A circuit breaker radiation electromagnetic wave feature extraction method

Abstract

The application discloses a circuit breaker radiation electromagnetic wave feature extraction method and belongs to the technical field of electromagnetic wave processing, and comprises the following steps: S1, simulating an arc process of a circuit breaker, and preprocessing temperature distribution cloud pictures of an arc region at continuous time points to obtain standard temperature distribution cloud pictures at the continuous time points; S2, generating a temperature weighted change intensity sequence according to the standard temperature distribution cloud pictures at the continuous time points, and constructing a temperature change derivative curve; and S3, generating an electromagnetic radiation signal picture according to the temperature change derivative curve. The application obtains temperature distribution through simulation calculation, avoids the influence of electromagnetic wave signals generated by auxiliary contact action and auxiliary contact gap discharge on measurement results, and successfully overcomes problems such as high cost and experimental condition limitation in a traditional test method.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave processing technology, specifically relating to a method for extracting the characteristics of electromagnetic waves radiated by a circuit breaker. Background Technology

[0002] In the design and application of high-voltage circuit breakers, the formation and extinction of electric arcs are often accompanied by strong radiated electromagnetic waves. These radiated electromagnetic waves have a significant impact on the performance evaluation, life prediction, and electromagnetic compatibility of circuit breakers. Traditional methods for extracting radiated electromagnetic wave features mainly rely on experimental techniques. For example, by setting up a circuit breaker breaking simulation test circuit in a laboratory environment, ultra-high frequency sensors and high-speed cameras are used to simultaneously detect the radiated electromagnetic wave signals, frequencies, and contact and arc states during the process. Although this method can obtain direct data on radiated electromagnetic waves, some unavoidable interferences exist in actual operation: auxiliary contact operation and auxiliary contact gap discharge also generate electromagnetic wave signals. These small current signals may also experience rapid current changes due to the fast switching speed, resulting in strong electromagnetic wave radiation. These high-amplitude electromagnetic wave signals are difficult to distinguish from the arc-extinguishing chamber signals, seriously affecting the measurement results. In addition, some high-voltage circuit breakers located far from the ground have a large degree of electromagnetic wave signal attenuation, requiring high-performance ultra-high frequency sensors to accurately capture the signals. The detection equipment is expensive and has some limitations.

[0003] Traditional detection methods based on radiated electromagnetic waves still suffer from problems in practical applications, such as signal source interference and insufficient experimental conditions, making it difficult to fully reflect the internal evolution process of circuit breakers. To further understand the coupling characteristics between heat and electricity during arcing or partial discharge, recent studies have attempted to obtain temperature distribution cloud maps inside circuit breakers through simulation to reveal the laws governing thermal field changes.

[0004] To establish a temperature-based breaking criterion, some scholars have developed an ANSYS simulation model based on the structure of a compressed air SF6 circuit breaker. This model uses two-dimensional arc plasma magnetohydrodynamics to simulate the circuit breaker's breaking process, simulating the temperature field of the circuit breaker under different short-circuit high currents. The results can be cross-validated with traditional TRV curves and conductivity criteria. This method of providing temperature distribution cloud maps is simple to calculate, provides clear judgment, and clearly reflects the evolution characteristics of the circuit breaker's temperature field. Building on this, this invention innovatively applies the temperature distribution cloud map to the identification and extraction of radiated electromagnetic wave characteristics. Summary of the Invention

[0005] To address the above problems, this invention proposes a method for extracting the electromagnetic wave characteristics radiated by circuit breakers.

[0006] The technical solution of the present invention is: a method for extracting the features of radiated electromagnetic waves from a circuit breaker, comprising the following steps:

[0007] S1. Simulate the arcing process of the circuit breaker and preprocess the temperature distribution cloud map of the arcing area at continuous time to obtain the standard temperature distribution cloud map at continuous time.

[0008] S2. Based on the standard temperature distribution cloud map at continuous time points, generate a temperature weighted change intensity sequence and construct a temperature change derivative curve;

[0009] S3. Generate an electromagnetic radiation signal graph based on the temperature change derivative curve.

