Cable fault determination method and device and electronic equipment

Abstract

The invention discloses a cable fault determination method and device and electronic equipment. The method comprises the steps that a cable to be measured is acquired, and the cable to be measured is a cable of a target type; determining instantaneous pulse data of the to-be-measured cable under the preset alternating-current voltage; determining a voltage difference mean value corresponding to the to-be-measured cable according to the target type; according to the voltage difference mean value and the positive period initial voltage, predicting a negative period initial voltage and a negative period final voltage corresponding to the to-be-measured cable; and determining the fault type of the to-be-measured cable according to the negative period starting voltage and the negative period ending voltage. The technical problem that it is difficult to accurately determine the cable fault in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of fault handling, and in particular, to a method, device, and electronic device for determining a cable fault. Background Art

[0002] As an important power transmission device, power cables are widely used in the construction of power grid assemblies. During the installation of power cables, damage may occur due to overstretching or bending, or physical damage may occur during transportation, such as damage to the insulating outer skin of the power cable; or many problems may occur during the design and manufacturing process, resulting in more or less damage to the insulation of the power cable, all of which will leave potential fault hazards.

[0003] Moreover, during the long-term operation of power cables, due to the influence of relevant factors such as the surrounding environment, the aging and deterioration of the power cable insulation will be accelerated, leading to further deterioration of the cable insulation defects. Due to the influence of the above-mentioned possible insulation defects, the electric field strength in some areas on the surface or inside of the insulating material will be higher than the average field strength, while the breakdown strength in some areas will be higher than the average breakdown field strength. At this time, partial discharge will occur earliest in these areas, and the remaining areas will still maintain their original insulation characteristics, thus generating a partial discharge phenomenon. Partial discharge is an important reason for the ultimate insulation breakdown of high-voltage electrical equipment and an important manifestation of insulation deterioration.

[0004] At present, the recognition effect of partial discharge signals of power cables is not ideal. In actual detection, there is noise interference caused by equipment and the environment. More importantly, the feature extraction and analysis of partial discharge signals are not accurate enough, which greatly weakens the guidance of partial discharge recognition for actual projects. The generation of partial discharge is the result of the combined action of multiple factors, such as the environment, voltage, shape, size, insulation defects, etc. The influence of multiple factors and the different degrees of influence of different factors make the partial discharge signal complex and variable, making it difficult to identify the type and characteristics of the discharge.

[0005] In view of the above problems, no effective solution has been proposed yet. Summary of the Invention

[0006] Embodiments of the present invention provide a method, device, and electronic device for determining a cable fault, so as to at least solve the technical problem in the related art that it is difficult to accurately determine a cable fault.

[0007] According to one aspect of an embodiment of the present invention, a method for determining a cable fault is provided, including: obtaining a cable to be measured, where the cable to be measured is a cable of a target type; determining instantaneous pulse data of the cable to be measured under a predetermined AC voltage, where the instantaneous pulse data includes a positive cycle start voltage corresponding to the cable to be measured, and the positive cycle start voltage is the voltage value corresponding to the first occurrence of an instantaneous pulse during the positive cycle of the predetermined AC voltage; determining an average voltage difference corresponding to the cable to be measured according to the target type; predicting a negative cycle start voltage and a negative cycle end voltage corresponding to the cable to be measured according to the average voltage difference and the positive cycle start voltage, where the negative cycle start voltage is the voltage value corresponding to the first occurrence of an instantaneous pulse during the negative cycle of the predetermined AC voltage, and the negative cycle end voltage is the voltage value corresponding to the last disappearance of an instantaneous pulse during the negative cycle of the predetermined AC voltage; determining the fault type of the cable to be measured according to the negative cycle start voltage and the negative cycle end voltage.

[0008] Optionally, determining an average voltage difference corresponding to the cable to be measured according to the target type includes: determining a plurality of absolute voltage differences according to the target type, where the plurality of absolute voltage differences includes a first absolute voltage difference and a second absolute voltage difference, the first absolute voltage difference is the absolute voltage difference between two consecutive instantaneous pulses in the falling part of the negative cycle, and the second absolute voltage difference is the absolute voltage difference between an instantaneous pulse in the positive cycle and the last instantaneous pulse in the negative cycle; determining the average voltage difference according to the plurality of absolute voltage differences.

[0009] Optionally, determining a plurality of absolute voltage differences according to the target type includes: obtaining a needle-plate electrode model corresponding to the target type; determining power parameter data corresponding to the needle-plate electrode model under multiple voltages, where the power parameter data includes a plurality of instantaneous pulse voltage data; determining the plurality of absolute voltage differences according to the power parameter data.

[0010] Optionally, before determining the instantaneous pulse data of the cable to be measured under a predetermined AC voltage, it further includes: determining a starting discharge voltage corresponding to the target type; determining a plurality of candidate AC voltages according to the starting discharge voltage; determining a discharge parameter stability index and a discharge behavior repetition index corresponding to each of the plurality of candidate AC voltages; determining the predetermined AC voltage from the plurality of candidate AC voltages according to the discharge parameter stability index and the discharge behavior repetition index corresponding to each of the plurality of candidate AC voltages.

[0011] Optionally, a plurality of candidate AC voltages are determined based on the starting discharge voltage, including: determining a plurality of candidate fault types corresponding to the cable to be measured; determining voltage range intervals respectively corresponding to the plurality of candidate fault types; and determining a plurality of candidate AC voltages based on the plurality of voltage range intervals and the starting discharge voltage.

[0012] Optionally, based on the average voltage difference and the starting voltage of the positive cycle, the starting voltage and the ending voltage of the negative cycle corresponding to the cable to be measured are predicted, including: retrieving a prediction function corresponding to the cable of the target type, where the prediction function is obtained by testing with a needle-plate electrode model corresponding to the target type; predicting the starting voltage and the ending voltage of the negative cycle based on the average voltage difference, the starting voltage of the positive cycle, and the prediction function.

[0013] Optionally, a plurality of absolute voltage differences are determined based on the target type, including: obtaining the environmental parameters corresponding to the cable to be measured; and retrieving the average voltage difference corresponding to the cable to be measured based on the target type and the environmental parameters.

[0014] According to one aspect of an embodiment of the present invention, a cable fault determination device is provided, including: an acquisition module configured to acquire a cable to be measured, where the cable to be measured is a cable of a target type; a first determination module configured to determine the instantaneous pulse data of the cable to be measured under a predetermined AC voltage, where the instantaneous pulse data includes the starting voltage of the positive cycle corresponding to the cable to be measured, and the starting voltage of the positive cycle is the voltage value corresponding to the first appearance of the instantaneous pulse during the positive cycle of the predetermined AC voltage; a second determination module configured to determine the average voltage difference corresponding to the cable to be measured based on the target type; a third determination module configured to predict the starting voltage and the ending voltage of the negative cycle corresponding to the cable to be measured based on the average voltage difference and the starting voltage of the positive cycle, where the starting voltage of the negative cycle is the voltage value corresponding to the first appearance of the instantaneous pulse during the negative cycle of the predetermined AC voltage, and the ending voltage of the negative cycle is the voltage value corresponding to the last disappearance of the instantaneous pulse during the negative cycle of the predetermined AC voltage; and a fourth determination module configured to determine the fault type of the cable to be measured based on the starting voltage of the negative cycle and the ending voltage of the negative cycle.

