Partial discharge signal detection method based on power frequency voltage transformer and related products

Abstract

The present invention discloses a partial discharge signal detection method based on a power frequency voltage transformer and related products, belonging to the field of insulation detection technology. The actual voltage signal on the grid side of the distribution network cable terminal is collected by means of a power frequency voltage transformer, and the original partial discharge signal is obtained through preprocessing. The discrete time Fourier transform is performed on the signal to obtain the z-domain signal of the original partial discharge signal; the frequency domain response of the power frequency voltage transformer is fitted to obtain the z-domain inverse transfer function; the z-domain signal of the original partial discharge signal is digitally compensated using the z-domain inverse transfer function to obtain the compensated z-domain signal, and then the signal is converted to the time domain through the inverse z-transformation to obtain the final original partial discharge signal. The voltage signal is collected by the original power frequency voltage transformer of the distribution network, and the frequency band limitation of the power frequency voltage transformer is overcome by digital compensation. The live detection and online real-time monitoring of the partial discharge signal of the distribution network cable can be realized without power outage and additional installation of transformers.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation detection, and in particular to a partial discharge signal detection method based on a power frequency voltage transformer and related products. Background Art

[0002] Partial discharge is an early manifestation of insulation degradation in power equipment and a major cause of further insulation degradation. Its condition can predict the insulation lifespan of power equipment and is a key indicator for assessing the condition of power equipment. For example, distribution network cables, as key components for long-distance energy transmission, have a direct impact on regional electricity consumption. Due to age, improper construction, and external damage, distribution network cables often fail or even explode. According to incomplete statistics, over 90% of distribution network cable failures are insulation failures, making the assessment of cable insulation condition crucial.

[0003] Currently, partial discharge (PD) signal detection is the most common and effective method for assessing cable insulation condition. However, due to the inherent randomness, variability, poor anti-interference capabilities, and complexity of PD, PD signal detection technology has yet to reach the desired level of development. Traditional PD signal detection often relies on offline detection methods. However, with increasing demands for power supply reliability and continuity in distribution networks, and the inability to perform power outages for maintenance, offline detection methods have significant limitations. High-frequency current transformers (HFCTs) offer high sensitivity and wide bandwidth, making them suitable for installation on the connection wires or cores of distribution network cables. While existing live detection methods using HFCTs exist, their installation locations are limited. In many cases, the connection wires are enclosed within the high-voltage compartment of a switchgear cabinet, making them inaccessible under live conditions. Distribution network cables must be shut down for installation, making their application and widespread adoption difficult.

[0004] Therefore, how to provide a live detection method for partial discharge signals of distribution network cables without shutting down the network has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a partial discharge signal detection method based on an industrial frequency voltage transformer and related products, so as to overcome the problem that high-frequency current transformers need to be shut down for installation and cannot meet the high-reliability power supply requirements of the distribution network.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] The present invention provides a method for detecting partial discharge signals based on a power frequency voltage transformer, comprising the following steps:

[0008] S1. Obtain the frequency domain response of the original power frequency voltage transformer of the distribution network through the frequency sweep method;

[0009] S2. Collecting the actual grid-side voltage signal of the distribution network cable terminal through a power frequency voltage transformer, preprocessing the actual grid-side voltage signal to obtain an original partial discharge signal, and performing a discrete-time Fourier transform on the original partial discharge signal to obtain a z-domain signal of the original partial discharge signal;

[0010] S3. Fit the frequency domain response to obtain a transfer function, and calculate the z-domain inverse transfer function based on the transfer function;

[0011] S4. Digitally compensate the z-domain signal of the original partial discharge signal using a z-domain inverse transfer function to obtain a z-domain signal of the compensated original partial discharge signal, and convert the z-domain signal of the compensated original partial discharge signal into the time domain using an inverse z-transform to obtain a final original partial discharge signal.