[0010] Furthermore, S1 includes the following sub-steps:

[0011] S11. Simulate the arc process of SF6 circuit breaker under different breaking current conditions and extract the temperature distribution cloud map of the arc region at continuous time.

[0012] S12. The temperature distribution map is cropped and converted into a grayscale image to obtain a standard temperature distribution cloud map for continuous time periods.

[0013] Furthermore, S2 includes the following sub-steps:

[0014] S21. Calculate the grayscale difference matrix between two adjacent standard temperature distribution cloud maps;

[0015] S22. Generate a temperature-weighted change intensity sequence based on the gray-level difference matrix of two adjacent standard temperature distribution cloud maps.

[0016] S23. Perform first-order difference on the temperature-weighted change intensity sequence and construct the temperature change derivative curve.

[0017] Furthermore, in S22, based on the grayscale difference matrix of the standard temperature distribution cloud maps of two adjacent frames, the weighted temperature change intensity of each frame of standard temperature distribution cloud map is calculated using a weighted mask to generate a temperature weighted change intensity sequence.

[0018] Furthermore, in S22, the weighted temperature change intensity S of the standard temperature distribution cloud map of the i-th frame. i The expression is:

[0019] ;

[0020] Among them, I i Let I be the grayscale value of the standard temperature distribution cloud map at this location in the i-th frame. i-1 Let x be the grayscale value of the standard temperature distribution cloud map at this location in the (i-1)th frame, where x is the horizontal coordinate of the location, y is the vertical coordinate of the location, and W is the weight mask.

[0021] Furthermore, S3 includes the following sub-steps:

[0022] S31. Extract effective abrupt change points based on the temperature change derivative curve;

[0023] S32. Generate an electromagnetic radiation signal diagram based on the effective mutation points.

[0024] Furthermore, in S32, the weighted temperature change intensity of the effective abrupt change point is normalized, and the normalization result is mapped to the electromagnetic radiation intensity pulse of the discrete time series to generate an electromagnetic radiation signal map.

[0025] The beneficial effects of this invention are: the invention obtains the temperature distribution through simulation calculation, avoiding the influence of electromagnetic wave signals generated by auxiliary contact action and auxiliary contact gap discharge on the measurement results, and successfully overcomes the problems of high cost and limited experimental conditions in traditional test methods; the simulation calculation of temperature data improves the evaluation efficiency, shortens the experimental cycle, and does not rely on laboratory simulation, directly deduce electromagnetic wave characteristics, ensuring the accuracy and authenticity of the results. Attached Figure Description

[0026] Figure 1 A flowchart of a method for extracting electromagnetic wave features radiated from a circuit breaker;

[0027] Figure 2(a) shows the temperature distribution cloud map at the moment when the moving and stationary contacts just separate;

[0028] Figure 2(b) shows the temperature distribution cloud map of the current when it first crosses zero;

[0029] Figure 2(c) shows the temperature distribution cloud map of the current peak value;

[0030] Figure 2(d) shows the temperature distribution cloud map of the arc extinction.

[0031] Figure 3 For weighted heatmaps;

[0032] Figure 4 This is a graph showing the area intensity of temperature change.

[0033] Figure 5 This is a derivative plot of the temperature jump.

[0034] Figure 6 This is a normalized electromagnetic radiation intensity map;

[0035] Figure 7 This is a graph showing the area intensity curve of temperature change in the embodiment;

[0036] Figure 8 This is a temperature mutation derivative diagram with mutation points marked in the example;

[0037] Figure 9 This is a normalized electromagnetic pulse diagram shown in the example. Detailed Implementation

[0038] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0039] like Figure 1 As shown, the present invention provides a method for extracting the radiated electromagnetic wave features of a circuit breaker, comprising the following steps:

[0040] S1. Simulate the arcing process of the circuit breaker and preprocess the temperature distribution cloud map of the arcing area at continuous time to obtain the standard temperature distribution cloud map at continuous time.

[0041] S2. Based on the standard temperature distribution cloud map at continuous time points, generate a temperature weighted change intensity sequence and construct a temperature change derivative curve;

[0042] S3. Generate an electromagnetic radiation signal graph based on the temperature change derivative curve.

