Switch cabinet partial discharge monitoring system, method, equipment and medium

Abstract

The invention discloses a partial discharge monitoring system, method, equipment and medium for a switch cabinet, and belongs to the technical field of insulation state monitoring of high-voltage electrical equipment, and the partial discharge monitoring system comprises an NO2 gas detection module, a pulse current signal acquisition module, a signal processing module, a data transmission module, a data analysis and diagnosis module and a user display and alarm module. According to the invention, by integrating dual monitoring technologies of NO2 gas detection and transient current signal acquisition and combining signal processing, data transmission, data analysis and diagnosis and a user display and alarm module, high-precision and high-reliability online monitoring of partial discharge of the high-voltage switch cabinet is realized; the defects that a traditional single method is prone to electromagnetic interference, low in sensitivity and not suitable for long-term online monitoring are overcome, and the anti-interference capacity, diagnosis accuracy and operation stability of a monitoring system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation status monitoring of high-voltage electrical equipment, and in particular to a switch cabinet partial discharge monitoring system, method, equipment and medium. Background Art

[0002] As a key power transmission and distribution equipment in the power system, high-voltage switchgear is widely used in substations, power plants and industrial enterprise distribution facilities. It undertakes important functions such as the on-off and transmission of electric energy, the protection of electrical equipment and fault isolation. Its safety and reliability are crucial to the stable operation of the entire power system.

[0003] However, high-voltage switchgear has a complex internal structure and dense equipment. During long-term operation, it is inevitably affected by environmental factors (such as moisture and dust), manufacturing process defects (such as bubbles, impurities, and cracks in the insulation material), and thermal, electrical, or mechanical stress during operation, which can lead to defects or tiny air gaps inside the insulation material. These insulation defects are very likely to cause partial discharge when exposed to high-voltage alternating electric fields for a long time. Although the discharge energy of partial discharge is weak at first, as the defects gradually expand and the number of discharges increases, it will gradually lead to the deterioration of the insulation material until a serious insulation breakdown accident occurs, causing equipment damage, and may even cause more serious power outages and threats to personal safety, causing huge economic losses and safety risks to power companies and society. Therefore, the development of an efficient, accurate, easy-to-implement, and economical online monitoring device for partial discharge in high-voltage switchgear has become one of the technical problems that need to be urgently solved in the field of insulation fault diagnosis in power systems. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to propose an online monitoring system for partial discharge of high-voltage switchgear based on the combination of NO2 sensor and transient current method, so as to solve the problems of high cost, low sensitivity, poor anti-interference and inability to conduct long-term online stable monitoring in the existing technology, and improve the real-time monitoring accuracy and stability of the insulation status of the switchgear.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a switch cabinet partial discharge monitoring system, which includes the following steps:

[0007] NO2 gas detection module, pulse current signal acquisition module, signal processing module, data transmission module, data analysis and diagnosis module and user display and alarm module; the NO2 gas detection module is used to obtain the NO2 gas concentration in the switch cabinet; the pulse current signal acquisition module is used to obtain the high-frequency pulse signal in the switch cabinet; the signal processing module is used to process the NO2 gas concentration and the high-frequency pulse signal to determine the spectral characteristics of the high-frequency pulse signal; the data transmission module is used to transmit the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal to the remote background monitoring platform; the data analysis and diagnosis module is used to determine the judgment result of the partial discharge fault based on the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal; the user display and alarm module is used to visualize the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal, and determine the alarm measures according to the judgment result.

[0008] As a preferred solution of the switch cabinet partial discharge monitoring system described in the present invention, the method of obtaining a high-frequency pulse signal within the switch cabinet includes: using a capacitive coupling sensor to form a capacitive coupling structure with a live phase line to obtain a discharge pulse signal within the switch cabinet; filtering out low-frequency interference signals from the discharge pulse signal while retaining the high-frequency pulse signal; and digitizing the high-frequency pulse signal to obtain a digitized high-frequency pulse signal. The beneficial effect of this preferred technical solution is that the capacitive coupling sensor forms a non-contact coupling structure with the live phase line, combined with a high-frequency filter circuit to filter out low-frequency interference and retain the high-frequency pulse signal, thereby achieving accurate acquisition of the transient current of the partial discharge, obtaining high-quality discharge characteristic signals without affecting the normal operation of the switch cabinet, and providing a reliable data basis for subsequent spectrum analysis.

[0009] As a preferred solution of the switch cabinet partial discharge monitoring system described in the present invention, the NO2 gas concentration and the high-frequency pulse signal are processed to determine the spectral characteristics of the high-frequency pulse signal, including: caching the digitized NO2 gas concentration and the digitized high-frequency pulse signal, and transmitting the digitized NO2 gas concentration and the digitized high-frequency pulse signal; performing FFT spectrum analysis on the digitized high-frequency pulse signal to obtain the spectral characteristics of the high-frequency pulse signal.

