GIL partial discharge detection method and device based on ultra-high frequency sensor at both ends of telescopic joint

Abstract

The application provides a GIL partial discharge detection method and device based on ultrahigh frequency sensing at both ends of a telescopic joint, and relates to the technical field of power supply equipment. The detection method comprises the following steps: synchronously collecting partial discharge ultrahigh frequency original signals of two telescopic joints to obtain partial discharge ultrahigh frequency original pulse waveforms of the two telescopic joints; calculating the propagation time delay AT of the partial discharge ultrahigh frequency original pulse waveforms of the two telescopic joints to calculate the position of a partial discharge source of a GIL device; generating a PRPD spectrum and a PRPS spectrum according to the phase distribution characteristics of the partial discharge ultrahigh frequency original pulse waveforms of the two telescopic joints to determine the type of the partial discharge source of the GIL device. The method does not need to additionally add sensors, and can realize rapid and accurate positioning and type identification of internal partial discharge sources of the GIL device by using the components of the GIL device itself, is convenient for on-site implementation, and can effectively improve the insulation state perception ability of the GIL device in operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power supply equipment, in particular to a GIL partial discharge detection method and device based on ultra-high frequency sensing at both ends of a telescopic joint. BACKGROUND

[0002] A gas-insulated transmission line (GIL) with a metal shell coaxially arranged with a conductor is a high-voltage and large-current power transmission equipment insulated by a high-pressure gas (such as SF6, SF6 mixed gas, etc.), which is widely used in power transmission occasions of large hydropower stations and nuclear power stations. The GIL equipment has large transmission capacity, low unit loss, small environmental impact, high operation reliability, and land saving, and has obvious advantages compared with traditional overhead lines.

[0003] Due to process control reasons, during the production process of the insulating part of the GIL equipment, there may be micro-bubbles left in the pot-type insulator and the post insulator, and there may be micro air gaps between the epoxy resin and the metal insert. During the on-site installation process, due to incomplete internal cleaning, there may be micro metal particles left in the GIL equipment. These micro defects left in the GIL equipment will cause partial discharge during operation, causing insulation deterioration, and eventually leading to a destructive insulation breakdown failure of the GIL equipment. Therefore, during the operation of the GIL equipment, using the charged detection or online monitoring method to detect whether there is an abnormal partial signal inside the GIL equipment is an important means to early detect latent insulation defects inside the GIL equipment and accurately assess the insulation operating state of the GIL equipment.

[0004] Due to the low gas leakage rate of the GIL equipment, the flange sealing surface is greatly reduced, and the built-in ultra-high frequency sensing method commonly used in GIS equipment is rarely used. In addition, the ultrasonic detection method commonly used in GIS equipment has limited sensing sensitivity, and there are many measurement points on the GIL equipment. In practical applications, the detection effectiveness is poor. SUMMARY

[0005] The purpose of the present application includes providing a GIL partial discharge detection method and device based on ultra-high frequency sensing at both ends of a telescopic joint, which does not require additional sensors and can achieve rapid and accurate positioning and type identification of internal partial discharge sources of the GIL equipment using its own components, facilitating on-site implementation and effectively improving the insulation state perception ability of the GIL equipment during operation.

[0006] Embodiments of the present application can be implemented as follows:

[0007] In a first aspect, the present application provides a GIL partial discharge detection method based on ultra-high frequency sensing at both ends of a telescopic joint, and the detection method comprises:

[0008] synchronously collecting partial discharge ultra-high frequency original signals of the two expansion joints;

[0009] According to the partial discharge ultra-high frequency original signals, partial discharge ultra-high frequency original pulse waveforms of the two expansion joints are obtained.

[0010] The propagation time delay ΔT of the partial discharge ultra-high frequency original pulse waveforms of the two expansion joints is calculated.

[0011] According to the propagation time delay ΔT, the location of the partial discharge source of the GIL device is calculated.

