Method and device for identifying surface flashover of internal insulating part of high-voltage tank type circuit breaker

Abstract

The invention relates to a method and a device for identifying surface flashover of an internal insulating part of a high-voltage tank type circuit breaker, and relates to the technical field of high-voltage test and detection. The method comprises the following steps: S1, additionally arranging a built-in ultrahigh frequency sensor on a cover plate of the high-voltage tank type circuit breaker; s2, acquiring an electromagnetic pulse signal in the high-voltage tank-type circuit breaker by using a built-in ultrahigh-frequency sensor, and extracting signal characteristics of the electromagnetic pulse signal; and S3, comparing the signal feature of the extracted electromagnetic pulse signal with the first standard feature of the electromagnetic pulse signal of partial discharge and the second standard feature of the electromagnetic pulse signal of surface flashover of the insulating part, and judging whether the extracted electromagnetic pulse signal is generated by surface flashover or not. According to the method and the device, whether the surface flashover occurs on the internal insulating part or not can be effectively judged in the predelivery test and on-site handover test processes of the high-voltage tank type circuit breaker.

Description

Technical Field

[0001] The present application relates to the technical field of high voltage testing and detection, and in particular to a method and device for identifying surface flashover of internal insulating parts of a high voltage tank type circuit breaker. Background Art

[0002] High-voltage tank circuit breakers are key substation equipment in power systems, and their operational reliability is related to the stability of the power system. There is an insulating support cylinder (i.e., insulating component) at each end of the high-voltage tank circuit breaker, which not only supports the high-voltage conductor but also withstands the high voltage, and its mechanical and electrical insulation performance is required to be high.

[0003] During the factory test and on-site acceptance test, the insulating parts may cause surface flashover due to the presence of tiny metal foreign matter on the surface, leaving traces of flashover discharge on the surface of the insulating parts. Since the energy of flashover discharge is small, the short-term impact on the surface insulation characteristics of the insulating parts is small, so that the high-voltage tank circuit breaker can pass the factory test and on-site acceptance test assessment normally. However, if the insulating parts with surface flashover are operated for a long time under operating conditions, the surface leakage current of the insulating parts will gradually increase, the surface flashover traces will be further deepened, and the surface insulation characteristics will drop sharply, which may cause insulation failure. Therefore, timely and accurate detection of surface flashover on insulating parts during factory tests and on-site acceptance tests is crucial to improving the operating reliability of high-voltage tank circuit breakers.

[0004] In the past, during the test process, the flashover and gap breakdown on the insulating parts were often distinguished by the discharge sound, and verified by repeated pressurization. If the test passed after re-pressurization, the high-voltage tank circuit breaker test would be judged to have passed, thereby putting the high-voltage tank circuit breaker with flashover on the insulating parts into operation, causing serious operational risks. Summary of the invention

[0005] The purpose of the present application is to provide a method and device for identifying surface flashover of internal insulating parts of a high-voltage tank type circuit breaker. The method and device can effectively determine whether surface flashover occurs on the internal insulating parts during factory testing and on-site acceptance testing of the high-voltage tank type circuit breaker.

[0006] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a method for identifying surface flashover of an internal insulating component of a high-voltage tank type circuit breaker, the method comprising:

[0007] S1: Install a built-in UHF sensor on the cover of the high-voltage tank circuit breaker;

[0008] S2: using the built-in UHF sensor to collect the electromagnetic pulse signal inside the high-voltage tank circuit breaker and extract the signal characteristics of the electromagnetic pulse signal;

[0009] S3: Compare the signal characteristics of the extracted electromagnetic pulse signal with the first standard characteristics of the electromagnetic pulse signal of partial discharge and the second standard characteristics of the electromagnetic pulse signal of the surface flashover of the insulating component to determine whether the extracted electromagnetic pulse signal is generated by the surface flashover.

[0010] In an optional embodiment, S3 includes:

[0011] If the signal feature of the extracted electromagnetic pulse signal is closer to the second standard feature than the first standard feature, the extracted electromagnetic pulse signal is an electromagnetic pulse signal of surface flashover of the insulating component; if the signal feature of the extracted electromagnetic pulse signal is closer to the first standard feature than the second standard feature, the extracted electromagnetic pulse signal is an electromagnetic pulse signal of partial discharge.

