Method for evaluating partial discharge development direction of gas insulated metal enclosed switchgear

Abstract

The application provides a partial discharge development direction evaluation method of a gas insulated metal enclosed switchgear, relates to the technical field of power equipment detection, and comprises the following steps: collecting a partial discharge signal inside the gas insulated metal enclosed switchgear; processing the partial discharge signal to obtain partial discharge original data; obtaining a partial discharge scatter diagram according to the partial discharge original data; performing scaling on the partial discharge scatter diagram and reconstructing to obtain a partial discharge spectrum diagram; constructing partial discharge spectrum diagrams at different moments according to a construction method of the partial discharge spectrum diagram; performing image processing on the partial discharge spectrum diagrams at different moments to convert the partial discharge spectrum diagrams at different moments into a gray-scale diagram array; processing the gray-scale diagram array to obtain a partial discharge spectrum diagram development trend diagram; and evaluating the strength change of a partial discharge activity according to the partial discharge spectrum diagram development trend diagram. The application evaluates the development direction of the partial discharge by constructing the partial discharge spectrum diagram.

Description

Technical Field

[0001] This invention relates to the field of power equipment testing technology, specifically to a method for evaluating the development trend of partial discharge in gas-insulated metal-enclosed switchgear. Background Technology

[0002] Partial discharge is a significant factor leading to reduced service life of electrical equipment and is also the most common abnormal operating condition for various electrical devices. Partial discharge detection is a key engineering technology and an important basis for determining whether the operating status of numerous electrical devices is normal. Timely detection of abnormal discharge is of great importance in preventing serious failures of electrical equipment.

[0003] Based on online partial discharge monitoring, more reasonable operation plans and maintenance strategies can be formulated by fully understanding the actual condition of the equipment. This allows for the full exploitation of the equipment's potential under optimal system safety conditions, extending its service life and reducing the equipment's total life cycle cost.

[0004] Current traditional GIS partial discharge (PD) online monitoring systems rely solely on information from individual sensors and expert diagnostic databases to diagnose PD fault types. During operation, these systems have revealed shortcomings such as inaccurate fault type diagnosis, false alarms, and missed alarms. These deficiencies severely impact the monitoring effectiveness, hindering timely warnings of insulation defects in GIS equipment and preventing the safe and stable operation of GIS devices. Consequently, traditional PD monitoring systems suffer from incomplete reference factors, hindering effective diagnosis and timely warnings of GIS equipment PD faults. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a method for evaluating the development trend of partial discharge in gas-insulated metal-enclosed switchgear.

[0006] This invention provides a method for evaluating the development trend of partial discharge in gas-insulated metal-enclosed switchgear, comprising:

[0007] Collect partial discharge signals inside gas-insulated, metal-enclosed switchgear;

[0008] The partial discharge signal is processed to obtain the raw partial discharge data;

[0009] A partial discharge scatter plot was obtained based on the original partial discharge data.

[0010] The partial discharge scatter plot is scaled and then reconstructed to obtain the partial discharge spectrum.

[0011] Partial discharge spectra at different times were constructed based on the partial discharge spectrum construction method;

[0012] The partial discharge spectra at different times are processed and converted into grayscale arrays;

[0013] The grayscale array of partial discharge spectra at different times is processed to obtain the development trend map of partial discharge spectra;

[0014] The intensity of partial discharge activity can be assessed based on the development trend diagram of the partial discharge spectrum.

[0015] As a further technical solution of the present invention, the acquisition of the partial discharge signal inside the gas-insulated metal-enclosed switchgear specifically involves: acquiring the partial discharge signal inside the gas-insulated metal-enclosed switchgear, wherein the signal should be a continuous partial discharge pulse signal, and the acquisition start time should be the zero-crossing point of the positive half-cycle of the power frequency sinusoidal voltage, and the total acquisition time t is an integer multiple of 20ms.

[0016] As a further technical solution of the present invention, the step of processing the partial discharge signal to obtain the original partial discharge data specifically includes:

[0017] The partial discharge signal is processed to obtain the raw partial discharge data D; the raw partial discharge data D consists of the phase in which the partial discharge occurs. and discharge quantity q i Composition, where i is the sequence number of the partial discharge occurrence, taking positive integers 1, 2, 3, ..., i.e.

[0018]

[0019] In the formula: n is the total number of partial discharges that occur within time t; the starting time for collecting partial discharge data, t=0, should be the zero-crossing point of the positive half-cycle of the power frequency sinusoidal voltage; The i-th partial discharge occurs at the power frequency phase, which is determined by the 20ms period corresponding to a 50Hz power frequency voltage, representing the time of partial discharge occurrence. Normalized to 0–360°, it satisfies equation (2):

[0020]

[0021] In the formula: mod 20 is The remainder when divided by 20 The unit is milliseconds (ms).

