Waveform measurement method, computer-readable storage medium, and computer device

Abstract

The present invention discloses a waveform measurement method, a computer-readable storage medium, and a computer device. The method includes: simultaneously applying a pulse voltage with a first predetermined period and an excitation voltage with a second predetermined period to a target insulating medium; using an ultrasonic probe to measure a plurality of space charge ultrasonic waveforms at a plurality of predetermined positions of the target insulating medium at a plurality of predetermined time points; determining a charge distribution waveform at a target position of the target insulating medium based on the plurality of space charge ultrasonic waveforms; only applying the excitation voltage to the target insulating medium; using a high-frequency coil to measure a plurality of partial discharge waveforms at the target position of the target insulating medium according to a plurality of predetermined time points; determining a partial discharge characteristic waveform corresponding to the plurality of predetermined time points at the target position of the target insulating medium based on the plurality of partial discharge waveforms; and determining a target charge waveform at the target position of the target insulating medium based on the charge distribution waveform and the partial discharge characteristic waveform.

Description

Technical Field

[0001] The present invention relates to the field of high voltage, and in particular, to a waveform measurement method, a computer-readable storage medium, and a computer device. Background Art

[0002] In the related art, usually only the external characteristic quantities caused by partial discharge of the insulating medium are measured, but the insulation aging condition, insulation defects, etc. of the insulating medium cannot be comprehensively and accurately evaluated based on the measurement data.

[0003] Therefore, in the related art, there is a technical problem that the insulating medium cannot be comprehensively and accurately evaluated.

[0004] In view of the above problems, no effective solution has been proposed yet. Summary of the Invention

[0005] Embodiments of the present invention provide a waveform measurement method, a computer-readable storage medium, and a computer device to at least solve the technical problem that the insulating medium cannot be comprehensively and accurately evaluated.

[0006] According to one aspect of the embodiments of the present invention, there is provided a waveform measurement method, including: applying a pulse voltage with a first predetermined period and an excitation voltage with a second predetermined period to a target insulating medium simultaneously; using an ultrasonic probe to measure a plurality of space charge ultrasonic waveforms at a plurality of predetermined positions of the target insulating medium at a plurality of predetermined time points respectively; determining a charge distribution waveform at a target position of the target insulating medium based on the plurality of space charge ultrasonic waveforms; applying only the excitation voltage to the target insulating medium; using a high-frequency coil to measure a plurality of partial discharge waveforms at the target position of the target insulating medium according to a plurality of predetermined time points; determining a partial discharge characteristic waveform corresponding to the plurality of predetermined time points at the target position of the target insulating medium based on the plurality of partial discharge waveforms; determining a target charge waveform at the target position of the target insulating medium based on the charge distribution waveform and the partial discharge characteristic waveform.

[0007] Optionally, using an ultrasonic probe to measure a plurality of space charge ultrasonic waveforms at a plurality of predetermined positions of the target insulating medium at a plurality of predetermined time points respectively includes: using an ultrasonic probe to measure a plurality of initial waveforms corresponding to each position at each of the plurality of predetermined positions at a plurality of predetermined time points respectively; calculating an average waveform for the plurality of initial waveforms corresponding to each position respectively to obtain a plurality of space charge ultrasonic waveforms corresponding to the plurality of predetermined positions respectively.

[0008] Optionally, based on multiple space charge ultrasonic waveforms, determining a charge distribution waveform at a target position of a target insulating medium includes: obtaining a reference signal of the target insulating medium when only a pulsed voltage with a predetermined period is applied; using the reference signal to filter out interference signals in the multiple space charge ultrasonic waveforms to obtain multiple target space charge ultrasonic waveforms; and determining a charge distribution waveform at the target position of the target insulating medium based on the multiple target space charge ultrasonic waveforms.

[0009] Optionally, determining a charge distribution waveform at a target position of a target insulating medium based on multiple target space charge ultrasonic waveforms includes: at multiple predetermined time points, determining the charge distribution change with time of the target insulating medium within a predetermined space range based on the multiple target space charge ultrasonic waveforms respectively corresponding to multiple predetermined positions; and determining a charge distribution waveform of the charge distribution change with time at the target position of the target insulating medium based on the charge distribution situation.

