Underground cable partial discharge fault detection method and device based on actual cable characteristics

Abstract

This invention relates to the field of discharge detection technology, and discloses a method and apparatus for detecting partial discharge faults in underground cables based on the actual characteristics of the cables. The invention acquires high-frequency characteristic data of the underground cable under test through measurement; constructs a structural model of the underground cable; calculates the total high-frequency attenuation loss of the cable using the high-frequency characteristic data based on the model, and calculates a high-frequency attenuation constant based on the calculated total high-frequency attenuation loss value; performs partial discharge analysis on cable samples with actual partial discharge locations based on the calculated high-frequency attenuation constant value; and adjusts the model based on the comparison results between the obtained partial discharge analysis location and the actual partial discharge location to obtain an optimal high-frequency attenuation constant as the target high-frequency attenuation constant, which is then used for partial discharge fault detection in the underground cable under test. This invention uses the high-frequency attenuation constant obtained through actual measurement and modeling to detect partial discharge faults in underground cables, which can effectively improve the accuracy of partial discharge signal analysis.

Description

Technical Field

[0001] This invention relates to the field of discharge detection technology, and in particular to a method and apparatus for detecting partial discharge faults in underground cables based on the actual characteristics of the cables. Background Technology

[0002] Currently, cable fault location is mainly achieved by analyzing monitored partial discharge signals. Partial discharge signals are ultra-high frequency signals, and their high-frequency components are attenuated during propagation, resulting in smaller signal peaks and larger waveforms. The degree of attenuation of the high-frequency components of the partial discharge signal determines the peak and waveform width of the partial discharge wave, and the degree of attenuation is determined by the high-frequency attenuation constant of the cable's physical structure.

[0003] In existing technologies, a high-frequency attenuation constant is typically assumed, and the partial discharge signal of underground cables is then analyzed based on this assumed attenuation constant. However, due to the different physical structures and material properties of different underground cables, their high-frequency attenuation constants vary. The assumed high-frequency attenuation constant often deviates significantly, leading to numerous errors in the partial discharge signal analysis results. Summary of the Invention

[0004] This invention provides a method and apparatus for detecting partial discharge faults in underground cables based on the actual characteristics of the cables, which solves the technical problem that existing schemes for analyzing partial discharge signals of underground cables based on assumed high-frequency attenuation constants have poor signal analysis accuracy.

[0005] The first aspect of this invention provides a method for detecting partial discharge faults in underground cables based on the actual characteristics of the cables, comprising:

[0006] Step S1: Obtain high-frequency characteristic data by measuring the high-frequency characteristics of the first test sample of the underground cable to be tested;

[0007] Step S2: Determine the structural parameters of the underground cable to be tested, and construct a structural model of the underground cable to be tested based on the structural parameters;

[0008] Step S3: Calculate the total high-frequency attenuation loss of the underground cable under test using the high-frequency characteristic data based on the current underground cable structure model under test, and obtain the calculated value of the total high-frequency attenuation loss.

[0009] Step S4: Calculate the high-frequency attenuation constant based on the obtained total high-frequency attenuation loss calculation value;

[0010] Step S5: Based on the obtained high-frequency attenuation constant calculation value, perform partial discharge analysis on the second test sample of the underground cable under test to obtain the partial discharge analysis location; the second test sample has an actual partial discharge location.

[0011] Step S6: Calculate the difference between the partial discharge analysis location and the actual partial discharge location, and determine whether the difference is greater than a preset difference threshold; if yes, adjust the current underground cable structure model to be tested and return to step S3; if no, use the current calculated high-frequency attenuation constant as the target high-frequency attenuation constant and execute step S7.

[0012] Step S7: Perform partial discharge fault detection on the underground cable under test according to the target high-frequency attenuation constant to obtain the corresponding partial discharge fault detection result.

[0013] According to one achievable method of the first aspect of the present invention, the step of calculating the total high-frequency attenuation loss of the underground cable under test using the high-frequency characteristic data based on the current structural model of the underground cable under test, and obtaining the calculated value of the total high-frequency attenuation loss, includes:

[0014] The effective contact point distance is determined based on the current underground cable structure model to be tested; the effective contact point distance is the gap distance corresponding to the gap between the semiconductor layer and the ground wire.

[0015] The high-frequency attenuation loss of different material parts of the underground cable under test is calculated based on the effective contact point distance and the high-frequency characteristic data; the high-frequency attenuation loss of different material parts includes the skin effect loss between the conductor and the ground wire and the high-frequency attenuation loss of the semiconductor layer.

[0016] The high-frequency attenuation loss of the different material parts is added together to obtain the calculated value of the total high-frequency attenuation loss.

