Segmentation characteristic analysis method for dynamic pressure generated by arc discharge in transformer oil

Abstract

The invention discloses a segmentation characteristic analysis method for dynamic pressure generated by arc discharge in transformer oil, and the method comprises the steps: carrying out an arc discharge experiment in a sealed oil-filled tank body of the transformer oil, observing the motion of bubbles generated by discharge, and measuring the voltage, current and pressure waveform of the arc discharge; analyzing the diameter change of the discharge bubble based on the bubble motion, and generating the frequency band characteristics of the pressure waveform based on the pressure waveform; carrying out arc discharge experiments with different energies, different boundary conditions and different current waveforms, and comparing the pressure waveforms to obtain influence factors of the pressure waveforms; according to the diameter change of discharge bubbles of arc discharge and the frequency band characteristics of arc discharge voltage, current and pressure waveforms, the segmentation characteristics of discharge pressure are formed.

Description

Technical Field

[0001] The invention relates to the technical field of transformer oil arc discharge, in particular to a method for analyzing segmented characteristics of dynamic pressure generated by arc discharge in transformer oil. Background Art

[0002] Arc discharge in transformer oil generates gas, which will increase the pressure in the oil tank, further leading to oil tank rupture or even explosion and fire. Due to the unclear understanding of the dynamic pressure waveform of arc discharge, the explosion-proof and pressure relief protection measures of the oil tank have not been effectively designed.

[0003] The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0004] In view of the shortcomings or defects of the above-mentioned prior art, a method for segmented characteristic analysis of dynamic pressure generated by arc discharge in transformer oil is provided, which can realize the recognition of the waveform characteristics of discharge dynamic pressure and reveal the generation mechanism of discharge dynamic pressure based on the physical processes in different discharge stages.

[0005] The purpose of the present invention is achieved through the following technical solutions.

[0006] A method for analyzing segmented characteristics of dynamic pressure generated by arc discharge in transformer oil includes: Carry out arc discharge experiments in the sealed oil-filled tank of transformer oil, observe the movement of bubbles generated by discharge and measure the arc discharge voltage, current and pressure waveforms; Analyze the change of discharge bubble diameter based on bubble motion and generate frequency band characteristics of pressure waveform based on pressure waveform; Conduct arc discharge experiments with different energies, different boundary conditions and different current waveforms, compare the pressure waveforms, and obtain the influencing factors of the pressure waveforms; According to the change of the discharge bubble diameter of the arc discharge, the frequency band characteristics of the arc discharge voltage, current and pressure waveform, the segmented characteristics of the discharge pressure are formed.

[0007] In the method described, the frequency band characteristics of the pressure waveform generated based on the pressure waveform include analyzing the part where the arc discharge voltage undergoes a sudden change, corresponding to the arc discharge arc starting and extinction process and the bubble collapse process; performing a fast Fourier transform on the discharge dynamic pressure waveform to obtain the frequency spectrum characteristics of the discharge dynamic pressure.

[0008] In the method, the arc discharge energy is changed by changing the peak value of the arc discharge current, the current duration, and the electrode distance to carry out arc discharge experiments with different energies.

[0009] In the method described, the boundary conditions of arc discharge are changed by changing the oil filling amount in the oil tank, the material of the oil tank, and the structural size of the oil tank to carry out arc discharge experiments with different boundary conditions.

[0010] In the method described, the arc discharge experiment with different current waveforms is carried out by changing the capacitance and inductance of the discharge circuit to change the discharge current waveform.

[0011] In the method, the voltage and current of the arc discharge are measured to obtain the arc resistance, power and energy.

[0012] In the method, a shadow imaging system and a high-speed camera are used to collect images of discharge bubbles, and the images of the discharge bubbles are analyzed to obtain changes in the diameters of the discharge bubbles.

[0013] In the method described, the shadow imaging system includes a light source that generates an optical fiber and a stop and a lens arranged along the optical path.

[0014] In the method described, the arc discharge experiment includes RLC The circuit includes a high-voltage DC power supply, capacitors and inductors, and a high-voltage differential probe and oscilloscope.

[0015] In the method, the arc discharge experiment includes a gas collection and volume counting system for measuring the discharge bubbles.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention obtains the segmented characteristics of arc discharge dynamic pressure based on the arc discharge shadow image, electrical parameters, bubble behavior, and pressure waveform, and reveals the dynamic pressure generation mechanism at different stages. In addition, the present invention provides a mechanism and engineering basis for correctly understanding the arc discharge pressure waveform in the transformer tank, which is helpful for the simulation of the dynamic pressure waveform in the transformer tank.

