Solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device and risk calculation method

Abstract

A solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device and a risk degree calculation method are disclosed. In the device, a fused silica Fresnel lens focuses the solar-blind ultraviolet light beam of the discharge in the switch cabinet. A solar-blind ultraviolet SiC avalanche diode is arranged at the rear end of the fused silica Fresnel lens to receive the focused solar-blind ultraviolet light beam of the discharge and generate an optical pulse signal. A polyethylene Fresnel lens focuses the mid-infrared light beam of the discharge in the switch cabinet to generate an optical pulse signal. The field of view angles of the polyethylene Fresnel lens and the fused silica Fresnel lens are not less than 120°. A metal-type high-speed infrared pyroelectric sensor is arranged at the rear end of the polyethylene Fresnel lens to receive the focused mid-infrared light beam of the discharge and generate an infrared optical pulse signal. A signal amplifier is connected to the solar-blind ultraviolet SiC avalanche diode and the metal-type high-speed infrared pyroelectric sensor to convert and amplify the pulse signal. A microprocessor is connected to the signal amplifier to sample the ultraviolet optical pulse signal and the infrared optical pulse signal and generate fault determination information.

Description

Technical Field

[0001] The present invention belongs to the technical field of switchgear equipment detection, and particularly relates to a solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device and a risk calculation method. Background Art

[0002] Internal partial discharge or abnormal arc in switchgear equipment is an indication of abnormal insulation status and also an inducement for insulation faults or accidents. Therefore, effective monitoring of partial discharge is an important means for fault prevention. However, conventional ground wave or ultrasonic detection methods are susceptible to electromagnetic interference or acoustic interference, resulting in relatively low signal-to-noise ratio and sensitivity of discharge detection. On the other hand, due to the unknown position of the discharge source and the signal propagation path, it is difficult to quantitatively detect on-line discharge. Generally, the rate of change is used for risk assessment, making it difficult to obtain equipment operation and maintenance and overhaul decision-making suggestions, and relying heavily on subjective experience.

[0003] In addition, some relevant literatures have adopted multi-spectral optical methods for discharge monitoring, but most of them do not have the response ability in the solar-blind ultraviolet band and the mid- and far-infrared bands. Most of the detections for the mid- and far-infrared are based on the measures of component infrared temperature measurement, rather than for the infrared pulse beam itself generated by discharge. In fact, as the discharge energy increases, the thermoionization effect caused will trigger more components of mid- and far-infrared band radiation. Therefore, the energy grading of discharge can be carried out by using the intensity changes of the beam components in the solar-blind ultraviolet band and the mid- and far-infrared bands. However, the multi-spectral partial discharge detections reported in the literature mainly monitor the spectral pulse components in the visible band and the near-infrared band, and it is difficult to intrinsically reflect the occurrence and development of high-energy discharges such as medium- and high-energy spark discharges and intermittent arcs.

[0004] The above information disclosed in the background art section is only used to enhance the understanding of the background of the present invention, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide a solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device and a risk calculation method, which not only have high anti-interference ability and signal-to-noise ratio, but also can quantitatively judge the discharge risk and provide effective early warning criteria for discharge faults. To achieve the above object, the present invention provides the following technical solutions:

[0006] A solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device of the present invention includes:

[0007] A fused silica Fresnel lens that focuses the solar-blind ultraviolet beam of the discharge in the switchgear;

[0008] The solar-blind ultraviolet SiC avalanche diode is arranged at the rear end of the fused silica Fresnel lens to receive the focused solar-blind ultraviolet beam of the discharge and generate an ultraviolet light pulse signal;

[0009] The polyethylene Fresnel lens focuses the mid- and far-infrared beam of the discharge in the switch cabinet. The field of view angle formed by the polyethylene Fresnel lens and the fused silica Fresnel lens is not less than 120°;

[0010] The metal-type high-speed infrared pyroelectric sensor is arranged at the rear end of the polyethylene Fresnel lens to receive the focused mid- and far-infrared beam of the discharge and generate an infrared light pulse signal;

[0011] The signal amplifier is connected to the solar-blind ultraviolet SiC avalanche diode and the metal-type high-speed infrared pyroelectric sensor to convert and amplify the ultraviolet light pulse signal and the infrared light pulse signal;

[0012] The microprocessor is connected to the signal amplifier to sample the ultraviolet light pulse signal and the infrared light pulse signal and generate fault determination information.

