Partial discharge detection system, method and equipment for transformer and medium

Abstract

The invention discloses a partial discharge detection system, method and device for a transformer and a medium, and belongs to the technical field of partial discharge detection. The system comprises a partial discharge detection sensor, a signal acquisition device and a signal processing device, the partial discharge detection sensor is used for acquiring potential signals of two preset points on the surface of a target transformer, the signal acquisition device is used for acquiring the potential signals and preprocessing the potential signals, and the signal processing device is used for extracting waveforms of the preprocessed potential signals. And judging whether the waveform contains a discharge characteristic or not, if the waveform contains the discharge characteristic, determining whether the spectrum distribution of the waveform accords with a partial discharge characteristic or not, and if so, determining that the target transformer has partial discharge. According to the invention, whether partial discharge occurs in the transformer is judged by collecting the potential signal, the detection accuracy is high, and the interference of noise can be eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of partial discharge detection, and more particularly to a partial discharge detection system and method for a transformer. Background Art

[0002] As the core equipment for power transmission and transformation of power systems, the safety and reliability of transformers will directly affect the safe and stable operation of power systems, while the insulation status of transformers directly affects the operating conditions of transformers. Among the many faults of transformers, discharge faults caused by insulation defects account for the majority. Therefore, whether partial discharge can be effectively and accurately detected is of vital importance to the safe and stable operation of transformers.

[0003] At present, the main methods for live detection of partial discharge in transformers include high-frequency current method, ultra-high frequency method, ultrasonic detection method, etc. Among them, the installation point of the high-frequency current method sensor is limited, and it is very susceptible to busbar corona interference. In actual detection, it strongly relies on the experience of the tester. The ultra-high frequency method has excellent performance in sensitivity and anti-interference, but to give full play to the advantages of the method itself, it is necessary to ensure the optimal sensor size, and its sensor needs to be pre-built-in. In existing projects, only oil valve sensors can be used for live implementation. Due to the limited size of the sensor, the detection sensitivity is insufficient. Therefore, the ultra-high frequency method is difficult to effectively implement for the majority of equipment in operation. The detection range of the ultrasonic detection method is small, and the local discharge on the winding is complicated due to the structure and the influence of oil-paper composite insulation. The signal is difficult to transmit, resulting in too low sensitivity, and it is easily interfered by mechanical noise on site. It is generally used as a means of auxiliary positioning. Summary of the invention

[0004] In view of the above problems, the present invention proposes a partial discharge detection system for a transformer, comprising: a partial discharge detection sensor, a signal acquisition device and a signal processing device;

[0005] The partial discharge detection sensor is used to collect potential signals at two preset points on the surface of the target transformer, the signal acquisition device is used to collect the potential signal and preprocess the potential signal, and the signal processing device is used to extract the waveform of the preprocessed potential signal to determine whether the waveform contains a discharge feature. If the waveform contains a discharge feature, it is determined whether the frequency spectrum distribution of the waveform meets the partial discharge feature. If so, it is determined that the target transformer has partial discharge.

[0006] Optionally, a partial discharge detection sensor, including a housing, an insulating film, a metal electrode, a matching resistor and a BNC adapter;

[0007] Two magnetic devices are arranged on the left and right sides of the outer bottom surface of the shell, respectively; a hollow is arranged in the middle of the bottom surface of the shell, and an insulating film is embedded in the hollow part; two metal electrodes are arranged on both sides of the surface of the insulating film facing the inside of the shell, respectively; a matching resistor is arranged between the two metal electrodes; a hole is opened on the upper surface of the shell, and the NBC adapter is passed through the hole;

[0008] The matching resistor is used to connect the two metal electrodes, and the coaxial cable core and the outer metal sheath of the BNC adapter used to connect the coaxial cable and stripped of the insulation layer are respectively connected to the two ends of the matching resistor.

[0009] Optionally, the magnetic attraction device is used to adsorb the partial discharge detection sensor to the surface of the target transformer.

[0010] Optionally, the insulating film and the surface of the magnetic attraction device facing the outside of the shell are in the same plane.

[0011] Optionally, the dielectric constant of the insulating film is between 2 and 4.

[0012] Optionally, the metal electrode is a copper metal plate.