[0017] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to achieve the extent that those skilled in the art can implement it according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0019] In the attached picture: Figure 1 It is a flow chart of a segmented characteristic analysis method of dynamic pressure generated by arc discharge in transformer oil; Figure 2 It is a schematic diagram of the arc discharge bubble observation, electrical parameters, gas production, and pressure waveform measurement platform; Figure 3 It is a schematic diagram of the electrical parameters, pressure waveform, and pressure segmentation characteristics of arc discharge; FIG4(a) is a curve showing the diameter and pressure variation of arc discharge bubbles, and FIG4(b) is an image taken by the arc discharge shadow method; Figure 5 It is the dynamic pressure segmentation characteristic under different arc energies.

[0020] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0022] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0023] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0024] For a better understanding, Figures 1 to 5 As shown, a segmented characteristic analysis method of dynamic pressure generated by arc discharge in transformer oil includes: Carry out arc discharge experiments in the sealed oil-filled tank of transformer oil, observe the movement of bubbles generated by discharge and measure the arc discharge voltage, current and pressure waveforms; Analyze the change of discharge bubble diameter based on bubble motion and generate frequency band characteristics of pressure waveform based on pressure waveform; Arc discharge experiments with different energies, different boundary conditions and different current waveforms were carried out, the pressure waveforms were compared, and the influencing factors of the pressure waveforms were obtained.

[0025] In the present invention, by changing the arc discharge energy, it is found that the pressure waveforms under different discharge energies have obvious segmented characteristics; by changing the oil tank boundary and using an oil tank made of flexible material, it is found that the amplitudes of the quasi-static pressure and the steady-state pressure are greatly reduced.

[0026] According to the change of the discharge bubble diameter of the arc discharge, the frequency band characteristics of the arc discharge voltage, current and pressure waveform, the segmented characteristics of the discharge pressure are formed.

[0027] Furthermore, the pressure waveform characteristics are divided into four stages: shock wave, pulsating pressure, quasi-static pressure, and steady-state pressure.

[0028] In a preferred embodiment of the method, the frequency band characteristics of the pressure waveform generated based on the pressure waveform include analyzing the part where the arc discharge voltage undergoes a sudden change, corresponding to the arc discharge arc starting and extinction process and the bubble collapse process; performing a fast Fourier transform on the discharge dynamic pressure waveform to obtain the frequency spectrum characteristics of the discharge dynamic pressure.

[0029] In a preferred embodiment of the method, arc discharge energy is changed by changing the peak value of arc discharge current, current duration, and electrode distance to carry out arc discharge experiments with different energies.

[0030] In a preferred embodiment of the method, arc discharge experiments with different boundary conditions are carried out by changing the oil filling amount in the oil tank, the material of the oil tank, and the structural size of the oil tank to change the boundary conditions of the arc discharge.

[0031] In a preferred embodiment of the method, arc discharge experiments with different current waveforms are carried out by changing the capacitance and inductance of the discharge circuit to change the discharge current waveform.

[0032] In a preferred embodiment of the method, the voltage and current of the arc discharge are measured to obtain the arc resistance, power and energy.

[0033] In a preferred embodiment of the method, a shadow imaging system and a high-speed camera are used to collect images of the discharge bubbles, and the images of the discharge bubbles are analyzed to obtain changes in the diameters of the discharge bubbles.

[0034] In a preferred embodiment of the method, the shadow imaging system includes a light source that generates an optical fiber and a stop and a lens arranged along the optical path.

[0035] In a preferred embodiment of the method, the arc discharge experiment includes RLC The circuit includes a high-voltage DC power supply, capacitors and inductors, and a high-voltage differential probe and oscilloscope.

[0036] In a preferred embodiment of the method, the arc discharge experiment includes a gas collection and volume counting system for measuring the discharge bubbles.

[0037] In one embodiment, the method includes, Carry out arc discharge experiments in a closed oil-filled box, observe the movement of bubbles generated by discharge, and measure the arc discharge voltage, current, and pressure waveforms. Analyze the variation law of discharge bubble diameter, electrical parameters, and frequency band characteristics of pressure waveform. Conduct discharge experiments with different energies, different boundary conditions, and different current waveforms, and compare the pressure waveform patterns. According to the motion law of arc discharge bubbles, electrical parameters and pressure characteristics, the segmented characteristics of discharge pressure are proposed.

[0038] In this implementation case, based on RLC The circuit builds an arc discharge experimental platform in oil, including the electrical parameter measurement of voltage and current, gas production volume statistics, high-speed observation of discharge bubbles using the shadow method, and discharge transient pressure measurement.