[0010] As a preferred embodiment of the switchgear partial discharge monitoring system described in the present invention, determining the partial discharge fault diagnosis result based on the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal includes: determining a first partial discharge fault diagnosis result based on the spectral characteristics of the high-frequency pulse signal; and verifying the first partial discharge fault diagnosis result using the NO2 gas concentration to determine a second partial discharge fault diagnosis result. This preferred technical solution has the beneficial effect of effectively avoiding misdiagnosis that may result from a single measurement method through a dual mechanism of first performing preliminary fault detection based on the spectral characteristics of the high-frequency pulse signal and then performing secondary verification using NO2 gas concentration measurement, thereby improving diagnostic accuracy and reliability.

[0011] As a preferred solution of the switch cabinet partial discharge monitoring system described in the present invention, the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal are visualized, and alarm measures are determined based on the judgment results, including: providing a digitized concentration real-time value and a data curve display for the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal; by setting the alarm threshold of the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal, the alarm measures are determined based on the comparison of the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal with the alarm threshold.

[0012] As a preferred embodiment of the switch cabinet partial discharge monitoring system described in the present invention, the method of obtaining the NO2 gas concentration in the switch cabinet includes: using a NO2 sensor to capture the NO2 gas in the switch cabinet to obtain a current signal; using a constant potential circuit to provide an operating voltage for the NO2 sensor; converting the current signal into a voltage signal based on a current-voltage conversion circuit, and amplifying the voltage signal using a signal amplification circuit to obtain an amplified voltage signal; and digitizing the amplified voltage signal using a high-speed analog-to-digital conversion chip to obtain a digitized NO2 gas concentration. The beneficial effect of this preferred technical solution is that by using a constant potential circuit to provide a stable operating voltage, and combining the current-voltage conversion circuit and the signal amplification circuit to process weak current signals, the NO2 gas generated by partial discharge can be converted into a high-precision digital signal, thereby achieving indirect monitoring of minor breakdowns of insulating materials, avoiding the influence of electromagnetic interference on traditional electrical measurement methods, and improving detection sensitivity and anti-interference capabilities.

[0013] As a preferred solution of the switch cabinet partial discharge monitoring system described in the present invention, the data transmission module adopts an RS485 interface or a wireless communication module to transmit the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal to a remote background monitoring platform.

[0014] Another object of the present invention is to provide a method for monitoring partial discharge of a switch cabinet.

[0015] To solve the above technical problems, the present invention provides the following technical solutions: a method for monitoring partial discharge in a switch cabinet, comprising: obtaining the NO2 gas concentration in the switch cabinet; obtaining a high-frequency pulse signal in the switch cabinet; processing the NO2 gas concentration and the high-frequency pulse signal to determine the spectral characteristics of the high-frequency pulse signal; transmitting the spectral characteristics of the NO2 gas concentration and the high-frequency pulse signal to a remote background monitoring platform; determining the judgment result of a partial discharge fault based on the spectral characteristics of the NO2 gas concentration and the high-frequency pulse signal; visualizing the spectral characteristics of the NO2 gas concentration and the high-frequency pulse signal, and determining alarm measures based on the judgment result.

[0016] The present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein the processor implements the steps of a switch cabinet partial discharge monitoring system when executing the computer program.

[0017] The present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, the steps of the switch cabinet partial discharge monitoring system are implemented.

[0018] Beneficial effects of the present invention: The present invention integrates the dual monitoring technology of NO2 gas detection and transient current signal acquisition, and combines signal processing, data transmission, data analysis and diagnosis, and user display and alarm modules to achieve high-precision, high-reliability online monitoring of partial discharge of high-voltage switchgear, overcoming the shortcomings of traditional single methods that are susceptible to electromagnetic interference, low sensitivity, and unsuitable for long-term online monitoring, and improves the anti-interference ability, diagnostic accuracy and operational stability of the monitoring system; effectively reduces the false alarm rate through the dual verification mechanism and improves the credibility of the monitoring results; not only reduces the operation and maintenance costs of high-voltage switchgear, reduces the workload of manual inspections, but also improves the safety and reliability of power system operation, provides a scientific basis for preventive maintenance, and effectively prevents major safety accidents caused by insulation failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0020] Figure 1 This is a flowchart of the online partial discharge monitoring system for air-type switchgear provided by one embodiment of the present invention.

[0021] Figure 2 This is a structural diagram of a transient current detection circuit provided by an embodiment of the present invention.

[0022] Figure 3 A schematic diagram of the structure of a computer device provided in one embodiment of the present invention.

[0023] Figure 4 A frequency domain diagram in a non-discharge state provided by an embodiment of the present invention.

[0024] Figure 5 This is a frequency domain diagram of a slight discharge provided by an embodiment of the present invention.

[0025] Figure 6 This is a frequency domain diagram under moderate discharge conditions provided by one embodiment of the present invention.

[0026] Figure 7 This is a frequency domain diagram of a severe discharge situation provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0030] Example 1, reference Figure 1 , which is the first embodiment of the present invention, provides a switch cabinet partial discharge monitoring system, comprising:

[0031] NO2 gas detection module, pulse current signal acquisition module, signal processing module, data transmission module, data analysis and diagnosis module, and user display and alarm module.

[0032] In an embodiment of the present invention, the NO2 gas detection module is used to obtain the NO2 gas concentration in the switch cabinet.