[0015] According to one aspect of an embodiment of the present invention, an electronic device is provided, including: a processor; and a memory for storing instructions executable by the processor; where the processor is configured to execute the instructions to implement the cable fault determination method described in any one of the above.

[0016] According to one aspect of an embodiment of the present invention, a computer-readable storage medium is provided. When instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device can execute the cable fault determination method described in any one of the above.

[0017] In an embodiment of the present invention, a cable to be measured is obtained, where the cable to be measured is a cable of a target type. Instantaneous pulse data of the cable to be measured under a predetermined AC voltage is determined, where the instantaneous pulse data includes a positive cycle start voltage corresponding to the cable to be measured, and the positive cycle start voltage is the voltage value corresponding to the first appearance of the instantaneous pulse within the positive cycle of the predetermined AC voltage. According to the target type, a mean voltage difference corresponding to the cable to be measured is determined. Based on the mean voltage difference and the positive cycle start voltage, a negative cycle start voltage and a negative cycle end voltage corresponding to the cable to be measured are predicted, where the negative cycle start voltage is the voltage value corresponding to the first appearance of the instantaneous pulse within the negative cycle of the predetermined AC voltage, and the negative cycle end voltage is the voltage value corresponding to the last disappearance of the instantaneous pulse within the negative cycle of the predetermined AC voltage. According to the negative cycle start voltage and the negative cycle end voltage, the fault type of the cable to be measured is determined. Since different defect types have different start and end voltage characteristics, the defect type of the cable can be inferred through the above voltages, thereby solving the technical problem in the related art that it is difficult to accurately determine the cable fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention, form a part of this application, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 is a flowchart of the cable fault determination method according to an embodiment of the present invention.

[0020] Figure 2 is a schematic diagram of the voltage difference of the method provided by an optional embodiment of the present invention.

[0021] Figure 3 is a PRPD spectrogram of leader discharge within 1 s at 0.96 kV provided by an optional embodiment of the present invention.

[0022] Figure 4 is a PRPD spectrogram of leader discharge within 1 s at 1.36 kV provided by an optional embodiment of the present invention.

[0023] Figure 5 is a PRPD spectrogram of leader discharge within 1 s at 1.93 kV provided by an optional embodiment of the present invention.

[0024] Figure 6PRPD spectrogram of leader discharge within 1 s at 2.28 kV provided for an alternative embodiment of the present invention.

[0025] Figure 7 Analysis spectrogram of discharge pulse sequence of leader discharge within 1 s at 1.36 kV provided for an alternative embodiment of the present invention.

[0026] Figure 8 Analysis spectrogram of discharge pulse sequence of leader discharge within 1 s at 1.93 kV provided for an alternative embodiment of the present invention.

[0027] Figure 9 Analysis spectrogram of discharge pulse sequence of leader discharge within 1 s at 2.28 kV provided for an alternative embodiment of the present invention.

[0028] Figure 10 dV statistical chart of leader discharge within 1 s at 1.36 kV provided for an alternative embodiment of the present invention.

[0029] Figure 11 dV statistical chart of leader discharge within 1 s at 1.93 kV provided for an alternative embodiment of the present invention.

[0030] Figure 12 dV statistical chart of leader discharge within 1 s at 2.28 kV provided for an alternative embodiment of the present invention.

[0031] Figure 13 Structural schematic diagram of a needle-plate electrode device provided for an alternative embodiment of the present invention.

[0032] Figure 14 It is a structural block diagram of a cable fault determination device according to an embodiment of the present invention.

[0033] Wherein, 1 - metal columnar electrode, 2 - electrode plate, 3 - tip, 4 - insulating housing. Detailed implementation manners

[0034] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily limit to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0036] Embodiment 1

[0037] According to an embodiment of the present invention, an embodiment of a method for determining a cable fault is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that here.

[0038] Figure 1 is a flowchart of a method for determining a cable fault according to an embodiment of the present invention. As Figure 1 shown, the method includes the following steps:

[0039] Step S102, obtain the cable to be measured, where the cable to be measured is a cable of a target type;

[0040] In step S102 provided in this application, the cable to be measured is obtained.

[0041] Among them, the cable to be measured is involved. The cable to be measured refers to the cable to be subjected to partial discharge testing. It may be a specific cable sample, or a cable with a specific type, size, material or insulation state. The cable to be measured is the test object in the experiment, and its partial discharge characteristics will be analyzed to evaluate the insulation condition of the cable or identify the possible defect types.

[0042] Among them, the cable of the target type is involved. The cable of the target type refers to the cable type selected according to the experimental purpose or requirements. This type can be based on the material, design, use environment or known problem type of the cable. For example, if the purpose of the experiment is to detect the partial discharge behavior of copper core cables under specific environmental conditions, then the cable of the target type is the copper core cable. Another example is that if it is necessary to evaluate the aging resistance performance of the cable, then the target type may be an aging cable that has been in operation for a long time. Or a cable that needs to be detected for faults with detection requirements.

[0043] Step S104: Determine the instantaneous pulse data of the cable to be measured under a predetermined AC voltage. The instantaneous pulse data includes the starting voltage of the positive cycle corresponding to the cable to be measured. The starting voltage of the positive cycle is the voltage value corresponding to the first occurrence of the instantaneous pulse within the positive cycle of the predetermined AC voltage.

[0044] In step S104 provided in this application, the instantaneous pulse data of the cable to be measured under a predetermined AC voltage is determined.

[0045] Among them, a predetermined AC voltage is involved. In partial discharge detection, the predetermined AC voltage refers to the AC voltage level set in the experiment for exciting partial discharge. This voltage level is pre-determined by the experimenter according to the experimental purpose and the characteristics of the cable to be measured.

[0046] Optionally, the predetermined AC voltage can be multiple predetermined AC voltages. For example, by comparing the starting voltages of the positive cycles at different voltage levels, the possible types of insulation defects in the cable can be preliminarily judged. For example, certain types of defects (such as air gap discharge) will start to discharge within the positive cycle at a lower voltage, while other types of defects (such as electrical tree) may require a higher voltage to start discharging, so as to detect different types of faults.

[0047] Among them, instantaneous pulse data is involved. Instantaneous pulse data refers to the real-time data of partial discharge pulses collected by a pulse detection device when partial discharge occurs. These data usually include information such as the amplitude, phase, and occurrence time of the pulses, and are used for subsequent analysis and evaluation.

[0048] Among them, the starting voltage of the positive cycle is involved. The starting voltage of the positive cycle is the voltage value of the positive half-cycle of the AC voltage when the pulse detection system first records a partial discharge pulse within one cycle of the AC voltage.

[0049] Determining the starting voltage of the positive cycle helps to accurately evaluate the discharge threshold of the cable, that is, at what voltage level partial discharge starts, which helps to evaluate the insulation performance of the cable and predict its long-term operation reliability.

[0050] Step S106: Determine the average voltage difference corresponding to the cable to be measured according to the target type.

[0051] In step S106 provided in this application, the average voltage difference corresponding to the cable to be measured is determined.

