Optical fiber isolated fault current demodulation device

Abstract

The application discloses a kind of optical fiber isolates fault current demodulation device, including first printed board, auxiliary printed board, laser device, collimating device, beam splitter, photosensitive tube and shell.First printed board is connected with photosensitive tube, and beam splitter is placed between photosensitive tube and collimating device with inclination;First printed board and laser device are connected by cable, and laser device is installed on auxiliary printed board;First printed board is connected with the shell of metal material by metal connecting piece.The first printed board is provided with high-voltage capacitor, and the shell is connected with internal signal ground connection through high-voltage capacitor;Optical fiber connector is connected with collimating device, and the light path is reflected after passing through beam splitter and enters the optical fiber in collimating device, and the light path carrying current information is transmitted into photosensitive tube through beam splitter;Photosensitive tube is connected with integrator, and integrator is connected with filter amplifier.The shell of metal material is used in the application, has good shielding performance, the shell is connected with internal signal ground connection through high-voltage capacitor, and the electromagnetic compatibility requirement is satisfied.

Description

Technical Field

[0001] This invention relates to current demodulation devices, and more particularly to a fiber optic isolated fault current demodulation device. Background Technology

[0002] With the development of power systems, traditional current transformers can no longer meet the high insulation requirements in ultra-high voltage (UHV) and intelligent GIS (Gas Insulated Substation) applications. To address this issue, two solutions are currently available: electronic current transformers and fiber optic current transformers. Electronic current transformers generally employ laser power supply and current transformers (CTs). The active power supply method of current transformers (current transformers) suffers from problems such as complex power supply systems and unstable photoelectric switching. CN103543312A proposed using magneto-optical glass as a sensing element to extract power from the sensing element instead of laser power supply, simplifying the power supply system. However, this method suffers from problems such as large size and unstable power extraction. Fiber optic current transformers are a type of passive current transformer with advantages such as simple insulation structure and large measurement dynamic range. However, in actual operation, all-fiber optic current transformers are susceptible to various factors such as temperature, vibration, interference, and optical path loss. In particular, photoelectric components such as light sources, optical fibers, and photoelectric monitoring components are affected. Furthermore, electromagnetic interference from the field environment on the weak current system of all-fiber optic current transformers may lead to a decrease in measurement accuracy or even failure. To address these issues, CN112162229A proposed a status monitoring device for fiber optic current sensors, which can extract and re-extract various optical parameters and signals from fiber optic current sensors, providing a reference for health status diagnosis. However, it does not fundamentally solve the problems of stability and electromagnetic compatibility. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide an optical fiber isolated fault current demodulation device that meets electromagnetic compatibility requirements.

[0004] Technical Solution: The fiber optic isolation fault current demodulation device of the present invention includes a first printed circuit board, an auxiliary printed circuit board, a laser device, a collimating device, a beam splitter, a phototube, an integrator, a filter amplifier, and a housing. The first printed circuit board is connected to the phototube, which has a photosensitive surface located on the axis of the collimating device. A beam splitter is placed obliquely between the phototube and the collimating device. The first printed circuit board and the laser tube are connected by a cable, and the laser tube is mounted on the auxiliary printed circuit board. The first printed circuit board is connected to the metal housing via a metal connector.

[0005] The integrator and the filter amplifier are respectively mounted on the first printed circuit board, and the filter amplifier is connected to an external processor.

[0006] The first printed circuit board, laser device, collimating device, beam splitter, phototube, integrator and filter amplifier are all housed inside the housing;

[0007] The first printed circuit board is also equipped with a high-voltage capacitor, and the outer casing is connected to the internal signal ground through the high-voltage capacitor;

[0008] The fiber optic connector is directly connected to the collimation device. The light path is reflected by the beam splitter and enters the fiber in the collimation device. The light carrying the current information is transmitted through the beam splitter and enters the phototube. The electrical signal output by the phototube is integrated by the integrator and demodulated to obtain the current signal, which is then filtered and amplified by the filter amplifier.

[0009] Furthermore, the outer shell is equipped with a buckle and a pull ring, which are connected and the pull ring can drive the buckle to move; it is equipped with gold fingers, buckles, and pull rings, which can realize plug-and-play, solving the inconvenience of existing products such as manual screw fixing and interface welding, and can flexibly configure the number of channels according to project needs.