[0043] This invention proposes a method for identifying the electromagnetic wave characteristics of circuit breakers based on temperature distribution images. This method aims to replace traditional methods that rely on sensor acquisition and experimental platforms, providing a technical approach for extracting electromagnetic radiation features based on image simulation results. Using temperature field distribution images during the arc extinguishing process of an SF6 circuit breaker as the data foundation, and combining MATLAB image processing algorithms, this method achieves electromagnetic radiation pulse modeling at the moment of violent arc evolution through multi-stage image preprocessing, weighted region analysis, abrupt change detection, and normalization mapping.

[0044] In this embodiment of the invention, S1 includes the following sub-steps:

[0045] S11. Simulate the arc process of SF6 circuit breaker under different breaking current conditions and extract the temperature distribution cloud map of the arc region at continuous time.

[0046] S12. The temperature distribution map is cropped and converted into a grayscale image to obtain a standard temperature distribution cloud map for continuous time periods.

[0047] The arcing process of SF6 circuit breakers under different breaking current conditions was simulated using multiphysics simulation software, and the temperature distribution map of the arc region over time was extracted. The output format is a series of temperature cloud maps in time order, as shown in Figures 2(a), 2(b), 2(c), and 2(d), which record the evolution of the temperature field at the moment when the moving and stationary contacts just separate, the first zero crossing of the current, the peak current, and the extinction of the arc, respectively. The data includes information such as sudden temperature rises and falls, providing a data foundation for subsequent feature extraction.

[0048] In this embodiment of the invention, S2 includes the following sub-steps:

[0049] S21. Calculate the grayscale difference matrix between two adjacent standard temperature distribution cloud maps;

[0050] S22. Generate a temperature-weighted change intensity sequence based on the gray-level difference matrix of two adjacent standard temperature distribution cloud maps.

[0051] S23. Perform first-order difference on the temperature-weighted change intensity sequence and construct the temperature change derivative curve.

[0052] The pre-defined image folder contains temperature distribution cloud maps (PNG format) named chronologically. The program automatically extracts the image time and sorts them to ensure accurate time sequence. Then, the image size is standardized, the main temperature distribution data is preserved, redundant edges and legend areas are cropped, and the images are converted to grayscale for subsequent analysis.

[0053] To better highlight the response characteristics of key regions of arc change, the algorithm introduces a two-dimensional Gaussian weighted mask, centered on the main discharge path region of the arc-extinguishing chamber (the center of the lower third of the image). This weighted mask can suppress the influence of peripheral irrelevant regions, allowing image change analysis to focus more on the core region of physical evolution. Figure 3 This is a heatmap showing the weight distribution of circuit breakers after weighting.

[0054] In image difference processing, this invention performs an absolute difference operation on the grayscale images between adjacent frames and introduces a Gaussian weighted mask to emphasize the contribution of temperature changes in the central region of the electric arc, thereby calculating the temperature change intensity index corresponding to each frame. This intensity value is regarded as an approximate measure of the temperature distribution change between images and can characterize the evolution trend of the thermal field over time. Specifically, the grayscale difference matrix of two adjacent frames is first calculated, and then element-wise multiplication with the weighted mask is performed and summed to obtain the weighted temperature change intensity of each frame.

[0055] In this embodiment of the invention, in step S22, based on the grayscale difference matrix of two adjacent standard temperature distribution cloud maps, a weighted temperature change intensity of each standard temperature distribution cloud map is calculated using a weighted mask, generating a weighted temperature change intensity sequence. This time series can effectively reflect the dynamic fluctuation characteristics of the entire temperature field during the arc development process and serves as the basic input for subsequent abrupt change detection and electromagnetic wave feature extraction.