[0052] Among them, the average voltage difference is involved. In the analysis of voltage-current characteristics, the average voltage difference refers to the average value of the voltage change between two consecutive partial discharge events within a specific time period. This value can be obtained by measuring the voltage levels before and after partial discharge, calculating the absolute value of the voltage difference before and after each partial discharge, and then taking the average. It reflects the pattern of partial discharge behavior with voltage change and is used to effectively identify partial discharge types and evaluate the cable insulation status.

[0053] Optionally, a simulation model corresponding to the cable to be measured can be generated to measure the average voltage difference. During the process of simulating the measurement model, it can be associated with cable type, operating conditions, partial discharge type and location, etc., so as to be able to determine an accurate average voltage difference.

[0054] Determining the average voltage difference corresponding to the cable to be measured according to the target type of the cable to be measured means that in the partial discharge detection experiment, it is necessary to retrieve the average voltage difference between partial discharge events according to the specific type or characteristics of the cable under test. Since the type or characteristics of the cable will directly affect the pattern of partial discharge. For example, some types of cables will start partial discharge at a lower voltage difference, while other types may require a higher voltage difference to generate discharge. Therefore, by calculating the average voltage difference of a specific cable type, the partial discharge characteristics of this type of cable can be more accurately identified. And because the average voltage difference of the same cable type has universality and has the general law of voltage change during partial discharge, the corresponding average voltage difference can be retrieved.

[0055] Step S108, predicting the negative cycle start voltage and the negative cycle end voltage corresponding to the cable to be measured according to the average voltage difference and the positive cycle start voltage, where the negative cycle start voltage is the voltage value corresponding to the first appearance of the instantaneous pulse within the negative cycle of the predetermined AC voltage, and the negative cycle end voltage is the voltage value corresponding to the last disappearance of the instantaneous pulse within the negative cycle of the predetermined AC voltage;

[0056] In step S108 provided in this application, the negative cycle start voltage and the negative cycle end voltage corresponding to the cable to be measured are predicted.

[0057] Among them, the negative cycle start voltage is involved. Opposite to the positive cycle start voltage, the negative cycle start voltage refers to the voltage value corresponding to the first appearance of the partial discharge pulse within the negative cycle of the predetermined AC voltage. It reflects the starting characteristics of partial discharge in the negative half cycle of voltage.

[0058] Among them, the negative cycle termination voltage is involved. During the negative cycle of the alternating voltage, the negative cycle termination voltage refers to the voltage value corresponding to the moment when the partial discharge pulse finally disappears. This parameter helps to judge the termination condition of partial discharge and is of great value for evaluating the impact of partial discharge on insulating materials and predicting the fault points of cables.

[0059] The process of predicting the negative cycle start voltage and the negative cycle termination voltage corresponding to the cable to be measured based on the average voltage difference and the positive cycle start voltage. By analyzing the voltage change law before and after the partial discharge event, the average voltage difference is obtained. Combining the known positive cycle start voltage, it can be inferred that within the negative half cycle of the alternating voltage cycle, the voltage ranges where partial discharge starts and ends. Since the occurrence of partial discharge is often related to the phase and amplitude of the voltage, the average voltage difference reflects the dynamic voltage change characteristics of partial discharge. Therefore, the negative cycle start voltage and the negative cycle termination voltage corresponding to the cable to be measured can be accurately predicted.

[0060] By predicting the negative cycle start voltage and the termination voltage, the partial discharge behavior can be predicted more accurately. The prediction of the negative cycle start voltage and the termination voltage can be used to evaluate the insulation performance of the cable, especially the discharge sensitivity of the insulation layer. A lower start voltage and a higher termination voltage may indicate defects in the insulation layer. These predicted values can provide a basis for the cable maintenance and replacement strategies. For example, if the predicted negative cycle start voltage and termination voltage are significantly different from the normal operating range, cable maintenance or replacement may be required in advance to avoid potential system risks.

[0061] Step S110: Determine the fault type of the cable to be measured based on the negative cycle start voltage and the negative cycle termination voltage.

[0062] In step S110 provided in this application, the fault type of the cable to be measured is determined.

[0063] Among them, the fault type is involved. The fault type refers to various electrical, mechanical or environmental problems that the cable may encounter during the operation and maintenance of power cables, such as partial discharge, electrical treeing, insulation aging, short circuit, open circuit, etc. A core goal of partial discharge detection is to identify and classify these fault types in order to take targeted maintenance and repair measures. For example, in the needle-plate electrode model, the local discharge of the simulated spike defect is more likely to occur in the negative half cycle of the voltage because the electric field lines near the spike are more concentrated in the negative half cycle, making it easier to initiate discharge. Therefore, when detecting spike defects, it is more effective to determine whether this type of fault occurs based on the negative cycle start voltage and the negative cycle termination voltage.

[0064] By analyzing the starting voltage and ending voltage of the negative cycle, the sensitive voltage range of partial discharge in the cable can be identified, and then the type of insulation defect in the cable can be inferred. This is because different defect types will have different starting and ending voltage characteristics. For example, air gap discharge may start at a relatively low starting voltage because the breakdown field strength in the air gap is lower than that of the solid insulation material. While electrical tree defects may start partial discharge at a higher voltage because they need to reach a certain degree of electric field concentration to trigger discharge. In addition, the severity of the defect will also affect the values of the starting and ending voltages. Cables with severe defects may start discharging at a lower voltage, and the ending voltage may also be lower.

[0065] In partial discharge analysis, special attention is paid to the starting voltage and ending voltage of the negative half-cycle to determine the fault type, mainly based on the physical characteristics and distribution characteristics of partial discharge. The generation of partial discharge is closely related to the polarity of the power supply voltage, the electric field distribution, and the characteristics of the insulation material. In a predetermined alternating voltage, partial discharge in the negative half-cycle is easier to detect and analyze. This is because for types of partial discharge such as tip discharge, the tip electrode is more likely to emit electrons when it is negatively polarized, thus triggering discharge. This is because the electric field strength at the tip is higher when it is negatively polarized, making the occurrence of partial discharge more regular and predictable. And leader discharge usually occurs in the initial stage of partial discharge. In tip discharge, leader discharge is more common in the negative half-cycle. The voltage characteristics of leader discharge, especially its starting voltage, are important indicators for partial discharge pattern recognition.

[0066] Optionally, the result can be determined comprehensively by combining the PRPD spectrogram of leader discharge, the analysis spectrogram of discharge pulse sequence, and the characteristics of the dV statistical graph. It can also be comprehensively analyzed by combining other partial discharge characteristics, such as discharge quantity, discharge repetition rate, phase distribution, and discharge mode. By comparing the correlations between these characteristics and known fault types, the specific defects in the cable can be identified and located more accurately, so as to take corresponding maintenance and preventive measures to ensure the stable operation of the power system.

[0067] Through the above steps S102 - S110, the cable to be measured is obtained, where the cable to be measured is a cable of the target type. Determine the instantaneous pulse data of the cable to be measured under a predetermined AC voltage, where the instantaneous pulse data includes the positive cycle start voltage corresponding to the cable to be measured, and the positive cycle start voltage is the voltage value corresponding to the first occurrence of the instantaneous pulse within the positive cycle of the predetermined AC voltage. Determine the average voltage difference corresponding to the cable to be measured according to the target type. Predict the negative cycle start voltage and the negative cycle end voltage corresponding to the cable to be measured based on the average voltage difference and the positive cycle start voltage, where the negative cycle start voltage is the voltage value corresponding to the first occurrence of the instantaneous pulse within the negative cycle of the predetermined AC voltage, and the negative cycle end voltage is the voltage value corresponding to the last disappearance of the instantaneous pulse within the negative cycle of the predetermined AC voltage. Determine the fault type of the cable to be measured based on the negative cycle start voltage and the negative cycle end voltage. Since different defect types have different start and end voltage characteristics, the defect type of the cable can be inferred through the above voltages, thus solving the technical problem in the related art that it is difficult to accurately determine the cable fault.

