Electric field measuring system and measuring method for interior of extra-high voltage GIS (Gas Insulated Switchgear)

Abstract

The invention provides an electric field measurement system and method for the interior of an ultra-high voltage GIS, and belongs to the technical field of electric field measurement. Comprising a laser, an electro-optical sensing probe, a photoelectric detector and a test assembly, the laser is connected with the output end of the electro-optical sensing probe through a polarization maintaining optical fiber penetrating through a GIS shell cover plate; the electro-optical sensing probe is fixed on the inner wall of the GIS shell through an epoxy resin adhesive, and the axial direction of the electro-optical sensing probe is parallel to the direction of an internal electric field of the GIS; the output end of the electro-optical sensing probe is connected with the photoelectric detector through a single-mode optical fiber penetrating through a cover plate of the GIS shell; the test assembly is used for performing response calibration on the electro-optical sensing probe; the electro-optical sensing probe adopts a serial double-wave-plate design and is used for performing non-contact electric field measurement in the GIS after response calibration is completed. According to the invention, accurate non-contact electric field measurement can be realized in a GIS with a compact space.

Description

Technical Field

[0001] This invention belongs to the field of electric field measurement technology, and particularly relates to an electric field measurement system and method for use inside ultra-high voltage GIS. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Ultra-high voltage GIS (Gas Insulated Gate Equipment) is a key piece of equipment in power systems, crucial for their safe and stable operation. The complex electric field distribution within GIS directly impacts its insulation performance and operational reliability. Therefore, accurate measurement of the internal electric field parameters of GIS is essential for assessing the equipment's insulation condition, enabling condition monitoring, and facilitating fault early warning.

[0004] However, existing electric field measurement techniques have significant limitations in ultra-high voltage GIS environments, for example: (1) Existing electric field measurement methods mostly use capacitive sensors. These sensors are large in size, while the internal space of GIS is usually very compact, making them difficult to install and even unable to adapt to the internal structure of the equipment. Moreover, these sensors have poor insulation performance. Once installed inside GIS, they may interfere with the internal electric field distribution of the equipment, thereby affecting the accuracy of the measurement results, and may even damage the original insulation structure of GIS, causing safety hazards.

[0005] (2) Existing measurement technologies have limitations in terms of response speed, measurement bandwidth and applicable electric field types (such as AC, DC, impulse electric field, etc.), making it difficult to cover the electric field measurement needs of ultra-high voltage GIS under complex working conditions.

[0006] (3) Most existing sensor designs use electro-optical sensing probes with quarter-wave plates. In real-world scenarios, the phase shift generated by the quarter-wave plate is prone to deviating from the ideal value due to manufacturing process errors, environmental factors, or optical path assembly errors, resulting in inaccurate polarization state conversion. In addition, the phase shift generated by the electro-optic crystal under the action of an electric field may also have additional deviations due to differences in the uniformity of the crystal itself or external interference. These phase shift deviations will directly accumulate in the subsequent optical signal conversion process, causing distortion in the mapping relationship between light intensity change and electric field intensity, ultimately affecting the accuracy and stability of electric field measurement. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention provides an electric field measurement system and method for use inside ultra-high voltage GIS, which can achieve accurate non-contact electric field measurement inside the compact space of GIS.

[0008] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of the present invention provides an electric field measurement system for use inside ultra-high voltage GIS.

[0009] An electric field measurement system for use inside ultra-high voltage GIS includes: a laser, an electro-optic sensing probe, a photodetector, and a test assembly; The laser is connected to the output end of the electro-optic sensing probe based on the Pockels effect through a polarization-maintaining optical fiber that passes through the first through hole in the GIS housing cover plate. The electro-optic sensing probe is fixed to the inner wall of the GIS housing with modified adhesive, and its axis is parallel to the direction of the electric field inside the GIS. The output end of the electro-optic sensing probe is connected to the photodetector through a single-mode optical fiber that passes through the second through hole of the GIS housing cover plate. The test component is used to calibrate the response of the electro-optic sensing probe; the electro-optic sensing probe adopts a serial dual-waveplate design, which is used to perform non-contact electric field measurement inside the GIS after the response calibration is completed.

[0010] Furthermore, the electro-optic sensing probe includes a first fiber collimator, a polarizer, a quarter-wave plate, an electro-optic crystal, a half-wave plate, an analyzer, and a second fiber collimator, which are aligned in sequence; wherein, the input end of the first fiber collimator is connected to the polarization-maintaining fiber, and the output end of the second fiber collimator is connected to the single-mode fiber.