[0013] In the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the microprocessor includes,

[0014] The acquisition unit is connected to the signal amplifier to acquire the ultraviolet light pulse signal and the infrared light pulse signal, and respectively pick up the pulse peak intensity and the peak time;

[0015] The digital-to-analog converter is connected to the acquisition unit for digital-to-analog conversion;

[0016] The processing unit is connected to the digital-to-analog conversion. The processing unit generates fault determination information based on the pulse peak intensity and the peak time.

[0017] In the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the response speed of the solar-blind ultraviolet SiC avalanche diode is not lower than the microsecond level, the quantum efficiency is not lower than 30%, and the response band range is from 190 nm to 285 nm.

[0018] In the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the response speed of the metal-type high-speed infrared pyroelectric sensor is at the microsecond level, the response band range covers 1.2 μm to 10 μm, and the temperature measurement range covers 10°C to 100°C.

[0019] In the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the signal amplifier includes an I-U conversion unit, a voltage follower and a voltage amplification unit, and the voltage amplification gain is not less than 20 dB.

[0020] In the described dual-channel discharge monitoring device for solar-blind ultraviolet and mid-infrared, the fused silica Fresnel lens, solar-blind ultraviolet SiC avalanche diode, polyethylene Fresnel lens, metal-type high-speed infrared pyroelectric sensor, signal amplifier, and microprocessor are integrated on a circuit board, and the circuit board is fixed on a fixed bracket.

[0021] In the described dual-channel discharge monitoring device for solar-blind ultraviolet and mid-infrared, the discharge detection device is adsorbed on the inner wall of the switch cabinet by magnetic attraction.

[0022] In the described dual-channel discharge monitoring device for solar-blind ultraviolet and mid-infrared, the magnetic attraction method is neodymium iron boron magnetic attraction.

[0023] A detection method based on the described dual-channel discharge monitoring device for solar-blind ultraviolet and mid-infrared includes the following steps.

[0024] The fused silica Fresnel lens focuses the solar-blind ultraviolet beam of the discharge in the switch cabinet, and the solar-blind ultraviolet SiC avalanche diode is arranged at the rear end of the fused silica Fresnel lens to receive the focused solar-blind ultraviolet beam of the discharge and generate an ultraviolet light pulse signal.

[0025] The polyethylene Fresnel lens focuses the mid- and far-infrared beam of the discharge in the switch cabinet, and the metal-type high-speed infrared pyroelectric sensor is arranged at the rear end of the polyethylene Fresnel lens to receive the focused mid- and far-infrared beam of the discharge and generate an infrared light pulse signal.

[0026] The signal amplifier is connected to the solar-blind ultraviolet SiC avalanche diode and the metal-type high-speed infrared pyroelectric sensor to convert and amplify the ultraviolet light pulse signal and the infrared light pulse signal.

[0027] The microprocessor is connected to the signal amplifier to sample the ultraviolet light pulse signal and the infrared light pulse signal and generate fault determination information, where

[0028] Calculate the average intensity q of the ultraviolet light pulses within a unit time T UV and the average intensity q of the infrared light pulses IR , calculate the average intensity t of the ultraviolet light pulses within a unit time UV and the active duration t of the infrared pulses IR , where

[0029]

[0030]

[0031] t UY =(T / Δt) -1 ·n UV ;

[0032] t IR= (T / Δt) -1 ·n IR ;

[0033] Wherein, T is an integer multiple of the power frequency voltage period; n UV and n IR are: divide the unit time T into (T / Δt) equal parts at equal interval time (Δt). Among all the time equal parts, the number of equal parts where the ultraviolet pulse intensity and the infrared pulse exceed the threshold Th are n UV and n IR ;