[0010] Furthermore, a gold finger is provided at the end of the first printed circuit board away from the collimation device, and the gold finger is composed of gold-plated conductive contact pieces.

[0011] Furthermore, the laser tube is a patch laser tube.

[0012] Furthermore, the inner diameter of the collimation device matches the outer diameter of the inserted fiber optic connector.

[0013] Furthermore, the phototube is a photodiode.

[0014] Furthermore, the collimation device is also equipped with a collimating lens, which is either a self-focusing collimating lens or a spherical collimating lens.

[0015] Furthermore, the outer casing is also provided with a nut post, and the first printed circuit board is fixed to the nut post with bolts; one end of the nut post is connected to the outer casing.

[0016] Furthermore, the first printed circuit board also includes a memory.

[0017] Compared with the prior art, the significant advantages of this invention are as follows:

[0018] 1. The outer shell of this invention is made of metal and has good shielding performance;

[0019] 2. The first printed circuit board of the present invention is also provided with a high-voltage capacitor. The outer casing is connected to the internal signal ground through the high-voltage capacitor, which realizes the rapid and effective discharge of interference signals, thereby meeting the electromagnetic compatibility requirements and solving the problem of poor electromagnetic compatibility performance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 for Figure 1 Top view;

[0022] Figure 3 This is the current waveform signal demodulated and output in Embodiment 1 of the present invention;

[0023] Explanation of reference numerals in the attached figures:

[0024] 1-First printed circuit board; 2-Auxiliary printed circuit board; 3-Laser device; 4-Collider latch; 5-Collider device; 6-Latch; 7-Pull ring; 8-Beam splitter; 9-Photosensitive surface; 10-Phototube; 11-Spring; 12-Outer shell; 13-Nut post; 14-Gold finger. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0027] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0029] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness or purpose of this application, should still fall within the scope of the technical content disclosed in this application. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and are not intended to limit the scope of this application. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this application.

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] In this invention, a laser tube is selected as the laser device, and a collimator is selected as the collimation device. For example... Figure 1 and Figure 2 As shown, the fiber optic isolation fault current demodulation device of the present invention includes a first printed circuit board 1, an auxiliary printed circuit board 2, a laser device 3, a collimating device 5, a beam splitter 8, a photodiode 10, and a metal housing 12. The laser device 3 is mounted on the auxiliary printed circuit board 2. The photodiode 10 is connected to the first printed circuit board 1. The beam splitter 8 is placed obliquely between the photodiode 10 and the collimating device 5. The first printed circuit board 1 is electrically connected to the laser device 3. The light emitted by the laser device 3 is reflected by the beam splitter 8 and enters the collimating device 5. The photodiode 10 is a photodiode, and the photodiode has a photosensitive surface 9. The photosensitive surface 9 is located on the axis of the collimating device 5. The collimating device 5 is mounted on the collimator latch 4.

[0033] The first printed circuit board 1, the laser device 3, the collimating device 5, the beam splitter 8, and the photosensitive tube 10 are all housed inside the housing 12; in this embodiment, the housing 12 is made of stainless steel, which has good shielding performance.

[0034] The first printed circuit board 1 is also soldered with a high-voltage capacitor. The outer casing 12 is connected to the internal signal ground through the high-voltage capacitor, which realizes the rapid and effective discharge of interference signals through the outer casing, thereby meeting the electromagnetic compatibility requirements and solving the problem of poor electromagnetic compatibility performance.

[0035] The first printed circuit board 1 is also equipped with an integrator 15 and a filter amplifier 17, which is connected to an external processor.

[0036] The laser device 3 is a surface-mount laser tube, which is mounted on the auxiliary printed circuit board 2.

[0037] The patch laser tube emits ultraviolet light. The beam splitter 8 has the characteristic of reflecting ultraviolet light but transmitting visible light. Therefore, the light emitted by the patch laser tube will only enter the access optical fiber through the collimating device 5 and will not enter the photodiode, thus solving the problem of interference between the light emitted by the laser device 3 and the photodiode.

