Phase-isolated enclosed bus internal conductor temperature measurement system based on machine vision

Abstract

The technical scheme adopted by the invention is as follows: the phase-isolated enclosed bus internal conductor temperature measurement system based on machine vision comprises a thermometer, an observation window, an industrial camera and an image processing unit, the thermometer adopts a dial thermometer, is arranged on the surface of the bus conductor and is used for acquiring the current temperature of the bus conductor; the observation window is arranged on the surface of the bus shell and directly faces the thermometer; the industrial camera is arranged on the outer side of the bus shell and is used for shooting a thermometer image through the observation window and sending the thermometer image to the image processing unit; the intelligent level of on-line temperature monitoring of the enclosed bus is greatly improved, and the reliability of long-term operation of equipment is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electromechanical engineering, and in particular relates to a temperature measurement system for internal conductors of a phase-isolated closed busbar based on machine vision. Background Art

[0002] The phase-isolated enclosed busbar is a high-current lead-out device for the generator in a power station. It is generally connected in a metal shell, and the internal conductor is supported on the shell by a support insulator. Since the enclosed busbar adopts a metal shell full connection, its internal conductor is partially invisible. At present, due to electrical insulation and full enclosure, the internal conductor is only equipped with a conductor dial thermometer at a key position, and the shell is opened with an observation window for manual reading. Since the setting position of the thermometer is generally below the busbar conductor, it is difficult to read, which wastes manpower and is inefficient, and the safety of the operator cannot be guaranteed. Summary of the invention

[0003] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology and to provide a temperature measurement system for the internal conductor of a phase-separated closed busbar based on machine vision, which can realize the machine vision non-contact online identification of the temperature of the conductor inside a fully enclosed metal casing, thereby changing the current situation that the thermometer of the conductor inside the closed busbar cannot lead out a signal due to insulation and can only be observed manually, greatly improving the intelligence level of online temperature monitoring of the closed busbar and improving the long-term operation reliability of the equipment.

[0004] The technical solution adopted by the present invention is: a temperature measurement system for the internal conductor of a phase-isolated closed busbar based on machine vision, comprising a thermometer, an observation window, an industrial camera and an image processing unit;

[0005] The thermometer is a dial thermometer, which is arranged on the surface of the bus conductor and is used to collect the current temperature of the bus conductor;

[0006] The observation window is arranged on the surface of the busbar housing and faces the thermometer;

[0007] The industrial camera is arranged outside the busbar housing and is used to capture the thermometer image through the observation window and send it to the image processing unit;

[0008] The image processing unit is used to identify the current temperature of the bus conductor according to the thermometer image.

[0009] In the above technical solution, the image processing unit identifies the pixel coordinate value of the temperature pointer in the current thermometer image; substitutes the pixel coordinate value of the temperature pointer into the straight line linear fitting equation corresponding to the thermometer to obtain the current temperature reading of the thermometer; the straight line linear fitting equation is used to characterize the mathematical relationship between the pixel coordinate value of the temperature pointer and the thermometer reading.

[0010] In the above technical solution, the process of establishing the linear fitting equation of the straight line includes: based on the image of the thermometer, the circular scale of the thermometer is stretched into a straight line segment; the pixel coordinate position of each scale line in the straight line segment is identified; according to the scale range and scale line position of the thermometer, the corresponding relationship between the pixel coordinate value and the temperature reading is established.

[0011] In the above technical solution, the process of the image processing unit identifying the pixel coordinate value of the temperature pointer in the current thermometer image includes: stretching the circular scale image of the thermometer into a straight line segment image, and using a template matching algorithm to identify the pixel coordinate value of the temperature pointer in the straight line segment image.

[0012] In the above technical scheme, the process of stretching the circular scale image of the thermometer into a straight line segment image includes: identifying the outer circle of the circular image of the thermometer, fitting the edge line of the outer circle of the thermometer with a square frame, and intercepting the image inside the square, establishing a polar coordinate system with pixels as units, and setting the center of the square as the polar coordinate origin; converting the polar coordinate system into a rectangular coordinate system, so that the circular scale image of the thermometer is stretched into a straight line segment image of the rectangular coordinate system.

[0013] In the above technical solution, the polar coordinate system is converted into a rectangular coordinate system using the following formula:

[0014]

[0015] Among them, (r1,∠θ) represents any point in the polar coordinate system, (X1,Y1) represents a point in the plane rectangular coordinate system; R represents the outer circle radius of the dial thermometer scale value.

