An experimental platform for bubble discharge in oil containing an optical diagnostic system

Abstract

The application provides an oil bubble discharge experiment platform comprising an optical diagnosis system, realizes quantitative research on bubble discharge characteristics of transformer oil under different parameters, and can observe clear images in a bubble discharge process, and the experiment platform comprises: a power supply system for power supply, wherein the power supply system comprises a test transformer, a protection resistor and a fast protection module; an experiment cavity for containing transformer oil; an electrode system installed in the experiment cavity and used for constructing a uniform electric field oil gap or a non-uniform electric field oil gap; a bubble generating system used for adding bubbles to the oil gap; a partial discharge detection system used for collecting partial discharge signals and analysis; and an optical diagnosis system used for observing the bubble discharge process of the oil gap in the experiment cavity; wherein the partial discharge detection system is further connected with the fast protection module, and is used for outputting signals to the fast protection module when a discharge or breakdown event occurs, so that the power supply system is cut off by the fast protection module.

Description

Technical Field

[0001] This invention relates to the field of transformer testing equipment technology, specifically to an oil bubble discharge experimental platform including an optical diagnostic system. Background Technology

[0002] During the manufacturing, installation, and operation of transformers, air bubble defects are inevitably generated in the oil-paper insulation system. As one of the most typical defects in transformer oil-paper insulation systems, air bubbles discharge first under relatively low electric field strength, reducing the insulation performance of the oil-paper system. For a long time, the understanding of how air bubbles reduce the insulation performance of oil-paper systems has remained at a qualitative level; quantitative research is lacking on the influence of parameters such as external field strength, air bubble size, and composition on the discharge characteristics of air bubbles in oil.

[0003] To address this issue, it is necessary to establish an experimental platform for bubble discharge in oil to study the degree of threat posed by bubbles to the insulation performance of transformer oil and the influencing factors. Furthermore, an optical diagnostic system should be constructed to observe the discharge process of bubbles in oil, thereby gaining a deeper understanding of the physical mechanism of discharge initiation within bubbles, elucidating the mechanism of transformer oil insulation performance degradation caused by bubble discharge, and providing a reference for assessing the threat of bubbles to the paper insulation performance of transformer oil and designing transformer insulation structures. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes an experimental platform for bubble discharge in transformer oil that includes an optical diagnostic system. This platform enables quantitative research on the characteristics of bubble discharge in transformer oil under different parameters and allows for the observation of clear images during the bubble discharge process.

[0005] The technical solution is as follows: an oil bubble discharge experimental platform including an optical diagnostic system, characterized in that it includes: a power supply system for power supply, the power supply system including a test transformer, a protection resistor, and a fast protection module;

[0006] The experimental chamber is used to hold transformer oil, and at least part of its shell is made of a light-transmitting material for optical diagnostics.

[0007] An electrode system is installed inside the experimental chamber to construct a uniform electric field oil gap or a non-uniform electric field oil gap.

[0008] A bubble generating system is used to introduce air bubbles into the oil gap;

[0009] A partial discharge detection system, wherein the partial discharge detection system is connected in parallel with the electrode system, is used to collect and analyze partial discharge signals;

[0010] An optical diagnostic system is used to observe the process of bubble discharge at the oil gap in the experimental chamber;

[0011] The test transformer is connected to the electrode system and is used to output voltage to the electrode system; the protection resistor is connected in series on the high-voltage side of the test transformer and is used to limit the current during discharge and breakdown; the partial discharge detection system is also connected to the fast protection module and is used to output a signal to the fast protection module when a discharge or breakdown event occurs, thereby triggering the fast protection module to cut off the power supply to the power system.

[0012] Furthermore, the power supply system also includes an electric voltage regulator, which is connected to the low-voltage side of the test transformer. By controlling the output of the voltage regulator, the high-voltage side output voltage of the test transformer can be continuously adjusted.

[0013] Furthermore, the fast protection module includes an oscilloscope and a solid-state relay. The oscilloscope can receive the signal output by the partial discharge detection system when a discharge or breakdown event occurs, and trigger the solid-state relay to cut off the power supply to the power system.

[0014] Furthermore, the electrode system includes a high-voltage electrode and a ground electrode, wherein the high-voltage electrode is a plate electrode or a rod electrode, and the ground electrode is a plate electrode.

[0015] Furthermore, the partial discharge detection system includes a coupling capacitor, a detection impedance, and a partial discharge tester; the coupling capacitor and the detection impedance are connected in series, and both are also connected in parallel in the discharge circuit formed by the electrode system for detecting partial discharge signals; the output terminal of the detection impedance is connected to the partial discharge tester for analyzing and converting the partial discharge signals.