[0034] Discharge fault determination: ① When q UV < threshold a1, it is determined that the fault is no discharge, and at this time the risk level R = 0; ② When q UV ≥ threshold a1, and q IR < threshold b, it is determined that the fault is low-energy partial discharge, and at this time the risk level R = 1; ③ When q UV ≥ threshold a1, and q IR ≥ threshold b, when t UV / t IR ∈ (0, threshold c1], it is determined as high-energy short-circuit type arc discharge, and at this time the risk level R = 4; when t UV / t IR ∈ (threshold c1, 1), it is determined as high-energy intermittent type arc discharge, and at this time the risk level R = 3; when t UV / t IR ∈ [1, threshold c2), it is determined as medium-energy partial discharge, and at this time the risk level R = 2; when t UV / t IR ∈ [threshold c2, ∞), it is determined as low-energy partial discharge, and at this time the risk level R = 1.

[0035] In the said detection, the threshold a1 is set according to 1.1 to 1.2 times of the on-site background noise level of the ultraviolet light path detection system, the threshold b is set according to 1.2 to 1.3 times of the allowable temperature level under the rated operating power of the switch cabinet, the threshold c1 is set within the range of 0.3 to 0.7, and the threshold c2 is set within the range of 1.3 to 1.7.

[0036] In the above technical solution, a discharge monitoring device and a risk calculation method for a solar-blind SiC avalanche diode and a high-speed pyroelectric tube provided by the present invention have the following beneficial effects: The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device uses solar-blind single-photon devices and infrared pyroelectric devices to detect discharges, avoiding electromagnetic, harmonic, and acoustic interference, and improving the confidence of discharge detection and the defect detection ability; The discharge risk quantification monitoring method of the solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device is based on the following principle, that is, low-energy discharges are mainly dominated by ultraviolet radiation, while high-energy discharges have a sudden increase in infrared radiation. By using the above principle to establish a dual-channel spectral signal judgment logic, the discharge energy level and risk can be quantitatively analyzed; The detection device proposed by the present invention has a simple structure and is easy to install, and can be deployed in fault-prone locations such as the switchgear busbar chamber and cable chamber, facilitating fault location and troubleshooting. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a schematic structural diagram of an embodiment of the solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device of the present invention;

[0039] Figure 2 It is a schematic diagram of an installation embodiment of the solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device in a switchgear busbar of the present invention;

[0040] Figure 3 It is a schematic diagram of the logical structure of the discharge risk monitoring method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] In order to make the purpose, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention to be protected, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] It should be noted that like reference numerals and letters indicate like items in the following figures. Therefore, once an item is defined in one figure, it is not necessary to further define and explain it in subsequent figures.

[0044] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0045] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0046] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "beneath" and "under" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0048] To enable those skilled in the art to better understand the technical solution of the present invention, as Figures 1 to 3 shown,

[0049] The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device includes,

[0050] a fused silica Fresnel lens 1 that focuses the solar-blind ultraviolet beam of the discharge in the switch cabinet;

[0051] a solar-blind ultraviolet SiC avalanche diode 2 that is arranged at the rear end of the fused silica Fresnel lens 1 to receive the focused solar-blind ultraviolet beam of the discharge and generate an ultraviolet light pulse signal;

[0052] a polyethylene Fresnel lens 3 that focuses the mid- and far-infrared beam of the discharge in the switch cabinet, and the field of view angle formed by the polyethylene Fresnel lens 3 and the fused silica Fresnel lens 1 is not less than 120°;

[0053] a metallic high-speed infrared pyroelectric sensor 4 that is arranged at the rear end of the polyethylene Fresnel lens 3 to receive the focused mid- and far-infrared beam of the discharge and generate an infrared light pulse signal;

[0054] a signal amplifier 5 that is connected to the solar-blind ultraviolet SiC avalanche diode 2 and the metallic high-speed infrared pyroelectric sensor 4 to convert and amplify the ultraviolet light pulse signal and the infrared light pulse signal;

[0055] a microprocessor 6 that is connected to the signal amplifier 5 to sample the ultraviolet light pulse signal and the infrared light pulse signal and generate fault determination information.