[0012] In an optional embodiment, in S1, the built-in UHF sensor is a monopole sensor, the pole plate of the built-in UHF sensor and the casing of the high-voltage tank circuit breaker are not at the same potential, the average equivalent height of the built-in UHF sensor within the frequency range of 300MHz to 1500MHz is not less than 10mm, and the signal lead-out port of the built-in UHF sensor adopts a T-type adapter, and a 50-ohm matching impedance is added to the T-type adapter.

[0013] In an optional implementation, in S2, the signal characteristics include time domain characteristics, spectrum distribution characteristics and time-frequency distribution characteristics.

[0014] In an optional embodiment, in S3, the first standard feature and the second standard feature include duration, half-wave time, signal decay rate and signal amplitude.

[0015] In an optional embodiment, in S3, the time domain features in the first standard features of the electromagnetic pulse signal of the partial discharge include a duration less than 1000 ns, a signal decay rate greater than a first rate threshold, a half-wave time less than 200 ns, and a signal amplitude less than a first amplitude threshold;

[0016] The time domain characteristics of the second standard characteristics of the electromagnetic pulse signal excited by surface flashover include a duration greater than 1500ns, a signal attenuation rate less than a second rate threshold, a half-wave time not less than 200ns, and a signal amplitude greater than a second amplitude threshold, wherein the second rate threshold is less than or equal to the first rate threshold, and the second amplitude threshold is greater than or equal to the first amplitude threshold.

[0017] In an optional embodiment, in S3, the spectrum distribution feature in the first standard feature of the electromagnetic pulse signal excited by partial discharge includes a main frequency distribution between 350 MHz and 400 MHz, and a frequency component distribution concentration greater than a first concentration threshold;

[0018] The spectrum distribution characteristics in the second standard characteristics of the electromagnetic pulse signal excited by surface flashover include a main frequency distribution between 200MHz and 550MHz, and a frequency component distribution concentration less than a second concentration threshold, wherein the second concentration threshold is less than or equal to the first concentration threshold.

[0019] In an optional embodiment, in S3, the time-frequency distribution characteristics in the first standard characteristics of the electromagnetic pulse signal excited by the partial discharge include that the instantaneous frequency of the main frequency is 800MHz to 1000MHz, the signal attenuation rate of the instantaneous frequency of the main frequency is greater than the third rate threshold, the duration of the instantaneous frequency of the main frequency is less than 200ns, the main frequency is 300MHz to 400MHz, the signal attenuation rate of the main frequency is less than the fourth rate threshold, and the duration of the main frequency is 50ns to 100ns;

[0020] The time-frequency distribution characteristics of the second standard characteristics of the electromagnetic pulse signal excited by surface flashover include the instantaneous frequency of the main frequency being 800MHz~1000MHz, the signal attenuation rate of the main frequency being less than the fifth rate threshold, the duration of the main frequency being 1000ns~1500ns, the main frequency being distributed between 200MHz~400MHz, and the signal amplitude being less than the third amplitude threshold.

[0021] In a second aspect, the present invention provides a device for identifying surface flashover of an internal insulating component of a high-voltage tank circuit breaker, the device comprising a built-in ultra-high frequency sensor, an ultra-high frequency amplification processing unit, an ultra-high frequency signal acquisition unit, and a detection and diagnosis terminal connected in sequence;

[0022] The built-in UHF sensor is added to the cover of the high-voltage tank circuit breaker to collect the electromagnetic pulse signal inside the high-voltage tank circuit breaker;

[0023] The UHF amplification processing unit is used to pre-process the electromagnetic pulse signal received by the built-in UHF sensor;

[0024] The UHF signal acquisition unit is used to acquire and store the pre-processed electromagnetic pulse signal;

[0025] The detection and diagnosis terminal is used to extract the signal characteristics of the electromagnetic pulse signal, and compare the signal characteristics of the extracted electromagnetic pulse signal with the first standard characteristics of the electromagnetic pulse signal of partial discharge and the second standard characteristics of the electromagnetic pulse signal of surface flashover of the insulating component to determine whether the extracted electromagnetic pulse signal is generated by surface flashover.