[0012] According to the phase distribution characteristics of the partial discharge ultra-high frequency original pulse waveforms of the two expansion joints, PRPD and PRPS maps are generated.

[0013] According to the PRPD and PRPS maps, the type of the partial discharge source of the GIL device is determined.

[0014] In an optional embodiment, the step of synchronously collecting partial discharge ultra-high frequency original signals of the two expansion joints comprises:

[0015] The ultra-high frequency transient current signals at the flanges of the two ends of the expansion joint are collected and coupled to obtain the partial discharge ultra-high frequency original signals.

[0016] In an optional embodiment, the step of collecting the ultra-high frequency transient current signals at the flanges of the two ends of the expansion joint and coupling to obtain the partial discharge ultra-high frequency original signals comprises:

[0017] Two insulating wires are respectively connected at the flanges of the two ends of the expansion joint to collect the ultra-high frequency transient current signals.

[0018] In an optional embodiment, the cross-sectional area of the insulating wire is not less than 5mm 2 The insulating wire is fixed to the bolt end of the current lead of the expansion joint by a wire nose through a bolt.

[0019] In an optional embodiment, the step of synchronously collecting partial discharge ultra-high frequency original signals of the two expansion joints further comprises:

[0020] A magnetic ring is additionally arranged on the current lead of the expansion joint to increase the ultra-high frequency transient current signals.

[0021] In an optional embodiment, the step of obtaining the partial discharge ultra-high frequency original pulse waveforms of the two expansion joints according to the partial discharge ultra-high frequency original signals comprises:

[0022] The partial discharge ultra-high frequency original signals are amplified and filtered, wherein the effective working frequency band is between 200MHz and 1500MHz, the amplification gain is not less than 50dB, and the signal-to-noise ratio is not less than 40dB.

[0023] The amplified and filtered partial discharge UHF original signal is collected in real time to obtain a partial discharge UHF original pulse waveform, wherein the sampling rate is not less than 2GS / s, the sampling analog bandwidth is not less than 1GHz, and the FIFO mode of continuous collection and storage is adopted, and the pulse collection dead time is not higher than 5us.

[0024] In an optional embodiment, the calculation formula of the position of the partial discharge source is:

[0025]

[0026] In the formula, l is the distance from the position of the partial discharge source to the expansion joint where the partial discharge UHF original signal is first detected, L is the length between the two expansion joints, and v is the propagation speed of electromagnetic waves in the GIL device.

[0027] In a second aspect, the application provides a GIL partial discharge detection device based on UHF sensing at both ends of an expansion joint, which comprises:

[0028] A UHF filter and amplifier unit is connected to the flanges at both ends of the expansion joint through two insulating conductors to collect a UHF transient current signal and perform amplification, filtering and coupling processing to obtain a partial discharge UHF original signal.

[0029] A UHF signal collection unit is connected to the UHF filter and amplifier unit, and is used to collect the amplified and filtered partial discharge UHF original signal in real time to obtain a partial discharge UHF original pulse waveform.

[0030] A storage control unit is connected to the UHF signal collection unit, and is used to calculate the propagation time delay AT of the partial discharge UHF original pulse waveforms of the two expansion joints, calculate the position of the partial discharge source of the GIL device according to the propagation time delay AT, generate a PRPD spectrum and a PRPS spectrum according to the phase distribution characteristics of the partial discharge UHF original pulse waveforms of the two expansion joints, and determine the type of the partial discharge source of the GIL device according to the PRPD spectrum and the PRPS spectrum.

[0031] In an optional embodiment, the effective working frequency band of the UHF filter and amplifier unit is between 200MHz and 1500MHz, the amplification gain is not less than 50dB, and the signal-to-noise ratio is not less than 40dB.

[0032] The sampling rate of the UHF signal collection unit is not less than 2GS / s, the sampling analog bandwidth is not less than 1GHz, and the FIFO mode of continuous collection and storage is adopted, and the pulse collection dead time is not higher than 5us.