[0038] The collimation device 5 is made of plastic. Its inner diameter can be designed to match the type of fiber optic connector required for precise insertion and alignment. In this embodiment, the collimation device 5 is designed for FC interface compatibility, allowing connection to FC-interface fibers. During operation, the fiber optic connector is directly connected to the collimation device 5.

[0039] The illumination direction of the patch laser tube and the surface of the beam splitter 8 should both be at a certain angle, preferably 45 degrees; the angle between the surface of the beam splitter 8 and the axis of the collimating device 5 is preferably 45 degrees.

[0040] The beam splitter 8 is made by coating a high-purity quartz sheet to reflect incident light in the ultraviolet band and transmit incident light in the visible band.

[0041] The photodiode 10 is selected as a photodiode to realize the conversion of light signals into electrical signals. Its light absorption layer can be InGaAs (indium gallium arsenide) material or silicon APD material. Preferably, the photodiode 10 should have low dark current characteristics.

[0042] Integrator 15 is an integrating circuit composed of a high-gain, high-bandwidth operational amplifier. Since the current demodulation device of this invention uses a high-frequency current sensor with an optical interface, and the high-frequency current sensor employs a Rogowski coil structure, according to Faraday's principle, the output signal of the Rogowski coil is the differential of the original current. Therefore, integrator 15 is needed to restore the original current signal.

[0043] The filter amplifier 17 is used to filter out interference signals. It includes an operational amplifier and a resistor-capacitor device and has first-order low-pass filtering characteristics. Preferably, its cutoff frequency is between 500Hz and 1KHz, which can ensure the accuracy of the 10th higher harmonics while effectively reducing the generation of signal aliasing.

[0044] During operation, the ultraviolet light emitted by the patch laser tube first illuminates the beam splitter 8. The beam splitter 8 has the characteristic of total internal reflection of ultraviolet light but transmission of visible light. Therefore, the light emitted by the patch laser tube undergoes total internal reflection by the beam splitter 8 before entering the collimating device 5, and then enters the optical fiber inserted into the collimating device 5. At the end of the optical fiber, the ultraviolet light is converted into visible light and returns. The returning light carries current information and passes through the optical fiber and the collimating device 5 before entering the beam splitter 8. Since the beam splitter 8 transmits all visible light, the returning light directly enters the phototube 10. The phototube 10 converts the optical signal into an electrical signal. The output electrical signal of the phototube 10 is integrated by the integrator 15 and demodulated to obtain the current signal. The current signal is then filtered and amplified by the filter amplifier 17 before being sent to the external processor.

[0045] In an optional embodiment, one end of the first printed circuit board 1 is provided with gold fingers 14, which are composed of gold-plated conductive contacts for hot-swapping. The use of gold fingers 14 enables hot-swapping, allowing users to more easily and flexibly configure the number of channels according to project needs.

[0046] In an optional embodiment, a memory 16 is also soldered onto the first printed circuit board 1, and the memory 16 is connected to the gold fingers 14. During the precision calibration stage of the production process, the gold fingers 14 store precision calibration data such as zero drift and gain error into the memory 16; when in use, compensation can be achieved by reading the precision calibration data, thus solving the discreteness problem of mass production.

[0047] In an optional embodiment, the outer casing 12 is provided with a buckle 6 and a pull ring 7. The buckle 6 and the pull ring 7 are connected. Pulling the pull ring 7 causes the buckle 6 to move, allowing the entire device to be pulled out. The buckle 6 and the pull ring 7 of the present invention are an interconnected structure. In use, after inserting the device of the present invention, pressing the pull ring 7 causes the buckle 6 to spring up, thus locking the entire device in place. When it is necessary to pull it out, pulling up the pull ring 7 causes the buckle 6 to retract, thereby allowing the entire device to be pulled out. This achieves plug-and-play functionality and solves the inconvenience of existing products that require manual screw fixing and interface welding.

[0048] In optional embodiments, the fiber optic isolated fault current demodulation device provided by the present invention can be made smaller in size. For example, the length of the device can be designed to be 64.1 mm; the width can be designed to be 13.5 mm; and the height can be designed to be 11.5 mm. This smaller size design makes the fiber optic isolated fault current demodulation device provided in this application compact, solving the problem of limited external interfaces.