[0026] Through the above technical scheme, the internal electromagnetic pulse signal of the circuit breaker can be monitored in real time during the factory test and on-site acceptance test of the high-voltage tank type circuit breaker. Through the signal characteristics of the extracted electromagnetic pulse signal, the local discharge pulse inside the high-voltage tank type circuit breaker and the electromagnetic pulse excited by the surface flashover of the internal insulating parts can be effectively identified, the surface flashover of the internal insulating parts of the high-voltage tank type circuit breaker can be discovered in time and accurately, and the external circuit interference can be eliminated, which can effectively improve the quality and efficiency of the factory test and on-site acceptance test management and control.

[0027] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A flow chart of a method for identifying surface flashover of an internal insulating component of a high-voltage tank circuit breaker provided in an embodiment of the present application;

[0030] Figure 2 It is the electromagnetic pulse signal of partial discharge inside the high-voltage tank circuit breaker;

[0031] Figure 3 It is the electromagnetic pulse signal of surface flashover of the internal insulation of the high-voltage tank circuit breaker;

[0032] Figure 4 It is the spectrum distribution of the electromagnetic pulse signal of the partial discharge inside the high-voltage tank circuit breaker;

[0033] Figure 5 It is the spectrum distribution of electromagnetic pulse signal along the surface flashover of internal insulation of high-voltage tank type circuit breaker;

[0034] Figure 6 It is the time-frequency distribution of the electromagnetic pulse signal of the partial discharge inside the high-voltage tank circuit breaker;

[0035] Figure 7 It is the time-frequency distribution of electromagnetic pulse signal along the surface flashover of the internal insulation of high-voltage tank circuit breaker;

[0036] Figure 8 A block diagram of the composition of a device for identifying surface flashover of internal insulating components of a high-voltage tank-type circuit breaker provided in an embodiment of the present application.

[0037] Icon: 1-Built-in UHF sensor; 2-UHF amplification and processing unit; 3-UHF signal acquisition unit; 4-Detection and diagnosis terminal. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0040] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] Please refer to Figure 1 The present embodiment provides a method for identifying surface flashover of internal insulating parts of a high-voltage tank type circuit breaker (hereinafter referred to as: method). The method uses a built-in ultra-high frequency sensor 1 installed inside the high-voltage tank type circuit breaker to collect electromagnetic pulse signals inside the high-voltage tank type circuit breaker in real time during factory tests and on-site acceptance tests through a high-speed acquisition unit. It determines whether surface flashover has occurred in the internal insulating parts based on the time-frequency characteristics of the electromagnetic pulse signals, thereby improving the quality control of factory and acceptance tests of high-voltage tank type circuit breakers.

[0042] Specifically, the method includes the following steps:

[0043] S1: A built-in UHF sensor 1 is installed on the cover plate of the high-voltage tank type circuit breaker.

[0044] Specifically, firstly, the cover plate on the high-voltage tank circuit breaker is used to install the built-in UHF sensor 1, which is a monopole sensor. The plate of the built-in UHF sensor 1 is not at the same potential as the shell of the high-voltage tank circuit breaker. The average equivalent height of the built-in UHF sensor 1 in the frequency range of 300MHz to 1500MHz is not less than 10mm. At the same time, the signal lead-out port of the built-in UHF sensor 1 adopts a T-type adapter, and a 50-ohm matching impedance is added to the T-type adapter. The built-in UHF sensor 1 is connected to the UHF amplification processing unit 2 through a signal cable, and the signal cable is not longer than 0.5m.

[0045] S2: Using the built-in UHF sensor 1 to collect the electromagnetic pulse signal inside the high-voltage tank circuit breaker, and extract the signal characteristics of the electromagnetic pulse signal.