[0013] On the other hand, the present invention also provides a partial discharge detection method for a transformer, comprising:

[0014] Collecting potential signals at two points of the target transformer, preprocessing the potential signals, and extracting the waveform of the preprocessed potential signals;

[0015] determining whether the waveform contains discharge characteristics;

[0016] If the waveform contains a discharge feature, it is determined whether the frequency spectrum distribution of the waveform conforms to the partial discharge feature. If so, it is determined that the target transformer has partial discharge.

[0017] Optionally, the potential signal is preprocessed, including: taking a difference of the potential signal to obtain a transient voltage signal, and filtering and amplifying the transient voltage signal.

[0018] In yet another aspect, the present invention further provides a computing device, comprising: one or more processors;

[0019] a processor for executing one or more programs;

[0020] When the one or more programs are executed by the one or more processors, the above-described method is implemented.

[0021] In yet another aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, the method described above is implemented.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a partial discharge detection system for transformers, comprising: a partial discharge detection sensor, a signal acquisition device and a signal processing device; the partial discharge detection sensor is used to collect potential signals of two preset points on the surface of a target transformer, the signal acquisition device is used to collect the potential signal and pre-process the potential signal, and the signal processing device is used to extract the waveform of the pre-processed potential signal to determine whether the waveform contains a discharge feature, and if the waveform contains a discharge feature, determine whether the frequency spectrum distribution of the waveform conforms to the partial discharge feature, and if so, determine that the target transformer has partial discharge. The present invention determines whether partial discharge occurs in the transformer by collecting potential signals, and has high detection accuracy and can eliminate noise interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of the sensor device of the present invention;

[0025] Figure 2 This is a diagram of the metal electrode structure of the sensor device of the present invention;

[0026] Figure 3 It is a bottom structural diagram of the sensor device of the present invention;

[0027] Figure 4 is an application flow chart of the system of the present invention;

[0028] Figure 5 is an installation diagram of the system of the present invention;

[0029] Figure 6 A signal diagram collected by the system of the present invention;

[0030] Figure 7 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0031] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0032] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0033] Embodiment 1:

[0034] The present invention proposes a partial discharge detection system for a transformer, comprising: a partial discharge detection sensor, such as Figure 1 As shown, a signal acquisition device and a signal processing device;

[0035] The partial discharge detection sensor is used to collect potential signals at two preset points on the surface of the target transformer, the signal acquisition device is used to collect the potential signal and preprocess the potential signal, and the signal processing device is used to extract the waveform of the preprocessed potential signal to determine whether the waveform contains a discharge feature. If the waveform contains a discharge feature, it is determined whether the frequency spectrum distribution of the waveform meets the partial discharge feature. If so, it is determined that the target transformer has partial discharge.

[0036] Among them, the partial discharge detection sensor includes a housing, an insulating film, a metal electrode, a matching resistor and a BNC adapter;

[0037] like Figure 2 and Figure 3 As shown, two magnetic devices are respectively arranged on the left and right sides of the bottom surface of the shell, an insulating film is arranged in the middle part, metal electrodes are respectively arranged on both sides of the bottom surface inside the shell, a matching resistor is arranged in the middle part, and a hole is opened on the upper surface of the shell, and the NBC adapter is passed through the hole;

[0038] Two magnetic devices are arranged on the left and right sides of the outer bottom surface of the shell, respectively; a hollow is arranged in the middle of the bottom surface of the shell, and an insulating film is embedded in the hollow part; two metal electrodes are arranged on both sides of the surface of the insulating film facing the inside of the shell, respectively; a matching resistor is arranged between the two metal electrodes; a hole is opened on the upper surface of the shell, and the NBC adapter is passed through the hole;

[0039] The matching resistor is used to connect the two metal electrodes, and the coaxial cable core and the outer metal sheath of the BNC adapter used to connect the coaxial cable and stripped of the insulation layer are respectively connected to the two ends of the matching resistor.

[0040] The magnetic attraction device is used to adsorb the partial discharge detection sensor onto the surface of the target transformer.

[0041] The insulating film and the surface of the magnetic attraction device facing the outside of the shell are in the same plane.

[0042] Among them, the dielectric constant of the insulating film is between 2 and 4.

[0043] Wherein, the metal electrode is a copper metal plate.