[0012] A further improvement of the present invention is that the step S1 specifically includes the following steps:

[0013] Injecting sinusoidal signals of different frequencies into the primary side of an existing power frequency voltage transformer in the distribution network, obtaining the amplitude of the secondary side output waveform of the power frequency voltage transformer, and calculating the frequency domain response of the power frequency voltage transformer based on the sinusoidal signals of different frequencies injected into the primary side and the amplitude of the secondary side output waveform;

[0014] Step S1 further includes the following steps:

[0015] Based on the frequency domain response of the power frequency voltage transformer, determine whether the sensitivity of the power frequency voltage transformer meets the preset requirements. If yes, execute step S2; if not, replace the power frequency voltage transformer with one whose sensitivity meets the preset requirements.

[0016] A further improvement of the present invention is that: the sinusoidal signals of different frequencies are specifically: 5 kHz~20 MHz; the preset requirement is specifically: the sensitivity of the power frequency voltage transformer in the range of 5 MHz~20 MHz is not less than -20 dB.

[0017] A further improvement of the present invention is that the transfer function is specifically:

[0018]

[0019] in, is the transfer function; is the number of real extreme points; and For the The coefficients associated with the real extreme points; is the sampling period; for The first delay operator in the transformation indicates that the sequence is delayed by one sampling period; is the number of complex pole pairs; and For the The numerator coefficient associated with each complex pole; 、 、 For the The denominator coefficients associated with the complex poles;

[0020] The z-domain inverse transfer function is specifically:

[0021]

[0022] in, is the inverse transfer function in the z domain; is the z-domain signal of the original partial discharge signal after compensation; is the z-domain signal of the original partial discharge signal; 、 、 and For the z domain and the The coefficients associated with the real extreme points; 、 and For the z domain and the The numerator coefficient associated with each complex pole; 、 and For the z domain and the The denominator coefficients associated with the complex poles; for The second delay operator in the transform indicates that the sequence is delayed by two sampling periods.

[0023] A further improvement of the present invention is that it further includes step S5: uploading the final original partial discharge signal to a cloud database;

[0024] In step S2, the actual voltage signal on the grid side is preprocessed by filtering and noise reduction in sequence.

[0025] A further improvement of the present invention is that: the inverse z-transform is used to convert the z-domain signal of the compensated original partial discharge signal into the time domain, and the final original partial discharge signal is obtained specifically as follows:

[0026] The z-domain signal of the compensated original partial discharge signal is converted into the time domain by using the inverse z-transform to obtain the compensated original partial discharge signal. The compensated original partial discharge signal is smoothed by using the empirical mode decomposition method to obtain the final original partial discharge signal.

[0027] A further improvement of the present invention is that the digital compensation is specifically:

[0028]

[0029] in, is the z-domain signal of the original partial discharge signal after compensation; is the z-domain signal of the original partial discharge signal; is the inverse transfer function in the z-domain.

[0030] The present invention further provides a partial discharge signal detection device based on a power frequency voltage transformer, which uses the above-mentioned partial discharge signal detection method based on a power frequency voltage transformer to obtain a partial discharge signal. The partial discharge signal detection device based on a power frequency voltage transformer includes:

[0031] A power frequency voltage transformer, a high-pass filter, an analog-to-digital conversion unit, a microprocessor, a storage unit, a network unit, and a display, wherein a power frequency voltage transformer is provided on the distribution network of the partial discharge signal to be measured, the output end of the power frequency voltage transformer is connected to the input end of the high-pass filter, the output end of the high-pass filter is connected to the microprocessor, and the analog-to-digital conversion unit, the storage unit, the network unit, and the display are electrically connected to the microprocessor respectively;

[0032] High-pass filter, used to extract the high-frequency analog signal of the actual voltage signal on the grid side;

[0033] an analog-to-digital conversion unit, for converting high-frequency analog signals into digital signals;

[0034] a storage unit, used for storing a final original partial discharge signal;

[0035] A network unit, used to upload the final raw partial discharge signal to a cloud database;

[0036] A display is used to display the final raw partial discharge signal in real time.