[0010] Optionally, determining a partial discharge characteristic waveform corresponding to multiple predetermined time points at a target position of a target insulating medium based on multiple partial discharge waveforms includes: extracting multiple discharge characteristic quantities of the target insulating medium at the target position based on the multiple partial discharge waveforms; and at multiple predetermined time points, determining a partial discharge characteristic waveform of the change of the discharge characteristics with time at the target position of the target insulating medium based on the multiple discharge characteristic quantities.

[0011] Optionally, determining a target charge waveform at a target position of a target insulating medium based on the charge distribution waveform and the partial discharge characteristic waveform includes: determining a target charge waveform of the change with time of the corresponding relationship between the charge distribution change and the discharge characteristic quantity at the target position of the target insulating medium according to the time parameters in the charge distribution waveform and the partial discharge characteristic waveform.

[0012] Optionally, the above method further includes: in the case where the target insulating medium is the insulating medium of a cable, determining insulation information at the target position of the cable in the case of an insulation defect based on the target charge waveform.

[0013] Optionally, the insulation defect includes at least one of the following: there is a needle electrode in the target insulating medium, there is a floating electrode in the target insulating medium, and there is a bubble in the target insulating medium.

[0014] According to another aspect of the embodiments of the present invention, there is also provided a computer-readable storage medium, where the computer-readable storage medium includes a stored program, and when the program runs, it controls a device where the computer-readable storage medium is located to execute the waveform measurement method of any one of the above.

[0015] According to another aspect of the embodiments of the present invention, a computer device is further provided, including: a memory and a processor, where the memory stores a computer program; the processor is configured to execute the computer program stored in the memory, and when the computer program runs, the processor executes the waveform measurement method of any one of the above.

[0016] In the embodiments of the present invention, a combined measurement method of space charge and partial discharge is adopted. By simultaneously applying a pulsed voltage and an excitation voltage to the target insulating medium, at multiple predetermined positions of the target insulating medium at multiple predetermined time points, the charge distribution waveform of the space charge in the target insulating medium at the target position is measured and processed. Then, only the excitation voltage is applied to the target insulating medium, and at the target position of the target insulating medium at the above-mentioned multiple predetermined time points, the partial discharge characteristic waveform of the target insulating medium at the target position is measured and extracted. This is equivalent to determining the change of the charge distribution with time at the target position of the target insulating medium, and the change of the discharge characteristics with time at the target position of the target insulating medium. Then, the target charge waveform at the target position of the target insulating medium can be determined according to the charge distribution waveform and the partial discharge characteristic waveform, achieving the purpose of obtaining more information about the target insulating medium, thus realizing the technical effect of analyzing and evaluating the target insulating medium using more comprehensive and rich information, and further solving the technical problem of being unable to comprehensively and accurately evaluate the insulating medium. Description of the Drawings

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. 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:

[0018] Figure 1 is a flowchart of the waveform measurement method according to the embodiments of the present invention;

[0019] Figure 2 is a schematic diagram of an apparatus for combined measurement of partial discharge and space charge of typical insulation defects according to an alternative embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of a reference waveform according to an alternative embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of the result after signal amplitude normalization according to an alternative embodiment of the present invention;

[0022] Figure 5 is a schematic diagram of the result after eliminating the interference waveform according to an alternative embodiment of the present invention;

[0023] Figure 6It is the PRPD spectrogram of partial discharge provided according to an alternative embodiment of the present invention;

[0024] Figure 7 It is the discharge waveform of partial discharge provided according to an alternative embodiment of the present invention;

[0025] Figure 8 It is the structural block diagram of the waveform measurement device provided according to an embodiment of the present invention. Detailed Embodiment

[0026] 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 of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than 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 including a series of steps or units does not necessarily have to be limited 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.

[0028] According to an embodiment of the present invention, an embodiment of a waveform measurement method 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 a different order than here.