[0016] In the above technical solution, a straight line linear fitting method is used to determine the temperature reading represented by each scale line based on the scale range of the thermometer, and based on the coordinate position of the scale line, the straight line linear fitting equation is solved:

[0017] Y = k·X + b;

[0018] Among them, Y represents the thermometer reading, X represents the current pixel coordinate value of the temperature pointer, b represents a constant, and k represents a coefficient.

[0019] In the above technical solution, the process of stretching the circular scale image of the thermometer into a straight line segment image also includes: identifying the starting point position of the circular scale of the thermometer through a template matching algorithm; and generating an image of the straight line segment in a rectangular coordinate system based on the starting point position of the circular scale.

[0020] In the above technical solution, the process of pulling the circular scale image of the thermometer into a straight line segment image also includes: performing multi-point uneven calibration on the straight line segment scale of the fitted rectangular coordinate system so that the middle scale line is linear in the calibrated thermometer image.

[0021] In the above technical solution, the image processing unit calculates the bus conductor temperature change rate according to the temperature of the bus conductor in a continuous time; and sends out a warning signal when the bus conductor temperature change rate exceeds a set threshold

[0022] The beneficial effects of the present invention are as follows: the present invention proposes a system based on machine vision and high-precision recognition of the thermometer dial of the conductor inside the closed busbar, which monitors the conductor temperature online and makes it impossible for operators to read the thermometer on site, thereby effectively improving the efficiency of temperature monitoring. The installation position and method of the industrial camera and the thermometer in the present invention can effectively obtain the current temperature of the busbar conductor while avoiding affecting the normal operation of the busbar.

[0023] Furthermore, the image data processing method proposed in the present invention establishes a straight line fitting equation for the scale of the thermometer by effectively identifying the starting position and scale of the thermometer and the position of the thermometer pointer, and then effectively obtains the reading of the circular dial thermometer, thereby improving the calculation efficiency while ensuring the accurate reading of the thermometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention;

[0025] Figure 2 Coordinate transformation schematic diagram of the present invention;

[0026] Figure 3 It is a schematic diagram of the circumference scale and pointer of the circular dial of the present invention pulled up into a rectangular coordinate system;

[0027] Figure 4 It is a schematic diagram of the use process of the present invention.

[0028] Among them, 1-busbar housing, 2-busbar conductor, 3-observation window, 4-thermometer, 5-industrial camera, 6-camera base, 7-control box. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but they do not constitute a limitation on the present invention.

[0030] like Figure 1 As shown, the present invention is a temperature measurement system for the internal conductor of a phase-isolated closed busbar based on machine vision, comprising a thermometer 4, an observation window 3, an industrial camera 5 and an image processing unit;

[0031] The thermometer 4 is a dial-type thermometer 4, which is arranged on the surface of the bus conductor 2 and is used to collect the current temperature of the bus conductor 2;

[0032] The observation window 3 is arranged on the surface of the busbar housing 1 and faces the thermometer 4;

[0033] The industrial camera 5 is arranged outside the busbar housing 1 and is used to take an image of the thermometer 4 through the observation window 3 and send it to the image processing unit;

[0034] The image processing unit is used to identify the current temperature of the bus conductor 2 according to the image of the thermometer 4 .

[0035] The busbar housing 1 is a circular metal housing of a fully connected enclosed busbar, which provides support points and electromagnetic shielding protection for the internal conductor. A dial thermometer 4 is provided on the conductor and a circular glass observation window is provided at the corresponding housing to facilitate operating personnel to read the temperature value with the naked eye.

[0036] The bus conductor 2 is the current-conducting part inside the closed busbar. It is a high-voltage (generator voltage 10kV~26kV / √3) and high-current (10kA~28kA) circular metal conductor, which is concentric with the busbar housing 1 and supported on the housing by supporting insulators (3~4) arranged symmetrically along the circumference. At the connection part where the conductor temperature is higher, a dial-type physical pointer thermometer 4 is often provided to display the temperature of the conductor at that location.

[0037] The thermometer 4 is a pointer-type circular dial thermometer 4, and the scale is 0 to 160°C according to the operating temperature range of the busbar.

[0038] The industrial camera 5 can be a surface array camera or a linear array camera. In this specific embodiment, a high-resolution, high-precision camera with a resolution of 1920 pixels × 1080 pixels is selected to identify edges. Since the device is inside the busbar housing 1, it has a dedicated light source and is integrated with the camera (industrial camera 5). The industrial camera 5 is also equipped with an image acquisition card to realize image acquisition and preprocessing obtained by the industrial camera lens. The data interface determines the transmission bandwidth according to the resolution and frame rate. The USB3.0, Camera Link or GigE interface can be selected in combination with the transmission distance. The USB3.0 interface is selected in this specific embodiment. The industrial camera 5 is also equipped with a dedicated communication interface for transmitting the image data of the thermometer 4 to the image processing unit. The present invention supports the industrial camera 5 by installing a camera base 6 under the busbar housing 1. At the same time, the present invention sets a local power supply control box 7 in the phase-isolated enclosed bus (IPB) corridor to provide a safe voltage power supply and the required signal data acquisition and control for the industrial camera 5 and the image processing unit.