[0011] Furthermore, the electro-optic sensing probe employs a serial dual-waveplate design. Specifically, the output of the quarter-waveplate within the electro-optic sensing probe is connected to the input of the electro-optic crystal, used to generate a polarization between the two polarization components of the linearly polarized light passing through the polarizer. The phase shift is achieved by connecting the output of the electro-optic crystal to the input of a half-wave plate, which is used to compensate for the phase shift deviation.

[0012] Furthermore, the modified adhesive uses an epoxy resin adhesive.

[0013] Furthermore, the epoxy resin adhesive has a buffer layer on the side that contacts the inner wall of the GIS to buffer the vibration of the electro-optic sensing module.

[0014] Furthermore, the first and second through holes are filled with epoxy resin and covered with a silicone layer to form a double-sealed structure.

[0015] Furthermore, the test components include a power supply, an electrode unit, and a measurement unit; wherein, the power supply includes a high-voltage AC generator, a DC source, and an impulse source, which are used to test the response characteristics of the electro-optic sensing probe under AC, DC, and impulse electric fields, respectively.

[0016] Furthermore, the testing components also include a fast pulse voltage generator for testing the time-domain response characteristics of the electro-optic sensing probe under a pulsed electric field.

[0017] A second aspect of the present invention provides a method for measuring electric fields inside ultra-high voltage GIS.

[0018] A method for measuring the electric field inside ultra-high voltage GIS, comprising: Based on the test components, the response calibration of the electro-optic sensing probe is performed; Based on the electro-optical sensing probe after response calibration, non-contact electric field measurement is performed inside the GIS.

[0019] Furthermore, the electro-optic sensing probe is calibrated, including: based on the test components, the linearity characteristics of the electro-optic sensing probe under different electric field intensities and the time-domain response characteristics under pulsed electric fields are tested sequentially to obtain the applicable electric field range and measurement bandwidth of the electro-optic sensing probe, respectively. The above one or more technical solutions have the following beneficial effects: (1) This invention employs an electro-optic sensing probe based on the Pockels effect, combined with epoxy resin adhesive to achieve a fully insulated design. The electro-optic sensing probe has a compact structure and, with the epoxy resin adhesive, can be flexibly installed on the inner wall of the GIS housing, solving the problem of poor installation compatibility of capacitive sensors. At the same time, the fully insulated design avoids interference from the sensing components with the original electric field distribution inside the GIS, and does not damage the insulation structure of the equipment itself, fundamentally eliminating the safety hazards caused by the characteristics of the sensor itself, and ensuring the stability and safety of the measurement environment.

[0020] (2) Based on the test components, the present invention performs a comprehensive response calibration of the electro-optic sensing probe, namely: using a high-voltage AC generator, a DC source, and an impulse source to test its response characteristics under AC, DC, and impulse electric fields respectively, and combining a fast pulse voltage generator to test the time domain response characteristics under the pulse electric field, ensuring that the electro-optic sensing probe has the characteristics of wide bandwidth and high response speed, which can cover the various electric field measurement needs of ultra-high voltage GIS under complex working conditions, effectively breaking through the limitations of existing technologies in measurement range and dynamic response.

[0021] (3) The electro-optic sensing probe of the present invention adopts a serial dual-waveplate design, that is: the output end of the 1 / 4 waveplate in the electro-optic sensing probe is connected to the input end of the electro-optic crystal, which is used to generate a polarization between the two polarization components of the linearly polarized light that has passed through the polarizer. The phase shift is compensated by the output of the electro-optic crystal, which is connected to the input of the half-wave plate. The half-wave plate compensates for the phase shift deviation to avoid inaccurate polarization state conversion or distortion of the mapping relationship between light intensity change and electric field intensity, thereby ensuring the accuracy and stability of electric field measurement.

[0022] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a structural diagram of an electric field measurement system for use inside an ultra-high voltage GIS according to Embodiment 1 of the present invention.

[0025] Figure 2 This is a structural diagram of the upper cover plate of the GIS shell in Embodiment 1 of the present invention; wherein, Figure 2 (a) in the figure is a cross-sectional view of the cover plate under partial magnification. Figure 2 (b) is a plan view of the cover plate under partial magnification.

[0026] Figure 3 This is a structural diagram of the electro-optic sensing probe in Embodiment 1 of the present invention.

[0027] Figure 4 This is a schematic diagram of the Laplace field curve of GIS without partial discharge in Embodiment 2 of the present invention.

[0028] Figure 5 This is a schematic diagram of the linearity test curve of the electro-optic sensing probe in Embodiment 2 of the present invention.