[0029] Figure 1 It is the flowchart of the waveform measurement method according to an embodiment of the present invention, as Figure 1 shown, the method includes the following steps:

[0030] Step S102, applying a pulse voltage with a first predetermined period and an excitation voltage with a second predetermined period to the target insulating medium simultaneously;

[0031] Step S104: Use an ultrasonic probe to measure multiple space charge ultrasonic waveforms at multiple predetermined positions of the target insulating medium at multiple predetermined time points;

[0032] Step S106: Based on the multiple space charge ultrasonic waveforms, determine the charge distribution waveform at the target position of the target insulating medium;

[0033] Step S108: Apply only an excitation voltage to the target insulating medium;

[0034] Step S110: Use a high-frequency coil to measure multiple partial discharge waveforms at the target position of the target insulating medium according to multiple predetermined time points;

[0035] Step S112: Based on the multiple partial discharge waveforms, determine the partial discharge characteristic waveforms corresponding to the multiple predetermined time points at the target position of the target insulating medium;

[0036] Step S114: Based on the charge distribution waveform and the partial discharge characteristic waveform, determine the target charge waveform at the target position of the target insulating medium.

[0037] Through the above steps, by adopting the combined measurement method of space charge and partial discharge, by simultaneously applying a pulse voltage and an excitation voltage to the target insulating medium, at multiple predetermined positions of the target insulating medium according to multiple predetermined time points, measure and process to obtain the charge distribution waveform of the target insulating medium at the target position, and then apply only the excitation voltage to the target insulating medium, at the target position of the target insulating medium according to the above multiple predetermined time points, measure and extract the partial discharge characteristic waveform of the target insulating medium at the target position, which is equivalent to determining the change of the charge distribution with time at the target position of the target insulating medium, and the change of the discharge characteristics with time at the target position of the target insulating medium. Then, the target charge waveform at the target position of the target insulating medium can be determined according to the charge distribution waveform and the partial discharge characteristic waveform, achieving the purpose of obtaining more information about the target insulating medium, thus realizing the technical effect of analyzing and evaluating the target insulating medium using more comprehensive and rich information, and further solving the technical problem of being unable to comprehensively and accurately evaluate the insulating medium.

[0038] As an alternative embodiment, multiple space charge ultrasonic waveforms are measured at multiple predetermined positions of the target insulating medium at multiple predetermined time points by using an ultrasonic probe, including: measuring multiple initial waveforms corresponding to each position at each of the multiple predetermined positions by using the ultrasonic probe at multiple predetermined time points; calculating the average waveform for the multiple initial waveforms corresponding to each position respectively to obtain multiple space charge ultrasonic waveforms corresponding to the multiple predetermined positions respectively. By calculating the average waveform based on the multiple initial waveforms, the errors caused by some reasons such as signal fluctuations can be greatly reduced, and at the same time, the number of the measured initial waveforms can be determined according to the actual measurement or evaluation requirements (for example, the signal-to-noise ratio during measurement). In addition, before calculating the average waveform, the waveforms with obvious measurement errors in the multiple initial waveforms can be removed first, or when calculating the average waveform, the measurement noise of the ultrasonic probe used for measurement can be considered and used as a calculation parameter to improve the accuracy of the determined multiple space charge ultrasonic waveforms.

[0039] As an alternative embodiment, based on the multiple space charge ultrasonic waveforms, the charge distribution waveform at the target position of the target insulating medium is determined, including: obtaining a reference signal when the target insulating medium is only applied with a pulsed voltage of a predetermined period; filtering out the interference signals in the multiple space charge ultrasonic waveforms by using the reference signal to obtain multiple target space charge ultrasonic waveforms; determining the charge distribution waveform at the target position of the target insulating medium based on the multiple target space charge ultrasonic waveforms.

[0040] For an insulating medium with a needle electrode, or a floating electrode, or a bubble existing inside the medium, the electric field distribution inside it is uneven. Therefore, there will be an electrostrictive force inside it. And during the space charge measurement, that is, in the process of determining the charge distribution waveform, the measured waveform will simultaneously include the ultrasound generated by the charge and the ultrasound generated by the electrostrictive force. And the ultrasound generated by the electrostrictive force does not contain space charge information. Therefore, the ultrasound generated by the electrostrictive force belongs to the interference signal. And the electrostrictive force is only related to the amplitude of the electric field distribution, and the electric field distribution is determined by the electrode structure inside the insulating medium and does not change with time. Therefore, in this embodiment, by applying only a pulsed voltage to the target insulating medium, the signal measured at this time can be used to characterize the ultrasound generated by the electrostrictive force in the target insulating medium, that is, this signal can be used as a reference signal to filter out the interference information in the multiple space charge ultrasonic waveforms.