[0068] As an optional embodiment, determining the average voltage difference corresponding to the cable to be measured according to the target type includes: determining a plurality of absolute voltage differences according to the target type, where the plurality of absolute voltage differences includes the first absolute voltage difference and the second absolute voltage difference, the first absolute voltage difference is the absolute value of the voltage difference between two consecutive instantaneous pulses in the descending part of the negative cycle, and the second absolute voltage difference is the absolute value of the voltage difference between the instantaneous pulse in the positive cycle and the last instantaneous pulse in the negative cycle; determining the average voltage difference based on the plurality of absolute voltage differences.

[0069] In this embodiment, the steps for determining the average voltage difference are described.

[0070] Among them, the first absolute voltage difference is involved. The first absolute voltage difference refers to the absolute value of the voltage difference between two consecutive instantaneous pulses (i.e., partial discharge events) in the descending part of the negative half - cycle of the AC voltage in partial discharge detection. This parameter particularly focuses on the voltage change characteristics of partial discharge during the voltage drop in the negative cycle, which helps to identify the defect type in the cable insulation.

[0071] Among them, the second absolute voltage difference is involved. The second absolute voltage difference refers to the absolute value of the voltage difference between the instantaneous pulse in the positive cycle and the last instantaneous pulse (partial discharge event) in the negative cycle in partial discharge detection. It focuses on the voltage change characteristics of partial discharge during the conversion between the positive and negative voltage cycles, and is also important for analyzing the partial discharge pattern and the cable fault type.

[0072] The process of determining the average voltage difference corresponding to the cable to be measured according to the target type requires detecting the voltage changes of partial discharges at different voltage levels and phases, and extracting the absolute value of the voltage difference between two consecutive instantaneous pulses (partial discharge events), including the first absolute voltage difference value in the descending part of the negative voltage cycle and the second absolute voltage difference value at the transition between the positive and negative cycles. These absolute voltage difference values reflect the dynamic voltage changes during partial discharge events and are key features for analyzing partial discharge patterns and cable fault types. After collecting these absolute voltage difference values, the average voltage difference is determined through statistical analysis methods. The average voltage difference provides information about the average behavior of partial discharge voltage changes, which can help understand the characteristics of partial discharges and the overall state of cable insulation.

[0073] In actual partial discharge detection and analysis, in addition to calculating the average voltage difference, the distribution characteristics of the voltage difference can be further analyzed, such as the peak value, variance, distribution shape, etc. of the voltage difference. These statistical parameters can provide more information about partial discharge behavior and help more precisely identify the type and severity of defects in the cable. In addition, the analysis of the average voltage difference can be combined with the operating environment parameters of the cable, such as temperature, humidity, the operating history and maintenance records of the cable, etc. By comprehensively analyzing these parameters, a more comprehensive cable condition monitoring model can be established to provide more accurate data support for cable fault prediction and maintenance decision-making.

[0074] As an alternative embodiment, according to the target type, a plurality of absolute voltage difference values are determined, including: obtaining a needle-plate electrode model corresponding to the target type; determining power parameter data corresponding to the needle-plate electrode model under various voltages, where the power parameter data includes a plurality of instantaneous pulse voltage data; and determining a plurality of absolute voltage difference values based on the power parameter data.

[0075] In this embodiment, a plurality of absolute voltage difference values are determined.

[0076] Among them, a needle-plate electrode model is involved. The needle-plate electrode model is an experimental device used to simulate and study partial discharge phenomena. It consists of a metal electrode with a sharp tip (needle electrode) and a planar electrode (plate electrode), and is usually used to test and analyze partial discharge behavior under different electric field distributions. In the study of cable partial discharges, the needle-plate electrode model can simulate spike or burr defects in the cable, which may cause partial discharges to occur.

[0077] Among them, power parameter data is involved. Power parameter data refers to a series of data reflecting partial discharge characteristics in partial discharge detection, specifically including voltage, current, discharge amount, discharge repetition rate, etc.

[0078] Among them, the involvement of multiple instantaneous pulse voltage data refers to the change data of the voltage levels before and after each partial discharge event (instantaneous pulse) recorded during the partial discharge detection process.

[0079] First, a corresponding needle-plate electrode model can be determined based on the target type of the cable to be measured to simulate the possible partial discharge defects in the cable. Then, partial discharge tests are carried out on the needle-plate electrode model under multiple voltages to obtain a series of instantaneous pulse voltage data. These data reflect the occurrence of partial discharge under different voltage levels, including information such as the voltage, phase, and discharge amount of the discharge. Finally, by processing these instantaneous pulse voltage data, the absolute value of the voltage difference between each consecutive partial discharge event is calculated, thereby obtaining a series of multiple absolute values of voltage differences. These absolute values of voltage differences can reflect the characteristics of the partial discharge behavior with voltage change, providing key quantitative indicators for subsequent fault type identification and condition assessment.

[0080] By carrying out partial discharge tests on the needle-plate electrode model under multiple voltages and calculating the absolute value of the voltage difference, the characteristics of partial discharge in the cable can be understood more comprehensively, improving the accuracy and reliability of cable fault type diagnosis.

[0081] As an alternative embodiment, before determining the instantaneous pulse data of the cable to be measured under a predetermined AC voltage, it further includes: determining the initial discharge voltage corresponding to the target type; determining a plurality of candidate AC voltages based on the initial discharge voltage; determining the discharge parameter stability index and the discharge behavior repetition index corresponding to the plurality of candidate AC voltages respectively; and determining the predetermined AC voltage from the plurality of candidate AC voltages based on the discharge parameter stability index and the discharge behavior repetition index corresponding to the plurality of candidate AC voltages respectively.

[0082] In this embodiment, the steps of determining the predetermined AC voltage are described.

[0083] Among them, the initial discharge voltage is involved. The initial discharge voltage is the voltage value when the partial discharge phenomenon first appears during the partial discharge detection. It reflects the threshold voltage at which the cable insulation material begins to have partial discharge and is an important parameter for evaluating the insulation performance of the cable.

[0084] Among them, the candidate AC voltages are involved. The candidate AC voltages refer to a series of voltage levels selected in the partial discharge detection experiment, and these voltage levels cover the range that may cause partial discharge phenomena. By conducting experiments at these voltages, partial discharge data at different voltage levels can be collected to analyze the voltage characteristics of partial discharge.

[0085] Among them, the discharge parameter stability index is involved. The discharge parameter stability index is an index used to quantify the stability of partial discharge parameters at a specific voltage level. It is usually calculated based on the degree of fluctuation of parameters such as the voltage, discharge quantity, and repetition rate of partial discharge over a period of time. Stable discharge parameters help to more accurately identify partial discharge patterns and cable conditions.