[0033] In an optional embodiment, the storage control unit stores a calculation formula of the position of the partial discharge source:

[0034]

[0035] wherein, l is the distance from the position of the partial discharge source to the expansion joint where the partial discharge UHF original signal is first detected, L is the length between two expansion joints, and v is the propagation speed of electromagnetic waves in the GIL device.

[0036] The GIL partial discharge detection method and device based on UHF sensing at both ends of the expansion joint provided by the embodiments of the present application have the following beneficial effects:

[0037] 1. The propagation time delay AT of the partial discharge UHF original pulse waveforms of the two expansion joints is obtained by synchronously collecting the partial discharge UHF original signals of the two expansion joints, so that the position of the partial discharge source of the GIL device is accurately positioned;

[0038] 2. The PRPD and PRPS maps are generated according to the phase distribution characteristics of the partial discharge UHF original pulse waveforms of the two expansion joints, so that the type of the partial discharge source of the GIL device is identified;

[0039] 3. The rapid and accurate positioning and type identification of the internal partial discharge source of the GIL device can be realized by using the components of the GIL device itself without additional sensors, which is convenient for on-site implementation and can effectively improve the insulation state perception ability of the GIL device in operation. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0041] Figure 1 It is an equivalent circuit diagram of the expansion joint;

[0042] Figure 2 It is an application scenario diagram of the GIL partial discharge detection device based on UHF sensing at both ends of the expansion joint provided by the first embodiment of the present application;

[0043] Figure 3 It is a schematic diagram of the position of the partial discharge source;

[0044] Figure 4 It is a flowchart of the GIL partial discharge detection method based on UHF sensing at both ends of the expansion joint provided by the second embodiment of the present application.

[0045] Figure icon: 10 - expansion joint; 11 - flow guide; 12 - bellows; 13 - pull rod; 20 - GIL partial discharge detection equipment based on ultra-high frequency sensor at both ends of expansion joint; 21 - ultra-high frequency filter amplification unit; 22 - ultra-high frequency signal acquisition unit; 23 - storage control unit. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0048] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0049] It should be noted that: the features in the embodiments of the present application can be combined with each other without conflict.

[0050] The expansion joint is an important component of the GIL device, and is used to compensate for the expansion deformation of the absorption tube in the axial, lateral and angular directions due to thermal expansion and contraction. The expansion joint used in the GIL device includes a pressure balance expansion joint, a hinge expansion joint and a composite large pull rod settlement expansion joint. The pressure balance expansion joint is used to absorb the axial thermal expansion of the GIL device and realize the detachable function, the hinge expansion joint is used to convert the axial displacement of the vertical shaft body linear segment into radial displacement for absorption, and the composite large pull rod settlement expansion joint is used to absorb the larger potential deformation position and seismic displacement in the pipe gallery.

[0051] The equivalent circuits of various types of expansion joints are similar, as shown in Figure 1 Figure 10, the expansion joint 10 includes a flow guide 11, a bellows 12 and a pull rod 13, wherein the material of the flow guide 11 is aluminum, and the electrical conductivity is 3.8*10 7 S / m, the material of the bellows 12 is stainless steel, and the electrical conductivity is 1.4*10 6 S / m, and the material of the pull rod 13 is cast iron, and the electrical conductivity is 5*10 6S / m. Thus, the resistance of the current guide 11 is small, and the current flowing through the expansion joint 10 is only through the current guide 11. Since the current guide 11 is usually a flat aluminum bar, there is a large inductance. Therefore, when the ultra-high frequency transient current passes through the current guide 11, a significant voltage difference will be generated at both ends of the current guide 11, i.e., at both ends of the expansion joint 10. The partial discharge detection inside the GIL device can be realized by sensing the voltage difference.

[0052] First embodiment

[0053] Please refer to Figure 2 The embodiment provides a GIL partial discharge detection device 20 based on ultra-high frequency sensing at both ends of an expansion joint (hereinafter referred to as "detection device"). The detection device includes an ultra-high frequency filtering and amplifying unit 21, an ultra-high frequency signal collecting unit 22, and a storage and control unit 23.