[0033] In an embodiment of the present invention, the pulse current signal acquisition module is used to acquire high-frequency pulse signals in the switch cabinet.

[0034] In the embodiment of the present invention, the signal processing module is used to process the NO2 gas concentration and the high-frequency pulse signal to determine the frequency spectrum characteristics of the high-frequency pulse signal.

[0035] In the embodiment of the present invention, the data transmission module is used to transmit the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal to the remote background monitoring platform.

[0036] In the embodiment of the present invention, the data analysis and diagnosis module is used to determine the judgment result of the partial discharge fault based on the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal.

[0037] In the embodiment of the present invention, the user display and alarm module is used to visualize the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal, and determine the alarm measures according to the judgment results.

[0038] It should be noted that during long-term operation, high-voltage switchgear is prone to partial discharge due to electrical stress, environmental factors, material aging, etc., which will gradually deteriorate the insulation performance and eventually lead to insulation breakdown and equipment failure; existing partial discharge monitoring technology mainly relies on a single detection method, such as ultrasonic detection, ultra-high frequency detection or transient ground voltage method, etc. These methods often have problems such as high cost, low sensitivity, and poor anti-interference, and are difficult to meet the stable detection needs in complex electromagnetic environments; especially in the power system operation environment, there are a large number of electromagnetic interference sources, making it difficult for a single detection method to accurately distinguish between real partial discharge signals and interference signals, resulting in frequent false alarms or missed alarms; at the same time, traditional monitoring equipment usually does not support long-term online stable monitoring, making it difficult to achieve continuous tracking and early warning of the insulation status of high-voltage switchgear, increasing the risk of safe operation of the power system.

[0039] Therefore, in response to the above-mentioned partial discharge monitoring problems, a dual verification monitoring mechanism for partial discharge signals is realized through the steps of NO2 gas detection module, pulse current signal acquisition module, signal processing module, data transmission module, data analysis and diagnosis module, and user display and alarm module; among them, the NO2 gas generated in the partial discharge process is combined with the high-frequency pulse signal to solve the problem that a single detection method is susceptible to interference; the high-frequency pulse signal is subjected to FFT spectrum analysis through the FPGA chip and microcontroller to extract the partial discharge characteristic frequency, thereby realizing effective distinction between interference signals and partial discharge signals; real-time data transmission and cloud analysis are adopted to realize remote monitoring and centralized management of multiple devices; combined with visual display and alarm mechanism, the timeliness and accuracy of early warning are improved.

[0040] Example 2, reference Figure 1 and Figure 2 , which is the second embodiment of the present invention, provides a switch cabinet partial discharge monitoring system based on the above embodiment.

[0041] It should be noted that since air is mainly affected by electron collision ionization during partial discharge, the essence of air discharge is the result of collisions between charged particles, gas molecules, and electrode surfaces. Charged particles in the air are accelerated by the electric field to gain energy and collide with nitrogen and oxygen, breaking their N-N triple bonds and O-O bonds. This collision ionizes single O atoms and N atoms, which then react with other particles to generate a variety of neutral molecules. Under the action of a high electric field, the air components N2, O2, HO2, and CO2 decompose into single O atoms, N atoms, OH radicals, and CO. The decomposition process is mainly as follows:

[0042]

[0043] The N atoms, O atoms, OH radicals, and CO generated by the reaction diffuse into the gas chamber, where they undergo complex chemical reactions with other gaseous components in the air, generating a variety of stable components. The O radical is highly active and can further react with O2 to form O3. The N radical is unstable and easily oxidized into the intermediate product NO, which is further oxidized to the more stable NO2. Therefore, the more severe the partial discharge, the higher the NO2 concentration; the more pronounced the insulation defect, the greater the electric field strength, and the greater the amount of NO2 generated. Therefore, the present invention selects NO2 gas for detection and as an early warning signal during online partial discharge monitoring.

[0044] In an embodiment of the present invention, obtaining the NO2 gas concentration in the switch cabinet includes the following steps A1-A4:

[0045] A1: Use the NO2 sensor to capture the NO2 gas in the switch cabinet and obtain the current signal.

[0046] A2: Use a constant potential circuit to provide working voltage for the NO2 sensor.

[0047] A3: The current signal is converted into a voltage signal based on a current-voltage conversion circuit, and the voltage signal is amplified by a signal amplification circuit to obtain an amplified voltage signal.

[0048] A4: The amplified voltage signal is digitally acquired through a high-speed analog-to-digital conversion chip to obtain the digital NO2 gas concentration.

[0049] Specifically, when using the NO2 sensor to capture the NO2 gas generated by partial discharge of the switch cabinet in step A1, the NO2 sensor is installed at the bottom of the high-voltage switch cabinet near the location where partial discharge is most likely to occur, so as to timely capture the NO2 gas released by the insulating material due to electrical stress during the partial discharge process.

[0050] In an optional embodiment, capturing NO2 gas generated by local discharge in the switch cabinet can also be achieved through an electrochemical redox sensor. The electrochemical redox sensor detects the current changes generated when NO2 gas undergoes an oxidation-reduction reaction with the electrode surface, and determines the gas concentration by measuring the current. It has the characteristics of fast response speed and high sensitivity, and is suitable for real-time monitoring of confined spaces inside the switch cabinet.