[0017] According to a method achievable according to a first aspect of the present invention, the calculation of the high-frequency attenuation loss of different material portions of the underground cable under test based on the effective contact point distance and the high-frequency characteristic data includes:

[0018] Calculate the skin effect loss of the conductor and ground wire based on the high-frequency characteristic data;

[0019] The high-frequency loss current of the semiconductor layer is calculated based on the effective contact point distance and the high-frequency characteristic data. The high-frequency attenuation loss of the semiconductor layer is calculated based on the high-frequency loss current and the resistance parameters of the semiconductor layer's resistive portion.

[0020] According to a method achievable according to a first aspect of the present invention, calculating the high-frequency loss current of the semiconductor layer based on the effective contact point distance and the high-frequency characteristic data includes:

[0021] The high-frequency loss current of the semiconductor layer is calculated using the following formula:

[0022]

[0023] in:

[0024]

[0025] In the formula, I r1 Let σ represent the high-frequency loss current of the semiconductor layer, j be the imaginary part, ω be the angular frequency, ε0 ​​be the vacuum dielectric constant, ε1 be the dielectric constant of the semiconductor layer, I(x) be the current distributed along the ground wire, x be the length of the ground wire, V0 be the voltage amplitude, and Z be the voltage distribution. c1 Z c All are high-frequency characteristic impedance coefficients, K1 is a proportionality coefficient with respect to the high-frequency characteristic impedance coefficient, and R d R is the radius of the insulation layer of the underground cable. c C is the radius of the conductor of the underground cable. tl For distributed conductivity, T is the period, and d is half the effective contact point distance.

[0026] According to one achievable method of the first aspect of the present invention, the adjustment of the current underground cable structure model to be measured includes:

[0027] The effective contact point distance in the current underground cable structure model to be tested is increased.

[0028] According to one aspect of the present invention, the preset difference threshold is a distance threshold, and the calculation of the difference between the partial discharge analysis location and the actual partial discharge location includes:

[0029] The distance between the partial discharge analysis location and the actual partial discharge location is calculated as the difference value.

[0030] According to one aspect of the invention, the partial discharge fault detection result includes the location of the partial discharge signal and the intensity of the partial discharge signal, and the method further includes:

[0031] When the intensity of the partial discharge signal exceeds a preset partial discharge signal intensity threshold, a corresponding warning message is output; the warning message includes the location of the corresponding partial discharge signal.

[0032] A second aspect of the present invention provides an underground cable partial discharge fault detection device based on the actual characteristics of the cable, comprising:

[0033] The acquisition module is used to acquire high-frequency characteristic data obtained by measuring the high-frequency characteristics of the first test sample of the underground cable under test;

[0034] The construction module is used to determine the structural parameters of the underground cable to be tested, and to construct a structural model of the underground cable to be tested based on the structural parameters.

[0035] The first calculation module is used to calculate the total high-frequency attenuation loss of the underground cable under test based on the current underground cable structure model and the high-frequency characteristic data, and obtain the calculated value of the total high-frequency attenuation loss.

[0036] The second calculation module is used to calculate the high-frequency attenuation constant based on the obtained high-frequency attenuation total loss calculation value;

[0037] The analysis module is used to perform partial discharge analysis on the second test sample of the underground cable under test based on the obtained high-frequency attenuation constant calculation value, and to obtain the partial discharge analysis location; the second test sample is located at the actual partial discharge location;

[0038] The adjustment module is used to calculate the difference between the partial discharge analysis location and the actual partial discharge location, and determine whether the difference is greater than a preset difference threshold. If so, the current underground cable structure model to be tested is adjusted and returned to the first calculation module. If not, the current high-frequency attenuation constant calculated value is used as the target high-frequency attenuation constant, and the detection module is executed.

[0039] The detection module is used to perform partial discharge fault detection on the underground cable under test according to the target high-frequency attenuation constant, and obtain the corresponding partial discharge fault detection results.

[0040] According to one achievable embodiment of the second aspect of the present invention, the first computing module includes:

[0041] A determining unit is used to determine the effective contact point distance based on the current underground cable structure model to be tested; the effective contact point distance is the gap distance corresponding to the gap between the semiconductor layer and the ground wire.

[0042] The first calculation unit is used to calculate the high-frequency attenuation loss of different material parts of the underground cable under test based on the effective contact point distance and the high-frequency characteristic data; the high-frequency attenuation loss of the different material parts includes the skin effect loss between the conductor and the ground wire and the high-frequency attenuation loss of the semiconductor layer.

[0043] The second calculation unit is used to add up the high-frequency attenuation losses of the different material parts to obtain the calculated value of the total high-frequency attenuation loss.