[0037] The present invention also provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the above-mentioned method for detecting partial discharge signals of a power frequency voltage transformer are implemented.

[0038] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the above-mentioned method for detecting partial discharge signals of a power frequency voltage transformer are implemented.

[0039] Compared with the prior art, the positive progress of the present invention is:

[0040] The present invention provides a partial discharge signal detection method based on a power frequency voltage transformer. The method uses a power frequency voltage transformer to collect the actual voltage signal on the grid side of a distribution network cable terminal, obtains an original partial discharge signal through preprocessing, and then performs a discrete-time Fourier transform on the original partial discharge signal to obtain a z-domain signal of the original partial discharge signal; fits the frequency domain response of the power frequency voltage transformer to obtain a z-domain inverse transfer function; digitally compensates the z-domain signal of the original partial discharge signal using the z-domain inverse transfer function to obtain a compensated z-domain signal, and then converts the compensated z-domain signal to the time domain through an inverse z-transform to obtain the final original partial discharge signal. The power frequency voltage transformer is a conventional protection device in the distribution network and is always in an energized operating state, without the need to shut down for installation. This method relies on the original power frequency voltage transformer of the distribution network to collect voltage signals, and overcomes the frequency band limitation of the power frequency voltage transformer through digital compensation. It can couple the voltage signal of the cable terminal in real time under the energized operating state, not only realizing the live detection of partial discharge signals of the distribution network cable, but also realizing online real-time monitoring without disassembling the power frequency voltage transformer. The use of this method can effectively solve the problem that traditional partial discharge detection requires power outage and high-frequency current transformers need to be shut down for installation, meeting the high-reliability power supply needs of the distribution network.

[0041] Furthermore, judging whether the sensitivity meets the preset requirements based on the frequency domain response can ensure that the selected power frequency voltage transformer can accurately capture the partial discharge signal in the target frequency band, avoiding signal omission or misjudgment due to performance mismatch of the power frequency voltage transformer, thereby improving the accuracy of detection.

[0042] Furthermore, during the actual operation of the power grid, voltage signals are easily affected by power frequency harmonics, transient interference from switching operations, and electromagnetic environment noise. Through filtering and noise reduction processing, frequency band noise unrelated to the partial discharge signal (such as clutter other than the power frequency fundamental wave) can be removed, avoiding the noise from drowning out the discharge signal and ensuring that only valid signal components are retained in the raw data of subsequent detection; the detection of partial discharge signals requires long-term monitoring of the insulation status, and the amount of raw signal data is huge. Uploading it to the cloud database can achieve real-time monitoring, while avoiding data loss caused by insufficient local storage capacity or hardware failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0044] Figure 1 This is a flow chart of a method for detecting partial discharge signals based on a power frequency voltage transformer according to the present invention;

[0045] Figure 2 This is a connection diagram of a partial discharge signal detection device based on a power frequency voltage transformer according to the present invention;

[0046] Figure 3 Schematic diagram of the amplitude-frequency response curve of the power frequency voltage transformer;

[0047] Figure 4 is the frequency domain spectrum of partial discharge signal;

[0048] Figure 5 This is the pulse injection response waveform of the power frequency voltage transformer. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0050] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0051] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0052] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0053] Furthermore, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be interpreted broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0055] See also Figure 1 , a partial discharge signal detection method based on a power frequency voltage transformer, comprising the following steps:

[0056] S1. Obtain the frequency domain response of the original power frequency voltage transformer of the distribution network through the frequency sweep method;

[0057] S2. Collecting the actual grid-side voltage signal of the distribution network cable terminal through a power frequency voltage transformer, preprocessing the actual grid-side voltage signal to obtain an original partial discharge signal, and performing a discrete-time Fourier transform on the original partial discharge signal to obtain a z-domain signal of the original partial discharge signal;

[0058] S3. Fit the frequency domain response to obtain a transfer function, and calculate the z-domain inverse transfer function based on the transfer function;

[0059] S4. Digitally compensate the z-domain signal of the original partial discharge signal using a z-domain inverse transfer function to obtain a z-domain signal of the compensated original partial discharge signal, and convert the z-domain signal of the compensated original partial discharge signal into the time domain using an inverse z-transform to obtain a final original partial discharge signal.