[0056] In a preferred embodiment of the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the microprocessor 6 includes,

[0057] an acquisition unit that is connected to the signal amplifier 5 to acquire the ultraviolet light pulse signal and the infrared light pulse signal, and respectively pick up the pulse peak intensity and peak time;

[0058] an analog-to-digital converter that is connected to the acquisition unit for analog-to-digital conversion;

[0059] a processing unit that is connected to the analog-to-digital conversion, and the processing unit generates fault determination information based on the pulse peak intensity and peak time.

[0060] In a preferred embodiment of the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the response speed of the solar-blind ultraviolet SiC avalanche diode 2 is not lower than the microsecond level, the quantum efficiency is not lower than 30%, and the response band range is from 190 nm to 285 nm.

[0061] In a preferred embodiment of the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the response speed of the metallic high-speed infrared pyroelectric sensor 4 is at the microsecond level, the response band range covers 1.2 μm to 10 μm, and the temperature measurement range covers 10°C to 100°C.

[0062] In a preferred embodiment of the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the signal amplifier 5 includes an I-U conversion unit, a voltage follower and a voltage amplification unit, and the voltage amplification gain is not less than 20 dB.

[0063] In a preferred embodiment of the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the fused silica Fresnel lens 1, the solar-blind ultraviolet SiC avalanche diode 2, the polyethylene Fresnel lens 3, the metal-type high-speed infrared pyroelectric sensor 4, the signal amplifier 5 and the microprocessor 6 are integrated on a circuit board 7, and the circuit board 7 is fixed on a fixed bracket.

[0064] In a preferred embodiment of the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the discharge detection device is adsorbed on the inner wall of the switch cabinet through a magnetic attraction method.

[0065] In a preferred embodiment of the described solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, the magnetic attraction method is neodymium iron boron magnetic attraction.

[0066] In one embodiment, the solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device includes a solar-blind ultraviolet SiC avalanche diode 2, a metallic high-speed infrared pyroelectric sensor 4, a fused silica Fresnel lens 1, a polyethylene Fresnel lens 3, a fixing bracket, a signal amplifier 5, and a microprocessor 6 with an AD function. The response speed of the solar-blind ultraviolet SiC avalanche diode 2 is not lower than the microsecond level, the quantum efficiency is not lower than 30%, and the response wavelength range is from 190 nm to 285 nm, which is used to convert the discharge radiation ultraviolet photons into current pulse signals. The response speed of the metallic high-speed infrared pyroelectric sensor 4 is at the microsecond level, the response wavelength range covers at least 1.2 μm to 10 μm, and the temperature measurement range covers at least 10 °C to 100 °C, which is used to convert the discharge infrared radiation into current pulse signals. The fused silica Fresnel lens 1 is installed at the front end of the solar-blind ultraviolet SiC avalanche diode 2 and is used to focus the solar-blind ultraviolet beam of the discharge in the switch cabinet. The above-mentioned polyethylene Fresnel lens 3 is installed at the front end of the metallic high-speed infrared pyroelectric sensor 4 and is used to focus the mid- and far-infrared beam of the discharge in the switch cabinet. The field-of-view angle range of the above two Fresnel lenses is not less than a 120° cone angle. The signal amplifier 5 includes I-U conversion, voltage following, and voltage amplification functions, and the voltage amplification gain is not less than 20 dB, which is used to convert and amplify the current pulse signals output by the above-mentioned solar-blind ultraviolet SiC avalanche diode 2 and metallic high-speed infrared pyroelectric sensor 4. The fixing bracket is used to fix the circuit board 7 composed of the above two Fresnel lenses, two photoelectric sensors, the signal amplification unit, and the microprocessor 6, and the discharge detection device is adsorbed on the inner wall of the switch cabinet by an aluminum-nickel-boron magnetic attraction method. The microprocessor 6 with an AD function is used, on the one hand, to sample the two-channel photoelectric pulse signals and pick up the pulse peak intensity (q) and peak time (t), and on the other hand, to execute the diagnostic warning algorithm. In another example, a partial discharge-arc fault simulation platform was built in the laboratory, and this device was used to conduct actual measurements on it, and the diagnostic warning algorithm was executed to illustrate the working process of data sampling, processing, and fault diagnosis of the present invention, and to verify the correct judgment rate of this device. The discrimination process is as shown in Figure 3 shown.