[0046] Specifically, the signal characteristics include time domain characteristics, spectrum distribution characteristics and time-frequency distribution characteristics.

[0047] The UHF amplification processing unit 2 pre-processes the electromagnetic pulse signal received by the built-in UHF sensor 1, amplifies the high-frequency component in the range of 300MHz to 1500MHz in the electromagnetic pulse signal, and the average gain in the frequency band is not less than 40dB. The UHF amplification processing unit 2 is connected to the UHF signal acquisition unit 3 through a signal cable, and the cable length is not longer than 20m. The input impedance of the UHF signal acquisition unit 3 is 50 ohms, the measurement range is not less than ±10V, the sampling rate is not less than 2Gs / S, and the analog bandwidth is not less than 800MHz.

[0048] The UHF signal acquisition unit 3 is connected to the detection and diagnosis terminal 4 via an optical fiber. The detection and diagnosis terminal 4 controls the UHF signal acquisition unit 3 to complete the acquisition and storage of the electromagnetic pulse signal inside the high-voltage tank type circuit breaker, and extract the signal characteristics of the electromagnetic pulse signal, wherein the signal characteristics may include time domain characteristics, spectrum distribution characteristics, and time-frequency distribution characteristics, which are used for subsequent identification of the electromagnetic pulse signal of partial discharge inside the high-voltage tank type circuit breaker and the electromagnetic pulse signal of surface flashover of the insulating component.

[0049] S3: Compare the signal characteristics of the extracted electromagnetic pulse signal with the first standard characteristics of the electromagnetic pulse signal of partial discharge and the second standard characteristics of the electromagnetic pulse signal of the surface flashover of the insulating component to determine whether the extracted electromagnetic pulse signal is generated by the surface flashover.

[0050] For example, if the signal feature of the extracted electromagnetic pulse signal is closer to the second standard feature than the first standard feature, the extracted electromagnetic pulse signal is an electromagnetic pulse signal of surface flashover of the insulating component; if the signal feature of the extracted electromagnetic pulse signal is closer to the first standard feature than the second standard feature, the extracted electromagnetic pulse signal is an electromagnetic pulse signal of local discharge.

[0051] Specifically, the first standard feature and the second standard feature include duration, half-wave time, signal attenuation rate and signal amplitude. That is to say, by comparing the duration, half-wave time, signal attenuation rate and signal amplitude of the extracted electromagnetic pulse signal with the corresponding parameters of the electromagnetic pulse of partial discharge and the electromagnetic pulse of insulating component surface flashover, it can be determined whether the extracted electromagnetic pulse signal belongs to the electromagnetic pulse signal of partial discharge or the electromagnetic pulse signal of insulating component surface flashover.

[0052] Regarding the time domain characteristics of electromagnetic pulse signals, the electromagnetic pulse signals of partial discharges caused by internal defects in high-voltage tank circuit breakers are as follows: Figure 2 As shown, it can be seen that the duration of the electromagnetic pulse signal of partial discharge is less than 1000ns, the signal attenuation rate is large, the half-wave time is less than 200ns, and the signal amplitude is significantly attenuated during the entire signal duration. Therefore, the time domain features in the first standard feature of the electromagnetic pulse signal of partial discharge can include a duration of less than 1000ns, a signal attenuation rate greater than the first rate threshold, a half-wave time less than 200ns, and a signal amplitude less than the first amplitude threshold.

[0053] The electromagnetic pulse signal of the surface flashover of the internal insulation of the high-voltage tank circuit breaker is as follows: Figure 3 As shown, it can be seen that the electromagnetic pulse signal excited by the surface flashover has a duration higher than 1500ns, a low signal attenuation rate, and no obvious attenuation of the signal amplitude during the entire signal duration. It can be seen that the time domain characteristics of the electromagnetic pulse signal excited by the surface flashover of the internal insulating parts of the high-voltage tank circuit breaker are significantly different from the internal partial discharge. Therefore, the time domain characteristics in the second standard characteristics of the electromagnetic pulse signal excited by the surface flashover may include a duration higher than 1500ns, a signal attenuation rate lower than the second rate threshold (the second rate threshold is less than or equal to the first rate threshold), a half-wave time not less than 200ns, and a signal amplitude greater than the second amplitude threshold (the second amplitude threshold is greater than or equal to the first amplitude threshold).