[0051] In another optional embodiment, the capture of NO2 gas generated by partial discharge of the switch cabinet using a NO2 sensor can also be achieved through optical absorption spectroscopy. Optical absorption spectroscopy is based on the selective absorption characteristics of light of different wavelengths in NO2 gas. It uses an infrared or ultraviolet light source of a specific wavelength to irradiate the gas and determines the NO2 concentration by measuring the change in the intensity of the transmitted light. It has the advantages of strong resistance to electromagnetic interference, high detection accuracy, and the ability to achieve long-distance non-contact detection. It is suitable for safety monitoring in high-voltage switch cabinet environments.

[0052] It should be noted that the present invention realizes real-time and accurate monitoring of NO2 gas generated during partial discharge by installing a NO2 sensor at the bottom of the high-voltage switchgear and equipping it with a constant potential circuit, a current-voltage conversion circuit, a signal amplification circuit and a high-speed analog-to-digital conversion chip; the NO2 gas detection module utilizes the physical and chemical properties of NO2 gas generated by the decomposition of the air medium during partial discharge to convert the tiny breakdown of the insulating material that is difficult to measure directly into a measurable gas concentration change, thereby realizing indirect monitoring of partial discharge, avoiding the influence of external electromagnetic interference on traditional electrical measurement methods, and improving the anti-interference ability of the monitoring system; a stable working voltage is provided by the constant potential circuit to ensure that the sensor works in the best state, and the application of the current-voltage conversion circuit and the signal amplification circuit enables the weak current signal to be effectively captured and converted, solving the problem of low sensitivity caused by weak signals in traditional methods, so that the monitoring device can still maintain stable operation in harsh electromagnetic environments, while reducing the false alarm rate of equipment failures, reducing the workload of manual inspections and operation and maintenance costs.

[0053] It should be noted that the principle of the transient current method is to couple the partial discharge signal through a coupling capacitor and measurement impedance by measuring the instantaneous voltage change generated when partial discharge occurs in the capacitor, and obtain a discharge pulse signal, thereby analyzing the degree and location of partial discharge. The transient current method detection circuit structure is as follows: Figure 2As shown in the figure, the voltage across the test capacitor drops instantaneously due to partial discharge, and then the coupling capacitor (C_k) discharges to the test capacitor (C_x) through the measurement impedance (Z_m). The discharge current forms a pulse voltage on the measurement impedance, which is converted into a digital signal for analysis by a high-speed analog-to-digital conversion chip.

[0054] In an embodiment of the present invention, obtaining a high-frequency pulse signal in a switch cabinet includes the following steps B1-B3:

[0055] B1: Use the capacitive coupling sensor and the energized phase line to form a capacitive coupling structure to obtain the discharge pulse signal in the switch cabinet.

[0056] B2: Filter out low-frequency interference signals from the discharge pulse signal and retain high-frequency pulse signals.

[0057] B3: Digitize the high-frequency pulse signal to obtain a digitized high-frequency pulse signal.

[0058] Specifically, in step B1, forming a capacitive coupling structure with a capacitive coupling sensor and a live phase line means installing a capacitive coupling sensor at a phase hole of a live display device of a high-voltage switch cabinet, and forming a capacitive coupling structure with the capacitive coupling sensor and the live phase line.

[0059] Specifically, the specific operation of retaining the high-frequency pulse signal in step B2 may be:

[0060] For the discharge pulse signal, the acquisition circuit is used to filter out the low-frequency interference signal and retain the high-frequency pulse signal. The acquisition circuit includes a high-frequency filtering circuit and a limiting protection circuit. The high-frequency filtering circuit is used to filter out the low-frequency interference signal, and the limiting protection circuit is used to retain the high-frequency pulse signal in the range of 300kHz to 20MHz.

[0061] Specifically, the specific operation of digitizing the high-frequency pulse signal in step B3 can be to digitize the high-frequency pulse signal through a high-speed analog-to-digital conversion chip to obtain a digitized high-frequency pulse signal, wherein the model of the high-speed analog-to-digital conversion chip is AD9226, the sampling frequency is 50MHz, and the resolution is 12 bits.

[0062] In an optional embodiment, obtaining high-frequency pulse signals using a capacitive coupling sensor can also be achieved through Rogowski coil coupling. Based on the principle of electromagnetic induction, the Rogowski coil is installed around a high-voltage cable or busbar, and the magnetic field changes caused by transient current changes generated by partial discharge are used to induce a corresponding voltage signal in the coil. The voltage signal is collected through a high-impedance detection circuit, and then pre-amplified and filtered to effectively capture high-frequency pulse signals in the range of 300kHz to 20MHz. It has the characteristics of convenient non-contact installation and strong spatial electromagnetic interference suppression capability, and is suitable for switch cabinet environments with limited space.