[0067] In another embodiment, the fixing bracket adopts an elbow structure, and the combinations of the two lenses and sensors (the fused silica Fresnel lens 1 installed at the front end of the solar-blind ultraviolet SiC avalanche diode 2 is one group, and the polyethylene Fresnel lens 3 installed at the front end of the metallic high-speed infrared pyroelectric sensor 4 is the second group) are placed on both sides respectively. The signal amplification unit is connected to the two combinations, and after converting and amplifying the data, it is transmitted to the microprocessor 6 with an AD function. The microprocessor 6 collects the data signals and executes the warning diagnosis. The signal amplification unit and the microprocessor 6 constitute the circuit board 7 and are installed on the fixing bracket. The detection device, the acquisition device, and the diagnosis device are integrated, and the equipment has a simple structure and is convenient for installation. It can be deployed in fault-prone parts such as the switch cabinet busbar chamber and cable chamber, which is convenient for fault location and troubleshooting.

[0068] In another example, as Figure 2 shown, when the device is deployed in failure-prone parts such as the switchgear busbar chamber and cable chamber, the sensing device can be selected to be installed at positions 1, 2, and 3 in Figure 2 . In this example, the device is adsorbed to the inner wall of the switchgear housing by means of an aluminum-iron-boron magnetic attraction. The polyethylene Fresnel lens 3 refracts the signal to the sensor through focusing, and divides the detection area into several bright areas and dark areas, so that the objects entering the detection area can generate variable pyroelectric infrared signals on the metal high-speed pyroelectric infrared sensor 4 in the form of temperature changes. Subsequently, the metal high-speed pyroelectric infrared sensor 4 converts the discharge infrared radiation into current pulse signals. The conversion of ultraviolet light is similar.

[0069] As Figure 2 shown, taking the layout method of the sensor in the switchgear busbar chamber as an example to illustrate the application method of the present invention, three points in the figure are selected as the typical layout positions of the sensor. The field-of-view angles of both types of Fresnel lenses are greater than the 120° cone angle, and can cover most of the faults in the busbar chamber.

[0070] In order to simulate partial and arc discharges in power equipment and obtain the infrared and ultraviolet signals of the discharges, a partial discharge - arc fault simulation platform is built. The test platform consists of a test transformer, a test cavity, a discharge defect model, and a signal detection module, and realizes the synchronous detection of the discharge signals inside the test cavity.

[0071] A method for calculating the risk degree based on the above-mentioned solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device includes the following steps.

[0072] The fused silica Fresnel lens 1 focuses the solar-blind ultraviolet light beam of the discharge in the switchgear. The solar-blind ultraviolet SiC avalanche diode 2 is arranged at the rear end of the fused silica Fresnel lens 1 to receive the focused solar-blind ultraviolet light beam of the discharge and generate ultraviolet light pulse signals.

[0073] The polyethylene Fresnel lens 3 focuses the mid-infrared light beam of the discharge in the switchgear. The metal high-speed pyroelectric infrared sensor 4 is arranged at the rear end of the polyethylene Fresnel lens 3 to receive the focused mid-infrared light beam of the discharge and generate infrared light pulse signals.

[0074] The signal amplifier 5 is connected to the solar-blind ultraviolet SiC avalanche diode 2 and the metal high-speed pyroelectric infrared sensor 4 to convert and amplify the ultraviolet light pulse signals and infrared light pulse signals.