[0041] As an alternative embodiment, determining the charge distribution waveform at the target position of the target insulating medium based on multiple target space charge ultrasonic waveforms includes: at multiple predetermined time points, determining the time-varying charge distribution of the target insulating medium within a predetermined space range based on multiple target space charge ultrasonic waveforms respectively corresponding to multiple predetermined positions; based on the charge distribution, determining the charge distribution waveform of the target insulating medium at the target position that changes with time. After determining multiple target space charge ultrasonic waveforms, since the target space charge ultrasonic waveforms correspond to multiple predetermined positions, the time-varying charge distribution within a predetermined space range including the multiple predetermined positions can be determined from the multiple target space charge ultrasonic waveforms. Furthermore, based on the charge distribution changes in the entire space within the predetermined range, the time-varying charge distribution at the target position within the predetermined range, i.e., the charge distribution waveform, can be determined.

[0042] As an alternative embodiment, determining the partial discharge characteristic waveforms corresponding to multiple predetermined time points at the target position of the target insulating medium based on multiple partial discharge waveforms includes: based on multiple partial discharge waveforms, extracting multiple discharge characteristic quantities of the target insulating medium at the target position; at multiple predetermined time points, determining the partial discharge characteristic waveforms of the target insulating medium at the target position whose discharge characteristics change with time based on the multiple discharge characteristic quantities. After obtaining multiple partial discharge waveforms, discharge characteristic quantities can be extracted based on these waveforms. For example, the number of discharges, the total discharge amount, or the average discharge amount, etc. Extracting discharge characteristic quantities can screen the information of the measured partial discharge waveforms, only retaining the information required for analyzing and evaluating the target insulating medium, so that the obtained partial discharge characteristic waveforms can more clearly and explicitly characterize the discharge characteristics of the target insulating medium at the target position.

[0043] As an alternative embodiment, determining the target charge waveform of the target insulating medium at the target position based on the charge distribution waveform and the partial discharge characteristic waveform includes: determining, according to the time parameters in the charge distribution waveform and the partial discharge characteristic waveform, the target charge waveform in which the correspondence relationship between the charge distribution change and the discharge characteristic quantity at the target position of the target insulating medium changes with time. Through the above operations, a charge distribution waveform for characterizing the change of the charge distribution of the target insulating medium at the target position with time, and a partial discharge characteristic waveform for characterizing the change of the discharge characteristics of the target insulating medium at the target position with time can be obtained. By aligning the data of the two waveforms according to the time parameters in the two waveforms, or integrating the data according to a predetermined data processing method, the correspondence relationship between the space charge and the discharge characteristics of the target insulating medium at the target position and their respective changes with the pressurization time can be obtained. Furthermore, the insulation aging condition, insulation defects, etc. of the target insulating medium at the target position can be comprehensively and accurately evaluated according to the target charge waveform.

[0044] As an alternative embodiment, the above method further includes: in the case where the target insulating medium is the insulating medium of a cable, determining the insulation information at the target position of the cable in the case of the existence of insulation defects based on the target charge waveform. Through the above method for obtaining the target charge waveform of the target insulating medium, this method can be applied to the determination of the insulation information of the insulating medium in the cable, and further, the on-line monitoring of the equipment state can be realized by analyzing the cable.

[0045] As an alternative embodiment, the above insulation defects include at least one of the following: there is a needle electrode in the target insulating medium, there is a floating electrode in the target insulating medium, and there is a bubble in the target insulating medium.

[0046] Based on the above embodiments and alternative embodiments, the present invention proposes an alternative implementation manner, which will be described below.

[0047] Insulation is crucial in the high-voltage field, which ensures the normal operation of various electrical equipment and devices. However, due to the increase in the operation time of the insulation material or the processing technology problems, local insulation defects and insulation aging phenomena often occur. Partial discharge is a very common phenomenon in the insulation aging process, which refers to a local tiny discharge phenomenon caused by local electric field distortion before the insulation breaks down. Partial discharge is accompanied by physical or chemical changes, mainly including various physical phenomena such as current pulses, electromagnetic waves, ultrasonic waves, heat and light, and chemical phenomena such as gas ionization. Therefore, the partial discharge situation of the cable can be judged by monitoring various physical or chemical quantities during the partial discharge process, so as to realize the on-line monitoring of the equipment state.