[0016] Furthermore, the partial discharge detection system also includes an industrial control computer, and the partial discharge tester is connected to the industrial control computer to plot the partial discharge signal spectrum.

[0017] Furthermore, the high-voltage end of the test transformer is connected to one end of the protective resistor, the low-voltage end of the test transformer is connected to one end of the electric voltage regulator, the other end of the protective resistor is connected to one end of the high-voltage electrode and one end of the coupling capacitor, the other end of the high-voltage electrode is opposite to one end of the ground electrode and the space between them is filled with transformer oil, the other end of the coupling capacitor is connected to one end of the detection impedance, the other end of the detection impedance, the other end of the electric voltage regulator, and the other end of the ground electrode are connected and grounded, the output end of the detection impedance is connected to the partial discharge tester and the oscilloscope, the oscilloscope is connected to the solid-state relay, and the solid-state relay is used to control the on / off state of the test transformer and the electric voltage regulator.

[0018] Furthermore, the bubble generating system includes a gas cylinder, a gas tube, a support, a needle holder, and a capillary tube. The gas cylinder has multiple types of gases, each containing a different type. The gas cylinder is also equipped with a pressure reducing valve for regulating the gas output rate. The outlet of the gas cylinder extends into the experimental chamber via the gas tube and connects to the needle holder. The support, the needle holder, and the capillary tube are placed in the experimental chamber. The needle holder is fixed to the support, and the capillary tube is detachably fixed to the needle holder, and its fixing angle can be adjusted. The capillary tube is used to introduce bubbles into the oil gap.

[0019] Furthermore, the optical diagnostic system includes a parallel light source and a high-speed camera. The light emitted by the parallel light source enters the area where the bubble is located in the experimental chamber and is collected by the high-speed camera. In the event of a discharge or breakdown event, the oscilloscope can also trigger the high-speed camera.

[0020] Furthermore, the optical diagnostic system also includes a lens group, which is equipped with a grating to eliminate interference from non-parallel light. The light emitted by the parallel light source is refracted by the lens group before entering the region where the bubble is located in the experimental chamber.

[0021] Main benefits: 1. The power supply system is designed with a fast protection module. When a discharge or breakdown event occurs, the fast protection module can quickly cut off the power frequency high voltage power supply to prevent the test equipment from being damaged by excessive current and to protect the safety of the test personnel.

[0022] 2. The electrode system can construct two types of electric fields, uniform and non-uniform, by changing the shape of the high-voltage electrode. The bubble generation system can generate bubbles with different compositions, sizes and flow rates by changing the gas in the gas cylinder, the inner diameter and tilt angle of the capillary tube, and the gas pressure of the gas cylinder pump, thereby realizing multi-parameter analysis of the factors affecting bubble discharge in transformer oil.

[0023] 3. By employing an optical diagnostic system, clear images of the bubble discharge process can be observed. By triggering the optical diagnostic system with an oscilloscope, clear images of the instantaneous discharge of bubbles in transformer oil can be obtained, which helps to provide a reference for studying the physical mechanism of bubble discharge initiation and the degradation mechanism of transformer oil insulation performance caused by bubbles. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the connection structure of the present invention;

[0025] Figure 2 The diagram shows the structure of two electrode systems. Detailed Implementation

[0026] like Figure 1The illustrated oil bubble discharge experimental platform, which includes an optical diagnostic system, comprises: a power supply system, including a test transformer 1 for outputting power frequency voltage; an electric voltage regulator 2, one side of which is connected to the low-voltage side of the test transformer 1 and the other side is grounded, for adjusting the high-voltage side output voltage so that it is continuously adjustable within the range of 0-100kVrms; a solid-state relay 3 in a fast protection module, which is connected between the test transformer 1 and the electric voltage regulator 2, and is triggered after the oscilloscope 7 detects a discharge signal, disconnecting the test transformer 1 from the electric voltage regulator 2, and can quickly cut off the power frequency high-voltage power supply within 3ms, effectively protecting equipment and personal safety; and a protection resistor 4, which is connected in series with the high-voltage side of the test transformer 1 to limit the current during discharge and breakdown.

[0027] Experimental chamber 17 is made of quartz glass with good light transmittance, and its dimensions can be 140×180×180mm. 3 Observation windows are provided on both sides, and through-plate sleeves are provided at the edges to hold the electrode system, which facilitates the wiring of the electrode system and the observation of discharge phenomena.