[0075] The microprocessor 6 is connected to the signal amplifier 5 to sample the ultraviolet light pulse signals and infrared light pulse signals and generate fault determination information, where

[0076] Calculate the average intensity q of ultraviolet light pulses within the unit time T UV and the average intensity q of infrared light pulses IR ; calculate the average intensity t of ultraviolet light pulses within the unit time UV and the active duration t of infrared pulses IR , where

[0077]

[0078]

[0079] t UV =(T / Δt) -1 ·n UV ;

[0080] t IR =(T / Δt) -1 ·n IR ;

[0081] where T is an integer multiple of the power frequency voltage period; n UV and n IR are: divide the unit time T into (T / Δt) equal parts at equal interval time (Δt). Among all the time equal parts, the number of equal parts where the ultraviolet pulse intensity and the infrared pulse exceed the threshold Th are n UV and n IR respectively;

[0082] Discharge fault determination: ① When q UV < threshold a1, it is determined that the fault is no discharge, and at this time the risk level R = 0; ② When q UV ≥ threshold a1 and q IR < threshold b, it is determined that the fault is low-energy partial discharge, and at this time the risk level R = 1; ③ When q UV ≥ threshold a1 and q IR ≥ threshold b, when t UV / t IR ∈(0, threshold c1], it is determined as high-energy short-circuit type arc discharge, and at this time the risk level R = 4; when t UV / t IR ∈(threshold c1, 1), it is determined as high-energy intermittent type arc discharge, and at this time the risk level R = 3; when t UV / t IR ∈[1, threshold c2), it is determined as medium-energy partial discharge, and at this time the risk level R = 2; when t UV / t IR ∈[threshold c2, ∞), it is determined as low-energy partial discharge, and at this time the risk level R = 1.

[0083] In the preferred embodiment of the described risk calculation method, the threshold value a1 is set according to 1.1 to 1.2 times the on-site background noise level of the ultraviolet light path detection system, the threshold value b is set according to 1.2 to 1.3 times the allowable temperature level under the rated operating power of the switch cabinet, the threshold value c1 is set within the range of 0.3 to 0.7, and the threshold value c2 is set within the range of 1.3 to 1.7.

[0084] In the preferred embodiment of the described risk calculation method, the microprocessor 6 with AD function serves as the signal detection module. On the one hand, it is used to sample two-way photoelectric pulse signals and pick up the pulse peak intensity (q) and peak time (t). On the other hand, it executes the diagnostic warning algorithm.

[0085] As Figure 3 shown, the microprocessor 6 samples the photoelectric pulse signal and calculates the average intensity q of the ultraviolet light pulse and infrared light pulse within the unit time T UV and q IR :

[0086]

[0087]

[0088] Calculate the active duration t of the ultraviolet light pulse and infrared pulse within the unit time UV and t IR :

[0089] t UV =(T / Δt) -1 ·n UV ;

[0090] t IR -(T / Δt) -1 ·n IR ;

[0091] In the above formula, T takes an integer multiple of the power frequency voltage period; n UV and n IR have the following meanings: Divide the unit time T into (T / Δt) equal parts at equal intervals (Δt). Among all the time equal parts, the number of equal parts where the ultraviolet pulse intensity and infrared pulse exceed the threshold value Th are n UV and n IR .

[0092] The microprocessor 6 determines the discharge fault:

[0093] ① When q UV < threshold value a1, at this time, it is determined that the fault is no discharge, and the risk level R = 0;

[0094] ② When q UV ≥ threshold value a1, and qIR When it is less than the threshold value b, it is determined that the fault is low-energy partial discharge at this time, and the risk level R = 1;

[0095] ③ When q UV ≥ the threshold value a1, and q IR ≥ the threshold value b, further determination is carried out:

[0096] When t UV / t IR ∈(0, the threshold value c1], it is determined as high-energy short-circuit type arc discharge at this time, and the risk level R = 4;

[0097] When t UV / t IR ∈(the threshold value c1, 1), it is determined as high-energy intermittent type arc discharge at this time, and the risk level R = 3; when tUV / tIR ∈ [1, the threshold value c2), it is determined as medium-energy partial discharge at this time, and the risk level R = 2;

[0098] When t UV / t IR ∈[the threshold value c2, ∞), it is determined as low-energy partial discharge at this time, and the risk level R = 1.