[0086] Among them, the discharge behavior repetition index is involved. The discharge behavior repetition index is an index used to quantify the repeatability of partial discharge behavior at a specific voltage level. It is calculated based on the occurrence frequency and phase distribution of partial discharge events over multiple voltage cycles, reflecting the regularity and predictability of partial discharge behavior.

[0087] Before performing partial discharge detection and analysis, determining the inception discharge voltage corresponding to the target type is the key first step. The inception discharge voltage provides a benchmark for selecting the candidate AC voltages in subsequent experiments. Subsequently, a series of candidate AC voltages are selected from multiple voltage levels including the inception discharge voltage to cover the voltage range where partial discharge may occur. After determining the candidate AC voltages, partial discharge experiments need to be carried out at each voltage level to collect and analyze the discharge parameter and discharge behavior data. By calculating the discharge parameter stability index and the discharge behavior repetition index, the stability and repeatability of partial discharge behavior at different voltage levels can be evaluated. The calculation of these two indices usually involves the statistical analysis of parameters such as the voltage, discharge quantity, and repetition rate of partial discharge over a period of time, as well as the investigation of the distribution law of partial discharge events over multiple voltage cycles. Finally, by comparing the discharge parameter stability index and the discharge behavior repetition index at different voltage levels, one or more predetermined AC voltages most suitable for partial discharge detection can be determined. The partial discharge behavior at these predetermined AC voltages is the most stable and has high repeatability, which means that the partial discharge data collected at these voltage levels can more truly reflect the partial discharge characteristics of the cable.

[0088] As an alternative embodiment, based on the inception discharge voltage, multiple candidate AC voltages are determined, including: determining multiple alternative fault types corresponding to the cable to be measured; determining the voltage range intervals corresponding to the multiple alternative fault types respectively; and determining multiple candidate AC voltages based on the multiple voltage range intervals and the inception discharge voltage.

[0089] In this embodiment, multiple candidate AC voltages are determined.

[0090] Among them, the alternative fault types are involved. The alternative fault types refer to a series of electrical or mechanical faults that may exist in the cable, such as partial discharge, electrical treeing, air gap discharge, insulation aging, short circuit, etc. These fault types will affect the performance and lifespan of the cable and need to be identified and located through detection and analysis.

[0091] Among them, a voltage range interval is involved. The voltage range interval is the range of voltage levels within which the partial discharge behavior may occur for each alternative fault type in partial discharge detection. Each fault type has its specific voltage sensitivity. By determining the voltage range interval, partial discharge detection can be purposefully carried out at these voltage levels to improve the accuracy and efficiency of detection.

[0092] Among them, alternative AC voltages are involved. The alternative AC voltages refer to a series of AC voltage values selected based on the inception discharge voltage and the voltage range interval of the alternative fault types. These voltage values will be used for subsequent partial discharge tests to obtain characteristic data of partial discharge at different voltage levels.

[0093] In the process of determining the alternative AC voltages based on the inception discharge voltage, it is first necessary to determine various alternative fault types that may exist in the cable to be measured. Subsequently, for each alternative fault type, it is necessary to determine the voltage range interval within which its partial discharge behavior may occur. This step is based on the existing research on the correlation between fault types and partial discharge behavior, as well as experimental data on the partial discharge sensitive voltage range of specific types of faults. For example, partial discharge of the electrical tree type fault may start at a relatively high voltage range, while partial discharge of the air gap discharge may start at a relatively low voltage range. Finally, the voltage range intervals of each alternative fault type determined are compared and integrated with the inception discharge voltage, and a series of alternative AC voltages are selected from these intervals for subsequent partial discharge detection experiments. These voltage values should cover the voltage sensitive ranges of all alternative fault types to ensure that the partial discharge behavior in the cable can be comprehensively detected and analyzed, and then the fault type of the cable can be identified.

[0094] By determining the voltage range interval related to the alternative fault types, partial discharge detection can be carried out at specific voltage levels, making the detection process more targeted and improving the detection efficiency and accuracy. There are differences in the voltage sensitivity of the partial discharge behavior of different fault types. By collecting partial discharge data at the alternative AC voltages, different fault types in the cable can be better identified and distinguished.

[0095] As an alternative embodiment, predicting the negative cycle inception voltage and the negative cycle termination voltage corresponding to the cable to be measured based on the average voltage difference and the positive cycle inception voltage includes: retrieving the prediction function corresponding to the cable of the target type, where the prediction function is obtained by testing the needle-plate electrode model corresponding to the target type; predicting the negative cycle inception voltage and the negative cycle termination voltage based on the average voltage difference, the positive cycle inception voltage, and the prediction function.

[0096] In this embodiment, the process of predicting the voltage is described.

[0097] Among them, a prediction function is involved. The prediction function refers to a mathematical model used to predict the starting voltage and ending voltage of the negative cycle. It is constructed based on a large amount of test data of the needle-plate electrode model for a specific cable type (target type), and can output the predicted starting voltage and ending voltage of the negative cycle by inputting the mean voltage difference and the starting voltage of the positive cycle.

[0098] In the process of predicting the starting voltage and ending voltage of the negative cycle based on the mean voltage difference and the starting voltage of the positive cycle, when detecting partial discharge of a specific cable, the mean voltage difference and the starting voltage of the positive cycle obtained through analysis are input into the corresponding prediction function. The prediction function will calculate the predicted starting voltage and ending voltage of the negative cycle according to the built-in mathematical model and historical test data. This prediction process can help engineers more accurately locate the sensitive voltage range of partial discharge, especially for partial discharge behavior in the negative half cycle, so as to make a more accurate judgment and evaluation of the potential defect types in the cable.

[0099] As an alternative embodiment, according to the target type, a plurality of absolute values of voltage differences are determined, including: obtaining the environmental parameters corresponding to the cable to be measured; and retrieving the mean voltage difference corresponding to the cable to be measured according to the target type and the environmental parameters.

[0100] Based on the above embodiments and alternative embodiments, an alternative implementation manner is provided, which is specifically described below.

[0101] In an alternative implementation manner of the present invention, a method for determining cable faults is provided, which relates to the technical field of identifying typical defect types of power cables, involves the corona generation of a needle-plate electrode (simulating a cable), and particularly relates to a method and system for jointly analyzing partial discharge signals of a needle-plate electrode based on the analysis of the partial discharge PRPD in a partial operation cycle and the spectrum diagram of the discharge pulse sequence.

[0102] When the voltage level is relatively high, corona discharge is likely to occur near the tip or burr of the cable conductor core. This is because a metal shell with a smaller radius of curvature is more likely to accumulate charges. As the charges continue to accumulate, the electric field strength in its vicinity increases continuously. When the electric field strength in its vicinity exceeds the breakdown field strength of the gas, the surrounding gas is ionized, and then corona discharge occurs. For the identification of partial discharge signals, the currently widely used statistical analysis method and time-frequency domain analysis method only extract the external manifestation characteristics of the discharge, and do not directly reflect the intrinsic characteristics of the discharge. Different types of discharges often have similarities in some characteristics, which makes it difficult to accurately detect the type of discharge defect using a single identification method. Therefore, an optional embodiment of the present invention designs a needle-plate electrode device to simulate the corona discharge of a power cable, and different defect sizes can be simulated by disassembling and replacing the needle electrodes with different lengths and radii of curvature. The partial discharge of the needle-plate electrode is measured using the pulse current method. Through the joint analysis of the PRPD of the partial discharge signal and the spectrum diagram of the discharge pulse sequence, the accuracy of defect type identification is improved, providing a certain basis for the defect assessment of power cables.