[0063] In another optional embodiment, obtaining high-frequency pulse signals using a capacitive coupling sensor can also be achieved through an ultra-high frequency antenna detection method. A dedicated broadband antenna is used to receive electromagnetic wave signals in the 300MHz-3GHz frequency band generated during the partial discharge process. Signal processing is performed through a low-noise amplifier and a bandpass filter to effectively suppress power frequency and other low-frequency interference, while retaining the characteristic frequency band signal of partial discharge. It has strong resistance to external interference and high positioning accuracy, and is suitable for real-time online monitoring of partial discharge inside metal-enclosed switchgear.

[0064] It should be noted that the present invention achieves accurate acquisition of high-frequency pulse signals generated by partial discharge by installing a capacitive coupling sensor at the phase hole of the energized display device of the high-voltage switch cabinet, combined with a high-frequency filtering circuit and a limiting protection circuit; by utilizing the principle that the transient current signal generated by partial discharge has a specific frequency characteristic, the high-frequency signal is obtained in combination with a capacitive coupling method, thereby avoiding interference with the normal operation of the switch cabinet; the high-frequency filtering circuit effectively filters out low-frequency interference signals and improves the signal-to-noise ratio of the signal; the limiting protection circuit ensures that the subsequent circuit will not be damaged when a large current pulse is generated, thereby enhancing the safety and stability of the equipment; the application of a high-speed analog-to-digital conversion chip ensures the complete acquisition of transient signals and provides high-quality original data for subsequent spectrum analysis; it solves the problem of difficulty in distinguishing local discharge signals from interference signals in traditional monitoring methods, improves the accuracy and reliability of monitoring, and provides a basis for early warning of partial discharge.

[0065] In an embodiment of the present invention, the NO2 gas concentration and the high-frequency pulse signal are processed to determine the spectrum characteristics of the high-frequency pulse signal, including the following steps C1-C2:

[0066] C1: Buffering the digitized NO2 gas concentration and the digitized high-frequency pulse signal, and transmitting the digitized NO2 gas concentration and the digitized high-frequency pulse signal.

[0067] C2: Perform FFT spectrum analysis on the digitized high-frequency pulse signal to obtain the spectrum characteristics of the high-frequency pulse signal.

[0068] Specifically, in step C1, the digitized NO2 gas concentration and the digitized high-frequency pulse signal are cached and the digitized NO2 gas concentration and the digitized high-frequency pulse signal are transmitted. The specific operations may be:

[0069] The FPGA chip is used to cache the digital NO2 gas concentration and the digital high-frequency pulse signal.

[0070] The digital NO2 gas concentration and the digital high-frequency pulse signal are transmitted to the microcontroller via the SPI interface.

[0071] Furthermore, in step C2, FFT spectrum analysis is performed on the digitized high-frequency pulse signal to obtain the spectrum characteristics of the high-frequency pulse signal. The specific operation may be:

[0072] A microcontroller is used to perform FFT spectrum analysis on the digitized high-frequency pulse signal to extract the characteristic frequency and waveform characteristics of the partial discharge, wherein the microcontroller refers to an STM32 microcontroller.

[0073] It should be noted that since the collected digitized high-frequency pulse signal is a time domain waveform, it contains a large amount of pulse information, but there is also interference and noise, which makes it difficult to intuitively see the characteristics. Therefore, the present invention performs FFT spectrum analysis on the digitized high-frequency pulse signal based on a microcontroller to extract the local discharge characteristic frequency and waveform characteristics of the high-frequency pulse signal. Then, the characteristic frequency components of the local discharge signal can be clearly distinguished from the spectrum diagram, effectively distinguishing the interference signal from the local discharge signal.

[0074] For example, FFT spectrum analysis can be specifically expressed by the following formula:

[0075]

[0076] Where X(k) is the kth frequency component in the frequency domain; x(n) is the current signal at the nth sampling point in the time domain; N is the number of sampling points; n is the time domain sampling point index, from 0 to N-1; and j is the imaginary unit.

[0077] In an embodiment of the present invention, an FFT spectrum analysis is performed on the digitized high-frequency pulse signal to obtain a complex number expression of the digitized high-frequency pulse signal in the frequency domain, that is, the form of the kth frequency component X(k) in the frequency domain is as follows:

[0078] X(k)=|X(k)|e j·arg[X(k)] ;

[0079] Where |X(k)| is the amplitude spectrum and arg[X(k)] is the phase spectrum.

[0080] It should be noted that partial discharge signals have typical high-frequency pulse characteristics in the spectrum. These characteristic frequencies can be clearly located through FFT spectrum analysis. At the same time, this method can intuitively display the spectrum characteristics of partial discharges of different degrees, making it easier for technicians to make judgments.

[0081] It should be noted that the present invention realizes efficient processing and feature extraction of transient current signals and NO2 gas concentration signals by adopting a signal processing module combining an FPGA chip with an STM32 microcontroller and applying FFT spectrum analysis technology; by utilizing the high-speed parallel processing capability of the FPGA chip, high-speed digitized signal data is cached in real time and transmitted to the microcontroller through the SPI interface for further processing, thereby avoiding data loss and processing delay; FFT spectrum analysis technology converts time domain signals into frequency domain signals, making the characteristic frequency components of partial discharge clearly visible, and effectively distinguishing between real partial discharge signals and external interference signals; the present invention solves the problem of difficulty in real-time processing of large amounts of data in traditional monitoring systems, and improves response speed and diagnostic accuracy; at the same time, the processing of NO2 gas concentration data provides a second level of verification for partial discharge diagnosis, enhances reliability, enables the monitoring device to accurately identify partial discharge characteristics in an electromagnetic environment, reduces the false alarm rate, and provides a scientific basis for preventive maintenance.