[0054] The ultra-high frequency filtering and amplifying unit 21 is connected to the flanges at both ends of the expansion joint 10 through two insulated wires to collect the ultra-high frequency transient current signal and perform amplification filtering and coupling processing to obtain the partial discharge ultra-high frequency original signal.

[0055] Specifically, the cross-sectional area of the insulated wire is not less than 5mm 2 , and the length is as short as possible. One end of the insulated wire is fixed to the bolt end of the current guide 11 of the expansion joint 10 through a wire nose and a bolt. The other end of the insulated wire is connected to the core wire and the shell of the N-type cable connector, which is convenient for connection with the rear-end ultra-high frequency signal collecting unit 22. If the sensing signal is small, a magnetic ring can be additionally arranged on the current guide 11 to additionally increase the inductance of the current guide and increase the ultra-high frequency transient current signal.

[0056] The ultra-high frequency signal collecting unit 22 is connected to the ultra-high frequency filtering and amplifying unit 21. The ultra-high frequency signal collecting unit 22 is used to collect the partial discharge ultra-high frequency original signal after amplification filtering in real time to obtain the partial discharge ultra-high frequency original pulse waveform.

[0057] Specifically, the ultra-high frequency signal collecting unit 22 amplifies and filters the ultra-high frequency weak signal sensed at both ends of the expansion joint 10 to improve the signal quality. The effective working frequency band of the ultra-high frequency signal collecting unit 22 is between 200MHz and 1500MHz, the amplification gain is not less than 50dB, and the signal-to-noise ratio is not less than 40dB.

[0058] The ultra-high frequency signal acquisition unit 22 realizes high-frequency real-time acquisition of the ultra-high frequency signal. In the embodiment, the sampling rate of the ultra-high frequency signal acquisition unit 22 is not less than 2 GS / s, the sampling analog bandwidth is not less than 1 GHz, the FIFO mode of continuous acquisition and storage is supported, and the pulse acquisition dead time is not higher than 5 us. The ultra-high frequency signal acquisition unit 22 has a synchronous signal access port, which facilitates extraction of the phase information of the partial discharge signal.

[0059] The storage control unit 23 is connected with the ultra-high frequency signal acquisition unit 22. The storage control unit 23 is used to calculate the propagation time delay AT of the partial discharge ultra-high frequency original pulse waveforms of the two expansion joints 10, calculate the position of the partial discharge source of the GIL device according to the propagation time delay AT, generate the PRPD spectrum and the PRPS spectrum according to the phase distribution characteristics of the partial discharge ultra-high frequency original pulse waveforms of the two expansion joints 10, and determine the type of the partial discharge source of the GIL device according to the PRPD spectrum and the PRPS spectrum.

[0060] Specifically, the storage control unit 23 can be connected with the ultra-high frequency signal acquisition unit 22 through an optical fiber or a network cable, collect and store and analyze the partial discharge ultra-high frequency original pulse waveforms of each measuring point, generate the PRPD spectrum and the PRPS spectrum according to the phase distribution characteristics of the partial discharge ultra-high frequency original pulse waveforms, and use the PRPD spectrum and the PRPS spectrum to identify the type of the partial discharge source. The sensing signals of two adjacent expansion joints 10 can be used to locate the partial discharge source. The storage control unit 23 is used to synchronously trigger the partial discharge ultra-high frequency original signals of the two expansion joints 10, calculate the propagation time delay AT of the partial discharge ultra-high frequency original pulse waveforms, and calculate the position of the partial discharge source of the GIL device by using the propagation time delay AT and combining the propagation speed v of the electromagnetic wave in the GIL device, wherein v can be taken as 294 m / us, and L is the length between the two expansion joints 10. The calculation formula of the position of the partial discharge source is as follows:

[0061]

[0062] In the formula, l is the distance from the position of the partial discharge source to the expansion joint 10 that first detects the partial discharge ultra-high frequency original signal.