[0022] As a further technical solution of the present invention, the step of obtaining a partial discharge scatter plot based on the original partial discharge data specifically includes:

[0023] The partial discharge scatter plot is obtained by taking the raw partial discharge data D within time t, with the horizontal axis representing the phase in which the partial discharge occurs. The vertical axis represents the discharge quantity q, which is the absolute value of the discharge quantity q, and the range of the absolute value of the discharge quantity q is [0, q]. max Phase The range is [0°, 360°].

[0024] As a further technical solution of the present invention, the step of scaling the partial discharge scatter plot and reconstructing the scaled partial discharge scatter plot to obtain a partial discharge spectrum specifically includes:

[0025] Scaling the partial discharge scatter plot involves scaling the discharge quantity q and phase separately. Normalization to a fixed range ensures that the data are on the same scale when assessing the development direction of subsequent partial discharge spectra. The specific normalization formula is as follows:

[0026]

[0027]

[0028] In the formula: q′ i and These represent the normalized discharge quantity and the phase in which partial discharge occurs, respectively; [] is the floor function; l and k are the normalization coefficients;

[0029] The scaled partial discharge scatter plot is reconstructed to obtain the partial discharge spectrum. The reconstruction process involves converting the partial discharge scatter plot into a matrix N, which has l rows and k columns. m×n (n is 1, 2, ..., k; m is 1, 2, ..., l) represents the number of partial discharges with a discharge quantity of m occurring at phase n within time t;

[0030] Then, with the phase n and discharge quantity m of the partial discharge occurring as the x and y coordinates, respectively, the number of partial discharges N is... m×n The color value is used to obtain the partial discharge spectrum; the color value is related to the number of partial discharges N. m×n The range (0, N) max The values ​​exhibit a linear relationship; color values ​​are in binary RGB format.

[0031] As a further technical solution of the present invention, the method for constructing partial discharge spectra at different times according to the partial discharge spectrum construction method specifically includes:

[0032] First, based on the partial discharge spectrum construction method, two partial discharge spectra are obtained: partial discharge spectrum... Figure 1 and partial discharge spectrum Figure 2 Partial discharge spectrum Figure 1 and partial discharge spectrum Figure 2 The partial discharge data acquisition time t is the same, i.e., the partial discharge spectrum... Figure 1The partial discharge spectrum was obtained from the partial discharge data from time t1 to t2. Figure 2 The partial discharge spectrum was obtained from the partial discharge data from time t3 to t4, and satisfies t2-t1=t4-t3. Figure 1 The start time t1 and end time t2 of the data acquisition were both earlier than the partial discharge spectrum. Figure 2 The data collection started at time t3.

[0033] As a further technical solution of the present invention, the step of image processing of the partial discharge spectra at different times and converting them into a grayscale array specifically includes:

[0034] Set the partial discharge spectra at different times and save them as PNG format images;

[0035] The graphs of partial discharge spectra at different times are converted into three-dimensional arrays;

[0036] The three-dimensional data of partial discharge spectra at different times are converted into grayscale arrays.

[0037] As a further technical solution of the present invention, the step of setting and saving the partial discharge spectrum at different times as a PNG format graphic specifically includes:

[0038] partial discharge spectrum Figure 1 and partial discharge spectrum Figure 2 The vertical axis, i.e., the range of discharge quantity, should be set to the same value. Save the image as a portable network graphic (PNG) with the same pixel count and a length and width of g×h; save the partial discharge spectrum. Figure 1 The graph and partial discharge spectrum Figure 2 The graphs only retain data information and do not include axes or axis titles;

[0039] The process of converting partial discharge spectra at different times into a three-dimensional array specifically includes:

[0040] partial discharge spectrum Figure 1 The graph and partial discharge spectrum Figure 2 The image is converted into two three-dimensional arrays, Q1 and Q2, with the format Q = (R; G; B), where R, G, and B are the brightness matrices of red, green, and blue for all pixels in the image, respectively. 1,1 ,R 1,2 ,…,R 1,h ;R 2,1 ,R 2,2 ,…,R 2,h ;…,R g,1 ,R g,2 ,…,R g,h ); G = (G 1,1 G 1,2,…,G 1,h G 2,1 G 2,2 ,…,G 2,h ;…,G g,1 G g,2 ,…,G g,h ); B = (B 1,1 B 1,2 ,…,B 1,h B 2,1 B 2,2 ,…,B 2,h ;…,B B,1 B B,2 ,…,B B,h );

