the two substations, one traveling wave acquisition device can be added approximately every 80 to 100 km in the middle of the line.

[0071] It should be noted that for lines with a mix of overhead and cable sections, to accurately pinpoint whether the fault is in the overhead or cable section, one traveling wave acquisition device should be installed at the boundary between the overhead and cable sections, based on the installation principles for purely overhead lines. If the line contains several cable sections, one traveling wave acquisition device must be installed at the boundary between each overhead and cable section.

[0072] For a double-circuit line on the same tower, if conditions limit the installation of only one traveling wave acquisition device per line, then one line will be installed on the first-level tower and the other line will be installed on the last-level tower.

[0073] For lines with different sections under the management of different regional bureaus, in order to accurately locate the faulty section, a traveling wave acquisition device can be installed at the boundary point of different jurisdictions, based on the principle of installation on pure overhead lines.

[0074] S11. Determine whether the faulty line contains a T-connection section. If the faulty line contains a T-connection section, install a traveling wave acquisition device at the intersection of the T-connections.

[0075] In one specific embodiment, step S4 specifically includes:

[0076] S401. Obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4.

[0077] S402. The fault time is obtained by multiplying the modulus maximum value and the sampling frequency.

[0078] S403. Calculate the specific location of the fault point in the fault section using the following formula based on the fault time:

[0079]

[0080]

[0081] In the formula, L M L represents the distance from the fault point to the installation point of the Mth traveling wave acquisition device, L is the total length between the installation points of the Mth and Nth traveling wave acquisition devices, v represents the traveling wave velocity, and t represents the traveling wave velocity. M t represents the fault time corresponding to the Mth traveling wave acquisition device. N L represents the fault time corresponding to the Nth traveling wave acquisition device. N This represents the distance from the fault point to the installation point of the Nth traveling wave acquisition device, where the installation points of the Mth and Nth traveling wave acquisition devices are two adjacent installation points.

[0082] In one specific embodiment, the method further includes:

[0083] S5. Based on a preset sampling frequency, acquire the fault current of the faulty line within a preset time period, and construct a fault current sequence, denoted as I1, I2, I3, ..., I n , among which, I n This represents the fault current of the nth fault.

[0084] S6. The rate of change of current is calculated using the following formula:

[0085]

[0086] In the formula, ΔI represents the rate of change of current, and t n This represents the nth time point;

[0087] S7. Compare the current change rate with the preset current change rate threshold. If the current change rate is greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a lightning strike fault. If the current change rate is not greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a non-lightning strike fault.

[0088] It should be noted that fault type identification mainly considers distinguishing between lightning-induced faults and non-lightning-induced faults. For non-lightning-induced fault types such as single-pole grounding faults, inter-pole short-circuit faults, and open-circuit faults, by comparing the fault current change rates of the two, it can be concluded that the fault current change rate of lightning current is much greater than that of non-lightning-induced faults (such as ground faults). Therefore, a current change rate threshold can be set based on manual experience or simulation results. By calculating the current change rate and comparing it with the current change rate threshold, the fault type of the faulty line can be determined.

[0089] The above is a detailed description of an embodiment of a traveling wave fault location method provided by the present invention. The following is a detailed description of an embodiment of a traveling wave fault location system provided by the present invention.

[0090] For easier understanding, please refer to Figure 5 The present invention provides a traveling wave fault location system, comprising:

[0091] The device screening module 100 is used to, when a fault occurs, acquire traveling wave signals and traveling wave directions from multiple preset traveling wave acquisition devices, and screen out two traveling wave acquisition devices with opposite traveling wave directions and the closest distance based on the traveling wave direction of the traveling wave signal. The multiple preset traveling wave acquisition devices have the same sampling frequency.

[0092] The wavelet decomposition module 200 is used to construct a cubic B-spline wavelet as a wavelet basis to perform wavelet decomposition on the selected traveling wave signal from the traveling wave acquisition device to obtain the highest frequency harmonic component.

[0093] The fault section judgment module 300 is used to simulate the harmonic components, obtain the harmonic spectrum, and obtain the direction of the first abrupt change point of the harmonic spectrum at scale 1. If the direction of the first abrupt change point is positive, it is determined that the fault section is located outside the installation point of the traveling wave acquisition device corresponding to the harmonic component and the line midpoint. If the direction of the first abrupt change point is negative, it is determined that the fault section is located between the installation point of the traveling wave acquisition device corresponding to the harmonic component and the line midpoint.

[0094] The fault location module 400 is used to obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4, calculate the fault time based on the modulus maxima and the sampling frequency, and use the fault time to calculate the specific location of the fault point in the fault section.