[0048] However, the occurrence of partial discharge is always accompanied by the movement of space charges inside the insulation. In related technologies, only external characteristic quantities caused by partial discharge, such as current pulses, ultrasounds, etc., are often measured. However, these external information can only reflect the characteristics of partial discharge to a certain extent, and the amount of information that can be obtained by their measurement is relatively low, and the assessment of insulation life cannot be realized.

[0049] In view of the above problems, an optional embodiment of the present invention proposes a method for jointly measuring partial discharge and space charges of typical insulation defects of a cable and obtaining effective signals. Since the movement of space charges inside the insulation plays a role in regulating the local electric field distribution, and thus affects the occurrence of partial discharge, there is a more direct relationship between partial discharge and the distribution of space charges inside the insulation. Joint measurement of partial discharge and space charges can obtain more information.

[0050] First, the measuring device applied in the optional embodiment of the present invention will be introduced below. Figure 2 is a schematic diagram of a device for jointly measuring partial discharge and space charges of typical insulation defects provided according to an optional embodiment of the present invention. As Figure 2 shown, the space charge measurement system includes two power supplies, namely a pulse power supply and a background power supply. Among them, the pulse power supply is used to generate a pulsed electric field in the specimen (i.e., the target insulating medium), so that the internal charges vibrate under the action of the electric field to generate ultrasounds; the background power supply is the excitation voltage of the typical defect specimen, which causes partial discharge and the migration of space charges. Water serves as the grounding electrode of the space charge measurement system on the one hand, and provides a propagation path for the ultrasound to propagate from the specimen to the ultrasound probe on the other hand. The high-frequency coil is placed on the wire connected to the high-voltage electrode and is used to measure the high-frequency current information accompanying the partial discharge process flowing through the high-voltage electrode.

[0051] When performing space charge measurement, the pulse power supply and the background power supply need to be applied simultaneously, while when performing partial discharge measurement, only the background power supply needs to be applied. Therefore, the operating conditions of the two measurements are different. Utilizing the characteristics that the development of space charges and partial discharge inside the dielectric is relatively slow, it can be considered that the space charges and the partial discharge conditions remain unchanged within a short period of time. Therefore, the measurement of partial discharge and space charges can be carried out separately within a short period of time. When collecting partial discharge signals, only the background power supply is applied and the pulse power supply is turned off, while when measuring space charge information within a short period of time, the background power supply remains unchanged and the pulse power supply is turned on.

[0052] The measurement of space charges is realized by means of the measurement of ultrasound signals, and the appearance of ultrasound is due to the action of electrostatic force inside the dielectric. When there is an electric field inside the insulating dielectric, the electrostatic force exerted on the dielectric can be expressed as follows:

[0053]

[0054] Among them, ρ is the space charge density inside the insulating medium, E is the internal electric field strength, П represents the permanent dipole, ε represents the relative permittivity, and a represents the electrostrictive coefficient.

[0055] The first term in the above formula is the Coulomb force acting on the charge, the second term is the dipole force, which is usually considered in piezoelectric materials, the third term is the force generated due to medium inhomogeneity, and the fourth term is the force generated due to non-uniform electric field distribution. The insulating material used is homogeneous and non-piezoelectric, so the second and third terms do not need to be considered here. However, for a medium containing tip electrodes (i.e., needle electrodes), floating electrodes, and air bubbles inside, the internal electric field distribution is non-uniform, so there is an electrostrictive force. When measuring space charge, there is ultrasound generated by the charge and the ultrasound generated by the electrostrictive force. The ultrasound generated by the electrostrictive force does not contain space charge information inside, so for the space charge measurement here, it belongs to interference signals and needs to be removed to obtain effective ultrasound signals.

[0056] The contribution of the electrostrictive force is related to the electric field distribution and amplitude, and the electric field distribution is determined by the internal electrode structure of the medium. Therefore, the contribution part of the electrostrictive force will not change with time. And the part of the Coulomb force will gradually change with the injection of space charge. Based on this, the effective ultrasound signal can be separated from the measurement result. Therefore, a reference signal needs to be obtained before measurement to characterize the influence of the electrostrictive force.