[0029] In the diagram: 1. Laser; 2. Electro-optic sensor probe; 3. Photodetector; 4. GIS housing; 5. Cover plate; 6. Via; 61. First via; 62. Second via; 7. Polarization-maintaining fiber; 8. Single-mode fiber; 9. Modified adhesive. Detailed Implementation

[0030] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0032] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0033] Example 1 This embodiment discloses an electric field measurement system for use inside ultra-high voltage GIS.

[0034] An electric field measurement system for use inside ultra-high voltage GIS includes: a laser 1, an electro-optic sensing probe 2, a photodetector 3, and a test component; Laser 1 is connected to the output end of electro-optic sensing probe 2 based on Pockels effect through polarization-maintaining fiber 7 that passes through the first through hole 61 of the upper cover plate 5 of GIS housing 4. The electro-optic sensing probe 2 is fixed to the inner wall of the GIS housing 4 by modified adhesive 9, and its axis is parallel to the direction of the electric field inside the GIS; the output end of the electro-optic sensing probe 2 is connected to the photodetector 3 through the single-mode optical fiber 8 that passes through the second through hole 62 of the upper cover plate 5 of the GIS housing 4. The test component is used to calibrate the response of the electro-optic sensing probe 2; the electro-optic sensing probe adopts a serial dual-waveplate design, which is used to perform non-contact electric field measurement inside the GIS after the response calibration is completed.

[0035] Based on the above systematic design, this invention enables accurate non-contact electric field measurement within the compact space of a GIS (Gas-Integrated System). To facilitate understanding of the technical solution of this invention, the specific implementation methods are further explained and described below.

[0036] An electric field measurement system for use inside ultra-high voltage GIS includes: a laser 1, an electro-optic sensing probe 2, a photodetector 3, and a test component.

[0037] like Figure 3 As shown, the electro-optic sensing probe includes a first fiber collimator, a polarizer, a quarter-wave plate, an electro-optic crystal, a half-wave plate, an analyzer, and a second fiber collimator, which are aligned in sequence.

[0038] The input end of the first fiber collimator is connected to the polarization-maintaining fiber, which transmits the optical signal emitted by the laser to the first fiber collimator of the sensing probe while maintaining the stability of the light's polarization state to avoid polarization distortion affecting measurement accuracy. The output end of the first fiber collimator is aligned with the input end of the polarizer. The output end of the polarizer is aligned with the input end of the quarter-wave plate. The output end of the quarter-wave plate is aligned with the input end of the electro-optic crystal. The output end of the electro-optic crystal is aligned with the input end of the half-wave plate. The output end of the half-wave plate is aligned with the input end of the analyzer. The output end of the analyzer is aligned with the input end of the second fiber collimator. The output end of the second fiber collimator is connected to a single-mode fiber.

[0039] In this embodiment, the laser used is a Thorlabs TLX1 C-Band with a center wavelength of 1550nm, a linewidth of 10 kHz, and an optical power of 0.02~20mW; the polarization-maintaining fiber is a PM1550 panda-type fiber optic patch cord; the first and second fiber collimators are both F280APC-1550; the single-mode fiber is an SM1550 single-mode fiber optic patch cord; and the photodetector is a PDB470C.

[0040] Furthermore, the electro-optic sensing probe employs a serial dual-waveplate design, where the output of a quarter-waveplate within the probe is connected to the input of an electro-optic crystal, used to generate polarization between the two polarization components of the linearly polarized light passing through the polarizer. The phase shift; the output end of the electro-optic crystal is connected to the input end of the half-wave plate. The half-wave plate is used to compensate for the phase shift deviation in order to avoid inaccurate polarization state conversion or distortion of the mapping relationship between light intensity change and electric field intensity, thereby ensuring the accuracy and stability of electric field measurement.

[0041] like Figure 1 As shown, the electro-optic sensing probe 2 is fixed to the inner wall of the GIS housing 4 by epoxy resin adhesive in the modified adhesive, and its axis is parallel to the direction of the electric field inside the GIS. Furthermore, the epoxy resin adhesive has a buffer layer on the side in contact with the inner wall of the GIS to cushion the vibration of the electro-optic sensing probe.

[0042] Therefore, this invention achieves a fully insulated design by employing an electro-optic sensing probe based on the Pockels effect, combined with epoxy resin adhesive. The electro-optic sensing probe has a compact structure and, with the epoxy resin adhesive, can be flexibly installed on the inner wall of the GIS housing, solving the problem of poor installation compatibility of capacitive sensors. Simultaneously, the fully insulated design avoids interference from the sensing component with the original electric field distribution inside the GIS and does not damage the equipment's own insulation structure, fundamentally eliminating safety hazards caused by the sensor's inherent characteristics and ensuring the stability and safety of the measurement environment.