[0060] This method uses a power frequency voltage transformer to collect the actual voltage signal on the grid side of the distribution network cable terminal. After preprocessing, the original partial discharge signal is obtained. This signal is then subjected to a discrete-time Fourier transform to obtain the z-domain signal of the original partial discharge signal. The frequency domain response of the power frequency voltage transformer is fitted to obtain the z-domain inverse transfer function. The z-domain signal of the original partial discharge signal is digitally compensated using the z-domain inverse transfer function to obtain the compensated z-domain signal. This signal is then converted to the time domain through an inverse z-transform to obtain the final original partial discharge signal. The power frequency voltage transformer is a conventional protection device in the distribution network and is always in an energized operating state, without the need for shutdown and installation. This method uses the existing power frequency voltage transformer in the distribution network to collect voltage signals and overcomes the frequency band limitation of the power frequency voltage transformer through digital compensation. This method can couple the voltage signal of the cable terminal in real time without power outage. This method not only realizes the live detection of partial discharge signals in the distribution network cable, but also enables online real-time monitoring. This solves the problem that traditional partial discharge detection requires power outage and high-frequency current transformers require shutdown and installation, which cannot meet the high-reliability power supply requirements of the distribution network.

[0061] Specifically, step S1 includes the following steps:

[0062] Injecting sinusoidal signals of different frequencies into the primary side of an existing power frequency voltage transformer in the distribution network, obtaining the amplitude of the secondary side output waveform of the power frequency voltage transformer, and calculating the frequency domain response of the power frequency voltage transformer based on the sinusoidal signals of different frequencies injected into the primary side and the amplitude of the secondary side output waveform;

[0063] Step S1 further includes the following steps:

[0064] Based on the frequency domain response of the power frequency voltage transformer, determine whether the sensitivity of the power frequency voltage transformer meets the preset requirements. If yes, execute step S2; if not, replace the power frequency voltage transformer with one whose sensitivity meets the preset requirements.

[0065] Judging whether the sensitivity meets the preset requirements based on the frequency domain response can ensure that the selected power frequency voltage transformer can accurately capture the partial discharge signal in the target frequency band, avoiding signal omission or misjudgment due to performance mismatch of the power frequency voltage transformer, thereby improving detection accuracy.

[0066] Specifically, the sinusoidal signals of different frequencies are specifically: 5 kHz~20 MHz; the preset requirement is specifically: the sensitivity of the power frequency voltage transformer in 5 MHz~20 MHz is not less than -20 dB.

[0067] Specifically, the transfer function is:

[0068]

[0069] in, is the transfer function; is the number of real extreme points; and For the The coefficients associated with the real extreme points; is the sampling period; for The first delay operator in the transformation indicates that the sequence is delayed by one sampling period; is the number of complex pole pairs; and For the The numerator coefficient associated with each complex pole; 、 、 For the The denominator coefficients associated with the complex poles;

[0070] The z-domain inverse transfer function is specifically:

[0071]

[0072] in, is the inverse transfer function in the z domain; is the z-domain signal of the original partial discharge signal after compensation; is the z-domain signal of the original partial discharge signal; 、 、 and For the z domain and the The coefficients associated with the real extreme points; 、 and For the z domain and the The numerator coefficient associated with each complex pole; 、 and For the z domain and the The denominator coefficients associated with the complex poles; for The second delay operator in the transform indicates that the sequence is delayed by two sampling periods.

[0073] Specifically, the method further includes step S5: uploading the final original partial discharge signal to a cloud database;

[0074] In step S2, the actual voltage signal on the grid side is preprocessed by filtering and noise reduction in sequence.