[0054] Regarding the spectrum distribution characteristics of electromagnetic pulse signals, the spectrum distribution of partial discharge electromagnetic pulses caused by internal defects in high-voltage tank circuit breakers is as follows: Figure 4 As shown, it can be seen that the main frequency of the electromagnetic pulse signal excited by partial discharge is mainly distributed between 350MHz and 400MHz, and the frequency component distribution is relatively concentrated. Therefore, the spectrum distribution feature in the first standard feature of the electromagnetic pulse signal excited by partial discharge may include that the main frequency is distributed between 350MHz and 400MHz, and the frequency component distribution concentration is greater than the first concentration threshold, wherein the concentration threshold is defined as the frequency component per unit time.

[0055] The spectrum distribution of electromagnetic pulses excited by surface flashover of internal insulation parts of high-voltage tank circuit breakers is as follows: Figure 5 As shown, it can be seen that the main frequency of the electromagnetic pulse signal is mainly distributed between 200MHz and 550MHz, and the frequency component distribution range is relatively wide. It can be seen that the spectrum distribution characteristics of the electromagnetic pulse excited by the surface flashover of the internal insulation of the high-voltage tank type circuit breaker are significantly different from the internal partial discharge. Therefore, the spectrum distribution characteristics in the second standard characteristics of the electromagnetic pulse signal excited by the surface flashover can include the main frequency distribution between 200MHz and 550MHz, and the frequency component distribution concentration is less than the second concentration threshold (the second concentration threshold is less than or equal to the first concentration threshold).

[0056] Regarding the time-frequency distribution characteristics of electromagnetic pulse signals, the time-frequency distribution of partial discharge electromagnetic pulses induced by internal defects of high-voltage tank circuit breakers is as follows: Figure 6 As shown, it can be seen that the instantaneous frequency of the main frequency of the local electromagnetic pulse signal is close to 1000MHz, but decays quickly and lasts less than 200ns. The main frequency is distributed around 400MHz, decays slowly, and lasts about 100ns. Therefore, the time-frequency distribution characteristics in the first standard characteristics of the electromagnetic pulse signal excited by partial discharge can include the instantaneous frequency of the main frequency being 800MHz to 1000MHz, the signal decay rate of the instantaneous frequency of the main frequency being greater than the third rate threshold, the duration of the instantaneous frequency of the main frequency being less than 200ns, the main frequency being 300MHz to 400MHz, the signal decay rate of the main frequency being less than the fourth rate threshold, and the duration of the main frequency being 50ns to 100ns.

[0057] The time-frequency distribution of electromagnetic pulses excited by surface flashover of the internal insulation of high-voltage tank circuit breakers is as follows: Figure 7 As shown, it can be seen that the instantaneous frequency of the main frequency of the electromagnetic pulse signal excited by the surface flashover is also close to 1000MHz, but the decay is slow, the duration is close to 1500ns, the main frequency is distributed around 200MHz~400MHz, and there is no obvious decay in the entire signal duration. It can be seen that the time-frequency distribution characteristics of the electromagnetic pulse excited by the surface flashover of the internal insulating parts of the high-voltage tank circuit breaker are also significantly different from the internal partial discharge. Therefore, the time-frequency distribution characteristics in the second standard characteristics of the electromagnetic pulse signal excited by the surface flashover can include the instantaneous frequency of the main frequency of 800MHz~1000MHz, the signal decay rate of the main frequency is less than the fifth rate threshold, the duration of the main frequency is 1000ns~1500ns, the main frequency is distributed in 200MHz~400MHz, and the signal amplitude is less than the third amplitude threshold.

[0058] In this way, judging whether the extracted electromagnetic pulse signal is generated by surface flashover through the signal characteristics of three aspects (time domain characteristics, spectrum distribution characteristics and time-frequency distribution characteristics) can make the judgment result accurate.