[0057] When obtaining the reference signal, only a pulsed power supply is applied. Since the amplitude of the pulsed power supply is low and the action time is short, it can be considered that there is no partial discharge at this time, and no space charge is injected into the insulating medium. At this time, an ultrasound signal can be measured, denoted as s1(t). The ultrasound signal therein contains the contribution of the fourth term in the electrostatic force formula received by the above medium, but does not contain the contribution of the first term. Assume that the ultrasound signal obtained from the formal space charge measurement is denoted as s2(t), which contains both the contribution of the first term and the fourth term. Let the pulsed electric field be e and the DC electric field be E. Then the electrostrictive force parts of the above two signals can be expressed as follows:

[0058]

[0059]

[0060] Among them, k represents the ratio of the DC voltage amplitude to the pulsed voltage amplitude.

[0061] Therefore, the elimination of the interference signal caused by the electrostrictive force with the help of the reference signal can be expressed as follows:

[0062] s0(t) = s2(t) - (1 + 2k)s1(t)

[0063] When measuring the space charge of typical defects, since partial discharge also generates ultrasonic waves, in order to avoid the influence of ultrasonic waves generated by partial discharge on the measurement of space charge, repetitive pulses need to be applied during the space charge measurement, and the signals measured by the ultrasonic probe are averaged. This can not only improve the signal-to-noise ratio of ultrasonic measurement but also eliminate the influence of possible ultrasonic waves generated by partial discharge.

[0064] When measuring partial discharge using a high-frequency coil, since the pulse power supply itself will generate relatively strong electromagnetic interference on the current coil, affecting the measurement of the coil for the true partial discharge current. Therefore, the pulse power supply needs to be turned off during the partial discharge measurement and alternated with the space charge measurement. Since the development of space charge and partial discharge is relatively slow, the measurement results of space charge and partial discharge can be considered corresponding within a short period.

[0065] Specifically, the optional implementation manner of the present invention includes the following steps:

[0066] 1. Only turn on the repetitive pulse power supply to collect ultrasonic signals as the reference waveform s1(t) for filtering out interference signals;

[0067] 2. Measure the space charge distribution:

[0068] 1) Use the ultrasonic probe to measure 2000 waveforms and take the average (depending on the signal-to-noise ratio of the experimental measurement) to obtain an ultrasonic waveform at one position;

[0069] 2) Move the ultrasonic probe to the next measurement position according to the established trajectory, continue to measure a certain number of ultrasonic waveforms, obtain the ultrasonic signals at this position, and repeat this process to measure the ultrasonic signals at all established positions;

[0070] 3) Complete the data acquisition for one measurement of space charge;

[0071] 4) Use the reference signal to filter out interference signals and complete the extraction of the space charge waveform;

[0072] 3. Turn off the pulse power supply;

[0073] 4. Use the high-frequency coil to measure the partial discharge pulse current signal;

[0074] 5. Extract the required partial discharge characteristic quantities;

[0075] 6. Complete the measurement of partial discharge at one time point;

[0076] 7. Since the time is short, it can be considered that the space charge and partial discharge have not changed. Therefore, the information of a group of corresponding insulation defect space charge and partial discharge obtained in the above steps;

[0077] 8. Repeat steps 2 - 6 at the next time point to observe the development of space charge and partial discharge with the increase of pressurization time.

[0078] Taking the combined measurement of space charge and partial discharge of a certain tip sample as an example. When performing space charge measurement, first apply only repetitive pulse voltage. Figure 3 It is a schematic diagram of the reference waveform provided according to an alternative embodiment of the present invention. As Figure 3 shown, first obtain the reference waveform. The ultrasonic waveform obtained by simultaneously applying the background voltage and the pulse voltage is also shown in Figure 3 and compared with the reference waveform. Since the amplitude of the pulse voltage is small, the amplitude of the reference waveform is also small. When the background voltage is first applied, there is no accumulation of space charge inside the insulating medium. According to the expression formula of electrostrictive force in the signal, there is only a proportional coefficient difference in amplitude between the two, and the waveforms are the same. Figure 4 It is a schematic diagram of the result after normalizing the signal amplitude provided according to an alternative embodiment of the present invention. As Figure 4 shown, it can be seen that the reference waveform actually contains the interference signal generated by electrostrictive force and can be used as a tool for interference elimination.