[0028] Combination Figure 2 The electrode system 12 shown is installed inside the experimental chamber 17 and is mainly made of 304 stainless steel. It has two forms: a high-voltage electrode and a ground electrode are fixed by an electrode bracket 12-1. The high-voltage electrode on the left is connected to the protective resistor 4 via a through-plate sleeve, and the ground electrode on the right is grounded via the through-plate sleeve. When both the high-voltage electrode and the ground electrode are plate electrodes, a uniform electric field oil gap can be constructed. When the high-voltage electrode and the ground electrode are a rod electrode and a plate electrode, respectively, a non-uniform electric field oil gap can be constructed. Figure 2 12-2 is a plate-shaped ground electrode, 12-3 is a plate-shaped high-voltage electrode, and 12-4 is a rod-shaped high-voltage electrode.

[0029] A bubble generation system, used to introduce bubbles into the oil gap, includes a gas cylinder 18, a gas pipe 16, a fixed support 15, a needle holder 14, and a capillary tube 13. The support 15 is placed at the bottom of the experimental chamber 17, the needle holder 14 is fixed to the fixed support 15, and the capillary tube 13 is fixed to the needle holder 14. One end of the gas pipe 16 is connected to the capillary tube 13, and the other end is connected to the gas cylinder 18 via a through-plate sleeve. The gas cylinder 18 is pumped, and the gas is converted into bubbles through the capillary tube 13 and enters the oil gap formed by the electrode system 12. The bubble generation system can generate bubbles of different compositions, sizes, and flow rates by changing the gas in the gas cylinder 18, the inner diameter and tilt angle of the capillary tube 13, and the pumping pressure of the gas cylinder 18, thereby enabling multi-parameter analysis of the factors affecting bubble discharge in transformer oil.

[0030] The partial discharge detection system includes a coupling capacitor 8, a detection impedance 9, a partial discharge tester 6, and an industrial control computer 5. The coupling capacitor 8 and the detection impedance 9 are connected in series, with one end of the coupling capacitor 8 connected to a protective resistor 4. The other end of the detection impedance 9 is grounded, and both are connected in parallel to the discharge circuit formed by the electrode system 12. The output of the detection impedance 9 is connected to the partial discharge tester 6 and an oscilloscope 7. The partial discharge tester 6 is connected to the industrial control computer 5. When a discharge event occurs, the detection impedance 9 outputs a signal to the partial discharge tester 6, which converts the signal and displays it on the industrial control computer 5. Simultaneously, the oscilloscope 7 detects the discharge signal and outputs a trigger signal to the solid-state relay 3, disconnecting the test transformer 1 from the electric voltage regulator 2.

[0031] The optical diagnostic system has two functions: observing discharge phenomena and observing the dynamic behavior of bubbles in oil. It includes a parallel light source 10, a lens group 11, and a high-speed camera 19. The parallel light source 10, lens group 11, and high-speed camera 19 are positioned on either side of the observation window of the experimental chamber 17, aligned with the location of the electrode system 12. The lens group 11 contains a grating to eliminate interference from non-parallel light in the channel's self-illumination. The high-speed camera 19 has adjustable exposure time and frame rate; the exposure time and frame rate can be set according to the timescale of the bubble's dynamic behavior to ensure high image clarity. During operation, the parallel light emitted from the parallel light source 10 is refracted by the lens group 11 and enters the bubble region within the experimental chamber 17. The light is deflected and captured by the high-speed camera 19 at the imaging plane on the other side of the experimental chamber 17. When a discharge event occurs, the oscilloscope 7 sends an action signal to the high-speed camera 19 via optical fiber, triggering the camera to capture the image of the instant of discharge.

[0032] During the experiment, a suitable high-voltage electrode is selected for the electrode system 12 and installed on the electrode holder 12-1. The entire system is then placed in the experimental chamber 17. Specifically, a rod electrode or plate electrode is installed on the metal screw of the electrode holder 12-1 via the tail threaded hole. The composition, size, and flow rate of the bubbles are set according to the research objective. Gas cylinders 18 with different types of gases are used to adjust the bubble composition. The inner diameter and tilt angle of the capillary tube 13 are changed to adjust the bubble size. The pumping pressure of the gas cylinder 18 is changed to adjust the bubble flow rate. After all equipment wiring is completed, the gas cylinder 18 is opened to allow the bubbles to flow in the oil gap. The industrial control computer 5, partial discharge tester 6, oscilloscope 7, parallel light source 10, and high-speed camera 19 are started. The test transformer 1 and electric voltage regulator 2 are started. The electric voltage regulator 2 is adjusted to gradually increase the high-voltage output voltage of the test transformer 1 until a discharge signal is detected. The discharge spectrum is recorded by the partial discharge tester 6 and the industrial control computer 5, and the images of the discharge process are recorded by the parallel light source 10 and the high-speed camera 19.