[0041] The process of converting the three-dimensional data of partial discharge spectra at different times into a grayscale array specifically includes:

[0042] partial discharge spectrum Figure 1 The graph and partial discharge spectrum Figure 2 The image is converted to a grayscale array Q. gray1 and Q gray2 The format is Q. gray =(H 1,1 H 1,2 ,…,H 1,h H 2,1 H 2,2 ,…,H 2,h ;…,H g,1 H g,2 ,…,H g,h ), where the grayscale value H is:

[0043] H=(0.299×R+0.587×G+0.114×B) / 255 (5)

[0044] Therefore, Q(x,y,t) can be used to represent the intensity of partial discharge at pixel (x,y) in the partial discharge spectrum obtained at a certain time t. This intensity can be equivalent to the normalized value of the number of partial discharges with a discharge amount of y occurring at phase x; the gray value H ranges from (0,1).

[0045] As a further technical solution of the present invention, the step of processing the grayscale image array of the partial discharge spectrum conversion at different times to obtain the partial discharge spectrum development trend map specifically includes:

[0046] Assuming that the intensity of the partial discharge at (x,y) remains constant over a very short time interval, we can obtain:

[0047] Q(x+dx,y+dy,t+dt)=Q(x,y,t) (6)

[0048] Taylor series expansion yields:

[0049]

[0050] Substituting into formula (6), we get:

[0051]

[0052] The strength of the trend in the development direction of the partial discharge spectrum is defined as follows:

[0053]

[0054] In the formula: f represents the intensity of the trend of any point in the partial discharge spectrum developing in the x direction, and p represents the intensity of the trend of any point in the partial discharge spectrum developing in the y direction;

[0055] Therefore, we can conclude that:

[0056]

[0057] According to the partial discharge spectrum of a fault in a gas-insulated metal-enclosed switchgear, the development of the partial discharge data stream is a smooth shift based on the partial discharge at the previous moment. Therefore...

[0058]

[0059] In the formula: ▽ represents the gradient;

[0060] Combining equations (6), (9) and (10), we can obtain

[0061]

[0062] In the formula: η is the weight;

[0063] The strength of the trend f, which represents the development direction of the partial discharge spectrum, can be calculated from equation (11). g×h and p g×h matrix.

[0064] As a further technical solution of the present invention, the method of assessing the intensity change of partial discharge activity based on the direction and length of the arrows on the partial discharge spectrum development trend diagram specifically includes:

[0065] The starting position of the arrow on the partial discharge spectrum development trend diagram indicates the location of the initial state of partial discharge, i.e. The direction of the arrow indicates that the number of partial discharges in the direction the arrow points will increase, and the length of the arrow indicates the probability of an increase in the number of partial discharges in the direction the arrow points. The number of partial discharges in the direction the arrow points refers to the number of partial discharges at the corresponding position in the coordinate system formed by the phase on the horizontal axis and the discharge quantity on the vertical axis, that is, the change in the intensity of partial discharge activity at these positions.

[0066] The present invention has the following advantages over the prior art:

[0067] This invention discloses a method for analyzing the partial discharge spectrum inside gas-insulated metal-enclosed switchgear, enabling the assessment of the development direction of the partial discharge spectrum within the equipment of power frequency voltage gas-insulated metal-enclosed switchgear. By constructing and reconstructing the partial discharge spectrum to form a diagram of possible changes in partial discharge direction, the development direction is assessed based on the direction and length of the arrows in the diagram; that is, the direction of the arrow indicates that the number of partial discharges in the direction pointed to by the arrow will increase, and the length of the arrow indicates the probability of an increase in the number of partial discharges in the direction pointed to by the arrow. The partial discharge in the direction pointed to by the arrow refers to the number of partial discharges at the corresponding position in the coordinate system formed by the phase on the horizontal axis and the discharge quantity on the vertical axis, i.e., the change in the intensity of partial discharge activity at these positions. Attached Figure Description

[0068] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0069] Figure 1 This is a flowchart of a method for analyzing the internal partial discharge spectrum of a gas-insulated metal-enclosed switchgear proposed in this invention;

[0070] Figure 2 This is a schematic diagram of the partial discharge spectrum construction process proposed in this invention;

[0071] Figure 3 This invention provides a scatter plot of partial discharge points for surface partial discharge in gas-insulated metal-enclosed switchgear.