[0044] According to one achievable embodiment of the second aspect of the present invention, the first computing unit comprises:

[0045] The first calculation subunit is used to calculate the skin effect loss of the conductor and ground wire based on the high-frequency characteristic data.

[0046] The second calculation subunit is used to calculate the high-frequency loss current of the semiconductor layer based on the effective contact point distance and the high-frequency characteristic data, and to calculate the high-frequency attenuation loss of the semiconductor layer based on the high-frequency loss current and the resistance parameters of the semiconductor layer's resistance portion.

[0047] According to one achievable method of the second aspect of the present invention, the second computing subunit is specifically used for:

[0048] The high-frequency loss current of the semiconductor layer is calculated using the following formula:

[0049]

[0050] in:

[0051]

[0052] In the formula, I r1 Let σ represent the high-frequency loss current of the semiconductor layer, j be the imaginary part, ω be the angular frequency, ε0 ​​be the vacuum dielectric constant, ε1 be the dielectric constant of the semiconductor layer, I(x) be the current distributed along the ground wire, x be the length of the ground wire, V0 be the voltage amplitude, and Z be the voltage distribution. c1 Z c All are high-frequency characteristic impedance coefficients, K1 is a proportionality coefficient with respect to the high-frequency characteristic impedance coefficient, and R d R is the radius of the insulation layer of the underground cable. c C is the radius of the conductor of the underground cable. tl For distributed conductivity, T is the period, and d is half the effective contact point distance.

[0053] According to one achievable embodiment of the second aspect of the present invention, the adjustment module comprises:

[0054] An adjustment unit is used to increase the effective contact point distance in the current underground cable structure model under test when the difference value is greater than a preset difference threshold.

[0055] According to one achievable method of the second aspect of the present invention, the preset difference threshold is a distance threshold, and the adjustment module includes:

[0056] The third calculation unit is used to calculate the distance between the partial discharge analysis location and the actual partial discharge location as the difference value.

[0057] According to one embodiment of the second aspect of the present invention, the partial discharge fault detection result includes the location of the partial discharge signal and the intensity of the partial discharge signal, and the apparatus further includes:

[0058] The early warning module is used to output corresponding early warning information when the intensity of the partial discharge signal is greater than a preset partial discharge signal intensity threshold; the early warning information includes the location of the corresponding partial discharge signal.

[0059] A third aspect of the present invention provides an underground cable partial discharge fault detection device based on the actual characteristics of the cable, comprising:

[0060] A memory for storing instructions; wherein the instructions are used to implement the underground cable partial discharge fault detection method based on the actual characteristics of the cable as described in any of the above-mentioned methods;

[0061] A processor for executing instructions in the memory.

[0062] The fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for detecting partial discharge faults in underground cables based on the actual characteristics of the cables as described in any of the above embodiments.

[0063] As can be seen from the above technical solutions, the present invention has the following advantages:

[0064] This invention obtains high-frequency characteristic data from the measurement of the high-frequency characteristics of a first test sample of an underground cable under test; constructs a structural model of the underground cable under test; calculates the total high-frequency attenuation loss of the underground cable under test using the high-frequency characteristic data based on the current structural model, and calculates the high-frequency attenuation constant based on the calculated total high-frequency attenuation loss value; performs partial discharge analysis on a second test sample of the underground cable under test with an actual partial discharge location based on the calculated high-frequency attenuation constant value, and obtains the partial discharge analysis location; then, based on the comparison results between the partial discharge analysis location and the actual partial discharge location, adjusts the structural model of the underground cable under test to obtain the optimal high-frequency attenuation constant as the target high-frequency attenuation constant, and then performs partial discharge fault detection on the underground cable under test based on the target high-frequency attenuation constant; this invention uses the high-frequency attenuation constant obtained through actual measurement and modeling to detect partial discharge faults in underground cables, which can effectively improve the accuracy of partial discharge signal analysis of underground cables compared to using a fixed high-frequency attenuation constant. Attached Figure Description

[0065] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0066] Figure 1 A flowchart of an optional embodiment of the present invention for a method of detecting partial discharge faults in underground cables based on the actual characteristics of the cables;

[0067] Figure 2 This is a schematic diagram of the underground cable structure model to be tested provided in an optional embodiment of the present invention;

[0068] Figure 3 The diagram below shows the structural connection of an underground cable partial discharge fault detection device based on the actual characteristics of the cable, which is provided as an optional embodiment of the present invention.