[0044] Among them, it is judged whether the waveform contains discharge characteristics. If the waveform contains discharge characteristics, it is determined whether the spectrum distribution of the waveform meets the local discharge characteristics, mainly from the characteristics, amplitude and spectrum of the waveform, including:

[0045] First, the waveform should show obvious pulse characteristics, which means that the waveform contains discharge characteristics. Secondly, the amplitude should be much larger than the background noise, and the amplitude ratio to the background noise should be greater than or equal to 5. Finally, from the spectrum, the frequency peak is obvious and concentrated in tens of MHz. If all three conditions are met, it is considered to be a partial discharge.

[0046] Wherein, the principle of the present invention is as follows:

[0047] The electromagnetic waves excited by the partial discharge are incident on the interface between the air and the transformer tank wall, and a plane is defined between the air (x<0) region and the tank wall (x>0).

[0048] The induced current density of a unit area of ​​metal wall in the yoz plane is calculated as:

[0049] I z =σE 0 e -x / δ e -jx / δ

[0050] The total induced current is:

[0051]

[0052] When the induced current induces a charge Q on the surface of the switch cabinet, the voltage across the capacitor is U, and we have:

[0053]

[0054] Then the amplitude of the TEV signal coupled to the sensor can be calculated as:

[0055]

[0056] When the electromagnetic wave propagates downward, it manifests as creeping voltage and current waves propagating along the surface of the box wall. The potential signals of the two points are collected through differential electrodes, and the transient voltage signal is obtained by difference. The operation process is as follows: Figure 4 As shown;

[0057] The partial discharge detection sensor based on the principle of micro-area potential difference is composed of a shell part, an insulating film, a metal plate electrode, a signal acquisition part and the like.

[0058] The shell part is made of metal, with a hollow bottom surface, and wraps around the sensor. A hole is opened on the upper surface of the metal shell to allow the BNC adapter to pass through.

[0059] For the insulating film part, a material with relatively high strength is selected, and the relative dielectric constant of the material is between 2 and 4, thereby forming a coupling capacitor for collecting signals.

[0060] The metal plate electrode is mainly a copper metal plate, with two pieces in total, which are connected by a matching resistor. Connect the coaxial cable through a BNC adapter, strip off the insulation layer, and connect the coaxial cable core and the outer metal sheath to the two ends of the matching resistor respectively.

[0061] The left and right sides of the bottom surface of the sensor are designed with magnetic devices, which can adsorb the sensor to the surface of the metal box wall. In the middle is an embedded insulating film.

[0062] The signal acquisition part filters and amplifies the signal collected by the sensor through the amplifier, and then connects it to the data acquisition device for data display, waveform spectrum analysis, discharge PRPD spectrum diagnosis and time difference positioning.

[0063] The invention is a local discharge detection sensor based on micro-area potential difference. The sensor can be used for local discharge detection of transformers with seams. The seams include unwelded seams, manhole seams, flange holes and the like.

[0064] The present invention can detect the voltage wave and current wave formed by the partial discharge electromagnetic wave signal in the box propagating through the gap to the outer surface of the transformer box, and identify the signal after passing through the amplifier and the signal acquisition device.

[0065] The present invention is equipped with a magnetic attraction device, which can change the position at any time on the outer surface of the transformer box to perform partial discharge detection tests. It can not only perform online detection, but also detect the signal strength of different positions by placing multiple sensors to obtain the time difference of relative positions. It has great potential in the positioning of partial discharge of transformers.

[0066] The present invention has a metal shell on the outside, which can shield external electromagnetic interference to a certain extent, and has a significant improvement in signal-to-noise ratio compared to other external detection methods. In addition, in the on-site operation environment, it can also protect internal components to a certain extent.

[0067] The present invention has two metal electrodes inside. During detection, the potentials corresponding to the two electrodes are subtracted to form a differential mode. This design can greatly reduce electromagnetic interference, mechanical interference, etc. mixed in the signal, and further improve the signal-to-noise ratio of the detection.

[0068] In summary, the present invention helps to provide a new detection method and idea for transformer partial discharge detection, and has great potential in the field of transformer partial discharge positioning.