[0079] After applying the background voltage for a certain period of time, space charge will accumulate inside the insulating medium. Figure 5 It is a schematic diagram of the result after eliminating the interference waveform provided according to an alternative embodiment of the present invention. It can be seen that the electrostrictive force has a great influence on the space charge signal, and this step is crucial for the correct extraction of the space charge signal. Figure 6 It is a PRPD spectrogram of partial discharge provided according to an alternative embodiment of the present invention. Figure 7 It is a discharge waveform of partial discharge provided according to an alternative embodiment of the present invention.

[0080] In summary, the alternative embodiments of the present invention have the following characteristics:

[0081] 1. It can specifically measure the space charge and partial discharge information around typical cable insulation defects such as needle tips, bubbles, and floating electrodes;

[0082] 2. It is proposed to perform combined measurement of space charge and partial discharge, based on which the corresponding relationship between partial discharge and space charge movement of typical insulation defects can be found to obtain more insulation information;

[0083] 3. Ultrasonic waves are generated during partial discharge, and the space charge measurement method based on the electroacoustic pulse measurement principle measures exactly the ultrasonic signal. During the combined measurement of space charge and partial discharge, the influence of ultrasonic waves generated by partial discharge and electrostrictive force on space charge measurement, as well as the influence of space charge measurement on partial discharge, are considered.

[0084] 4. The measurement results of space charge include the distribution and migration of space charge. Partial discharge can measure parameters such as discharge quantity, PRPD spectrogram, discharge frequency, etc.

[0085] According to an embodiment of the present invention, there is also provided a waveform measurement device. Figure 8 It is a structural block diagram of the waveform measurement device provided according to an embodiment of the present invention, as Figure 8 shown. The device includes: a first voltage application module 81, a first measurement module 82, a first determination module 83, a second voltage application module 84, a second measurement module 85, a second determination module 86, and a third determination module 87. The device will be described below.

[0086] The first voltage application module 81 is configured to simultaneously apply a pulsed voltage with a first predetermined period and an excitation voltage with a second predetermined period to a target insulating medium; the first measurement module 82 is connected to the first voltage application module 81, and is configured to measure a plurality of space charge ultrasonic waveforms at a plurality of predetermined positions of the target insulating medium at a plurality of predetermined time points by using an ultrasonic probe; the first determination module 83 is connected to the first measurement module 82, and is configured to determine a charge distribution waveform at a target position of the target insulating medium based on the plurality of space charge ultrasonic waveforms; the second voltage application module 84 is connected to the first determination module 83, and is configured to apply only the excitation voltage to the target insulating medium; the second measurement module 85 is connected to the second voltage application module 84, and is configured to measure a plurality of partial discharge waveforms at a target position of the target insulating medium at a plurality of predetermined time points by using a high-frequency coil; the second determination module 86 is connected to the second measurement module 85, and is configured to determine a partial discharge characteristic waveform corresponding to the plurality of predetermined time points at the target position of the target insulating medium based on the plurality of partial discharge waveforms; the third determination module 87 is connected to the second determination module 86, and is configured to determine a target charge waveform at the target position of the target insulating medium based on the charge distribution waveform and the partial discharge characteristic waveform.

[0087] According to an embodiment of the present invention, there is also provided a computer-readable storage medium. The computer-readable storage medium includes a stored program, wherein when the program runs, it controls the device where the computer-readable storage medium is located to execute the waveform measurement method of any one of the above.

[0088] According to an embodiment of the present invention, there is also provided a computer device, including: a memory and a processor. The memory stores a computer program; the processor is configured to execute the computer program stored in the memory, and when the computer program runs, it causes the processor to execute the waveform measurement method of any one of the above.

[0089] 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.

[0090] In the above embodiments of the present invention, the descriptions of the respective embodiments have their own emphases. For parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0091] In the 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 merely illustrative. For example, the division of the units can be a logical function division. In actual implementation, there can 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 couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the units or modules can be in electrical or other forms.