[0043] like Figure 1 As shown, the laser is connected to the output end of the electro-optic sensing probe based on the Pockels effect through a polarization-maintaining optical fiber passing through the first through hole of the GIS housing cover plate; the output end of the electro-optic sensing probe is connected to the photodetector through a single-mode optical fiber passing through the second through hole of the GIS housing cover plate.

[0044] Based on the above electro-optic sensing probe with serial dual-waveplate design, non-contact electric field measurement is performed inside the GIS. Specifically, the Pockels effect is an electro-optic effect. When an electric field is applied to certain crystal materials, their refractive index changes, thereby affecting the phase of the light wave passing through the crystal.

[0045] An optical electric field sensor probe (electro-optical sensor probe) based on the Pockels effect is placed inside the GIS and fixed with epoxy resin adhesive, which is a high-strength insulating material. An optical fiber is led out of the GIS through a sealed interface via 6 (i.e., the first via 61 and the second via 62 on the cover plate 5), ensuring that the airtightness of the GIS is not affected, thereby enabling the measurement of the electric field inside the GIS. Figure 2 As shown, the first and second through holes are filled with epoxy resin and covered with a silicone layer to form a double-sealing structure; wherein, Figure 2 (a) in the figure is a cross-sectional view of the cover plate under partial magnification. Figure 2 (b) is a plan view of the cover plate under partial magnification.

[0046] In practical operation, the laser beam is adjusted to linearly polarized light by a polarizer, ensuring that the magnitude and phase of the polarization components in the z and y directions are identical. After passing through a quarter-wave plate, a polarization relationship is generated between the two polarization components. The phase shift of the beam results in circularly polarized light. When an electric field is applied, the crystal is anisotropic, and the refractive indices experienced by the two polarization components differ and are linearly related to the amplitude of the electric field. This causes the phase shift between the polarization components of the beam in the z and y directions to be linearly related to the magnitude of the electric field. In this case, the beam exhibits elliptically polarized light, i.e.: ; in, Indicates the intrinsic refractive index of an electro-optic crystal. The electro-optic coefficient represents the electro-optic coefficient of the electro-optic crystal. The length of the electro-optic crystal in the direction of light transmission. Indicates electric field strength. Indicates the wavelength of the light beam. This indicates elliptical polarization.

[0047] When a beam passes through a half-wave plate, the phase difference increases. To supplement, namely: ; After passing through the analyzer, the light beam is adjusted to linear polarization. The phase shift between the two polarization components of the beam is converted into a change in light intensity. The phase shift is measured by detecting the light intensity of the beam. ; in, Indicates the output optical power. Indicates the input optical power; This represents the elliptically polarized light after processing with a half-wave plate. Therefore, by detecting the output optical power... Information about changes in the electric field can then be obtained.

[0048] When the condition is met When, we can obtain the following expression, that is: ; ; in, This represents the average electric field strength inside the crystal. Based on this, the modulation relationship between the external electric field and the optical power can be obtained. After the optical signal is received by the photodetector at the back end, the optical power can be converted into a corresponding electrical signal.

[0049] To ensure the measurement accuracy of the electro-optic sensing probe, this invention also constructs a test assembly to calibrate the probe's response. The test assembly includes a power supply, electrode units, a measurement unit, and a fast pulse voltage generator. The power supply comprises a high-voltage AC generator, a DC source, and an impulse source, used to test the response characteristics of the electro-optic sensing probe under AC, DC, and impulse electric fields, respectively. The fast pulse voltage generator is used to test the time-domain response characteristics of the electro-optic sensing probe under a pulsed electric field. In practical applications, based on the test assembly, the linearity characteristics of the electro-optic sensing probe under different electric field strengths and its time-domain response characteristics under a pulsed electric field are tested sequentially to obtain the applicable electric field range and measurement bandwidth of the electro-optic sensing probe. Therefore, by combining the fast pulse voltage generator with the time-domain response characteristics under a pulsed electric field, the electro-optic sensing probe is ensured to possess wide bandwidth and high response speed, covering various electric field measurement needs of ultra-high voltage GIS under complex operating conditions, effectively overcoming the limitations of existing technologies in measurement range and dynamic response.

[0050] To further demonstrate the significant advantages of the present invention, the following experiments were conducted in this embodiment: like Figure 4 The figure shown is the Laplace field curve of the GIS without partial discharge, measured on a laboratory-scale 1100kV GIS experimental platform in this embodiment, used to represent the Laplace field. From... Figure 4 As can be seen, the electric field measurement system provided by this invention can stably measure the 50Hz power frequency electric field, and therefore can also measure the electric field inside GIS. Figure 5 The diagram shows the test results of the linearity test of the electro-optic sensor probe using a laboratory linearity testing platform in this embodiment. This linearity testing platform consists of a voltage regulator, a power frequency test transformer, a protective resistor, and parallel plate electrodes. Figure 5 As can be seen, the fitted straight line passes through the data points, meaning that the applied electric field and the sensor response are linearly related. Therefore, the electro-optic sensing probe of this invention has good linearity and excellent performance.