[0056] Figure 4 This is the area-intensity curve of temperature change. A first-order difference is performed on the temperature-weighted intensity sequence to construct the temperature change derivative curve, which is used to characterize the dynamic evolution rate of the internal thermal field of the circuit breaker over time. This derivative sequence can quantitatively reflect the severity and direction of temperature change between two adjacent image frames, and is a core indicator for measuring abrupt changes in the temperature field. Figure 5As shown, compared to the original intensity curve, the derivative curve is more sensitive to short-term, drastic temperature fluctuations, and can more accurately reveal the discontinuous behavior during the arc's establishment, extension, or extinction. By setting a derivative threshold (e.g., 9,000,000 grayscale pixels) and combining it with a central temperature change criterion, only key nodes that simultaneously satisfy both abrupt changes and local responses are identified, avoiding misjudgments. Physically, these abrupt changes typically correspond to rapid transitions in the arc plasma state, such as strong current interruption, electric field reconstruction, or magnetohydrodynamic backlash, thus becoming the trigger moments for significant release of radiated electromagnetic waves. Therefore, derivative abrupt changes not only have image processing significance but also constitute the theoretical support for inferring the characteristics of temperature-driven electromagnetic waves, serving as an important intermediary for temperature-electromagnetic coupling modeling in this invention.

[0057] In this embodiment of the invention, in S22, the weighted temperature change intensity S of the standard temperature distribution cloud map of the i-th frame is... i The expression is:

[0058] ;

[0059] Among them, I i Let I be the grayscale value of the standard temperature distribution cloud map at this location in the i-th frame. i-1 Let x be the grayscale value of the standard temperature distribution cloud map at this location in the (i-1)th frame, where x is the horizontal coordinate of the location, y is the vertical coordinate of the location, and W is the weight mask.

[0060] In this embodiment of the invention, S3 includes the following sub-steps:

[0061] S31. Extract effective abrupt change points based on the temperature change derivative curve;

[0062] S32. Generate an electromagnetic radiation signal diagram based on the effective mutation points.

[0063] In this embodiment of the invention, in step S32, the weighted temperature change intensity of the effective abrupt change point is normalized, and the normalization result is mapped to a discrete time series of electromagnetic radiation intensity pulses to generate an electromagnetic radiation signal map.

[0064] In this embodiment of the invention, to avoid misjudgment caused by gradual temperature changes or image noise, the average temperature of the central region is further introduced as a criterion. Only when the gray value of the central region changes significantly (exceeding a set threshold) is the derivative abrupt change considered a valid pulse. For negative abrupt changes that occur immediately after the arc heats up, a "abrupt change fallback recognition mechanism" is also designed to avoid misidentifying a natural temperature fallback as secondary radiation.

[0065] like Figure 6As shown, the intensity changes of all effective abrupt change points are ultimately normalized and mapped to a set of electromagnetic radiation intensity pulses in a discrete time series, forming an electromagnetic radiation signal graph. This graph can be used to analyze the radiated electromagnetic wave characteristics of circuit breakers during arc extinguishing, thus providing theoretical support and practical tools for radiation identification based on simulation images.

[0066] This method requires no on-site signal acquisition, relying solely on temperature image data. It utilizes MATLAB to automatically identify temperature abrupt changes and approximately reconstruct electromagnetic wave characteristics, making it widely applicable for extracting radiated electromagnetic wave features. Its image-driven feature extraction path exhibits good repeatability and data adaptability, making it suitable for embedding into electrical simulation processes for electromagnetic characteristic prediction or verification.

[0067] In this embodiment of the invention, to verify the feasibility of extracting electromagnetic wave features from temperature abrupt changes as described in the present invention, 122 simulated temperature distribution cloud maps of an SF6 high-voltage circuit breaker during a complete breaking process were selected as data input. This set of images covers the entire process from moving contact separation, long arc stretching, arc extinguishing to cooling, with complete temporal sequence, dramatic changes, and good representativeness.

[0068] In the image processing section, all cloud images are first preprocessed uniformly, including size standardization, preservation of bottom structural information, left-side cropping and padding, and grayscale conversion, to ensure the accuracy and stability of subsequent image difference and weighted analysis. Simultaneously, a two-dimensional Gaussian center-weighted mask is constructed from the image coordinate system. This mask focuses on the arc-extinguishing chamber region (slightly below the image center), assigning higher weights to this region to more sensitively identify temperature changes along the main arc path.

[0069] Absolute difference processing is performed on adjacent grayscale images, and combined with the weighted mask mentioned above, the temperature weighted change intensity of each frame is calculated. This sequence reflects the overall heat transfer intensity change of the electric arc during the time evolution process.