[0069] Figure label:

[0070] 1-Acquisition module; 2-Construction module; 3-First calculation module; 4-Second calculation module; 5-Analysis module; 6-Adjustment module; 7-Detection module. Detailed Implementation

[0071] This invention provides a method and apparatus for detecting partial discharge faults in underground cables based on the actual characteristics of the cables. This method addresses the technical problem that existing schemes for analyzing partial discharge signals of underground cables based on assumed high-frequency attenuation constants have poor signal analysis accuracy.

[0072] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0073] A typical underground cable structure usually consists of a cable sheath, ground wire, semiconductor layer, insulation layer, semiconductor layer again, and conductor connected in sequence. When defects begin to appear in an underground cable during operation, they are usually accompanied by partial discharge. At the source of the partial discharge fault, the partial discharge signal is an ultra-high frequency signal, and the partial discharge wave spectrum is mainly composed of high-frequency signals. After the partial discharge wave is generated, it propagates to both ends of the underground cable. During the propagation of the high-frequency signal to both ends, due to the physical characteristics of the cable, the high-frequency components attenuate more significantly compared to the low-frequency components. The high-frequency attenuation constant of the underground cable determines how the high-frequency signal attenuates.

[0074] When partial discharge signals propagate through underground cables, the transmission loss varies greatly due to differences in cable structure and insulation material characteristics. Cables with high losses may deliver very weak signals to the receiving end. If the cable's high-frequency attenuation constant is unknown, improper partial discharge monitoring device settings can lead to insufficient sensitivity in the online monitoring system, making it difficult to detect and locate faults. During normal operation, the analysis of partial discharge electromagnetic waves measured by general partial discharge monitoring devices also faces similar problems. Since partial discharge signals affect the assessment of cable health, it is necessary to judge and process the collected current traveling waves and partial discharge electromagnetic waves. Without a reliable high-frequency attenuation constant, general devices cannot extract useful information for maintenance departments. The design and selection of the sensitivity of the online monitoring system, as well as the judgment and processing of the collected current traveling waves and partial discharge electromagnetic waves, all depend on a reliable high-frequency attenuation constant. However, existing methods assume a high-frequency attenuation constant for the underground cable, which leads to insufficient sensitivity in the online monitoring system. Furthermore, the assumed high-frequency attenuation constant often deviates significantly, resulting in numerous errors in the partial discharge signal analysis results.

[0075] To address the above problems, this invention provides a method for detecting partial discharge faults in underground cables based on the actual characteristics of the cables.

[0076] Please see Figure 1 , Figure 1 The flowchart illustrates a method for detecting partial discharge faults in underground cables based on the actual characteristics of the cables, as provided in an embodiment of the present invention.

[0077] The present invention provides a method for detecting partial discharge faults in underground cables based on the actual characteristics of the cables, comprising steps S1-S6.

[0078] Step S1: Obtain high-frequency characteristic data by measuring the high-frequency characteristics of the first test sample of the underground cable to be tested.

[0079] As a specific implementation method, the high-frequency characteristics of the first test sample of the underground cable under test are measured using a high-frequency impedance analyzer.

[0080] The high-frequency characteristic data is used to calculate the high-frequency loss of the underground cable under test. The high-frequency characteristic data includes the conductivity of the semiconductor layer, the vacuum dielectric constant, the dielectric constant of the semiconductor layer, the high-frequency characteristic impedance coefficient, and the distributed conductivity.

[0081] Step S2: Determine the structural parameters of the underground cable to be tested, and construct a structural model of the underground cable to be tested based on the structural parameters.

[0082] In this embodiment, the structure of the underground cable to be tested is accurately modeled according to the structural characteristics of different underground cables.

[0083] As a specific implementation method, the constructed model of the underground cable structure to be tested can be as follows: Figure 2 As shown.

[0084] Specifically, the underground cable structure model to be tested can be modeled using finite element software. The specific modeling process can refer to existing technologies, but this embodiment does not limit it.

[0085] Step S3: Calculate the total high-frequency attenuation loss of the underground cable under test using the high-frequency characteristic data based on the current underground cable structure model, and obtain the calculated value of the total high-frequency attenuation loss.

[0086] like Figure 2 The model shown illustrates that the current generated by the high-frequency signal flows through the insulating material, the semiconductor layer, and the air before entering the ground wire. During the installation of underground cables, tension and bending can cause gaps between the ground wire and the semiconductor layer. Therefore, an effective contact point distance can be estimated to calculate the loss. The current generated by the high-frequency signal incurs losses as it flows through these layers, which is the fundamental cause of high-frequency signal attenuation.