[0072] Figure 4 According to the present invention Figure 3 Normalized partial discharge scatter plot;

[0073] Figure 5 According to the present invention Figure 4 A partial discharge spectrum was obtained;

[0074] Figure 6a This is a schematic diagram of the partial discharge spectrum at a certain moment as proposed in this invention;

[0075] Figure 6b This is a schematic diagram of the partial discharge spectrum at another moment proposed in this invention;

[0076] Figure 7a The present invention proposes Figure 6a A PNG format image of a partial discharge spectrum;

[0077] Figure 7b The present invention proposes Figure 6b A PNG format image of a partial discharge spectrum;

[0078] Figure 8 The result obtained from Equation 5-11 Figure 7a Development to Figure 7b A trend chart of possible development directions;

[0079] Figure 9 To Figure 8 The diagram shows the trend of the development direction of the partial discharge spectrum. Detailed Implementation

[0080] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be understood that the specific embodiments described are merely used to explain this application and are not intended to limit this application.

[0081] The present invention provides a method for analyzing the partial discharge spectrum inside a gas-insulated metal-enclosed switchgear, enabling the assessment of the development trend of the partial discharge spectrum within the gas-insulated metal-enclosed switchgear for power frequency voltage applications.

[0082] See Figure 1 and Figure 2 This invention provides a method for evaluating the development trend of partial discharge in gas-insulated metal-enclosed switchgear, comprising:

[0083] Step 101: Collect partial discharge signals inside the gas-insulated metal-enclosed switchgear;

[0084] Step 102: Process the partial discharge signal to obtain the raw partial discharge data;

[0085] Step 103: Obtain a partial discharge scatter plot based on the original partial discharge data;

[0086] Step 104: Scale the partial discharge scatter plot and reconstruct the scaled partial discharge scatter plot to obtain the partial discharge spectrum.

[0087] Step 105: Construct partial discharge spectra at different times according to the partial discharge spectrum construction method;

[0088] Step 106: Perform image processing on the partial discharge spectra at different times and convert them into grayscale arrays;

[0089] Step 107: Process the grayscale array of partial discharge spectrum conversion at different times to obtain the development trend map of partial discharge spectrum;

[0090] Step 108: Assess the intensity changes of partial discharge activity based on the partial discharge spectrum development trend diagram.

[0091] This invention provides a method for analyzing the partial discharge spectrum inside gas-insulated metal-enclosed switchgear, enabling the assessment of the development trend of the partial discharge spectrum within the equipment of gas-insulated metal-enclosed switchgear used for power frequency voltage. The method assesses the development trend of the partial discharge spectrum by constructing it.

[0092] In step 101, the partial discharge signal inside the gas-insulated metal-enclosed switchgear is acquired. Specifically, the partial discharge signal inside the gas-insulated metal-enclosed switchgear is acquired. The signal should be a continuous partial discharge pulse signal, and the acquisition start time should be the zero point of the positive half-cycle of the power frequency sinusoidal voltage. The total acquisition time t is an integer multiple of 20ms.

[0093] See Figure 2 This is a schematic diagram of the partial discharge spectrum construction process in an embodiment of this application;

[0094] like Figure 1 As shown, the construction of a partial discharge spectrum includes the following steps:

[0095] The partial discharge signal is processed to obtain the raw partial discharge data D; the raw partial discharge data D is derived from the phase in which the partial discharge occurs. and discharge quantity q i Composition (i is the sequence number of the partial discharge occurrence, taking positive integers 1, 2, 3, ...), i.e.

[0096]

[0097] In the formula: n is the total number of partial discharges that occur within time t; the starting time for collecting partial discharge data (i.e., t=0) should be the zero-crossing point of the positive half-cycle of the power frequency sinusoidal voltage; The i-th partial discharge occurs at the power frequency phase, which is determined by the 20ms period corresponding to a 50Hz power frequency voltage, representing the time of partial discharge occurrence. Normalized to 0–360°, it satisfies equation (2):

[0098]

[0099] In the formula: mod 20 is The remainder when divided by 20 The unit is milliseconds (ms).

[0100] To obtain effective partial discharge characteristics, the value of t should not be too long or too short. If the value of t is too small, the partial discharge data will not have statistical regularity, which will reduce the accuracy of the assessment of the development direction of the partial discharge spectrum. Therefore, t should be no less than 10 s. If the value of t is too large, the amount of data will increase, but the accuracy of the assessment will not be significantly improved, and the computational burden will also increase.