[0095] In one specific embodiment, the system further includes:

[0096] The first device deployment module is used to obtain the length of the faulty line and determine whether the length of the faulty line is greater than a preset length threshold. If the length of the faulty line is not greater than the preset length threshold, a traveling wave acquisition device is deployed at the connection point of the substations at both ends of the line. If the length of the faulty line is greater than the preset length threshold, a traveling wave acquisition device is deployed at the connection point of the substations at both ends of the line, and a traveling wave acquisition device is installed at a preset distance along the faulty line.

[0097] The second device deployment module is used to determine whether the faulty line contains a T-connection section. If the faulty line is determined to contain a T-connection section, a traveling wave acquisition device is installed at the intersection of the T-connections.

[0098] In one specific embodiment, the fault location module specifically includes:

[0099] The first calculation module is used to obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4.

[0100] The second calculation module is used to perform a product operation based on the modulus maximum value and the sampling frequency to obtain the fault time.

[0101] The third calculation module is used to calculate the specific location of the fault point in the fault section using the following formula based on the fault time:

[0102]

[0103]

[0104] In the formula, L M L represents the distance from the fault point to the installation point of the Mth traveling wave acquisition device, L is the total length between the installation points of the Mth and Nth traveling wave acquisition devices, v represents the traveling wave velocity, and t represents the traveling wave velocity.M t represents the fault time corresponding to the Mth traveling wave acquisition device. N L represents the fault time corresponding to the Nth traveling wave acquisition device. N This represents the distance from the fault point to the installation point of the Nth traveling wave acquisition device, where the installation points of the Mth and Nth traveling wave acquisition devices are two adjacent installation points.

[0105] In one specific embodiment, the system further includes:

[0106] The current acquisition module is used to acquire the fault current of the faulty line within a preset time period based on a preset acquisition frequency, and construct a fault current sequence, denoted as I1, I2, I3, ..., I n , among which, I n This represents the fault current of the nth fault.

[0107] The rate of change calculation module is used to calculate the rate of change of current using the following formula:

[0108]

[0109] In the formula, ΔI represents the rate of change of current, and t n This represents the nth time point;

[0110] The comparison module is used to compare the current change rate with a preset current change rate threshold. If the current change rate is greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a lightning strike fault. If the current change rate is not greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a non-lightning strike fault.

[0111] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0112] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0113] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0114] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0115] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for locating traveling wave faults, characterized in that, Includes the following steps: When a fault occurs, traveling wave signals and directions are acquired by multiple preset traveling wave acquisition devices. Based on the traveling wave direction of the traveling wave signal, two traveling wave acquisition devices with opposite traveling wave directions and the closest distance are selected. The multiple preset traveling wave acquisition devices have the same sampling frequency. A cubic B-spline wavelet is constructed as a wavelet basis, and the traveling wave signal of the selected traveling wave acquisition device is decomposed by wavelet to obtain the highest frequency harmonic component. The harmonic components are simulated to obtain the harmonic spectrum. The direction of the first abrupt change point of the harmonic spectrum at scale 1 is obtained. If the direction of the first abrupt change point is positive, it is determined that the fault section is located outside the installation point of the traveling wave acquisition device corresponding to the harmonic component and the midpoint of the line. If the direction of the first abrupt change point is negative, it is determined that the fault section is located between the installation point of the traveling wave acquisition device corresponding to the harmonic component and the midpoint of the line. Obtain the wavelet coefficient modulus maxima and corresponding modulus maxima at scale 4 of the harmonic spectrum. Calculate the fault time based on the modulus maxima and the sampling frequency. Use the fault time to calculate the specific location of the fault point in the fault segment.

2. The traveling wave fault location method according to claim 1, characterized in that, After a fault occurs, traveling wave signals and arrival times are acquired from multiple preset traveling wave acquisition devices. Based on the traveling wave direction, two traveling wave acquisition devices with opposite directions and closest distances are selected. Prior to the step where the multiple preset traveling wave acquisition devices have the same sampling frequency, the following steps are included: The length of the faulty line is obtained, and it is determined whether the length of the faulty line is greater than a preset length threshold. If the length of the faulty line is not greater than the preset length threshold, a traveling wave acquisition device is set up at the connection point of the substations at both ends of the line. If the length of the faulty line is greater than the preset length threshold, a traveling wave acquisition device is set up at the connection point of the substations at both ends of the line, and a traveling wave acquisition device is installed at a preset distance along the faulty line. Determine whether the faulty line contains a T-junction section. If it is determined that the faulty line contains a T-junction section, then install a traveling wave acquisition device at the junction of the T-junctions.