[0099] Taking the surface discharge as an example, laboratory actual measurement found that when the applied voltage is lower than 8.8 kV, the discharge amount is relatively low and the discharge amount shows a steady growth trend with the increase of the applied voltage. At this time, it is the low-energy discharge stage; when the applied voltage is between 8.8 kV and 13 kV, the discharge amount suddenly increases, and the discharge develops into the medium-energy discharge stage; after the applied voltage is greater than 13 kV, with the increase of the applied voltage, the discharge amount increases significantly, and the discharge is close to the breakdown state, which is the high-energy intermittent arc discharge stage; when the voltage continues to increase, a channel from high voltage to low voltage will be formed, which can also be called the through arc channel at this time. That is, after the discharge breakdown, it is called the high-energy short-circuit type arc discharge.

[0100] In the discharge determination, the given descriptions of each threshold value are as follows. First, measure the background noise. Before the discharge test, the voltage regulating platform should be closed first, and the background noise level Un in each wave band should be recorded before pressurization, and the background noise in different wave bands should be filtered out respectively during the process of test data acquisition, so as to ensure that the obtained pulse signals are all generated by partial discharge. It is determined that Un < 2Mv. The allowable temperature under the rated operating power of the switch cabinet is 24 °C.

[0101] Through experimental determination, the threshold value a1 is set according to 1.15 times of the on-site background noise level of the ultraviolet light path detection system, the threshold value b is set according to 1.25 times of the allowable temperature level under the rated operating power of the switch cabinet, the threshold value c1 is set to 0.5, and the threshold value c2 is set to 1.5.

[0102] After verification through repeated experiments, the accuracy rate of the device for fault determination and early warning reaches 96%.

[0103] Finally, it should be noted that the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0104] Only some exemplary embodiments of the present invention have been described above by way of illustration. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device, characterized in that, It includes, a fused silica Fresnel lens that focuses the discharge solar-blind ultraviolet beam inside the switchgear cabinet; a solar-blind ultraviolet SiC avalanche diode disposed at the rear end of the fused silica Fresnel lens to receive the focused discharge solar-blind ultraviolet beam and generate an ultraviolet light pulse signal; a polyethylene Fresnel lens that focuses the discharge mid-infrared beam inside the switchgear cabinet, and the field of view angle formed by the polyethylene Fresnel lens and the fused silica Fresnel lens is not less than 120°; a metal-type high-speed infrared pyroelectric sensor disposed at the rear end of the polyethylene Fresnel lens to receive the focused discharge mid-infrared beam and generate an infrared light pulse signal; a signal amplifier connected to the solar-blind ultraviolet SiC avalanche diode and the metal-type high-speed infrared pyroelectric sensor to convert and amplify the ultraviolet light pulse signal and the infrared light pulse signal; a microprocessor connected to the signal amplifier to sample the ultraviolet light pulse signal and the infrared light pulse signal and generate fault determination information; Wherein, the microprocessor is configured to: calculate the average intensity of ultraviolet light pulses within a unit time T and the average intensity of infrared light pulses , calculate the average intensity of ultraviolet light pulses within a unit time and the active duration of infrared pulses , wherein, ； ； ； ； where T is an integer multiple of the power frequency voltage period; n UV and n IR are: divide the unit time T into (T / Δt) equal parts at equal interval time (Δt). Among all the time equal parts, the number of equal parts where the ultraviolet pulse intensity and the infrared pulse exceed the threshold Th are n UV and n IR ; According to the average intensity of the ultraviolet light pulse , the average intensity of the infrared light pulse , calculate the average intensity of the ultraviolet light pulse per unit time and the active duration of the infrared pulse to generate fault determination information.

2. The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to claim 1, characterized in that The microprocessor includes, an acquisition unit connected to the signal amplifier to acquire the ultraviolet light pulse signal and the infrared light pulse signal, and respectively pick up the pulse peak intensity and the peak time; an analog-to-digital converter connected to the acquisition unit for analog-to-digital conversion; a processing unit connected to the analog-to-digital conversion, and the processing unit generates fault determination information based on the pulse peak intensity and the peak time.

3. The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to claim 1, characterized in that, The response speed of the solar-blind ultraviolet SiC avalanche diode is not less than the microsecond level, the quantum efficiency is not less than 30%, and the response wavelength range is from 190 nm to 285 nm.