[0101] In step 103, a partial discharge scatter plot is obtained based on the original partial discharge data; specifically, this includes:

[0102] The partial discharge scatter plot is obtained by taking the raw partial discharge data D within time t, with the horizontal axis representing the phase in which the partial discharge occurs. The vertical axis represents the discharge quantity q, which is the absolute value of the discharge quantity q, and the range of the absolute value of the discharge quantity q is [0, q]. max Phase The range is [0°, 360°]; as an example, such as Figure 3 The figure shows a scatter plot of partial discharge on the surface of a gas-insulated, metal-enclosed switchgear, with time t = 3000 s and q = 0. max It is 500pC.

[0103] In step 104, the partial discharge scatter plot is scaled and reconstructed to obtain the partial discharge spectrum, specifically including:

[0104] Scaling the partial discharge scatter plot involves scaling the discharge quantity q and phase separately. Normalization to a fixed range ensures that the data are on the same scale when assessing the development direction of subsequent partial discharge spectra. The specific normalization formula is as follows:

[0105]

[0106]

[0107] In the formula: q′ i and These represent the normalized discharge quantity and the phase of partial discharge, respectively; [] represents the rounding operation; l and k are normalization coefficients, which should be selected from 64, 128, 256, 512, and 1024 for easier subsequent computer calculations.

[0108] As an example, such as Figure 4 The following is based on Figure 3 Normalized partial discharge scatter plot.

[0109] The scaled partial discharge scatter plot is reconstructed to obtain the partial discharge spectrum. The reconstruction process involves converting the partial discharge scatter plot into a matrix N, which has l rows and k columns. m×n (n is 1, 2, ..., k; m is 1, 2, ..., l) represents the number of partial discharges with a discharge quantity of m at phase n within time t.

[0110] Then, with the phase n and discharge quantity m of the partial discharge occurring as the x and y coordinates, respectively, the number of partial discharges N is... m×n The color value is used to obtain the partial discharge spectrum. The color value is related to the number of partial discharges N. m×n The range (0, N) max The relationship is linear. Color values ​​use binary RGB format.

[0111] As an example, such as Figure 5 The following is based on Figure 4 A partial discharge spectrum is obtained. The color value range of the partial discharge spectrum is (#F0F0F0, #000000), and the number of partial discharge occurrences ranges (0, 600).

[0112] In this embodiment of the invention, the assessment of the development direction of partial discharge spectra is achieved by comparing partial discharge spectra at different times to analyze the possible directions of change in partial discharge, thus indexing the changes in partial discharge. Partial discharge spectra at different times are constructed according to the partial discharge spectra construction method; specifically, this includes:

[0113] First, based on the partial discharge spectrum construction method, two partial discharge spectra are obtained: partial discharge spectrum... Figure 1 and partial discharge spectrum Figure 2 Partial discharge spectrum Figure 1 and partial discharge spectrum Figure 2 The partial discharge data acquisition time t is the same, i.e., the partial discharge spectrum... Figure 1 The partial discharge spectrum was obtained from the partial discharge data from time t1 to t2. Figure 2 The partial discharge spectrum was obtained from the partial discharge data from time t3 to t4, and satisfies t2-t1=t4-t3. Figure 1 The start time t1 and end time t2 of the data acquisition were both earlier than the partial discharge spectrum. Figure 2 The data collection started at time t3. For example... Figure 6a and Figure 6b The image shows two partial discharge spectra at different times.

[0114] In step 106, the partial discharge spectra at different times are processed and converted into a grayscale array; specifically, this includes:

[0115] Set the partial discharge spectra at different times and save them as PNG format images;

[0116] The graphs of partial discharge spectra at different times are converted into three-dimensional arrays;

[0117] The three-dimensional data of partial discharge spectra at different times are converted into grayscale arrays.

[0118] Save the partial discharge spectra at different times as PNG format images; specifically including:

[0119] Partial discharge spectra at different times were constructed based on the partial discharge spectrum construction method, and the partial discharge spectra were obtained. Figure 1 and partial discharge spectrum Figure 2 ; partial discharge spectrum Figure 1 and partial discharge spectrum Figure 2 The vertical axis, i.e., the range of discharge quantity, is set to the same value. Save the image as a portable network graphic (PNG) with identical pixel dimensions and a length and width of g × h. Save the partial discharge spectrum. Figure 1 The graph and partial discharge spectrum Figure 2 The graph retains only the data information and does not include axes, axis titles, or other information. As an example, such as... Figure 7a and Figure 7b for Figure 6a and Figure 6b The two partial discharge spectra shown are PNG format images. Image 1 and Image 2 have the same length and width, 647×594, meaning g is 647 and h is 594.