[0063] Please refer to Figure 3 for the derivation process of the calculation formula of the position of the partial discharge source.

[0064] It is assumed that the distance from the position of the partial discharge source (the position of point O in the figure) to the expansion joint 10 (the expansion joint 10 on the right side in the figure) that first detects the partial discharge ultra-high frequency original signal is l, and the length between the two expansion joints 10 is L.

[0065] The distance from the location of the partial discharge source to the expansion joint 10 (the expansion joint 10 on the left side in the figure) where the partial discharge UHF original signal is finally detected is l+v*DeltaT, and l+l+v*DeltaT=L, so l=(L-v*DeltaT) / 2.

[0066] The GIL partial discharge detection device 20 based on UHF sensing at both ends of the expansion joint provided by the embodiment of the application has the following beneficial effects:

[0067] 1. The propagation time delay DeltaT of the partial discharge UHF original pulse waveforms of the two expansion joints 10 is obtained by synchronously collecting the partial discharge UHF original signals of the two expansion joints 10, and the location of the partial discharge source of the GIL device is accurately positioned.

[0068] 2. The PRPD and PRPS maps are generated according to the phase distribution characteristics of the partial discharge UHF original pulse waveforms of the two expansion joints 10, and the type of the partial discharge source of the GIL device is identified.

[0069] 3. The rapid and accurate positioning and type identification of the internal partial discharge source of the GIL device can be realized by using the components of the GIL device itself without additional sensors, which is convenient for on-site implementation and can effectively improve the insulation state perception ability of the GIL device in operation.

[0070] Second embodiment

[0071] Please refer to Figure 4 The embodiment provides a GIL partial discharge detection method based on UHF sensing at both ends of the expansion joint (hereinafter referred to as "detection method"), which can be realized by the detection device provided in the first embodiment, and the detection method comprises the following steps:

[0072] S1: Synchronously collecting the partial discharge UHF original signals of the two expansion joints 10.

[0073] Specifically, two insulating wires are connected to the flanges at both ends of the expansion joint 10 to collect the UHF transient current signals and couple to obtain the partial discharge UHF original signals. The cross-sectional area of the insulating wire is not less than 5mm 2 The insulating wire is fixed to the bolt end of the current lead 11 of the expansion joint 10 by a bolt through a wire nose, and a magnetic ring can be additionally arranged on the current lead 11 of the expansion joint 10 to increase the UHF transient current signal if the sensing signal is small.

[0074] S2: Obtaining the partial discharge UHF original pulse waveforms of the two expansion joints 10 according to the partial discharge UHF original signals.

[0075] Specifically, the partial discharge ultrahigh frequency original signal is amplified and filtered, wherein the effective working frequency band is between 200MHz and 1500MHz, the amplification gain is not less than 50dB, and the signal-to-noise ratio is not less than 40dB. The partial discharge ultrahigh frequency original signal after the amplification and filtering is collected in real time, and the partial discharge ultrahigh frequency original pulse waveform is obtained, wherein the sampling rate is not less than 2GS / s, the sampling analog bandwidth is not less than 1GHz, the FIFO mode of continuous collection and storage is adopted, and the pulse collection dead time is not higher than 5us.

[0076] S3: Calculate the propagation time delay ΔT of the partial discharge ultrahigh frequency original pulse waveforms of the two expansion joints 10.

[0077] Specifically, the propagation time delay ΔT of the partial discharge ultrahigh frequency original pulse waveforms of the two expansion joints 10 can reflect the difference between the distances from the partial discharge source to the two expansion joints 10.

[0078] S4: According to the propagation time delay ΔT, the position of the partial discharge source of the GIL device is calculated.

[0079] Specifically, the calculation formula of the position of the partial discharge source is:

[0080]

[0081] In the formula, l is the distance from the position of the partial discharge source to the expansion joint 10 that detects the partial discharge ultrahigh frequency original signal first, L is the length between the two expansion joints 10, and v is the propagation speed of the electromagnetic wave in the GIL device.