[0103] Aiming at the problem that it is currently difficult to accurately identify typical defects of power cables, the purpose of an optional embodiment of the present invention is to provide a method for jointly analyzing the partial discharge signal of a needle-plate electrode based on the PRPD and the spectrum diagram of the discharge pulse sequence, measuring the voltage, discharge amount, and phase information of the partial discharge of the needle-plate electrode, counting the number, peak value, and width of the characteristic peaks of the voltage difference, and comprehensively analyzing the partial discharge using the PRPD spectrum combined with the spectrum diagram of the discharge pulse sequence to obtain the inception voltage and extinction voltage of the partial discharge, extracting the characteristic quantities of the partial discharge of the needle-plate electrode and providing a certain basis for the identification of partial discharge types, calculating the mean value of the absolute value of the voltage difference, namely dV1- and dV2+, and the inception voltage VI+ of the positive half-cycle of the partial discharge, and then obtaining the estimated values of the inception voltage VI- and extinction voltage VX- of the negative half-cycle of the partial discharge. Extract the characteristics of the PRPD spectrum, the spectrum diagram of the discharge pulse sequence, and the dV statistical chart, and compare with the parameters obtained from other defects.

[0104] An optional embodiment of the present invention provides a method for jointly analyzing the partial discharge signal of a needle-plate electrode based on the PRPD and the spectrum diagram of the discharge pulse sequence, Figure 2 As shown in the schematic diagram of the voltage difference of the method provided by the optional embodiment of the present invention, it will be introduced below:

[0105] S1, measure the voltage, discharge amount, and phase information of the partial discharge of the needle-plate electrode at different voltages, divide the measured data into data containing only the leader discharge part and complete partial discharge data, and use the data containing only the leader discharge part to draw the PRPD spectrum of the leader discharge at different voltages;

[0106] Specifically, measure the voltage, discharge quantity, and phase of partial discharge at different voltages. Project the three-dimensional spectrogram Hn(q, φ) constructed by the PRPD pattern onto the φ-q plane, and determine the gray level at the corresponding position according to the discharge times n(q, φ), then the gray-scale image of partial discharge can be obtained. The two-dimensional and three-dimensional spectrograms and gray-scale images constructed by the PRPD pattern can all intuitively reflect the relationship between the discharge quantity, discharge phase, and discharge times of partial discharge.

[0107] S2. Use the data containing only the leader discharge part to construct the dV-dV diagram of the leader discharge at different voltages. The abscissa is dU(i), and the ordinate is dU(i + 1), where,

[0108] dU(i) = U(i + 1) - U(i)

[0109] In the formula, U(i + 1) is the partial discharge voltage after U(i) and adjacent to it;

[0110] S3. Use the dU(i) obtained in step S2 to construct the dV statistical diagram of the leader discharge at different voltages, and count the number, peak value, width of the voltage difference characteristic peak, and the mean value of the absolute value of the voltage difference of each characteristic peak;

[0111] S4. Use the complete partial discharge data to calculate the mean value of the absolute value of the voltage difference, that is, dV1- and dV2+;

[0112] Specifically, since there is basically 1 partial discharge per cycle in the positive half-cycle, and the partial discharge is mainly concentrated in the negative half-cycle. According to the PRPD spectrogram of each cycle, define dV1+, dV1-, dV2+ and dV2-: dV2- is the absolute value of the voltage difference between the first partial discharge in the negative half-cycle and the partial discharge voltage in the positive half-cycle; dV1- is the absolute value of the voltage difference between two consecutive partial discharges in the descending part of the negative half-cycle; dV1+ is the absolute value of the voltage difference between two consecutive partial discharges in the ascending part of the negative half-cycle; dV2+ is the absolute value of the voltage difference between the partial discharge in the positive half-cycle and the last partial discharge in the negative half-cycle.

[0113] S5. Use the mean values of the absolute values of the voltage differences dV1- and dV2+ obtained in S4 and the starting voltage VI+ of the positive half-cycle of partial discharge to obtain the estimated values of the starting voltage VI- and the ending voltage VX- of the negative half-cycle of partial discharge:

[0114]

[0115] S6. Extract the characteristics of the PRPD spectrogram, discharge pulse sequence analysis spectrogram, and dV statistical diagram of the leader discharge, and combine with the starting voltage VI- and ending voltage VX- of the negative half-cycle of partial discharge obtained in S5 to conduct a comparative analysis with other defects to obtain the final defect result.

[0116] Compared with the partial discharge diagnosis technology in the related art, in the optional implementation manner of the present invention, through the partial discharge test experiment of the needle-plate electrode, by using the combined analysis method of the PRPD and the discharge pulse sequence analysis spectrogram, the partial discharge inception voltage and the extinction voltage are obtained, providing a certain basis for the identification of partial discharge signals.

[0117] In addition, in the optional implementation manner of the present invention, the partial discharge signal is measured based on the needle-plate electrode, accurately simulating the corona discharge of the spike defect of the power cable. The experimental device is simple, and by combining the traditional PRPD spectrogram and the discharge pulse sequence analysis spectrogram, the identification of the power cable defect type is made more accurate, facilitating the timely repair or replacement of the faulty cable, which is of great significance for improving the stability of the power system and maximizing the cable benefits.

[0118] Figure 3 The PRPD spectrogram of the leader discharge within 1 s at 0.96 kV provided by the optional implementation manner of the present invention, Figure 4 The PRPD spectrogram of the leader discharge within 1 s at 1.36 kV provided by the optional implementation manner of the present invention, Figure 5 The PRPD spectrogram of the leader discharge within 1 s at 1.93 kV provided by the optional implementation manner of the present invention, Figure 6 The PRPD spectrogram of the leader discharge within 1 s at 2.28 kV provided by the optional implementation manner of the present invention, Figure 7 The discharge pulse sequence analysis spectrogram of the leader discharge within 1 s at 1.36 kV provided by the optional implementation manner of the present invention, Figure 8 The discharge pulse sequence analysis spectrogram of the leader discharge within 1 s at 1.93 kV provided by the optional implementation manner of the present invention, Figure 9 The discharge pulse sequence analysis spectrogram of the leader discharge within 1 s at 2.28 kV provided by the optional implementation manner of the present invention, Figure 10 The dV statistical chart of the leader discharge within 1 s at 1.36 kV provided by the optional implementation manner of the present invention, Figure 11 The dV statistical chart of the leader discharge within 1 s at 1.93 kV provided by the optional implementation manner of the present invention, Figure 12 The dV statistical chart of the leader discharge within 1 s at 2.28 kV provided by the optional implementation manner of the present invention. Figure 13 The structural schematic diagram of the needle-plate electrode device provided by the optional implementation manner of the present invention. It will be introduced below in combination with the above figures.

[0119] In the monitoring of partial discharge of power cables, tips, burrs, etc. are one of the typical defect types. This defect can generate an extremely uneven electric field and then corona discharge occurs. Therefore, the present invention uses a needle-plate electrode for simulation.