[0051] Example 2 This embodiment discloses a method for measuring electric fields inside ultra-high voltage GIS.

[0052] A method for measuring the electric field inside ultra-high voltage GIS, comprising: Based on the test components, the response calibration of the electro-optic sensing probe is performed; Based on the electro-optical sensing probe after response calibration, non-contact electric field measurement is performed inside the GIS. Furthermore, the electro-optic sensing probe is calibrated, including: based on the test components, the linearity characteristics of the electro-optic sensing probe under different electric field intensities and the time-domain response characteristics under pulsed electric fields are tested sequentially to obtain the applicable electric field range and measurement bandwidth of the electro-optic sensing probe, respectively.

[0053] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. An electric field measurement system for use inside ultra-high voltage GIS, characterized in that, include: Lasers, electro-optic sensing probes, photodetectors, and test components; The laser is connected to the output end of the electro-optic sensing probe based on the Pockels effect through a polarization-maintaining optical fiber that passes through the first through hole in the GIS housing cover plate. The electro-optic sensing probe is fixed to the inner wall of the GIS housing with a modified adhesive, and its axis is parallel to the direction of the electric field inside the GIS; the output end of the electro-optic sensing probe is connected to the photodetector through a single-mode optical fiber that passes through the second through hole of the GIS housing cover plate. The test components are used to calibrate the response of the electro-optic sensing probe; The electro-optic sensing probe adopts a serial dual-waveplate design, which is used to perform non-contact electric field measurement inside the GIS after response calibration.

2. The electric field measurement system for ultra-high voltage GIS as described in claim 1, characterized in that, The electro-optic sensing probe includes a first fiber collimator, a polarizer, a quarter-wave plate, an electro-optic crystal, a half-wave plate, an analyzer, and a second fiber collimator, arranged in sequence; wherein, the input end of the first fiber collimator is connected to a polarization-maintaining fiber, and the output end of the second fiber collimator is connected to a single-mode fiber.

3. An electric field measurement system for use inside ultra-high voltage GIS as described in any one of claims 1-2, characterized in that, The electro-optic sensing probe employs a serial dual-waveplate design. Specifically, the output of the quarter-waveplate within the probe is connected to the input of the electro-optic crystal, used to generate polarization between the two polarization components of the linearly polarized light passing through the polarizer. Phase shift; The output terminal of the electro-optic crystal is connected to the input terminal of the half-wave plate, which is used to compensate for phase shift deviation.

4. The electric field measurement system for ultra-high voltage GIS as described in claim 1, characterized in that, The modified adhesive is an epoxy resin adhesive.

5. The electric field measurement system for ultra-high voltage GIS as described in claim 4, characterized in that, The epoxy resin adhesive has a buffer layer on the side that contacts the inner wall of the GIS to buffer the vibration of the electro-optic sensing module.

6. The electric field measurement system for ultra-high voltage GIS as described in claim 1, characterized in that, The first and second vias are filled with epoxy resin and covered with a silicone layer to form a double-sealed structure.

7. The electric field measurement system for ultra-high voltage GIS as described in claim 1, characterized in that, The test assembly includes a power supply, an electrode unit, and a measurement unit; wherein the power supply includes a high-voltage AC generator, a DC source, and an impulse source, which are used to test the response characteristics of the electro-optic sensing probe under AC, DC, and impulse electric fields, respectively.

8. The electric field measurement system for ultra-high voltage GIS as described in claim 7, characterized in that, The testing components also include a fast pulse voltage generator for testing the time-domain response characteristics of the electro-optic sensing probe under a pulsed electric field.

9. A method for measuring the electric field inside ultra-high voltage GIS, characterized in that, include: Based on the test components, the response calibration of the electro-optic sensing probe is performed; Based on the electro-optical sensing probe after response calibration, non-contact electric field measurement is performed inside the GIS.

10. The electric field measurement method for ultra-high voltage GIS as described in claim 9, characterized in that, The response calibration of the electro-optic sensing probe includes: based on the test components, sequentially testing the linearity characteristics of the electro-optic sensing probe under different electric field intensities and the time-domain response characteristics under pulsed electric fields, so as to obtain the applicable electric field range and measurement bandwidth of the electro-optic sensing probe respectively.

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