[0082] In an embodiment of the present invention, the data transmission module uses an RS485 interface or a wireless communication module to transmit the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal to the remote background monitoring platform, thereby providing remote monitoring and data storage for further analysis.

[0083] In an embodiment of the present invention, determining the result of a partial discharge fault based on the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal includes the following steps D1-D2:

[0084] D1: Determine the judgment result of the first partial discharge fault based on the frequency spectrum characteristics of the high-frequency pulse signal.

[0085] D2: Use the NO2 gas concentration to verify the judgment result of the first partial discharge fault and determine the judgment result of the second partial discharge fault.

[0086] Specifically, determining the judgment result of the first partial discharge fault in step D1 refers to performing high-frequency discharge feature detection based on the frequency spectrum feature of the high-frequency pulse signal to preliminarily determine whether the partial discharge fault exists.

[0087] Specifically, determining the judgment result of the first partial discharge fault in step D2 means verifying the result of the preliminary determination of whether the partial discharge fault exists by analyzing the NO2 gas concentration, and determining whether the partial discharge fault exists and the severity.

[0088] Exemplarily, the present invention utilizes a dual verification strategy during data analysis and partial discharge fault diagnosis to improve the reliability of partial discharge fault diagnosis. This process is implemented in a host computer. First, a high-frequency pulse signal is acquired using a transient current method. After processing through FFT spectrum analysis, the resulting FFT spectrum is observed to determine whether high-frequency discharge characteristics exist. The severity of the actual partial discharge fault is then further verified by measuring NO2 gas concentration. If a significant partial discharge characteristic frequency appears in the FFT spectrum of the high-frequency pulse signal acquired using the transient current method, a preliminary judgment is made that a partial discharge fault may exist. If the NO2 gas concentration measurement signal indicates an increase in concentration, this further confirms that the partial discharge fault persists and is of high severity, thereby effectively improving diagnostic accuracy.

[0089] In an optional embodiment, dual verification and diagnosis of partial discharge faults based on the spectral characteristics of NO2 gas concentration and high-frequency pulse signals can also be achieved through a fuzzy expert system; wherein, by regularizing expert experience knowledge, a fuzzy rule base containing gas concentration levels and high-frequency signal characteristic intensities is constructed, and the fuzzy reasoning mechanism is used to calculate the membership and match the rules of the input NO2 gas concentration value and the spectral characteristics of the high-frequency pulse signal, and comprehensively evaluate the type, location and severity of the partial discharge fault. Through defuzzification processing, a clear fault diagnosis conclusion and confidence level are output, which effectively handles the uncertainty and ambiguity of the system monitoring data and improves the accuracy and reliability of fault diagnosis.

[0090] In another optional embodiment, dual verification and diagnosis of partial discharge faults based on the spectral characteristics of NO2 gas concentration and high-frequency pulse signals can also be achieved through a hybrid model of deep learning convolutional neural networks and long short-term memory networks; wherein the deep learning convolutional neural network is used to extract the spatial characteristics of the high-frequency pulse signal spectrum graph, and the long short-term memory network is used to capture the temporal variation pattern of NO2 gas concentration. The two features are deeply integrated in the network to establish a mapping relationship between gas concentration, current signal and fault type, and the network parameters are trained through historical fault case data to realize automatic classification and recognition of partial discharge fault types and severity assessment.

[0091] It should be noted that the present invention analyzes the FFT spectrum characteristics of the transient current signal to determine whether there are high-frequency discharge characteristics, and then combines the NO2 gas concentration measurement results to further verify the existence and severity of local discharge, effectively avoiding the misjudgment that may be caused by a single measurement method and improving the diagnostic accuracy; compared with the traditional single measurement method, the present invention can more comprehensively evaluate the local discharge status, reduce false alarms caused by environmental interference or sensor errors, and enhance credibility; secondly, the quantitative processing of data analysis results makes the monitoring results between different devices comparable, provides an objective basis for the evaluation of the health status of the equipment, solves the problem that the diagnostic results of the traditional monitoring system are unstable and susceptible to interference, provides technical support for the preventive maintenance and life assessment of power equipment, and effectively reduces the risk of accidental equipment failure.

[0092] In an embodiment of the present invention, the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal are visualized, and an alarm measure is determined based on the judgment result, including the following steps E1-E2:

[0093] E1: Based on the spectrum characteristics of NO2 gas concentration and high-frequency pulse signal, it provides digital concentration real-time value and data curve display.

[0094] E2: By setting the alarm threshold of the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal, the alarm measures are determined based on the comparison between the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal and the alarm threshold.