[0082] S5: According to the phase distribution characteristics of the partial discharge ultrahigh frequency original pulse waveforms of the two expansion joints 10, PRPD and PRPS maps are generated.

[0083] Specifically, the phase of the partial discharge ultrahigh frequency original pulse waveform is obtained in combination with the operating voltage, and the PRPD and PRPS maps are generated through the phase repetition characteristics of the partial discharge ultrahigh frequency original pulse waveform.

[0084] S6: According to the PRPD and PRPS maps, the type of the partial discharge source of the GIL device is determined.

[0085] Specifically, the discharge type is identified according to the PRPD and PRPS maps.

[0086] The GIL partial discharge detection method based on the ultrahigh frequency sensing of the two ends of the expansion joint provided in the embodiments has the following beneficial effects:

[0087] 1. By synchronously collecting the partial discharge ultrahigh frequency original signals of two expansion joints 10, the propagation time delay ΔT of the partial discharge ultrahigh frequency original pulse waveforms of the two expansion joints 10 is obtained, and the position of the partial discharge source of the GIL device is accurately positioned;

[0088] 2. According to the phase distribution characteristics of the partial discharge ultrahigh frequency original pulse waveforms of the two expansion joints 10, the PRPD spectrum and the PRPS spectrum are generated, and the type of the partial discharge source of the GIL device is identified;

[0089] 3. Without the need for additional sensors, the internal partial discharge source of the GIL device can be quickly and accurately positioned and the type identified by using the components of the GIL device itself, which is convenient for on-site implementation and can effectively improve the insulation state perception ability of the GIL device in operation.

[0090] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A GIL partial discharge detection method based on ultra-high frequency sensing at both ends of a telescopic joint, characterized in that, The detection method comprises: Synchronously collecting partial discharge ultra-high frequency original signals of two expansion joints (10); According to the partial discharge ultra-high frequency original signals, partial discharge ultra-high frequency original pulse waveforms of the two expansion joints (10) are obtained; The propagation time delay ΔT of the partial discharge ultra-high frequency original pulse waveforms of the two expansion joints (10) is calculated; According to the propagation time delay ΔT, the position of the partial discharge source of the GIL device is calculated; According to the phase distribution characteristics of the partial discharge ultra-high frequency original pulse waveforms of the two expansion joints (10), a PRPD spectrum and a PRPS spectrum are generated; According to the PRPD spectrum and the PRPS spectrum, the type of the partial discharge source of the GIL device is determined.

2. The GIL partial discharge detection method based on the two-end telescopic joint UHF sensor according to claim 1, characterized in that, The step of synchronously collecting partial discharge ultra-high frequency original signals of two expansion joints (10) comprises: Collecting ultra-high frequency transient current signals at the flanges at both ends of the expansion joint (10) and coupling to obtain the partial discharge ultra-high frequency original signals.

3. The GIL partial discharge detection method based on the two-end telescopic joint UHF sensor of claim 2, characterized in that, The step of collecting ultra-high frequency transient current signals at the flanges at both ends of the expansion joint (10) and coupling to obtain the partial discharge ultra-high frequency original signals comprises: Two insulating wires are connected at the flanges at both ends of the expansion joint (10) to collect the ultra-high frequency transient current signals.

4. The GIL partial discharge detection method based on the two-end telescopic joint UHF sensor of claim 3, characterized in that, The cross-sectional area of the insulated conductor wire is not less than 5 mm 2 The insulated conductor wire is fixed by a wire nose through a bolt at the bolt end of the flow guide row (11) of the expansion joint (10).

5. The GIL partial discharge detection method based on the two-end telescopic joint UHF sensor of claim 2, characterized in that, The step of synchronously collecting partial discharge ultra-high frequency original signals of two expansion joints (10) further comprises: A magnetic ring is additionally arranged on the current guide (11) of the expansion joint (10) to increase the ultra-high frequency transient current signals.