[0069] The verification results are as follows:

[0070] As Figure 5 As shown in the figure, the sensor is attached to the outer surface of the metal box. There is a cover plate on the top of the box, and there is a gap between the box and the bottom box. The other end is connected to the signal acquisition device. A monopole probe connected to a standard pulse source is inserted into the reserved hole on the top of the metal box to simulate partial discharge signals. The position of the sensor is constantly adjusted for detection. The collected signal is as follows: Figure 6 shown.

[0071] Embodiment 2:

[0072] The present invention also proposes a partial discharge detection method for a transformer, such as Figure 7 As shown, including:

[0073] Step 1, collecting potential signals at two points of the target transformer, preprocessing the potential signals, and extracting the waveform of the preprocessed potential signals;

[0074] Step 2, determining whether the waveform contains discharge characteristics;

[0075] Step 3: If the waveform contains a discharge feature, determine whether the frequency spectrum distribution of the waveform conforms to the partial discharge feature; if so, determine that the target transformer has partial discharge.

[0076] The preprocessing of the potential signal includes: taking a difference of the potential signal to obtain a transient voltage signal, and filtering and amplifying the transient voltage signal.

[0077] The present invention determines whether partial discharge occurs in the transformer by collecting potential signals, has high detection accuracy and can eliminate noise interference.

[0078] Embodiment 3:

[0079] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding functions, so as to implement the steps of the method in the above embodiment.

[0080] Embodiment 4:

[0081] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It is understandable that the computer-readable storage medium here can include both a built-in storage medium in a computer device and an extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiment.

[0082] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0083] 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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 flowchart and / or block diagram. 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.

[0084] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0085] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0086] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0087] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A partial discharge detection system for a transformer, characterized in that: include: Partial discharge detection sensor, signal acquisition device and signal processing device; The partial discharge detection sensor is used to collect potential signals at two preset points on the surface of the target transformer, the signal acquisition device is used to collect the potential signal and preprocess the potential signal, and the signal processing device is used to extract the waveform of the preprocessed potential signal to determine whether the waveform contains a discharge feature. If the waveform contains a discharge feature, it is determined whether the frequency spectrum distribution of the waveform meets the partial discharge feature. If so, it is determined that the target transformer has partial discharge.

2. The partial discharge detection system according to claim 1, characterized in that: The partial discharge detection sensor comprises a housing, an insulating film, a metal electrode, a matching resistor and a BNC adapter; Two magnetic devices are arranged on the left and right sides of the outer bottom surface of the shell, respectively; a hollow is arranged in the middle of the bottom surface of the shell, and an insulating film is embedded in the hollow part; two metal electrodes are arranged on both sides of the surface of the insulating film facing the inside of the shell, respectively; a matching resistor is arranged between the two metal electrodes; a hole is opened on the upper surface of the shell, and the NBC adapter is passed through the hole; The matching resistor is used to connect the two metal electrodes, and the coaxial cable core and the outer metal sheath of the BNC adapter used to connect the coaxial cable and stripped of the insulation layer are respectively connected to the two ends of the matching resistor.

3. The partial discharge detection system according to claim 2, characterized in that: The magnetic attraction device is used to adsorb the partial discharge detection sensor onto the surface of the target transformer.

4. The partial discharge detection system according to claim 2, characterized in that: The insulating film and the surface of the magnetic attraction device facing the outside of the shell are in the same plane.

5. The partial discharge detection system according to claim 2, characterized in that: The dielectric constant of the insulating film is between 2 and 4.

6. The partial discharge detection system according to claim 2, characterized in that: The metal electrode is a copper metal plate.

7. A partial discharge detection method for a transformer, characterized in that: include: Collecting potential signals at two points of the target transformer, preprocessing the potential signals, and extracting the waveform of the preprocessed potential signals; determining whether the waveform contains discharge characteristics; If the waveform contains a discharge feature, it is determined whether the frequency spectrum distribution of the waveform conforms to the partial discharge feature. If so, it is determined that the target transformer has partial discharge.

8. The partial discharge detection method according to claim 7, characterized in that: The preprocessing of the potential signal includes: taking a difference of the potential signal to obtain a transient voltage signal, and filtering and amplifying the transient voltage signal.

9. A computer device, characterized in that: include: one or more processors; a processor for executing one or more programs; When the one or more programs are executed by the one or more processors, the method according to claim 7 or 8 is implemented.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed, the method according to claim 7 or 8 is implemented.

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