[0033] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An experimental platform for bubble discharge in oil including an optical diagnostic system, characterized in that, include: A power supply system for supplying power, the power supply system including a test transformer, a protective resistor, and a fast protection module; The experimental chamber is used to hold transformer oil, and at least part of its shell is made of a light-transmitting material for optical diagnostics. An electrode system is installed inside the experimental chamber to construct a uniform electric field oil gap or a non-uniform electric field oil gap. A bubble generating system is used to introduce air bubbles into the oil gap; A partial discharge detection system, wherein the partial discharge detection system is connected in parallel with the electrode system, is used to collect and analyze partial discharge signals; An optical diagnostic system is used to observe the process of bubble discharge at the oil gap in the experimental chamber; The test transformer is connected to the electrode system and is used to output voltage to the electrode system; the protection resistor is connected in series on the high-voltage side of the test transformer and is used to limit the current during discharge and breakdown; the partial discharge detection system is also connected to the fast protection module and is used to output a signal to the fast protection module when a discharge or breakdown event occurs, thereby triggering the fast protection module to cut off the power supply to the power system.

2. The oil bubble discharge experimental platform including an optical diagnostic system according to claim 1, characterized in that: The power system also includes an electric voltage regulator, which is connected to the low-voltage side of the test transformer. By controlling the output of the voltage regulator, the high-voltage side output voltage of the test transformer can be continuously adjusted.

3. The oil bubble discharge experimental platform including an optical diagnostic system according to claim 2, characterized in that: The fast protection module includes an oscilloscope and a solid-state relay. The oscilloscope can receive the signal output by the partial discharge detection system when a discharge or breakdown event occurs, and trigger the solid-state relay to cut off the power supply to the power system.

4. The oil bubble discharge experimental platform including an optical diagnostic system according to claim 3, characterized in that: The electrode system includes a high-voltage electrode and a ground electrode. The high-voltage electrode is a plate electrode or a rod electrode, and the ground electrode is a plate electrode.

5. The oil bubble discharge experimental platform including an optical diagnostic system according to claim 4, characterized in that: The partial discharge detection system includes a coupling capacitor, a detection impedance, and a partial discharge tester. The coupling capacitor and the detection impedance are connected in series, and they are also connected in parallel in the discharge circuit formed by the electrode system for detecting partial discharge signals. The output terminal of the detection impedance is connected to the partial discharge tester for analyzing and converting the partial discharge signals.

6. The oil bubble discharge experimental platform including an optical diagnostic system according to claim 5, characterized in that: The partial discharge detection system also includes an industrial control computer, and the partial discharge tester is connected to the industrial control computer to realize the plotting of the partial discharge signal spectrum.

7. An oil bubble discharge experimental platform including an optical diagnostic system according to claim 5 or 6, characterized in that: The high-voltage end of the test transformer is connected to one end of the protective resistor, and the low-voltage end of the test transformer is connected to one end of the electric voltage regulator. The other end of the protective resistor is connected to one end of the high-voltage electrode and one end of the coupling capacitor. The other end of the high-voltage electrode is opposite to one end of the ground electrode, and the space between them is filled with transformer oil. The other end of the coupling capacitor is connected to one end of the detection impedance. The other end of the detection impedance, the other end of the electric voltage regulator, and the other end of the ground electrode are connected together and grounded. The output end of the detection impedance is connected to the partial discharge tester and the oscilloscope. The oscilloscope is connected to the solid-state relay, which is used to control the on / off state of the test transformer and the electric voltage regulator.

8. The oil bubble discharge experimental platform including an optical diagnostic system according to claim 1, characterized in that: The bubble generating system includes a gas cylinder, a gas tube, a support, a needle holder, and a capillary tube. The gas cylinder has multiple types and contains different kinds of gases. The gas cylinder is also equipped with a pressure reducing valve for regulating the gas output rate. The outlet of the gas cylinder extends into the experimental chamber via the gas tube and is connected to the needle holder. The support, the needle holder, and the capillary tube are placed in the experimental chamber. The needle holder is fixed to the support. The capillary tube is detachably fixed to the needle holder, and its fixing angle can be adjusted. The capillary tube is used to add bubbles into the oil gap.

9. An oil bubble discharge experimental platform comprising an optical diagnostic system according to any one of claims 3-6, characterized in that: The optical diagnostic system includes a parallel light source and a high-speed camera. The light emitted by the parallel light source enters the area where the bubble is located in the experimental chamber and is collected by the high-speed camera. In the event of a discharge or breakdown event, the oscilloscope can also trigger the high-speed camera.

10. An oil bubble discharge experimental platform including an optical diagnostic system according to claim 9, characterized in that: The optical diagnostic system also includes a lens group, which has a grating to eliminate non-parallel light interference. The light emitted by the parallel light source is refracted by the lens group before entering the region where the bubble is located in the experimental chamber.

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