[0087] In this embodiment, using the established model and combining it with the high-frequency characteristics of the material obtained from actual measurements, the high-frequency attenuation loss of different parts of the cable can be calculated. Adding these values ​​together yields the total high-frequency attenuation loss. The relationship between the total high-frequency attenuation loss and frequency is also known as the high-frequency attenuation constant.

[0088] In one feasible approach, the step of calculating the total high-frequency attenuation loss of the underground cable under test using the high-frequency characteristic data based on the current structural model of the underground cable under test, and obtaining the calculated value of the total high-frequency attenuation loss, includes:

[0089] The effective contact point distance is determined based on the current underground cable structure model to be tested; the effective contact point distance is the gap distance corresponding to the gap between the semiconductor layer and the ground wire.

[0090] The high-frequency attenuation loss of different material parts of the underground cable under test is calculated based on the effective contact point distance and the high-frequency characteristic data; the high-frequency attenuation loss of different material parts includes the skin effect loss between the conductor and the ground wire and the high-frequency attenuation loss of the semiconductor layer.

[0091] The high-frequency attenuation loss of the different material parts is added together to obtain the calculated value of the total high-frequency attenuation loss.

[0092] When a conductor carries alternating current or an alternating electromagnetic field, the current distribution inside the conductor is uneven. The current concentrates in the conductor's "skin," meaning it's concentrated in a thin outer layer. The closer to the conductor's surface, the greater the current density, while the current inside the conductor is actually smaller. This increases the conductor's resistance and consequently, its power loss. This phenomenon is called the skin effect. The skin effect loss between the conductor and the ground wire can be calculated based on existing fundamental physical formulas; however, this embodiment does not impose any limitations on this calculation.

[0093] In one feasible manner, calculating the high-frequency attenuation loss of different material portions of the underground cable under test based on the effective contact point distance and the high-frequency characteristic data includes:

[0094] Calculate the skin effect loss of the conductor and ground wire based on the high-frequency characteristic data;

[0095] The high-frequency loss current of the semiconductor layer is calculated based on the effective contact point distance and the high-frequency characteristic data. The high-frequency attenuation loss of the semiconductor layer is calculated based on the high-frequency loss current and the resistance parameters of the semiconductor layer's resistive portion.

[0096] In one feasible manner, calculating the high-frequency loss current of the semiconductor layer based on the effective contact point distance and the high-frequency characteristic data includes:

[0097] The high-frequency loss current of the semiconductor layer is calculated using the following formula:

[0098]

[0099] in:

[0100]

[0101] In the formula, I r1 Let σ represent the high-frequency loss current of the semiconductor layer, j be the imaginary part, ω be the angular frequency, ε0 ​​be the vacuum dielectric constant, ε1 be the dielectric constant of the semiconductor layer, I(x) be the current distributed along the ground wire, x be the length of the ground wire, V0 be the voltage amplitude, and Z be the voltage distribution. c1 Z c All are high-frequency characteristic impedance coefficients, K1 is a proportionality coefficient with respect to the high-frequency characteristic impedance coefficient, and R d R is the radius of the insulation layer of the underground cable. c C is the radius of the conductor of the underground cable. tl For distributed conductivity, T is the period, and d is half the effective contact point distance.

[0102] Where ω and T are the values ​​of the corresponding high-frequency impedance analyzer, ω = 2πf, and f is the operating frequency of the high-frequency impedance analyzer.

[0103] I r1 This is the current flowing into the resistive component of the semiconductor layer, which causes the actual losses. By multiplying this current by the resistive component of the semiconductor layer and integrating, the high-frequency attenuation loss of the semiconductor layer can be calculated.

[0104] It should be noted that the above calculation formula can be adjusted according to actual circumstances. For example, to improve the accuracy of the calculation, a correction factor for the radius of the conductor / insulation layer can be added to reduce the error in radius measurement.

[0105] Step S4: Calculate the high-frequency attenuation constant based on the obtained total high-frequency attenuation loss calculation value.

[0106] The relationship between the total loss of high-frequency attenuation and frequency is also known as the high-frequency attenuation constant.

[0107] Step S5: Based on the obtained high-frequency attenuation constant calculation value, perform partial discharge analysis on the second test sample of the underground cable under test to obtain the partial discharge analysis location; the second test sample has an actual partial discharge location.

[0108] Step S6: Calculate the difference between the partial discharge analysis location and the actual partial discharge location, and determine whether the difference is greater than a preset difference threshold. If yes, adjust the current underground cable structure model to be tested and return to step S3. If no, use the current calculated high-frequency attenuation constant as the target high-frequency attenuation constant and execute step S7.

[0109] In one feasible approach, the preset difference threshold is a distance threshold, and the calculation of the difference between the partial discharge analysis location and the actual partial discharge location includes:

[0110] The distance between the partial discharge analysis location and the actual partial discharge location is calculated as the difference value.