[0059] Please refer to Figure 8 The present embodiment also provides a device for identifying surface flashover of internal insulating parts of a high-voltage tank-type circuit breaker (hereinafter referred to as: device), which includes a built-in ultra-high frequency sensor 1, an ultra-high frequency amplification processing unit 2, an ultra-high frequency signal acquisition unit 3 and a detection and diagnosis terminal 4 connected in sequence.

[0060] Specifically, the built-in UHF sensor 1 is mounted on a cover plate of the high-voltage tank type circuit breaker to collect electromagnetic pulse signals inside the high-voltage tank type circuit breaker.

[0061] The UHF amplification processing unit 2 is used to pre-process the electromagnetic pulse signal received by the built-in UHF sensor 1 .

[0062] The UHF signal acquisition unit 3 is used to acquire and store the pre-processed electromagnetic pulse signal.

[0063] The detection and diagnosis terminal 4 is used to extract the signal characteristics of the electromagnetic pulse signal, and compare the signal characteristics of the extracted electromagnetic pulse signal with the first standard characteristics of the electromagnetic pulse signal of local discharge and the second standard characteristics of the electromagnetic pulse signal of surface flashover of the insulating component to determine whether the extracted electromagnetic pulse signal is generated by surface flashover.

[0064] By adopting the method and device proposed in this embodiment, the electromagnetic pulse signal inside the circuit breaker can be monitored in real time during the factory test and on-site handover test of the high-voltage tank type circuit breaker. By extracting the time domain characteristics, spectrum distribution characteristics and time-frequency distribution characteristics of the electromagnetic pulse signal, the local discharge pulse inside the high-voltage tank type circuit breaker and the electromagnetic pulse excited by the surface flashover of the internal insulating parts can be effectively identified.

[0065] By utilizing the method and device proposed in this embodiment, surface flashover of internal insulating parts of high-voltage tank circuit breakers can be detected in a timely and accurate manner, external circuit interference can be eliminated, and the quality and efficiency of factory testing and on-site handover testing management can be effectively improved.

[0066] It should be noted that, in the absence of conflict, the features in the embodiments of this application may be combined with each other.

[0067] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for identifying surface flashover of internal insulation of a high-voltage tank circuit breaker, characterized in that: The method comprises: S1: Install a built-in UHF sensor (1) on the cover of the high-voltage tank circuit breaker; S2: using the built-in ultra-high frequency sensor (1) to collect the electromagnetic pulse signal inside the high-voltage tank circuit breaker and extract the signal characteristics of the electromagnetic pulse signal; S3: Compare the signal characteristics of the extracted electromagnetic pulse signal with the first standard characteristics of the electromagnetic pulse signal of partial discharge and the second standard characteristics of the electromagnetic pulse signal of the surface flashover of the insulating component to determine whether the extracted electromagnetic pulse signal is generated by the surface flashover.

2. The method for identifying surface flashover of internal insulation of a high-voltage tank type circuit breaker according to claim 1, characterized in that S3 include: If the signal feature of the extracted electromagnetic pulse signal is closer to the second standard feature than the first standard feature, the extracted electromagnetic pulse signal is an electromagnetic pulse signal of surface flashover of the insulating component; if the signal feature of the extracted electromagnetic pulse signal is closer to the first standard feature than the second standard feature, the extracted electromagnetic pulse signal is an electromagnetic pulse signal of partial discharge.

3. The method for identifying surface flashover of internal insulation of a high-voltage tank type circuit breaker according to claim 1, characterized in that: In S1, the built-in ultra-high frequency sensor (1) is a monopole sensor, the pole plate of the built-in ultra-high frequency sensor (1) and the shell of the high-voltage tank circuit breaker are not at the same potential, the average equivalent height of the built-in ultra-high frequency sensor (1) within the frequency range of 300MHz to 1500MHz is not less than 10mm, and the signal lead-out port of the built-in ultra-high frequency sensor (1) adopts a T-type adapter, and a 50-ohm matching impedance is added to the T-type adapter.