[0049] In an optional embodiment, a spring 11 is also provided on the outer side of the housing 12. In use, the spring 11 can further enhance the good contact with the ground plane and improve the shielding effect; at the same time, it solves the problem that existing products cannot meet the electromagnetic compatibility level 4 requirements in electrostatic and rapid transient operating environments.

[0050] In an optional embodiment, the housing 12 is further provided with a nut post 13, and the first printed circuit board 1 is fixed to the nut post 13 with bolts, so that the interference signal of the internal signal can be quickly and effectively discharged to the housing, thereby solving the problem that the existing products cannot meet the electromagnetic compatibility level 4 requirements.

[0051] like Figure 3 The demodulated output current waveform signal and input AC waveform signal are shown in this example. The input signal is a 50Hz AC waveform. The positive half-cycle of the input waveform completely coincides with the positive half-cycle of the output waveform, indicating that the time delay is very small, the response bandwidth is high, and the accuracy is high. The negative half-cycle of the input waveform is modulated to a positive level output, which solves the problem that most integrated ADC MCUs do not support negative level input.

[0052] Example 2

[0053] The difference between this embodiment and Embodiment 1 is that the collimating device further includes a collimating lens, which can be a self-focusing collimating lens (G-lens) or a spherical collimating lens (C-lens). Compared to Embodiment 1, this embodiment increases the intensity of light entering the optical fiber, thereby further improving the product's accuracy performance.

[0054] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

[0055] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

[0056] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A fiber optic isolated fault current demodulation device, characterized in that: The device includes a first printed circuit board (1), an auxiliary printed circuit board (2), a laser device (3), a collimating device (5), a beam splitter (8), a phototube (10), and a housing (12). The first printed circuit board (1) is connected to the phototube (10), and the beam splitter (8) is placed at an angle between the phototube (10) and the collimating device (5). The first printed circuit board (1) and the laser device (3) are connected by a cable, and the laser device (3) is mounted on the auxiliary printed circuit board (2). The first printed circuit board (1) is connected to the metal housing (12) by a metal connector. The first printed circuit board (1), laser device (3), collimating device (5), beam splitter (8) and phototube (10) are all housed inside the outer casing (12); The first printed circuit board (1) is also provided with a high voltage capacitor, and the outer casing (12) is connected to the internal signal ground through the high voltage capacitor; The fiber optic connector is connected to the collimation device (5). The optical path is reflected by the beam splitter (8) and enters the optical fiber in the collimation device (5). The returning optical path carrying current information is transmitted through the beam splitter (8) and enters the phototube (10). The phototube (10) is connected to the integrator (15), and the integrator (15) is connected to the filter amplifier (17).

2. The fiber optic isolated fault current demodulation device according to claim 1, characterized in that, The phototube (10) is provided with a photosensitive surface (9), which is located on the axis of the collimation device (5).

3. The fiber optic isolated fault current demodulation device according to claim 1, characterized in that, The outer casing (12) is provided with a buckle (6) and a pull ring (7), the buckle (6) and the pull ring (7) are connected, and the pull ring (7) drives the buckle (6) to move.

4. The fiber optic isolated fault current demodulation device according to claim 1, characterized in that, The first printed circuit board (1) is provided with a gold finger (14) at the end away from the collimation device (5), and the gold finger (14) is composed of gold-plated conductive contact pieces.

5. The fiber optic isolated fault current demodulation device according to claim 1, characterized in that, The laser device (3) is a patch laser tube.

6. The fiber optic isolated fault current demodulation device according to claim 1, characterized in that, The phototube (10) is a photodiode.

7. The fiber optic isolated fault current demodulation device according to any one of claims 1-6, characterized in that, The collimation device (5) is also equipped with a collimating lens, which is either a self-focusing collimating lens or a spherical collimating lens.

8. The fiber optic isolated fault current demodulation device according to any one of claims 1-6, characterized in that, The first printed circuit board (1) is fixed to the nut post (13) by bolts, and one end of the nut post (13) is connected to the outer shell (12).

9. The fiber optic isolated fault current demodulation device according to any one of claims 1-6, characterized in that, The first printed circuit board (1) is also provided with an integrator (15) and a filter amplifier (17), which is connected to an external processor.

10. The fiber optic isolated fault current demodulation device according to any one of claims 1-6, characterized in that, The first printed circuit board (1) is also provided with a memory (16).

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