[0111] It should be noted that this difference value can also be calculated using other comparison values. For example, the distance between the partial discharge analysis location and the actual partial discharge location can be calculated, and the ratio between the distance value and the actual partial discharge location can be used as the difference value.

[0112] In one feasible approach, adjusting the current model of the underground cable structure to be measured includes:

[0113] The effective contact point distance in the current underground cable structure model to be tested is increased.

[0114] The step size for increasing the effective contact point distance can be set according to the actual situation.

[0115] In other implementations, other parameters in the underground cable structure model to be tested, such as the radius of the semiconductor layer and the radius of the insulation layer, can also be adjusted. The purpose of these adjustments is to allow for the corresponding adjustment of the calculated value of the total high-frequency attenuation loss in subsequent calculations.

[0116] Step S7: Perform partial discharge fault detection on the underground cable under test according to the target high-frequency attenuation constant to obtain the corresponding partial discharge fault detection result.

[0117] It should be noted that, based on existing technology, partial discharge fault detection of the underground cable under test can be achieved according to the target high-frequency attenuation constant. In this embodiment, the specific detection process is not limited.

[0118] In one feasible manner, the partial discharge fault detection result includes the location and intensity of the partial discharge signal, and the method further includes:

[0119] When the intensity of the partial discharge signal exceeds a preset partial discharge signal intensity threshold, a corresponding warning message is output; the warning message includes the location of the corresponding partial discharge signal.

[0120] In this embodiment, timely early warning of abnormal partial discharge fault detection can be achieved.

[0121] The above embodiments of the present invention use high-frequency attenuation constants obtained through actual measurement and modeling to detect partial discharge faults in underground cables. Compared with the method of using fixed high-frequency attenuation constants, this method can effectively improve the accuracy of partial discharge signal analysis in underground cables.

[0122] The present invention also provides an underground cable partial discharge fault detection device based on the actual characteristics of the cable, which can be used to perform the underground cable partial discharge fault detection method based on the actual characteristics of the cable as described in any of the above embodiments of the present invention.

[0123] Please see Figure 3 , Figure 3 The diagram shows a structural connection block diagram of an underground cable partial discharge fault detection device based on the actual characteristics of the cable, according to an embodiment of the present invention.

[0124] This invention provides an underground cable partial discharge fault detection device based on the actual characteristics of the cable, comprising:

[0125] Module 1 is used to acquire high-frequency characteristic data obtained by measuring the high-frequency characteristics of the first test sample of the underground cable under test;

[0126] Module 2 is used to determine the structural parameters of the underground cable to be tested and to construct a structural model of the underground cable to be tested based on the structural parameters.

[0127] The first calculation module 3 is used to calculate the total high-frequency attenuation loss of the underground cable under test based on the current underground cable structure model and the high-frequency characteristic data, and obtain the calculated value of the total high-frequency attenuation loss.

[0128] The second calculation module 3 is used to calculate the high-frequency attenuation constant based on the obtained high-frequency attenuation total loss calculation value;

[0129] Analysis module 4 is used to perform partial discharge analysis on the second test sample of the underground cable under test based on the obtained high-frequency attenuation constant calculation value, and to obtain the partial discharge analysis location; the second test sample has an actual partial discharge location.

[0130] The adjustment module 5 is used to calculate the difference between the partial discharge analysis location and the actual partial discharge location, and determine whether the difference is greater than a preset difference threshold. If so, the current underground cable structure model to be tested is adjusted and returned to the first calculation module 3. If not, the current high-frequency attenuation constant calculation value is used as the target high-frequency attenuation constant, and the detection module 6 is executed.

[0131] The detection module 6 is used to perform partial discharge fault detection on the underground cable under test according to the target high-frequency attenuation constant, and obtain the corresponding partial discharge fault detection result.

[0132] In one feasible implementation, the first computing module 3 includes:

[0133] The determining unit is used to determine the effective contact point distance based on the current underground cable structure model to be tested; the effective contact point distance is the gap distance corresponding to the gap between the semiconductor layer and the ground wire.

[0134] The first calculation unit is used to calculate the high-frequency attenuation loss of different material parts of the underground cable under test based on the effective contact point distance and the high-frequency characteristic data; the high-frequency attenuation loss of the different material parts includes the skin effect loss between the conductor and the ground wire and the high-frequency attenuation loss of the semiconductor layer.

[0135] The second calculation unit is used to add up the high-frequency attenuation losses of the different material parts to obtain the calculated value of the total high-frequency attenuation loss.