4. The method for identifying surface flashover of internal insulation of a high-voltage tank type circuit breaker according to claim 1, characterized in that: In S2, the signal features include time domain features, spectrum distribution features and time-frequency distribution features.

5. The method for identifying surface flashover of internal insulation of a high-voltage tank type circuit breaker according to claim 1, characterized in that: In S3, the first standard feature and the second standard feature include duration, half-wave time, signal decay rate and signal amplitude.

6. The method for identifying surface flashover of internal insulation of a high-voltage tank type circuit breaker according to claim 5, characterized in that: In S3, the time domain features in the first standard features of the electromagnetic pulse signal of the partial discharge include a duration less than 1000 ns, a signal decay rate greater than a first rate threshold, a half-wave time less than 200 ns, and a signal amplitude less than a first amplitude threshold; The time domain characteristics of the second standard characteristics of the electromagnetic pulse signal excited by surface flashover include a duration greater than 1500ns, a signal attenuation rate less than a second rate threshold, a half-wave time not less than 200ns, and a signal amplitude greater than a second amplitude threshold, wherein the second rate threshold is less than or equal to the first rate threshold, and the second amplitude threshold is greater than or equal to the first amplitude threshold.

7. The method for identifying surface flashover of internal insulation of a high-voltage tank type circuit breaker according to claim 5, characterized in that: In S3, the spectrum distribution characteristics in the first standard characteristics of the electromagnetic pulse signal excited by partial discharge include that the main frequency is distributed between 350 MHz and 400 MHz, and the frequency component distribution concentration is greater than the first concentration threshold; The spectrum distribution characteristics in the second standard characteristics of the electromagnetic pulse signal excited by surface flashover include a main frequency distribution between 200MHz and 550MHz, and a frequency component distribution concentration less than a second concentration threshold, wherein the second concentration threshold is less than or equal to the first concentration threshold.

8. The method for identifying surface flashover of internal insulation of a high-voltage tank type circuit breaker according to claim 5, characterized in that: In S3, the time-frequency distribution characteristics in the first standard characteristics of the electromagnetic pulse signal excited by partial discharge include that the instantaneous frequency of the main frequency is 800MHz to 1000MHz, the signal attenuation rate of the instantaneous frequency of the main frequency is greater than the third rate threshold, the duration of the instantaneous frequency of the main frequency is less than 200ns, the main frequency is 300MHz to 400MHz, the signal attenuation rate of the main frequency is less than the fourth rate threshold, and the duration of the main frequency is 50ns to 100ns; The time-frequency distribution characteristics of the second standard characteristics of the electromagnetic pulse signal excited by surface flashover include the instantaneous frequency of the main frequency being 800MHz~1000MHz, the signal attenuation rate of the main frequency being less than the fifth rate threshold, the duration of the main frequency being 1000ns~1500ns, the main frequency being distributed between 200MHz~400MHz, and the signal amplitude being less than the third amplitude threshold.

9. A device for identifying surface flashover of internal insulation of a high-voltage tank circuit breaker, characterized in that: The device comprises a built-in ultra-high frequency sensor (1), an ultra-high frequency amplification processing unit (2), an ultra-high frequency signal acquisition unit (3) and a detection and diagnosis terminal (4) which are connected in sequence; The built-in ultra-high frequency sensor (1) is mounted on a cover plate of the high-voltage tank type circuit breaker and is used to collect electromagnetic pulse signals inside the high-voltage tank type circuit breaker; The ultra-high frequency amplification processing unit (2) is used to pre-process the electromagnetic pulse signal received by the built-in ultra-high frequency sensor (1); The ultra-high frequency signal acquisition unit (3) is used to acquire and store the pre-processed electromagnetic pulse signal; The detection and diagnosis terminal (4) is used to extract signal characteristics of the electromagnetic pulse signal, and compare the signal characteristics of the extracted electromagnetic pulse signal with a first standard characteristic of an electromagnetic pulse signal of a partial discharge and a second standard characteristic of an electromagnetic pulse signal of a surface flashover of an insulating component, to determine whether the extracted electromagnetic pulse signal is generated by a surface flashover.

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