[0075] During actual grid operation, voltage signals are susceptible to power frequency harmonics, transient interference from switching operations, and electromagnetic environmental noise. Filtering and noise reduction processing can remove frequency band noise unrelated to partial discharge signals (such as clutter other than the power frequency fundamental), preventing noise from overwhelming the discharge signal and ensuring that only valid signal components are retained in the raw data for subsequent testing. Detection of partial discharge signals requires long-term monitoring of insulation status, and the amount of raw signal data is huge. Uploading it to a cloud database enables real-time monitoring while avoiding data loss caused by insufficient local storage capacity or hardware failure.

[0076] Specifically, the inverse z-transform is used to convert the z-domain signal of the compensated original partial discharge signal into the time domain to obtain the final original partial discharge signal:

[0077] The inverse z-transform is used to convert the compensated original partial discharge signal from the z-domain to the time domain, obtaining the compensated original partial discharge signal. This compensated original partial discharge signal is then smoothed using the empirical mode decomposition method to obtain the final original partial discharge signal. This method is only a practical digital compensation algorithm process and can be used as a reference for field testing. By designing an algorithm tailored to the field conditions, the detection of partial discharge signals can be further optimized.

[0078] Specifically, the digital compensation is:

[0079]

[0080] in, is the z-domain signal of the original partial discharge signal after compensation; is the z-domain signal of the original partial discharge signal; is the inverse transfer function in the z-domain.

[0081] Based on the same inventive concept, the present invention further provides a partial discharge signal detection device based on a power frequency voltage transformer, which uses the above-mentioned partial discharge signal detection method based on a power frequency voltage transformer to obtain a partial discharge signal. The partial discharge signal detection device based on a power frequency voltage transformer includes:

[0082] A power frequency voltage transformer, a high-pass filter, an analog-to-digital conversion unit, a microprocessor, a storage unit, a network unit, and a display, wherein a power frequency voltage transformer is provided on the distribution network of the partial discharge signal to be measured, the output end of the power frequency voltage transformer is connected to the input end of the high-pass filter, the output end of the high-pass filter is connected to the microprocessor, and the analog-to-digital conversion unit, the storage unit, the network unit, and the display are electrically connected to the microprocessor respectively;

[0083] High-pass filter, used to extract the high-frequency analog signal of the actual voltage signal on the grid side;

[0084] an analog-to-digital conversion unit, for converting high-frequency analog signals into digital signals;

[0085] a storage unit, used for storing a final original partial discharge signal;

[0086] A network unit, used to upload the final raw partial discharge signal to a cloud database;

[0087] A display is used to display the final raw partial discharge signal in real time.

[0088] Example 1

[0089] See also Figure 2 A partial discharge signal detection device based on a power frequency voltage transformer includes a high-voltage detection unit and a data acquisition control unit, the high-voltage detection unit includes a power frequency voltage transformer and a high-pass filter; the data acquisition control unit includes an analog-to-digital conversion unit, a microprocessor, a storage unit, a network unit and a display; the power frequency voltage transformer, the high-pass filter, the analog-to-digital conversion unit, the microprocessor, the storage unit, the network unit and the display, wherein a power frequency voltage transformer is provided on the distribution network of the partial discharge signal to be measured, the output end of the power frequency voltage transformer is connected to the input end of the high-pass filter, the output end of the high-pass filter is connected to the microprocessor, and the analog-to-digital conversion unit, the storage unit, the network unit and the display are respectively electrically connected to the microprocessor.