[0136] In one feasible implementation, the first computing unit includes:

[0137] The first calculation subunit is used to calculate the skin effect loss of the conductor and ground wire based on the high-frequency characteristic data.

[0138] The second calculation subunit is used to calculate the high-frequency loss current of the semiconductor layer based on the effective contact point distance and the high-frequency characteristic data, and to calculate the high-frequency attenuation loss of the semiconductor layer based on the high-frequency loss current and the resistance parameters of the semiconductor layer's resistance portion.

[0139] In one feasible implementation, the second computational subunit is specifically used for:

[0140] The high-frequency loss current of the semiconductor layer is calculated using the following formula:

[0141]

[0142] in:

[0143]

[0144] In the formula, I r1 Let σ represent the high-frequency loss current of the semiconductor layer, j be the imaginary part, ω be the angular frequency, ε0 ​​be the vacuum dielectric constant, ε1 be the dielectric constant of the semiconductor layer, I(x) be the current distributed along the ground wire, x be the length of the ground wire, V0 be the voltage amplitude, and Z be the voltage distribution. c1 Z c All are high-frequency characteristic impedance coefficients, K1 is a proportionality coefficient with respect to the high-frequency characteristic impedance coefficient, and R d R is the radius of the insulation layer of the underground cable. c C is the radius of the conductor of the underground cable. tl For distributed conductivity, T is the period, and d is half the effective contact point distance.

[0145] In one feasible implementation, the adjustment module 5 includes:

[0146] An adjustment unit is used to increase the effective contact point distance in the current underground cable structure model under test when the difference value is greater than a preset difference threshold.

[0147] In one feasible implementation, the preset difference threshold is a distance threshold, and the adjustment module 5 includes:

[0148] The third calculation unit is used to calculate the distance between the partial discharge analysis location and the actual partial discharge location as the difference value.

[0149] In one feasible embodiment, the partial discharge fault detection result includes the location and intensity of the partial discharge signal, and the device further includes:

[0150] The early warning module is used to output corresponding early warning information when the intensity of the partial discharge signal is greater than a preset partial discharge signal intensity threshold; the early warning information includes the location of the corresponding partial discharge signal.

[0151] The present invention also provides an underground cable partial discharge fault detection device based on the actual characteristics of the cable, comprising:

[0152] A memory for storing instructions; wherein the instructions are used to implement the underground cable partial discharge fault detection method based on the actual characteristics of the cable as described in any of the above embodiments;

[0153] A processor for executing instructions in the memory.

[0154] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the underground cable partial discharge fault detection method based on the actual characteristics of the cable as described in any of the above embodiments.

[0155] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and the specific beneficial effects of the devices, modules, and units described above can be referred to the corresponding beneficial effects in the foregoing method embodiments, and will not be repeated here.

[0156] In the several embodiments provided in this application, 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 modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0157] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0158] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0159] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0160] The above-described 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 detecting partial discharge faults in underground cables based on the actual characteristics of the cables, characterized in that, include: Step S1: Obtain high-frequency characteristic data by measuring the high-frequency characteristics of the first test sample of the underground cable to be tested; Step S2: Determine the structural parameters of the underground cable to be tested, and construct a structural model of the underground cable to be tested based on the structural parameters; Step S3: Calculate the total high-frequency attenuation loss of the underground cable under test using the high-frequency characteristic data based on the current underground cable structure model under test, and obtain the calculated value of the total high-frequency attenuation loss. Step S4: Calculate the high-frequency attenuation constant based on the obtained total high-frequency attenuation loss calculation value; Step S5: Based on the obtained high-frequency attenuation constant calculation value, perform partial discharge analysis on the second test sample of the underground cable under test to obtain the partial discharge analysis location; the second test sample has an actual partial discharge location. Step S6: Calculate the difference between the partial discharge analysis location and the actual partial discharge location, and determine whether the difference is greater than a preset difference threshold; if yes, adjust the current underground cable structure model to be tested and return to step S3; if no, use the current calculated high-frequency attenuation constant as the target high-frequency attenuation constant and execute step S7. Step S7: Perform partial discharge fault detection on the underground cable under test according to the target high-frequency attenuation constant to obtain the corresponding partial discharge fault detection result; The calculation of the total high-frequency attenuation loss of the underground cable under test based on the current structural model of the cable under test and the high-frequency characteristic data, to obtain the calculated value of the total high-frequency attenuation loss, includes: The effective contact point distance is determined based on the current underground cable structure model to be tested; the effective contact point distance is the gap distance corresponding to the gap between the semiconductor layer and the ground wire. The high-frequency attenuation loss of different material parts of the underground cable under test is calculated based on the effective contact point distance and the high-frequency characteristic data; the high-frequency attenuation loss of different material parts includes the skin effect loss between the conductor and the ground wire and the high-frequency attenuation loss of the semiconductor layer. The high-frequency attenuation loss of the different material parts is added together to obtain the calculated value of the total high-frequency attenuation loss.