[0120] partial discharge spectrum Figure 1 The graph and partial discharge spectrum Figure 2 The graph is converted into a three-dimensional array; specifically including:

[0121] partial discharge spectrum Figure 1 The graph and partial discharge spectrum Figure 2 The image is converted into two three-dimensional arrays, Q1 and Q2, with the format Q = (R; G; B), where R, G, and B are the brightness matrices of red, green, and blue for all pixels in the image, respectively. 1,1 ,R 1,2 ,…,R 1,h ;R2,1 ,R 2,2 ,…,R 2,h ;…,R g,1 ,R g,2 ,…,R g,h ); G = (G 1,1 G 1,2 ,…,G 1,h G 2,1 G 2,2 ,…,G 2,h ;…,G g,1 G g,2 ,…,G g,h ); B = (B 1,1 B 1,2 ,…,B 1,h B 2,1 B 2,2 ,…,B 2,h ;…,B B,1 B B,2 ,…,B B,h The R, G, and B refer to the red, green, and blue colors in the RGB color model, with each color having 256 levels of brightness. For example, R... g,h This represents the red brightness level at pixel positions g and h, and its value is an integer between (0, 255), such as R. 1.1 =0, G 1.1 =0, B 1.1 =0 means that the brightness of the red, green and blue colors of the pixel at position (1,1) is 0, that is, the pixel is black.

[0122] partial discharge spectrum Figure 1 The graph and partial discharge spectrum Figure 2 The image is converted to a grayscale array Q. gray1 and Q gray2 The format is Q. gray =(H 1,1 H 1,2 ,…,H 1,h H 2,1 H 2,2 ,…,H 2,h ;…,H g,1 H g,2 ,…,H g,h ), where the grayscale value H is:

[0123] H=(0.299×R+0.587×G+0.114×B) / 255 (5)

[0124] Therefore, Q(x,y,t) can be used to represent the intensity of partial discharge at pixel (x,y) in the partial discharge spectrum obtained at a certain time t. This intensity can be equivalent to the normalized value of the number of partial discharges with a discharge amount of y occurring at phase x; the gray value H ranges from (0,1).

[0125] In this embodiment of the invention, the grayscale image arrays converted from partial discharge spectra at different times are processed to obtain a partial discharge spectrum development trend map, specifically including:

[0126] Assuming that the intensity of the partial discharge at (x,y) remains constant over a very short time interval, we can obtain...

[0127] Q(x+dx,y+dy,t+dt)=Q(x,y,t) (6)

[0128] Taylor series expansion yields

[0129]

[0130] Substituting into formula (6), we get

[0131]

[0132] The strength of the trend in the development direction of the partial discharge spectrum is defined as...

[0133]

[0134] In the formula: f represents the intensity of the trend of any point in the partial discharge spectrum developing in the x direction, and p represents the intensity of the trend of any point in the partial discharge spectrum developing in the y direction;

[0135] From this we can obtain

[0136]

[0137] According to the partial discharge spectrum of a fault in a gas-insulated metal-enclosed switchgear, the development of the partial discharge data stream is a smooth movement based on the partial discharge at the previous moment, without any jumps or interruptions.

[0138] therefore,

[0139]

[0140] In the formula: ▽ represents the gradient;

[0141] Combining equations (6), (9) and (10), we can obtain

[0142]

[0143] In the formula: η is the weight.

[0144] The strength of the trend f, which represents the development direction of the partial discharge spectrum, can be calculated from equation (11). g×h and p g×h matrix.

[0145] As an example, such as Figure 8 This is a trend diagram of the possible development direction of the partial discharge spectrum after evolving from Figure 1 to Figure 2, obtained according to equations (5)-(11). Figure 8 Each arrow in the diagram corresponds to a phase. and discharge quantity q′ i The strength of the partial discharge change at the location.

[0146] like Figure 9 To further Figure 8 Explanation of the development trend of the partial discharge spectrum shown. The starting position of the arrow in the figure is the location of the initial state of partial discharge, i.e. The direction of the arrow indicates that the number of partial discharges in that direction will increase, and the length of the arrow indicates the probability of an increase in the number of partial discharges in that direction. Partial discharges in the direction the arrow points refer to the number of partial discharges at the corresponding position on the coordinate system formed by the phase on the horizontal axis and the discharge quantity on the vertical axis; that is, the variation in the intensity of partial discharge activity at these positions.

[0147] The present invention has been described in detail above, but it is not limited to the embodiments described above. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the invention. Many other changes and modifications can be made without departing from the concept and scope of the invention. It should be understood that the present invention is not limited to the specific embodiments, and the scope of the invention is defined by the appended claims.