[0090] The power frequency voltage transformer is an electromagnetic voltage transformer sold on the market. The high-frequency bandwidth of the power frequency voltage transformer is designed to be 10 kHz-20 MHz. Before use, its frequency domain response at high frequency needs to be measured and verified to ensure that its sensitivity reaches -10 dB at around 10 MHz. The input end of the power frequency voltage transformer is connected to the distribution network cable terminal, and the output end of the power frequency voltage transformer is connected to the input end of the high-pass filter. The high-pass filter adopts a Butterworth filter with a -3dB bandwidth of 5 kHz-30 MHz and a -40dB rejection bandwidth of 2 kHz-80 MHz. The output end of the high-pass filter is connected to the input end of the analog-to-digital converter. The analog-to-digital converter adopts a dual-channel AD9689 (Analog-to-Digital 9689, analog-to-digital converter), with a single-channel sampling rate of 2.6GS / s and a sampling bit number of 14 bits. The output end of the analog-to-digital converter is connected to the microprocessor. The microprocessor adopts FPGA (Field-Programmable Gate Array) + ARM (Advanced RISC Machine (Advanced Reduced Instruction Set Computer) architecture uses FPGA to store the signal data collected by the analog-to-digital converter into a storage unit, and then uses ARM to filter, reduce noise and perform digital compensation on the high-frequency signal data in the memory. The final original partial discharge signal is displayed on the monitor and uploaded to the cloud database through the network unit to achieve real-time monitoring.

[0091] Example 2

[0092] A method for detecting partial discharge signals based on a power frequency voltage transformer comprises the following steps:

[0093] Measure the frequency domain response of the power frequency voltage transformer and observe whether its sensitivity at 10 MHz reaches -10 dB. If it meets the requirement, it indicates that the power frequency voltage transformer is capable of measuring partial discharge signals. Connect it to the distribution network cable terminal and perform measurements.

[0094] The actual voltage signal on the grid side of the distribution network cable terminal is extracted using a power frequency voltage transformer;

[0095] The low-frequency part of the actual voltage signal on the grid side is filtered out using a high-pass filter and filtered and noise-reduced using a microprocessor to obtain the original partial discharge signal.

[0096] The measured frequency domain response of the power frequency voltage transformer is input into Vector Fitting Toolbox to fit the transfer function. ; Take its z-domain inverse transfer function ;

[0097] Using the z-domain inverse transfer function The original partial discharge signal is digitally compensated, that is, the z-domain inverse transfer function Z-domain signal of the original partial discharge signal The z-domain signal of the compensated original partial discharge signal is obtained by multiplication, and then converted to the time domain through an inverse z-transform to obtain the compensated partial discharge signal. The compensated partial discharge signal is smoothed using the empirical mode decomposition (EMD) method to obtain the final original partial discharge signal, which is then uploaded to the cloud database.

[0098] The method of the present invention does not require the additional installation of special partial discharge sensors, saving the cost of purchasing and installing sensors, and will not interfere with their original protection and measurement functions, nor will it have a negative impact on the normal operation of the cable network. It is easy to use, simple and efficient. The power frequency voltage transformer used has high sensitivity at high frequencies and has a high gain in the frequency range of 1 MHz and above, and can effectively detect rapidly changing partial discharge signals. Digital compensation is a method of waveform reconstruction using the transfer function of the power frequency voltage transformer. It only needs to measure the transfer function of the power frequency voltage transformer to obtain partial discharge signals under different working environments, ensuring the accuracy and versatility of the measurement.

[0099] See also Figure 3 In practical application, the amplitude-frequency response curve does not need to shut down the distribution network, and only requires offline measurement of the power frequency voltage transformer of the same specification; Figure 3 The amplitude-frequency response curve shown is obtained using the swept-frequency method. This involves using a function generator to inject sinusoidal signals of varying frequencies, ranging from low (5 kHz) to high (20 MHz), into the primary side of the power-frequency voltage transformer, recording the output waveform amplitude on the secondary side, and calculating the actual transformation ratio. When used as a partial discharge sensor, the gain in the high-frequency region, near 10 MHz, should be as close to -10 dB as possible to ensure its sensitivity meets measurement requirements. Figure 4 The frequency domain spectrum of the partial discharge signal shown is a verification of the detection effect of the partial discharge signal of the power frequency voltage transformer. Figure 4 It can be seen that the amplitude of the partial discharge signal is highest in the range of 10 MHz to 20 MHz, which is exactly the same as the frequency range of Figure 3 The high sensitivity frequency range of the power frequency voltage transformer overlaps, indicating that the power frequency voltage transformer has the ability to measure partial discharge signals. By injecting a sinusoidal signal on the primary side of the power frequency voltage transformer using a partial discharge calibrator and observing the output signal on the secondary side, the waveform comparison chart is the basis for judging whether the power frequency voltage transformer has the ability to measure partial discharge. Figure 5, the injected signal discharge amount is 100 pC, and it can be seen that the output signal is relatively clear, proving that the power frequency voltage transformer can be used as a partial discharge sensor.