2. The method for detecting partial discharge faults in underground cables based on actual cable characteristics according to claim 1, characterized in that, The calculation of high-frequency attenuation loss of different material sections of the underground cable under test based on the effective contact point distance and the high-frequency characteristic data includes: Calculate the skin effect loss of the conductor and ground wire based on the high-frequency characteristic data; The high-frequency loss current of the semiconductor layer is calculated based on the effective contact point distance and the high-frequency characteristic data. The high-frequency attenuation loss of the semiconductor layer is calculated based on the high-frequency loss current and the resistance parameters of the semiconductor layer's resistive portion.

3. The method for detecting partial discharge faults in underground cables based on actual cable characteristics according to claim 2, characterized in that, The calculation of the high-frequency loss current of the semiconductor layer based on the effective contact point distance and the high-frequency characteristic data includes: The high-frequency loss current of the semiconductor layer is calculated using the following formula: ； in: ； In the formula, This represents the high-frequency loss current of the semiconductor layer. The conductivity of the semiconductor layer, The virtual part, Angular frequency, It is the vacuum dielectric constant. The dielectric constant of the semiconductor layer is . For the current distributed along the ground wire, Indicates the length of the ground wire. Voltage amplitude, , All are high-frequency characteristic impedance coefficients. This is a proportionality coefficient with respect to the high-frequency characteristic impedance coefficient. The radius of the insulation layer of the underground cable. Let be the radius of the conductor of the underground cable. For distributed conductivity, For a period of time, It is half the effective contact point distance.

4. The method for detecting partial discharge faults in underground cables based on actual cable characteristics according to claim 1, characterized in that, The adjustment of the current underground cable structure model to be tested includes: The effective contact point distance in the current underground cable structure model to be tested is increased.

5. The method for detecting partial discharge faults in underground cables based on actual cable characteristics according to claim 1, characterized in that, The preset difference threshold is a distance threshold, and the calculation of the difference between the partial discharge analysis location and the actual partial discharge location includes: The distance between the partial discharge analysis location and the actual partial discharge location is calculated as the difference value.

6. The method for detecting partial discharge faults in underground cables based on actual cable characteristics according to claim 1, characterized in that, The partial discharge fault detection results include the location and intensity of the partial discharge signal, and the method further includes: When the intensity of the partial discharge signal exceeds a preset partial discharge signal intensity threshold, a corresponding warning message is output; the warning message includes the location of the corresponding partial discharge signal.

7. A partial discharge fault detection device for underground cables based on actual cable characteristics, the device being used to implement the partial discharge fault detection method for underground cables based on actual cable characteristics as described in claim 1, characterized in that, include: The acquisition module is used to acquire high-frequency characteristic data obtained by measuring the high-frequency characteristics of the first test sample of the underground cable under test; The construction module is used to determine the structural parameters of the underground cable to be tested, and to construct a structural model of the underground cable to be tested based on the structural parameters. The first calculation module is used to calculate the total high-frequency attenuation loss of the underground cable under test based on the current underground cable structure model and the high-frequency characteristic data, and obtain the calculated value of the total high-frequency attenuation loss. The second calculation module is used to calculate the high-frequency attenuation constant based on the obtained high-frequency attenuation total loss calculation value; The analysis module is used to perform partial discharge analysis on the second test sample of the underground cable under test based on the obtained high-frequency attenuation constant calculation value, and to obtain the partial discharge analysis location; the second test sample is located at the actual partial discharge location; The adjustment module is used to calculate the difference between the partial discharge analysis location and the actual partial discharge location, and determine whether the difference is greater than a preset difference threshold. If so, the current underground cable structure model to be tested is adjusted and returned to the first calculation module. If not, the current high-frequency attenuation constant calculated value is used as the target high-frequency attenuation constant, and the detection module is executed. The detection module is used to perform partial discharge fault detection on the underground cable under test according to the target high-frequency attenuation constant, and obtain the corresponding partial discharge fault detection results.

8. A partial discharge fault detection device for underground cables based on actual cable characteristics, characterized in that, include: A memory for storing instructions; wherein the instructions are used to implement the underground cable partial discharge fault detection method based on the actual characteristics of the cable as described in any one of claims 1-6; A processor for executing instructions in the memory.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for detecting partial discharge faults in underground cables based on the actual characteristics of the cables as described in any one of claims 1-6.

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