[0120] When conducting the detection, a pulse current test device for detecting partial discharge signals is arranged beside the metal conductor needle-plate electrode device.

[0121] When the externally applied voltage rises to the point where the field strength at this location reaches the breakdown field strength of the gas, corona discharge occurs near the tip of the needle. It is a self-sustained discharge form unique to extremely non-uniform electric fields. In this embodiment, when the actual test voltage applied to the metal columnar electrode rises to 0.96 kV, partial discharge signals can be observed in the software of the test device. At this time, the discharge occurs in the negative half-cycle. When the actual test voltage applied to the metal columnar electrode rises to 1.36 kV, discharge signals are generated in both the positive and negative half-cycles.

[0122] As Figures 3 to 6 shown, it is the PRPD spectrogram of leader discharge under different voltages. Among them, Figure 3 shows the PRPD spectrogram of the metal conductor needle-plate electrode device when the externally applied voltage is 0.96 kV; Figure 4 shows the PRPD spectrogram of the metal conductor needle-plate electrode device when the externally applied voltage is 1.36 kV; Figure 5 shows the PRPD spectrogram of the metal conductor needle-plate electrode device when the externally applied voltage is 1.93 kV; Figure 6 shows the PRPD spectrogram of the metal conductor needle-plate electrode device when the externally applied voltage is 2.28 kV.

[0123] As Figures 7 to 9 shown, it is the analysis spectrogram of the discharge pulse sequence of leader discharge under different voltages. Among them, Figure 7 shows the analysis spectrogram of the discharge pulse sequence of the metal conductor needle-plate electrode device when the externally applied voltage is 1.36 kV;

[0124] Figure 8 shows the analysis spectrogram of the discharge pulse sequence of the metal conductor needle-plate electrode device when the externally applied voltage is 1.93 kV; Figure 10 shows the analysis spectrogram of the discharge pulse sequence of the metal conductor needle-plate electrode device when the externally applied voltage is 2.28 kV.

[0125] As Figures 10 to 12 shown, it is the dV statistical chart of leader discharge under different voltages. Among them, Figure 10 shows the dV statistical chart of the metal conductor needle-plate electrode device when the externally applied voltage is 1.36 kV; Figure 11 shows the dV statistical chart of the metal conductor needle-plate electrode device when the externally applied voltage is 1.93 kV; Figure 12 shows the dV statistical chart of the metal conductor needle-plate electrode device when the externally applied voltage is 2.28 kV.

[0126] As Figures 3 to 6It can be seen that when the applied voltage is 0.96 kV, partial discharge signals are first detected in the negative half-cycle. In the figure, the sequences with higher amplitudes are the leader discharge signals. After a partial discharge with a high discharge amount, a series of partial discharges with lower and similar amplitudes follow. The partial discharge signal with a high discharge amount retained is the leader discharge signal. When the applied voltage rises to 1.36 kV, partial discharges occur in both the positive and negative half-cycles. This is because it is easier for the needle electrode to emit electrons when it is in the negative polarity, and at the same time, secondary electron emission occurs when positive ions strike the cathode, causing partial discharges to always appear first when the tip of the needle is in the negative polarity. When the applied voltage is 0.96 kV, partial discharges occur near 270°, and the PRPD spectrogram is symmetric about 270°. When the applied voltage gradually increases, partial discharges occur in the positive half-cycle and the discharge amount is less than that in the negative half-cycle. The phase distribution of the leader discharges in the negative half-cycle moves to the left of 270° and the range gradually decreases, while the discharge amount gradually increases but the increase amplitude is small. The positive and negative half-cycles are extremely asymmetric.

[0127] As Figures 7 to 9 It can be seen that as the applied voltage increases, the number of leader discharges per cycle remains at 1 - 3 times. Considering all discharge signals, the corona discharge repetition rate of the needle-plate electrode increases with the increase of the applied voltage.

[0128] As Figures 10 to 12 It can be seen that as the applied voltage increases, the characteristic peaks of the voltage difference in the dV statistical graph are similar to the normal distribution and change from 3 to the final 2. The frequencies of ±dV1 near 0 gradually decrease, that is to say, the number of leader discharges tends to a fixed value of 1 in both the positive and negative half-cycles. When the applied voltage is 0.96 kV, the discharge is not strong, the number of leader discharges per cycle is 0 or 1, and the discharge only occurs in the negative half-cycle, so there is no need to consider the voltage difference; when the applied voltage is 1.36 kV, the average value of the absolute value of dV1- is 4.77 V, the average value of the absolute value of dV2+ is 2.11 kV, the average value of the partial discharge inception voltage VI+ in the positive half-cycle is 1.32 kV, the estimated value of the inception voltage VI- in the negative half-cycle is 800.48 V, and the estimated value of the termination voltage VX- is 795.71 V; when the applied voltage is 1.93 kV, the average value of the absolute value of dV1- is 9.15 V, the average value of the absolute value of dV2+ is 2.15 kV, the average value of the partial discharge inception voltage VI+ in the positive half-cycle is 1.40 kV, the estimated value of the inception voltage VI- in the negative half-cycle is 751.40 V, and the estimated value of the termination voltage VX- is 742.26 kV.

[0129] Optionally, an embodiment of the metal conductor needle-plate electrode device disclosed in the present invention can be as Figure 2As shown in the figure. The device includes metal columnar electrodes 1 and electrode plates 2 arranged at intervals, and an insulating housing 4. The metal columnar electrode 1 is connected to high voltage, and the electrode plate 2 is grounded. One end of the metal columnar electrode 1 arranged relative to the electrode plate 2 is provided with a needle tip 3. The distance between the needle tip 3 and the electrode plate 2 is 6 mm. There is a screw on the metal columnar electrode 1, and the needle tip can be detachably replaced. Air is filled between the metal columnar electrode 1 and the electrode plate 2. The voltage of the high voltage applied to the columnar electrode 1 is greater than or equal to 0.96 kV. When the test voltage rises to 0.96 kV, corona discharge in the negative half cycle can be observed on the test software for the metal conductor needle-plate electrode device; when the test voltage rises to 1.36 kV, corona discharge also starts to occur in the positive half cycle on the test software for the metal conductor needle-plate electrode device. A pulse current method test device for measuring partial discharge data is arranged beside the metal conductor needle-plate electrode device. In order to obtain the above results through the above tests. Through the above optional implementation manners, the results of faults or defects can be accurately determined.

[0130] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0131] Through the description of the above implementation manners, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation manner. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions for causing a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods of the various embodiments of the present invention.

[0132] Embodiment 2

[0133] According to an embodiment of the present invention, there is also provided a device for implementing the method for determining the fault of the above cable. Figure 14 It is a structural block diagram of a device for determining the fault of a cable according to an embodiment of the present invention, as Figure 14 shown. The device includes: an acquisition module 1402, a first determination module 1404, a second determination module 1406, a third determination module 1408, and a fourth determination module 1410. The device will be described in detail below.