3. The traveling wave fault location method according to claim 2, characterized in that, The steps of obtaining the wavelet coefficient modulus maxima points and corresponding modulus maxima at scale 4 of the harmonic spectrum, calculating the fault time based on the modulus maxima and the sampling frequency, and using the fault time to calculate the specific location of the fault point in the fault segment specifically include: Obtain the wavelet coefficient modulus maxima and their corresponding modulus maxima at scale 4 of the harmonic spectrum; The fault time is obtained by multiplying the modulus maximum value by the sampling frequency. The specific location of the fault point in the fault section is calculated using the following formula based on the fault time: In the formula, L M L represents the distance from the fault point to the installation point of the Mth traveling wave acquisition device, L is the total length between the installation points of the Mth and Nth traveling wave acquisition devices, v represents the traveling wave velocity, and t represents the traveling wave velocity. M t represents the fault time corresponding to the Mth traveling wave acquisition device. N L represents the fault time corresponding to the Nth traveling wave acquisition device. N This represents the distance from the fault point to the installation point of the Nth traveling wave acquisition device, where the installation points of the Mth and Nth traveling wave acquisition devices are two adjacent installation points.

4. The traveling wave fault location method according to claim 1, characterized in that, Also includes: Based on a preset sampling frequency, the fault current of the faulty line within a preset time period is acquired, and a fault current sequence is constructed, denoted as I1, I2, I3, ..., I... n , among which, I n This represents the fault current of the nth fault. The rate of change of current is calculated using the following formula: In the formula, ΔI represents the rate of change of current, and t n This represents the nth time point; The current change rate is compared with a preset current change rate threshold. If the current change rate is greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a lightning strike fault. If the current change rate is not greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a non-lightning strike fault.

5. A traveling wave fault location system, characterized in that, include: The device screening module is used to, when a fault occurs, acquire traveling wave signals and traveling wave directions from multiple preset traveling wave acquisition devices, and screen out two traveling wave acquisition devices with opposite traveling wave directions and the closest distance based on the traveling wave direction of the traveling wave signal, wherein the multiple preset traveling wave acquisition devices have the same sampling frequency. The wavelet decomposition module is used to construct a cubic B-spline wavelet as a wavelet basis to perform wavelet decomposition on the traveling wave signal of the selected traveling wave acquisition device to obtain the highest frequency harmonic component. The fault section judgment module is used to simulate the harmonic components, obtain the harmonic spectrum, and obtain the direction of the first abrupt change point of the harmonic spectrum at scale 1. If the direction of the first abrupt change point is positive, it is determined that the fault section is located outside the installation point of the traveling wave acquisition device corresponding to the harmonic component and the line midpoint. If the direction of the first abrupt change point is negative, it is determined that the fault section is located between the installation point of the traveling wave acquisition device corresponding to the harmonic component and the line midpoint. The fault location module is used to obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4, calculate the fault time based on the modulus maxima and the sampling frequency, and use the fault time to calculate the specific location of the fault point in the fault section.

6. The traveling wave fault location system according to claim 5, characterized in that, Also includes: The first device deployment module is used to obtain the length of the faulty line and determine whether the length of the faulty line is greater than a preset length threshold. If the length of the faulty line is not greater than the preset length threshold, a traveling wave acquisition device is deployed at the connection point of the substations at both ends of the line. If the length of the faulty line is greater than the preset length threshold, a traveling wave acquisition device is deployed at the connection point of the substations at both ends of the line, and a traveling wave acquisition device is installed at a preset distance along the faulty line. The second device deployment module is used to determine whether the faulty line contains a T-connection section. If the faulty line is determined to contain a T-connection section, a traveling wave acquisition device is installed at the intersection of the T-connections.

7. The traveling wave fault location system according to claim 6, characterized in that, The fault location module specifically includes: The first calculation module is used to obtain the wavelet coefficient modulus maxima points and corresponding modulus maxima of the harmonic spectrum at scale 4. The second calculation module is used to perform a product operation based on the modulus maximum value and the sampling frequency to obtain the fault time. The third calculation module is used to calculate the specific location of the fault point in the fault section using the following formula based on the fault time. In the formula, L M L represents the distance from the fault point to the installation point of the Mth traveling wave acquisition device, L is the total length between the installation points of the Mth and Nth traveling wave acquisition devices, v represents the traveling wave velocity, and t represents the traveling wave velocity. M t represents the fault time corresponding to the Mth traveling wave acquisition device. N L represents the fault time corresponding to the Nth traveling wave acquisition device. N This represents the distance from the fault point to the installation point of the Nth traveling wave acquisition device, where the installation points of the Mth and Nth traveling wave acquisition devices are two adjacent installation points.

8. The traveling wave fault location system according to claim 5, characterized in that, Also includes: The current acquisition module is used to acquire the fault current of the faulty line within a preset time period based on a preset acquisition frequency, and construct a fault current sequence, denoted as I1, I2, I3, ..., I n , among which, I n This represents the fault current of the nth fault. The rate of change calculation module is used to calculate the rate of change of current using the following formula: In the formula, ΔI represents the rate of change of current, and t n This represents the nth time point; The comparison module is used to compare the current change rate with a preset current change rate threshold. If the current change rate is greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a lightning strike fault. If the current change rate is not greater than the preset current change rate threshold, the fault type of the faulty line is determined to be a non-lightning strike fault.

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