[0095] Specifically, the alarm measures determined in step E2 include:

[0096] By setting the alarm threshold of the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal, and comparing the spectral characteristics of the NO2 gas concentration and the high-frequency pulse signal with the alarm threshold, it is determined whether to issue an alarm signal, and the alarm information is uploaded to the remote background monitoring platform.

[0097] For example, in the present invention, the user can set the alarm threshold of the NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal, and then compare the real-time monitored NO2 gas concentration and the spectral characteristics of the high-frequency pulse signal with the alarm threshold in subsequent online monitoring. When the NO2 gas concentration or the spectral characteristics of the high-frequency pulse signal exceeds the alarm threshold, the device will automatically issue an audible and visual alarm, and upload the alarm information to the monitoring center so that technical personnel can take timely countermeasures.

[0098] It should be noted that the present invention realizes the intuitive presentation and timely warning of the partial discharge status by displaying the transient current waveform spectrum and NO2 gas concentration information in real time and setting a customizable alarm threshold, so that operation and maintenance personnel can intuitively understand the equipment status and judge the health status of the equipment without professional knowledge; secondly, the design of the custom alarm threshold enables the monitoring system to be personalized according to the characteristics and operating environment of different equipment, avoiding the problems of excessive alarms or missed reports that may be caused by fixed thresholds; the sound and light alarm function ensures that on-site personnel can be reminded in time when abnormal situations occur, and at the same time, alarm information is sent to the remote monitoring center through the communication module to form a multi-level early warning mechanism; it solves the problems of untimely information feedback and imperfect early warning mechanism of traditional monitoring systems, improves the initiative and pertinence of power system operation and maintenance, provides protection for the safe operation of equipment, and reduces the risk of accidents caused by partial discharge.

[0099] In summary, the present invention integrates the dual monitoring technology of NO2 gas detection and transient current signal acquisition, and combines signal processing, data transmission, data analysis and diagnosis, and user display and alarm modules to achieve high-precision and high-reliability online monitoring of partial discharge of high-voltage switchgear. It overcomes the shortcomings of traditional single methods that are susceptible to electromagnetic interference, have low sensitivity, and are not suitable for long-term online monitoring, and improves the anti-interference ability, diagnostic accuracy and operational stability of the monitoring system; effectively reduces the false alarm rate through the dual verification mechanism and improves the credibility of the monitoring results; not only reduces the operation and maintenance costs of high-voltage switchgear and reduces the workload of manual inspections, but also improves the safety and reliability of power system operation, provides a scientific basis for preventive maintenance, and effectively prevents major safety accidents caused by insulation failures.

[0100] Example 3 is the third embodiment of the present invention. This embodiment provides a switch cabinet partial discharge monitoring method, including: obtaining the NO2 gas concentration in the switch cabinet; obtaining the high-frequency pulse signal in the switch cabinet; processing the NO2 gas concentration and the high-frequency pulse signal to determine the spectral characteristics of the high-frequency pulse signal; transmitting the spectral characteristics of the NO2 gas concentration and the high-frequency pulse signal to a remote background monitoring platform; determining the judgment result of the partial discharge fault based on the spectral characteristics of the NO2 gas concentration and the high-frequency pulse signal; visualizing the spectral characteristics of the NO2 gas concentration and the high-frequency pulse signal, and determining the alarm measures according to the judgment result.

[0101] Example 4 is the fourth embodiment of the present invention, which is different from the first three embodiments in that: Figure 3As shown, if the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0102] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0103] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0104] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one or combination of the following technologies known in the art can be used: a discrete logic circuit having logic gate circuits for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0105] Example 5, with reference to Figures 4 to 7 , which is the fifth embodiment of the present invention, provides a switch cabinet partial discharge monitoring system. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0106] This embodiment uses a standardized high-voltage switchgear test platform to fully verify the partial discharge monitoring system of the present invention. Defects of varying degrees are artificially created in the insulating material to simulate partial discharge phenomena that may occur during actual operation. The NO2 gas detection module is installed at the bottom of the switchgear, closest to the discharge point. The capacitive coupling sensor of the pulse current signal acquisition module is installed at the phase hole of the charge display device. Continuous monitoring is performed for 30 minutes at each discharge level to ensure data stability and repeatability. Table 1 shows the key monitoring parameters for different discharge levels.

[0107] Table 1 Key monitoring parameters at different discharge levels

[0108] Discharge level Partial discharge voltage (kV) FFT frequency (MHz) Main peak amplitude <![CDATA[NO2 concentration (ppm)]]> No discharge 0 none <3 0.01 slight 5 2.8-3.2 10-20 0.12 Moderate 8 2.8-3.5 30-50 0.38 serious 12 2.7-3.6 60-90 0.76