6. The GIL partial discharge detection method based on the two-end telescopic joint UHF sensor according to claim 1, characterized in that, The step of obtaining partial discharge ultra-high frequency original pulse waveforms of the two expansion joints (10) according to the partial discharge ultra-high frequency original signals comprises: The partial discharge ultra-high frequency original signals are amplified and filtered, wherein the effective working frequency band is between 200MHz and 1500MHz, the amplification gain is not less than 50dB, and the signal-to-noise ratio is not less than 40dB; The partial discharge ultra-high frequency original signals after the amplification and filtering are collected in real time to obtain the partial discharge ultra-high frequency original pulse waveforms, wherein the sampling rate is not less than 2GS / s, the sampling analog bandwidth is not less than 1GHz, the FIFO mode of continuous collection and storage is adopted, and the pulse collection dead time is not higher than 5us.

7. The GIL partial discharge detection method based on the two-end telescopic joint UHF sensor according to claim 1, characterized in that, The calculation formula of the position of the partial discharge source is: In the formula, l is the distance from the position of the partial discharge source to the expansion joint (10) that first detects the partial discharge ultra-high frequency original signal, L is the length between the two expansion joints (10), and v is the propagation speed of electromagnetic waves in the GIL device.

8. A GIL partial discharge detection device based on very high frequency sensing at both ends of a telescopic joint, characterized in that, The detection device comprises: An ultra-high frequency filtering and amplifying unit (21) that connects two insulating wires at the flanges at both ends of the expansion joint (10) to collect the ultra-high frequency transient current signals and perform amplification and filtering and coupling processing to obtain the partial discharge ultra-high frequency original signals; An ultra-high frequency signal collecting unit (22) connected with the ultra-high frequency filtering and amplifying unit (21), the ultra-high frequency signal collecting unit (22) being configured to collect the partial discharge ultra-high frequency original signals after the amplification and filtering in real time to obtain the partial discharge ultra-high frequency original pulse waveforms; and An ultra-high frequency signal collecting unit (22) connected with the ultra-high frequency filtering and amplifying unit (21), the ultra-high frequency signal collecting unit (22) being configured to collect the partial discharge ultra-high frequency original signals after the amplification and filtering in real time to obtain the partial discharge ultra-high frequency original pulse waveforms. The storage control unit (23) is connected with the ultra-high frequency signal acquisition unit (22), and the storage control unit (23) is used for calculating the propagation time delay ΔT of the partial discharge ultra-high frequency original pulse waveforms of the two telescopic joints (10); according to the propagation time delay ΔT, the position of the partial discharge source of the GIL equipment is calculated; according to the phase distribution characteristics of the partial discharge ultra-high frequency original pulse waveforms of the two telescopic joints (10), the PRPD spectrum and the PRPS spectrum are generated; and according to the PRPD spectrum and the PRPS spectrum, the type of the partial discharge source of the GIL equipment is determined.

9. The GIL partial discharge detection device based on the two-end telescopic joint UHF sensor of claim 8, wherein, The effective working frequency band of the ultra-high frequency filter amplification unit (21) is between 200 MHz and 1500 MHz, the amplification gain is not less than 50 dB, and the signal-to-noise ratio is not less than 40 dB. The sampling rate of the ultra-high frequency signal acquisition unit (22) is not less than 2 GS / s, the sampling analog bandwidth is not less than 1 GHz, and the FIFO mode of continuous acquisition storage is adopted, and the pulse acquisition dead time is not higher than 5 us.

10. The GIL partial discharge detection device based on the two-end telescopic joint UHF sensor of claim 8, wherein, The storage control unit (23) stores the calculation formula of the position of the partial discharge source: In the formula, l is the distance from the position of the partial discharge source to the telescopic joint (10) that first detects the partial discharge ultra-high frequency original signal, L is the length between the two telescopic joints (10), and v is the propagation speed of the electromagnetic wave in the GIL equipment.

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