[0070] Figure 7 The temperature change intensity curve calculated based on image weighted difference is displayed. The horizontal axis represents the simulation time (milliseconds), and the vertical axis represents the weighted sum of the image pixel intensity differences. Several temperature fluctuation nodes can be clearly seen, characterizing the nonlinear transition process of the thermal field inside the circuit breaker.

[0071] like Figure 8 As shown, based on this, the intensity sequence is subjected to first-order difference to obtain the rate of temperature change (derivative), which is used to further identify drastic thermal change points. To avoid misidentifying slow changes or local disturbances as electromagnetic wave events, the algorithm introduces the average temperature change in the central region as an auxiliary judgment criterion, sets a temperature change threshold, and only when the derivative change is accompanied by a sudden change in the central temperature is it determined as a valid change point.

[0072] Finally, the derivative intensities of the aforementioned effective abrupt change points are normalized and mapped to a pulse intensity map of the radiated electromagnetic wave. Figure 8 In the diagram, a normalized pulse appears only when a drastic temperature change is detected and the central region shows a significant response; at other times, the pulse is zero. This diagram can be considered an "approximate signal spectrum" of the radiated electromagnetic waves of the circuit breaker throughout its operation.

[0073] like Figure 9 As shown, the pulse diagram visually illustrates the emission nodes of multiple electromagnetic events, forming discrete but physically meaningful radiation signals. The timing of these pulses closely matches the key processes of the electric arc within the circuit breaker, verifying the reliability and accuracy of the method of this invention in deriving electromagnetic wave emission characteristics from temperature distribution diagrams without relying on additional sensors or experimental platforms.

[0074] In summary, this set of verifications, based on 122 frames of temperature distribution images, fully demonstrates the effectiveness of this method in extracting features of radiated electromagnetic waves, laying a solid foundation for the simulation recognition and diagnostic applications of this type of signal.

[0075] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A circuit breaker radiated electromagnetic wave feature extraction method, characterized by, The method comprises the following steps: S1, simulating the arc process of the circuit breaker, and preprocessing the temperature distribution cloud picture of the arc area at continuous time to obtain the standard temperature distribution cloud picture at continuous time; S2, generating a temperature weighted change intensity sequence and constructing a temperature change derivative curve according to the standard temperature distribution cloud picture at continuous time; S3, generating an electromagnetic radiation signal picture according to the temperature change derivative curve; The S2 comprises the following sub-steps: S21, calculating the gray difference matrix of adjacent two frames of standard temperature distribution cloud pictures; S22, generating a temperature weighted change intensity sequence according to the gray difference matrix of adjacent two frames of standard temperature distribution cloud pictures; S23, first-order difference of the temperature weighted change intensity sequence, and constructing a temperature change derivative curve; In the S22, the weighted temperature change intensity of each frame of standard temperature distribution cloud picture is calculated by using a weight mask according to the gray difference matrix of adjacent two frames of standard temperature distribution cloud pictures, and a temperature weighted change intensity sequence is generated; In the S22, the weighted temperature change intensity S of the i-th frame standard temperature distribution cloud picture i The expression is: ； where I i is the gray value of the standard temperature distribution cloud image at the i-th frame at the position, I i-1 is the gray value of the standard temperature distribution cloud image at the i-1-th frame at the position, x is the horizontal coordinate of the position, y is the vertical coordinate of the position, and W is a weight mask. The S3 comprises the following sub-steps: S31, extracting effective mutation points according to the temperature change derivative curve; S32, generating an electromagnetic radiation signal picture according to the effective mutation points; In the S32, the weighted temperature change intensity of the effective mutation points is normalized, and the normalized result is mapped to the electromagnetic radiation intensity pulse of the discrete time sequence to generate the electromagnetic radiation signal picture.

2. The circuit breaker radiated electromagnetic wave feature extraction method according to claim 1, characterized by, The S1 comprises the following sub-steps: S11, simulating the arc process of the SF6 circuit breaker under different breaking current conditions, and extracting the temperature distribution cloud picture of the arc area at continuous time; S12, cutting the temperature distribution picture, and converting the cut temperature distribution picture into a gray picture to obtain the standard temperature distribution cloud picture at continuous time.

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