4. The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to claim 1, characterized in that, The response speed of the metal-type high-speed infrared pyroelectric sensor is at the microsecond level, the response wavelength range covers 1.2 μm to 10 μm, and the temperature measurement range covers 10°C to 100°C.

5. The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to claim 1, characterized in that, The signal amplifier includes an I-U conversion unit, a voltage follower and a voltage amplification unit, and the voltage amplification gain is not less than 20 dB.

6. The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to claim 1, characterized in that, The fused silica Fresnel lens, the solar-blind ultraviolet SiC avalanche diode, the polyethylene Fresnel lens, the metal-type high-speed infrared pyroelectric sensor, the signal amplifier and the microprocessor are integrated on a circuit board, and the circuit board is fixed on a fixed bracket.

7. The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to claim 1, characterized in that, The discharge monitoring device is adsorbed on the inner wall of the switchgear cabinet by a magnetic adsorption method.

8. The solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to claim 7, characterized in that, The magnetic adsorption method is Alnico magnetic adsorption.

9. A method for calculating the risk level of a solar-blind ultraviolet and mid-infrared dual-channel discharge monitoring device according to any one of claims 1-8, characterized in that, It includes the following steps, The fused silica Fresnel lens focuses the discharge solar-blind ultraviolet beam inside the switchgear cabinet, and the solar-blind ultraviolet SiC avalanche diode is disposed at the rear end of the fused silica Fresnel lens to receive the focused discharge solar-blind ultraviolet beam and generate an ultraviolet light pulse signal; The polyethylene Fresnel lens focuses the discharge mid-infrared beam inside the switchgear cabinet, and the metal-type high-speed infrared pyroelectric sensor is disposed at the rear end of the polyethylene Fresnel lens to receive the focused discharge mid-infrared beam and generate an infrared light pulse signal; The signal amplifier is connected to the solar-blind ultraviolet SiC avalanche diode and the metal-type high-speed infrared pyroelectric sensor to convert and amplify the ultraviolet light pulse signal and the infrared light pulse signal; The microprocessor is connected to the signal amplifier to sample the ultraviolet light pulse signal and the infrared light pulse signal and generate fault determination information, where, Calculate the average intensity of ultraviolet light pulses within a unit time T and the average intensity of infrared light pulses ; calculate the average intensity of ultraviolet light pulses within a unit time and the active duration of infrared pulses , where ; ; ; ; where T is an integer multiple of the power frequency voltage period; n UV and n IR are: divide the unit time T into (T / Δt) equal parts at equal interval times (Δt). Among all the time equal parts, the number of equal parts where the ultraviolet pulse intensity and the infrared pulse exceed the threshold Th are n UV and n IR ; Discharge fault determination: ① When q UV < threshold a1, it is determined that the fault is no discharge, and the risk level R = 0 at this time; ② When q UV ≥ threshold a1 and q IR < threshold b, it is determined that the fault is low-energy partial discharge, and the risk level R = 1 at this time; ③ When q UV ≥ threshold a1 and q IR ≥ threshold b, when t UV / t IR ∈(0, threshold c1], it is determined as high-energy short-circuit type arc discharge, and the risk level R = 4 at this time; when t UV / t IR ∈(threshold c1, 1), it is determined as high-energy intermittent type arc discharge, and the risk level R = 3 at this time; when t UV / t IR ∈[1, threshold c2), it is determined as medium-energy partial discharge, and the risk level R = 2 at this time; when t UV / t IR ∈[threshold c2, ∞), it is determined as low-energy partial discharge, and the risk level R = 1 at this time.

10. The risk calculation method according to claim 9, wherein, The threshold value a1 is set according to 1.1 to 1.2 times the on-site background noise level of the ultraviolet light path detection system, the threshold value b is set according to 1.2 to 1.3 times the allowable temperature level under the rated operating power of the switch cabinet, the threshold value c1 is set within the range of 0.3 to 0.7, and the threshold value c2 is set within the range of 1.3 to 1.7.

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