Claims

1. A method for evaluating the development trend of partial discharge in gas-insulated metal-enclosed switchgear, characterized in that, include: Collect partial discharge signals inside gas-insulated, metal-enclosed switchgear; The partial discharge signal is processed to obtain the raw partial discharge data; A partial discharge scatter plot was obtained based on the original partial discharge data. The partial discharge scatter plot is scaled and then reconstructed to obtain the partial discharge spectrum. Partial discharge spectra at different times were constructed based on the partial discharge spectrum construction method; The partial discharge spectra at different times are processed and converted into grayscale arrays; The grayscale array of partial discharge spectra at different times is processed to obtain the development trend map of partial discharge spectra; The intensity changes of partial discharge activity can be assessed based on the development trend diagram of the partial discharge spectrum. The process of processing the grayscale array of partial discharge spectra converted at different times to obtain the partial discharge spectrum development trend map specifically includes: Assuming that the intensity of the partial discharge at (x, y) remains constant over a very short time interval, we can obtain: （6）； Where Q(x, y, t) is the intensity of the partial discharge at pixel (x, y) in the partial discharge spectrum obtained at a certain time t. This intensity is equivalent to the normalized value of the number of times a partial discharge with a discharge amount of y occurs at phase x. Taylor series expansion yields: （7）； Substituting into formula (6), we get: （8）； The strength of the trend in the development direction of the partial discharge spectrum is defined as follows: （9）； In the formula: f represents the intensity of the trend of any point in the partial discharge spectrum developing in the x direction, and p represents the intensity of the trend of any point in the partial discharge spectrum developing in the y direction; Therefore, we can conclude that: （10）； According to the partial discharge spectrum of a fault in a gas-insulated metal-enclosed switchgear, the development of the partial discharge data stream is a smooth shift based on the partial discharge at the previous moment. Therefore... （11）； In the formula: ▽ represents the gradient; Combining equations (6), (9), and (10), the optimization objective function for the development of partial discharge data stream can be obtained as follows: （12）； In the formula: η is the weight; The strength of the trend f, representing the development direction of the partial discharge spectrum, can be calculated using equation (12). g×h and p g×h matrix.

2. The method for evaluating the development trend of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 1, characterized in that, The acquisition of the partial discharge signal inside the gas-insulated metal-enclosed switchgear specifically involves: acquiring the partial discharge signal inside the gas-insulated metal-enclosed switchgear, which should be a continuous partial discharge pulse signal, and the acquisition start time should be the zero-crossing point of the positive half-cycle of the power frequency sinusoidal voltage, with the total acquisition time t being an integer multiple of 20ms.

3. The method for evaluating the development trend of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 1, characterized in that, The process of processing the partial discharge signal to obtain raw partial discharge data specifically includes: The partial discharge signal is processed to obtain the raw partial discharge data D; the raw partial discharge data D is derived from the phase φ of the partial discharge. i and discharge quantity q i Composition, where i is the sequence number of the partial discharge occurrence, taking positive integers 1, 2, 3, …, i.e. （1）； In the formula: the starting time t=0 for partial discharge data acquisition should be the zero-crossing point of the positive half-cycle of the power frequency sinusoidal voltage; φ i The i-th partial discharge occurs at the power frequency phase, which is determined by the 20ms period corresponding to the 50Hz power frequency voltage, and the time t during the partial discharge is calculated. φ Normalized to 0~360°, it satisfies equation (2): （2）； In the formula: t φ mod 20 is t φ The remainder when divided by 20, t φ The unit is milliseconds (ms).

4. The method for evaluating the development trend of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 1, characterized in that, The step of obtaining a partial discharge scatter plot based on the original partial discharge data specifically includes: A partial discharge scatter plot is obtained by taking the raw partial discharge data D within time t. The horizontal axis represents the phase φ of the partial discharge, and the vertical axis represents the discharge quantity q. The discharge quantity q is taken as its absolute value, and the range of the absolute value of the discharge quantity q is [0, q]. max The phase φ ranges from [0° to 360°].