[0109] For the above Table 1, Figure 4 、 Figure 5 、 Figure 6 as well as Figure 7 The following are the frequency domain diagrams corresponding to the four different discharge states in Table 1. It can be seen from the figure that Figure 4 The display shows a flat background noise, and no obvious peak signal appears in the entire monitoring frequency band, indicating that the system has good anti-interference ability under normal operating conditions; Figure 5 A clear characteristic peak appears in the 2.8-3.2MHz frequency band, and the main peak amplitude reaches 10-20, indicating that the present invention can effectively capture early partial discharge signals and provide an important basis for fault warning. Figure 6 The spectrum characteristics are more obvious, the main peak amplitude is enhanced to 30-50, and the frequency range is extended to 2.8-3.5MHz, indicating that the dual verification mechanism can accurately reflect the changes in discharge intensity; Figure 7It presents a significant high-energy distribution, with the main peak amplitude reaching 60-90 and the frequency distribution range further extended to 2.7-3.6MHz, clearly indicating the characteristics of severe partial discharge; experimental results show that the two methods of NO2 gas detection and high-frequency pulse signal detection are highly consistent and complementary, and the dual verification mechanism can effectively distinguish different degrees of partial discharge, avoiding the misjudgment that may occur in a single detection method.

[0110] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A switchgear partial discharge monitoring system, characterized by: include, NO2 gas detection module, pulse current signal acquisition module, signal processing module, data transmission module, data analysis and diagnosis module, and user display and alarm module; The NO2 gas detection module is used to obtain the NO2 gas concentration in the switch cabinet; The pulse current signal acquisition module is used to obtain high-frequency pulse signals in the switch cabinet; The signal processing module is used to process the NO2 gas concentration and the high-frequency pulse signal to determine the frequency spectrum characteristics of the high-frequency pulse signal; The data transmission module is used to transmit the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal to a remote background monitoring platform; The data analysis and diagnosis module is used to determine the judgment result of the partial discharge fault based on the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal; The user display and alarm module is used to visualize the NO2 gas concentration and the frequency spectrum characteristics of the high-frequency pulse signal, and determine the alarm measures according to the judgment result.

2. A switch cabinet partial discharge monitoring system according to claim 1, characterized in that: The obtaining of the high-frequency pulse signal in the switch cabinet includes: A capacitive coupling structure is formed by using a capacitive coupling sensor and a live phase line to obtain the discharge pulse signal in the switch cabinet; filtering out low-frequency interference signals from the discharge pulse signal and retaining high-frequency pulse signals; The high-frequency pulse signal is digitized to obtain a digitized high-frequency pulse signal.

3. A switch cabinet partial discharge monitoring system according to claim 2, characterized in that: Processing the NO2 gas concentration and the high-frequency pulse signal to determine the frequency spectrum characteristics of the high-frequency pulse signal includes: Buffering the digitized NO2 gas concentration and the digitized high-frequency pulse signal, and transmitting the digitized NO2 gas concentration and the digitized high-frequency pulse signal; Perform FFT spectrum analysis on the digitized high-frequency pulse signal to obtain the spectrum characteristics of the high-frequency pulse signal.

4. A switch cabinet partial discharge monitoring system according to claim 3, characterized in that: Determining a partial discharge fault judgment result based on the NO2 gas concentration and the frequency spectrum characteristics of the high-frequency pulse signal includes: Determining a judgment result of a first partial discharge fault based on a frequency spectrum characteristic of the high-frequency pulse signal; The NO2 gas concentration is used to verify the judgment result of the first partial discharge fault and determine the judgment result of the second partial discharge fault.

5. A switch cabinet partial discharge monitoring system according to claim 4, characterized in that: Visualizing the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal, and determining an alarm measure based on the judgment result, including: According to the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal, a digital concentration real-time value and a data curve display are provided; By setting alarm thresholds of the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal, alarm measures are determined based on the comparison between the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal and the alarm thresholds.

6. A switch cabinet partial discharge monitoring system according to claim 5, characterized in that: The obtaining of the NO2 gas concentration in the switch cabinet includes: Use the NO2 sensor to capture the NO2 gas in the switch cabinet and obtain the current signal; Using a constant potential circuit to provide an operating voltage for the NO2 sensor; Converting the current signal into a voltage signal based on a current-voltage conversion circuit, and amplifying the voltage signal using a signal amplification circuit to obtain an amplified voltage signal; The amplified voltage signal is digitally collected by a high-speed analog-to-digital conversion chip to obtain a digital NO2 gas concentration.

7. A switch cabinet partial discharge monitoring system according to claim 6, characterized in that: The data transmission module adopts an RS485 interface or a wireless communication module to transmit the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal to a remote background monitoring platform.

8. A switch cabinet partial discharge monitoring method, using a switch cabinet partial discharge monitoring system according to any one of claims 1 to 7, characterized in that: include, Obtain NO2 gas concentration in the switch cabinet; Obtain high-frequency pulse signals in the switch cabinet; Processing the NO2 gas concentration and the high-frequency pulse signal to determine the spectrum characteristics of the high-frequency pulse signal; Transmit NO2 gas concentration and spectrum characteristics of high-frequency pulse signals to the remote background monitoring platform; Determine the result of partial discharge fault based on the NO2 gas concentration and the spectrum characteristics of the high-frequency pulse signal; The spectrum characteristics of NO2 gas concentration and high-frequency pulse signal are visualized, and the alarm measures are determined based on the judgment results.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the switch cabinet partial discharge monitoring system according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the switch cabinet partial discharge monitoring system according to any one of claims 1 to 7 are implemented.

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