[0100] Based on the same inventive concept, an embodiment of the present application provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of a method for detecting partial discharge signals of a power frequency voltage transformer. The memory may include internal memory, such as a high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device. The processor, network interface, and memory are interconnected via an internal bus, which may be an industrial standard architecture bus, a peripheral component interconnect standard bus, an extended industrial standard architecture bus, etc. The bus may be classified as an address bus, a data bus, a control bus, etc. The memory is used to store programs. Specifically, the programs may include program code, which includes computer operating instructions. The memory may include both internal memory and non-volatile memory, and provides instructions and data to the processor.

[0101] Based on the same inventive concept, embodiments of the present application provide a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the steps of the method for detecting partial discharge signals in a power frequency voltage transformer. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include RAM (Random Access Memory) and / or cache memory. The non-volatile memory may include ROM (Read Only Memory), a hard disk, flash memory, an optical disk, a magnetic disk, and the like.

[0102] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROMs (Compact Disc Read-Only Memory), optical storage, etc.) containing computer-usable program code.

[0103] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0104] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0105] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0106] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of the present invention. Their purpose is to clearly illustrate the concept, principles, and application of the present invention through specific examples, and is in no way intended to limit the scope of protection of the present invention to these specific embodiments. In fact, the true value of this invention lies in its technical ideas and innovations, not in its form of expression or implementation.

[0107] For ordinary technicians in the relevant technical field, after thoroughly reading and understanding the technical solutions of the present invention, they are fully capable of making various forms of changes, modifications or equivalent replacements to the specific implementation methods of the invention based on their own professional knowledge and skills. These changes may include but are not limited to: adjusting the value range of technical parameters, optimizing algorithm processes to improve efficiency, replacing some technical components to achieve better compatibility or reduce costs, etc. As long as these modified technical solutions still substantially maintain the technical features claimed for protection by the original invention, that is, they can still achieve the core functions and effects of the present invention, then these changes should be deemed to fall within the scope of protection of the pending claims of the present invention.

[0108] Furthermore, with the continuous advancement and development of technology, new technical means and methods continue to emerge, providing ample room for further improvement and perfection of the present invention. Therefore, the scope of protection of the present invention should also include reasonably foreseeable improvements and extensions based on existing technologies. As long as these improvements and extensions do not deviate from the basic principles and core concepts of the present invention, they should be considered equivalent to the present invention and equally protected by patent rights.

Claims

1. A method for detecting partial discharge signals based on a power frequency voltage transformer, characterized in that: The following steps are involved: S1. Obtain the frequency domain response of the original power frequency voltage transformer of the distribution network through the frequency sweep method; S2. Collecting the actual grid-side voltage signal of the distribution network cable terminal through a power frequency voltage transformer, preprocessing the actual grid-side voltage signal to obtain an original partial discharge signal, and performing a discrete-time Fourier transform on the original partial discharge signal to obtain a z-domain signal of the original partial discharge signal; S3. Fit the frequency domain response to obtain a transfer function, and calculate the z-domain inverse transfer function based on the transfer function; S4, digitally compensating the z-domain signal of the original partial discharge signal using a z-domain inverse transfer function to obtain a z-domain signal of the compensated original partial discharge signal, and converting the z-domain signal of the compensated original partial discharge signal into the time domain using an inverse z-transform to obtain a final original partial discharge signal; said step S1 specifically comprises the following steps: Injecting sinusoidal signals of different frequencies into the primary side of an existing power frequency voltage transformer in the distribution network, obtaining the amplitude of the secondary side output waveform of the power frequency voltage transformer, and calculating the frequency domain response of the power frequency voltage transformer based on the sinusoidal signals of different frequencies injected into the primary side and the amplitude of the secondary side output waveform; Step S1 further includes the following steps: Based on the frequency domain response of the power frequency voltage transformer, determine whether the sensitivity of the power frequency voltage transformer meets the preset requirements. If so, execute step S2; if not, replace the power frequency voltage transformer with one whose sensitivity meets the preset requirements. The digital compensation is specifically: in, is the z-domain signal of the original partial discharge signal after compensation; is the z-domain signal of the original partial discharge signal; is the inverse transfer function in the z-domain.