5. The method for evaluating the development trend of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 1, characterized in that, The process of scaling the partial discharge scatter plot and reconstructing the scaled partial discharge scatter plot to obtain the partial discharge spectrum specifically includes: Scaling the partial discharge scatter plot involves normalizing both the discharge quantity q and phase φ to a fixed range, ensuring that the data are at the same scale when assessing the subsequent development direction of the partial discharge spectrum. The specific normalization formula is as follows: （3）； （4）； In the formula: q′ i and φ′ i , respectively, represent the normalized discharge quantity and the phase of partial discharge; [ ] is the floor function; l and k are the normalization coefficients; The scaled partial discharge scatter plot is reconstructed to obtain the partial discharge spectrum. The reconstruction process involves converting the partial discharge scatter plot into a matrix N, which has l rows and k columns. m×n (n is 1, 2, …, k; m is 1, 2, …, l) represents the number of partial discharges with a discharge quantity of m occurring at phase n within time t; Then, with the phase n and discharge quantity m of the partial discharge occurring as the x and y coordinates, respectively, the number of partial discharges N is... m×n The color value is used to obtain the partial discharge spectrum; the color value is related to the number of partial discharges N. m×n The range (0, N) max The values ​​exhibit a linear relationship; color values ​​are in binary RGB format.

6. The method for evaluating the development trend of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 1, characterized in that, The method for constructing partial discharge spectra at different times based on the partial discharge spectrum construction method specifically includes: First, based on the partial discharge spectrum construction method, two partial discharge spectra are obtained: partial discharge spectrum 1 and partial discharge spectrum 2. The partial discharge data acquisition time t of partial discharge spectrum 1 and partial discharge spectrum 2 is the same, that is, partial discharge spectrum 1 is obtained from partial discharge data from time t1 to t2, and partial discharge spectrum 2 is obtained from partial discharge data from time t3 to t4, and satisfies t2−t1= t4−t3. The start time t1 and end time t2 of partial discharge spectrum 1 are both earlier than the start time t3 of partial discharge spectrum 2.

7. The method for evaluating the development direction of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 1, characterized in that, The process of image processing the partial discharge spectra at different times and converting them into a grayscale array specifically includes: Set the partial discharge spectra at different times and save them as PNG format images; The graphs of partial discharge spectra at different times are converted into three-dimensional arrays; The three-dimensional data of partial discharge spectra at different times are converted into grayscale arrays.

8. The method for evaluating the development trend of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 7, characterized in that, The step of setting and saving partial discharge spectra at different times as PNG format images specifically includes: Set the vertical axis of partial discharge spectrum 1 and partial discharge spectrum 2, i.e. the range of discharge quantity, to the same value, and save them as portable network graphics PNG format graphics. The image pixels should be the same, and the length and width should be g×h. The saved graphics of partial discharge spectrum 1 and partial discharge spectrum 2 only retain the data information and do not include the coordinate axes and coordinate axis titles. The process of converting partial discharge spectra at different times into a three-dimensional array specifically includes: The partial discharge spectrum images 1 and 2 are converted into three-dimensional arrays Q1 and Q2, respectively, with the format Q=(R;G;B). R, G, and B are the brightness matrices of red, green, and blue for all pixels in the images, respectively. 1,1 , R 1,2 , …, R 1,h ; R 2,1 , R 2,2 , …, R 2,h ; …, R g,1 , R g,2 , …, R g,h );G =( G 1,1 G 1,2 ,…, G 1,h G 2,1 G 2,2 , …, G 2,h ; …, G g,1 G g,2 , …, G g,h B = (B) 1,1 B 1,2 , …,B 1,h B 2,1 B 2,2 , …, B 2,h ; …, B B,1 B B,2 , …, B B,h ); The process of converting the three-dimensional data of partial discharge spectra at different times into a grayscale array specifically includes: Convert the partial discharge spectrum 1 and partial discharge spectrum 2 into a grayscale array Q. gray1 and Q gray2 The format is Q. gray =(H 1,1 H 1,2 , …, H 1,h H 2,1 H 2,2 , …, H 2,h ; …, H g,1 H g,2 , …, H g,h ), where the grayscale value H is: （5）； The grayscale value H ranges from (0, 1).

9. The method for evaluating the development trend of partial discharge in a gas-insulated metal-enclosed switchgear according to claim 1, characterized in that, The method of assessing the intensity changes of partial discharge activity based on the direction and length of the arrows on the partial discharge spectrum development trend diagram includes: The starting position of the arrow on the partial discharge spectrum development trend diagram is the position of the initial state of partial discharge, i.e., (φ′). i , q′ i The direction of the arrow indicates that the number of partial discharges in the direction the arrow points will increase, and the length of the arrow indicates the probability of an increase in the number of partial discharges in the direction the arrow points. The number of partial discharges in the direction the arrow points refers to the number of partial discharges at the corresponding position in the coordinate system formed by the phase on the horizontal axis and the discharge quantity on the vertical axis, that is, the change in the intensity of partial discharge activity at these positions.

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