[0134] An acquisition module 1402 is configured to acquire a cable to be measured, where the cable to be measured is a cable of a target type; a first determination module 1404 is connected to the acquisition module 1402 and is configured to determine instantaneous pulse data of the cable to be measured under a predetermined AC voltage, where the instantaneous pulse data includes a positive cycle start voltage corresponding to the cable to be measured, and the positive cycle start voltage is the voltage value corresponding to the first occurrence of an instantaneous pulse within the positive cycle of the predetermined AC voltage; a second determination module 1406 is connected to the first determination module 1404 and is configured to determine an average voltage difference corresponding to the cable to be measured according to the target type; a third determination module 1408 is connected to the second determination module 1406 and is configured to predict a negative cycle start voltage and a negative cycle end voltage corresponding to the cable to be measured based on the average voltage difference and the positive cycle start voltage, where the negative cycle start voltage is the voltage value corresponding to the first occurrence of an instantaneous pulse within the negative cycle of the predetermined AC voltage, and the negative cycle end voltage is the voltage value corresponding to the last disappearance of an instantaneous pulse within the negative cycle of the predetermined AC voltage; a fourth determination module 1410 is connected to the third determination module 1408 and is configured to determine the fault type of the cable to be measured based on the negative cycle start voltage and the negative cycle end voltage.

[0135] It should be noted here that the acquisition module 1402, the first determination module 1404, the second determination module 1406, the third determination module 1408, and the fourth determination module 1410 correspond to steps S102 to S110 in the method for determining a cable fault. The instances and application scenarios implemented by the multiple modules and the corresponding steps are the same, but are not limited to the content disclosed in the above-mentioned embodiment 1.

[0136] Embodiment 3

[0137] According to another aspect of the embodiments of the present invention, an electronic device is further provided, including: a processor; a memory for storing processor-executable instructions, where the processor is configured to execute the instructions to implement the method for determining a cable fault in any one of the above.

[0138] Embodiment 4

[0139] According to another aspect of the embodiments of the present invention, a computer-readable storage medium is further provided. When the instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device can execute the method for determining a cable fault in any one of the above.

[0140] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0141] In the above embodiments of the present invention, the descriptions of the respective embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0142] In several embodiments provided by the present application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only illustrative. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of units or modules can be in an electrical or other form.

[0143] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0144] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0145] If the above integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an 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 for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the respective embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, read-only memories (ROMs), random access memories (RAMs), mobile hard disks, magnetic disks, or optical discs and other various media that can store program codes.

[0146] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for determining a cable fault, characterized in that: include: Acquire a cable to be measured, wherein the cable to be measured is a cable of a target type; Determine the instantaneous pulse data of the cable to be measured under a predetermined alternating voltage, wherein the instantaneous pulse data includes a positive cycle starting voltage corresponding to the cable to be measured, and the positive cycle starting voltage is a voltage value corresponding to the first appearance of the instantaneous pulse in the positive cycle of the predetermined alternating voltage; Determining a voltage difference mean value corresponding to the cable to be measured according to the target type; According to the voltage difference mean value and the positive cycle start voltage, predict the negative cycle start voltage and negative cycle end voltage corresponding to the cable to be measured, wherein the negative cycle start voltage is the voltage value corresponding to the first appearance of the instantaneous pulse in the negative cycle of the predetermined alternating voltage, and the negative cycle end voltage is the voltage value corresponding to the last disappearance of the instantaneous pulse in the negative cycle of the predetermined alternating voltage; The fault type of the cable to be measured is determined according to the negative cycle start voltage and the negative cycle end voltage.

2. The method according to claim 1, characterized in that Determining a voltage difference mean value corresponding to the cable to be measured according to the target type includes: Determine a plurality of voltage difference absolute values ​​according to the target type, wherein the plurality of voltage difference absolute values ​​include a first voltage difference absolute value and a second voltage difference absolute value, the first voltage difference absolute value is the absolute value of the voltage difference between two consecutive instantaneous pulses in the falling part of the negative cycle, and the second voltage difference absolute value is the absolute value of the voltage difference between the instantaneous pulse in the positive cycle and the last instantaneous pulse in the negative cycle; The voltage difference average is determined according to a plurality of voltage difference absolute values.

3. The method according to claim 2, characterized in that According to the target type, multiple voltage difference absolute values ​​are determined, including: Acquire a needle-plate electrode model corresponding to the target type; Determining power parameter data corresponding to the needle-plate electrode model under multiple voltages, wherein the power parameter data includes multiple instantaneous pulse voltage data; The plurality of voltage difference absolute values ​​are determined according to the power parameter data.

4. The method according to claim 1, characterized in that Before determining the instantaneous pulse data of the cable to be measured under a predetermined AC voltage, the method further includes: determining a starting discharge voltage corresponding to the target type; Determining a plurality of alternate current voltages to be selected according to the starting discharge voltage; Determine a discharge parameter stability index and a discharge behavior repetition index respectively corresponding to the plurality of selected AC voltages; The predetermined AC voltage is determined from the plurality of candidate AC voltages according to the discharge parameter stability indexes and the discharge behavior repetition indexes respectively corresponding to the plurality of candidate AC voltages.

5. The method according to claim 4, characterized in that According to the starting discharge voltage, a plurality of alternate current voltages to be selected are determined, including: Determine a plurality of candidate fault types corresponding to the cable to be measured; Determine voltage range intervals corresponding to the multiple candidate fault types respectively; A plurality of alternate current voltages to be selected are determined according to a plurality of voltage ranges and the initial discharge voltage.

6. The method according to claim 1, characterized in that Predicting a negative cycle start voltage and a negative cycle end voltage corresponding to the cable to be measured according to the voltage difference mean value and the positive cycle start voltage, including: Retrieving a prediction function corresponding to the target type of cable, wherein the prediction function is obtained by testing a needle plate electrode model corresponding to the target type; The negative cycle start voltage and the negative cycle end voltage are predicted based on the voltage difference mean, the positive cycle start voltage and the prediction function.

7. The method according to any one of claims 1 to 6, characterized in that: According to the target type, multiple voltage difference absolute values ​​are determined, including: Obtaining environmental parameters corresponding to the cable to be measured; According to the target type and the environmental parameters, a voltage difference mean value corresponding to the cable to be measured is retrieved.

8. A cable fault determination device, characterized in that: include: An acquisition module, used for acquiring a cable to be measured, wherein the cable to be measured is a cable of a target type; A first determination module is used to determine the instantaneous pulse data of the cable to be measured under a predetermined AC voltage, wherein the instantaneous pulse data includes a positive cycle starting voltage corresponding to the cable to be measured, and the positive cycle starting voltage is a voltage value corresponding to the first appearance of the instantaneous pulse in the positive cycle of the predetermined AC voltage; A second determination module, used to determine a voltage difference mean value corresponding to the cable to be measured according to the target type; A third determination module is used to predict the negative cycle start voltage and the negative cycle end voltage corresponding to the cable to be measured based on the voltage difference mean value and the positive cycle start voltage, wherein the negative cycle start voltage is the voltage value corresponding to the first appearance of the instantaneous pulse in the negative cycle of the predetermined alternating voltage, and the negative cycle end voltage is the voltage value corresponding to the last disappearance of the instantaneous pulse in the negative cycle of the predetermined alternating voltage; The fourth determination module is used to determine the fault type of the cable to be measured according to the negative cycle start voltage and the negative cycle end voltage.

9. An electronic device, characterized in that: include: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instructions to implement the cable fault determination method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: When the instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute the cable fault determination method according to any one of claims 1 to 7.

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