2. The method for detecting partial discharge signals based on a power frequency voltage transformer according to claim 1, wherein: The sinusoidal signals of different frequencies are specifically: 5 kHz~20 MHz; the preset requirement is specifically: the sensitivity of the power frequency voltage transformer in the range of 5 MHz~20 MHz is not less than -20 dB.

3. The method for detecting partial discharge signals based on a power frequency voltage transformer according to claim 1, characterized in that: The transfer function is specifically: in, is the transfer function; is the number of real extreme points; and For the The coefficients associated with the real extreme points; is the sampling period; for The first delay operator in the transformation indicates that the sequence is delayed by one sampling period; is the number of complex pole pairs; and For the The numerator coefficient associated with each complex pole; 、 、 For the The denominator coefficients associated with the complex poles; The z-domain inverse transfer function is specifically: in, is the inverse transfer function in the z domain; is the z-domain signal of the original partial discharge signal after compensation; is the z-domain signal of the original partial discharge signal; 、 、 and For the z domain and the The coefficients associated with the real extreme points; 、 and For the z domain and the The numerator coefficient associated with each complex pole; 、 and For the z domain and the The denominator coefficients associated with the complex poles; for The second delay operator in the transform indicates that the sequence is delayed by two sampling periods.

4. The method for detecting partial discharge signals based on a power frequency voltage transformer according to claim 1, characterized in that: The method further includes step S5: uploading the final original partial discharge signal to a cloud database; In step S2, the actual voltage signal on the grid side is preprocessed by filtering and noise reduction in sequence.

5. The method for detecting partial discharge signals based on a power frequency voltage transformer according to claim 1, characterized in that: The inverse z-transform is used to convert the z-domain signal of the compensated original partial discharge signal into the time domain to obtain the final original partial discharge signal: The z-domain signal of the compensated original partial discharge signal is converted into the time domain by using the inverse z-transform to obtain the compensated original partial discharge signal. The compensated original partial discharge signal is smoothed by using the empirical mode decomposition method to obtain the final original partial discharge signal.

6. A partial discharge signal detection device based on a power frequency voltage transformer, characterized in that: A partial discharge signal is obtained by using the partial discharge signal detection method based on a power frequency voltage transformer as described in any one of claims 1 to 5. The partial discharge signal detection device based on a power frequency voltage transformer comprises: A power frequency voltage transformer, a high-pass filter, an analog-to-digital conversion unit, a microprocessor, a storage unit, a network unit, and a display, wherein a power frequency voltage transformer is provided on the distribution network of the partial discharge signal to be measured, the output end of the power frequency voltage transformer is connected to the input end of the high-pass filter, the output end of the high-pass filter is connected to the microprocessor, and the analog-to-digital conversion unit, the storage unit, the network unit, and the display are electrically connected to the microprocessor respectively; High-pass filter, used to extract the high-frequency analog signal of the actual voltage signal on the grid side; an analog-to-digital conversion unit, for converting high-frequency analog signals into digital signals; a storage unit, used for storing a final original partial discharge signal; A network unit, used to upload the final raw partial discharge signal to a cloud database; A display is used to display the final raw partial discharge signal in real time.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for detecting partial discharge signals based on a power frequency voltage transformer according to any one of claims 1 to 5 are implemented.

8. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for detecting partial discharge signals based on a power frequency voltage transformer as claimed in any one of claims 1 to 5 are implemented.

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