[0092] 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.

[0093] In addition, the functional units in the various embodiments of the present invention 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-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0094] If the above-mentioned integrated units are implemented in the form of software functional units and sold or used as independent products, they 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 this 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 various embodiments of the present invention. The foregoing 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.

[0095] 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 waveform measurement method, characterized in that, Including: Applying a pulse voltage with a first predetermined period and an excitation voltage with a second predetermined period to the target insulating medium simultaneously; Using an ultrasonic probe to measure a plurality of space charge ultrasonic waveforms at a plurality of predetermined positions of the target insulating medium at a plurality of predetermined time points respectively; Based on the plurality of space charge ultrasonic waveforms, determining a charge distribution waveform at a target position of the target insulating medium, including: obtaining a reference signal when only the pulse voltage with the first predetermined period is applied to the target insulating medium; using the reference signal to filter out interference signals in the plurality of space charge ultrasonic waveforms to obtain a plurality of target space charge ultrasonic waveforms; determining the charge distribution waveform at the target position of the target insulating medium based on the plurality of target space charge ultrasonic waveforms; Applying only the excitation voltage to the target insulating medium; Using a high-frequency coil to measure a plurality of partial discharge waveforms at the target position of the target insulating medium according to the plurality of predetermined time points; Based on the plurality of partial discharge waveforms, determining a partial discharge characteristic waveform corresponding to the plurality of predetermined time points at the target position of the target insulating medium; Based on the charge distribution waveform and the partial discharge characteristic waveform, determining a target charge waveform at the target position of the target insulating medium, including: determining the target charge waveform in which the correspondence relationship between the charge distribution change and the discharge characteristic quantity at the target position of the target insulating medium changes with time according to the time parameters in the charge distribution waveform and the partial discharge characteristic waveform.

2. The method according to claim 1, characterized in that, The step of using an ultrasonic probe to measure a plurality of space charge ultrasonic waveforms at a plurality of predetermined positions of the target insulating medium at a plurality of predetermined time points respectively includes: Using the ultrasonic probe to measure a plurality of initial waveforms corresponding to each position at each of the plurality of predetermined positions at a plurality of predetermined time points respectively; Calculating an average waveform for the plurality of initial waveforms corresponding to each position respectively to obtain the plurality of space charge ultrasonic waveforms corresponding to the plurality of predetermined positions respectively.

3. The method according to claim 1, wherein The step of determining the charge distribution waveform at the target position of the target insulating medium based on the plurality of target space charge ultrasonic waveforms includes: According to the plurality of predetermined time points, based on the plurality of target space charge ultrasonic waveforms corresponding to the plurality of predetermined positions respectively, determining the charge distribution situation changing with time of the target insulating medium within a predetermined space range; Based on the charge distribution situation, determining the charge distribution waveform in which the charge distribution at the target position of the target insulating medium changes with time.

4. The method according to claim 1, characterized in that, The step of determining the partial discharge characteristic waveform corresponding to the plurality of predetermined time points at the target position of the target insulating medium based on the plurality of partial discharge waveforms includes: Based on the plurality of partial discharge waveforms, extracting a plurality of discharge characteristic quantities at the target position of the target insulating medium; According to the plurality of predetermined time points, based on the plurality of discharge characteristic quantities, determining the partial discharge characteristic waveform in which the discharge characteristics at the target position of the target insulating medium change with time.

5. The method according to any one of claims 1 to 4, characterized in that The method further includes: When the target insulating medium is the insulating medium of a cable, determining the insulation information at the target position of the cable in the case of an insulation defect based on the target charge waveform.

6. The method according to claim 5, wherein The insulation defect includes at least one of the following: There is a needle tip electrode in the target insulating medium, there is a floating electrode in the target insulating medium, and there is a bubble in the target insulating medium.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein when the program runs, it controls the device where the computer-readable storage medium is located to execute the waveform measurement method according to any one of claims 1 to 6.

8. A computer device, characterized in that, It includes: A memory and a processor, The memory stores a computer program; The processor is configured to execute the computer program stored in the memory, and when the computer program runs, the processor executes the waveform measurement method according to any one of claims 1 to 6.

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