[0039] In one embodiment, the schematic diagram of the experimental platform is as follows: Figure 2 ; In this embodiment, the arc resistance, power and energy can be further calculated from the voltage and current measurement results of the arc discharge. The obtained discharge pressure waveform is as follows: Figure 3 shown.

[0040] Combination Figure 3 , which further confirms that, in the present invention: by changing the arc discharge energy, it is found that the pressure waveforms under different discharge energies all have obvious segmented characteristics; by changing the oil tank boundary and using an oil tank made of flexible material, it is found that the amplitudes of the quasi-static pressure and the steady-state pressure are greatly reduced.

[0041] In another embodiment, the image of the discharge bubble is analyzed in combination with an image processing algorithm to obtain the change in the discharge bubble diameter. In combination with the discharge pressure waveform, a corresponding graph of the discharge bubble diameter change and the discharge pressure is drawn, as shown in FIG4(a). The image is taken using the arc discharge shadow method, as shown in FIG4(b).

[0042] Combining the above figures, it can be found that When the arc is about to go out, the internal plasma temperature decreases, the electron density decreases, and the arc resistance and voltage increase in macroscopic terms. The arc bubbles are about to collapse due to insufficient energy in high-speed images. The mechanism is explained as follows: the arc discharge first generates shock waves due to the breakdown and expansion process of the arc channel; the diameter of the discharge bubble changes periodically, and the essential reason is the pressure imbalance between the bubble and the liquid. The bubble undergoes a periodic expansion and contraction process, generating pulsating pressure; as the arc deposition energy increases, the arc gas production increases, the pressure inside the gas is almost balanced with the liquid pressure, the bubble diameter remains almost unchanged, and a quasi-static pressure is generated; as the discharge ends, the arc energy is no longer injected, the discharge bubble collapses, the discharge gas temperature decreases, the discharge pressure decreases, and finally reaches a steady-state pressure.

[0043] In addition, in the present invention, experiments were carried out at different discharge energies, and dynamic pressure waveforms at different arc deposition energies were obtained, all of which met the above characteristics, such as Figure 5 shown.

[0044] In another more specific embodiment, The experimental equipment includes the following: The arc discharge device comprises the aforementioned RLC A circuit including a high voltage DC power supply, capacitors and inductors, and a high voltage differential probe and an oscilloscope; A pressure sensor, which is used to monitor the pressure fluctuation in the fuel tank in real time; High-speed camera and shadow imaging system: used to record the movement trajectory of discharge bubbles; A data acquisition system for recording the pressure sensor signal and the video data of the high-speed camera; The transformer oil tank includes a sealed oil-filled tank body, which is used to simulate actual working conditions.

[0045] The experimental variables include the following: Arc discharge energy: adjusted by changing the current peak value (such as 10kA, 20kA, 30kA) and current duration (such as 1ms, 2ms, 3ms); Boundary conditions: In addition to changing the fuel tank to a flexible material, the fuel tank can also be adjusted by changing the fuel volume in the tank (such as 10L, 20L, 30L), the material of the tank (such as stainless steel, aluminum), and the size of the tank structure (such as diameter 10cm, 20cm); Current waveform: It can be changed by adjusting the capacitance (such as 1μF, 2μF, 3μF) and inductance (such as 1mH, 2mH, 3mH) in the discharge circuit; In this more specific embodiment, the following steps are included: Preparation stage: build the experimental platform and ensure the normal operation of all equipment; Parameter setting: according to the experimental design, set different arc discharge parameters and boundary conditions; Data acquisition: Start the arc discharge experiment and record the data from the pressure sensor and the video taken by the high-speed camera at the same time; Data analysis: Process the collected pressure waveform data and bubble motion images to extract the required features; The pressure waveform data processing includes the following steps: Preprocessing: Filter the original pressure waveform data to remove noise interference; Feature extraction: extract the peak value, duration and frequency characteristics of the pressure waveform; Spectrum analysis: Perform fast Fourier transform (FFT) on the pressure waveform to obtain a spectrum diagram; Mutation point detection: Identify the part of the pressure waveform where the voltage suddenly changes, and compare it with the observation during the experiment to establish the relationship between the sudden change part and the arc starting, arc extinction and bubble collapse process; The bubble motion image processing includes the following steps: Image preprocessing: denoising and smoothing the bubble motion images taken by high-speed cameras; Bubble edge detection: Use image processing algorithms (such as Canny edge detection) to extract the edges of bubbles; Bubble diameter calculation: Based on edge information, calculate the change of bubble diameter over time.

[0046] In another embodiment, a set of exemplary experimental data is provided: Arc discharge parameters: current peak value is 20kA, duration is 2ms; Boundary conditions: The oil tank is filled with 20L of oil, made of stainless steel, and has a diameter of 20cm; Current waveform: The discharge circuit capacitance is 2μF and the inductance is 2mH; Among them, the pressure waveform spectrum analysis is as follows: Raw data: collected pressure waveform data; Preprocessing results: The pressure waveform data after filtering is smoother; Spectrum: The spectrum of the pressure waveform obtained by FFT shows the main frequency components; Mutation point: Identify that the voltage mutation occurs at 1ms, corresponding to the arc starting process; at 2.5ms, corresponding to the arc extinction process.

[0047] Finally, the segmented characteristics of the dynamic pressure waveform are as follows: Arc starting stage: The pressure waveform rises significantly at 1ms, indicating that the arc begins to discharge; Stable discharge stage: from 1ms to 2.5ms, the pressure waveform is maintained at a high level, indicating that the arc is in a stable discharge state; Arc extinction stage: At 2.5ms, the pressure waveform drops rapidly, indicating that the arc is extinguished.

[0048] In summary, the present disclosure discloses a method for analyzing the segmented characteristics of dynamic pressure generated by arc discharge in transformer oil, and discloses the mechanism of arc discharge pressure generation, which confirms the engineering rationality of the dynamic pressure segmentation of discharge proposed by the present invention. The present invention can be further used in the research of transformer explosion-proof pressure relief, and is helpful for dynamic pressure simulation calculation. In addition, the analysis of the dynamic pressure waveform characteristics generated by arc discharge in liquid media, the analysis of shock waves, bubble pulsation pressure, and quasi-static pressure are also of certain significance for improving the cross-frontier of this field and fluid mechanics and guiding engineering practice applications.

[0049] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for analyzing the segmented characteristics of dynamic pressure generated by arc discharge in transformer oil, characterized in that: It includes the following steps, Carry out arc discharge experiments in the sealed oil-filled tank of transformer oil, observe the movement of bubbles generated by discharge and measure the arc discharge voltage, current and pressure waveforms; Analyze the change of discharge bubble diameter based on bubble motion and generate frequency band characteristics of pressure waveform based on pressure waveform; Conduct arc discharge experiments with different energies, different boundary conditions and different current waveforms, compare the pressure waveforms, and obtain the influencing factors of the pressure waveforms; According to the change of the discharge bubble diameter of the arc discharge, the frequency band characteristics of the arc discharge voltage, current and pressure waveform, the segmented characteristics of the discharge pressure are formed.

2. The method according to claim 1, characterized in that The frequency band characteristics of the pressure waveform generated based on the pressure waveform include analyzing the part where the arc discharge voltage suddenly changes, corresponding to the arc discharge arc starting and extinction process and the bubble collapse process; performing fast Fourier transform on the discharge dynamic pressure waveform to obtain the frequency spectrum characteristics of the discharge dynamic pressure.

3. The method according to claim 1, characterized in that The arc discharge energy is changed by changing the arc discharge current peak value, current duration, and electrode distance to carry out arc discharge experiments with different energies.

4. The method according to claim 1, characterized in that: Arc discharge experiments with different boundary conditions are carried out by changing the oil filling amount in the oil tank, the material of the oil tank, and the structural size of the oil tank to change the boundary conditions of the arc discharge.

5. The method according to claim 1, characterized in that By changing the capacitance and inductance of the discharge circuit to change the discharge current waveform, arc discharge experiments with different current waveforms are carried out to obtain the influencing factors of the pressure waveform.

6. The method according to claim 1, characterized in that Measure the voltage and current of arc discharge to obtain arc resistance, power and energy.

7. The method according to claim 1, characterized in that The images of discharge bubbles are collected by a shadow imaging system and a high-speed camera, and the images of discharge bubbles are analyzed to obtain the changes in the diameters of the discharge bubbles.

8. The method according to claim 7, characterized in that The shadow imaging system includes a light source that generates an optical fiber and an aperture and a lens arranged along the optical path.

9. The method according to claim 1, characterized in that: Arc discharge experiments include RLC The circuit includes a high-voltage DC power supply, capacitors and inductors, and a high-voltage differential probe and oscilloscope.

10. The method according to claim 1, characterized in that Arc discharge experiments include a gas collection and volume counting system to measure the discharge bubbles.

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