[0039] Therefore, the image processing unit is equipped with a machine recognition and AI algorithm processing unit for high-precision recognition of the thermometer 4 image. After the image enhancement, edge and contour pixel-level recognition algorithm is applied, the reading of the temperature pointer and the temperature reading change trend (change per unit time) can be identified, and an early warning can be issued according to the set threshold.

[0040] like Figure 4 As shown, the present invention specifically comprises the following steps:

[0041] Step 1, the industrial camera 5 captures the circular dial image of the thermometer 4 through the observation window 3, and converts it into a digital format file with a resolution of 1920 pixels × 1080 pixels; and sends it to the image processing unit.

[0042] Step 2: The image processing unit identifies the pixel coordinate value of the temperature pointer in the current thermometer 4 image.

[0043] Specifically, the process of the image processing unit identifying the pixel coordinate value of the temperature pointer in the current image of the thermometer 4 includes: pulling the circumferential scale image of the thermometer 4 into a straight line segment image, and using a template matching algorithm to identify the pixel coordinate value of the temperature pointer in the straight line segment. The present invention converts the circular dial into a straight line segment, and identifies the pixel coordinate value of the temperature pointer in the straight line segment through a template matching algorithm, which can effectively realize high-precision pixel point level edge recognition and improve the recognition accuracy of the temperature reading.

[0044] The process of identifying the pixel coordinate value of the temperature pointer in the straight line segment by the template matching algorithm includes: manually intercepting the image part of the pointer from a clear thermometer 4 image as a template. This part usually includes the shape and color characteristics of the pointer. Read the thermometer 4 image, and perform grayscale and denoising to reduce the influence of noise on matching. Use the cv2.matchTemplate() function to search for the pointer template in the thermometer 4 image. OpenCV provides a variety of matching methods, such as normalized correlation matching (cv2.TM_CCOEFF_NORMED). This function will output a similarity map, in which each pixel value indicates the degree of matching between the template and the image at that position. Use the cv2.minMaxLoc() function to find the maximum value position in the similarity map, which is the most likely position of the thermometer 4 pointer. Based on this position, the starting point or feature point of the thermometer 4 pointer can be determined.

[0045] like Figure 2 As shown, the process of stretching the circular scale of the thermometer 4 into a straight line segment includes: identifying the outer circle of the circular image of the thermometer 4, fitting the edge line of the outer circle of the thermometer 4 with a square frame, and intercepting the image inside the square, establishing a polar coordinate system with pixels as units, and setting the center of the square as the polar coordinate origin; converting the polar coordinate system into a rectangular coordinate system, so that the circular scale image of the thermometer 4 is stretched to a straight line segment image of the rectangular coordinate system.

[0046] Preferably, if Figure 3As shown, the process of pulling the circular scale image of the thermometer 4 up to the straight line segment image of the rectangular coordinate system also includes: identifying the starting point position of the circular scale of the thermometer 4 through a template matching algorithm; generating the straight line segment of the rectangular coordinate system based on the starting point position of the circular scale. Since the circular scale of the circular dial of the thermometer 4 is not a full circle, by determining the starting point position of the circular scale as the starting position of the straight line segment image, the recognition progress can be effectively improved and the subsequent calculation cost can be reduced. In this specific embodiment, according to the range of 0 to 160°C of the circular dial temperature scale, image templates are established for 0°C, 160°C and the dial pointer, and the starting point of the straight line segment of 0 to 160°C in the rectangular coordinate system is determined through template matching.

[0047] Preferably, the process of pulling the circumferential scale of the thermometer 4 to a straight line segment of a rectangular coordinate system further includes: performing multi-point uneven calibration on the fitted straight line segment scale of the rectangular coordinate system, so that the scale line in the thermometer 4 is linear in the image of the calibrated thermometer 4. In this specific embodiment, the scale of 0 to 160°C is adjusted between the starting points of the straight line segment, so that the distribution distortion of the linear conversion scale is minimized, thereby achieving the highest recognition accuracy;

[0048] Preferably, the polar coordinate system is converted to a rectangular coordinate system using the following formula:

[0049]

[0050] Wherein, (r1, ∠θ) represents any point on the polar coordinate system, (X1, Y1) represents a point on the plane rectangular coordinate system; R represents the outer radius of the circular dial thermometer scale. The method and process of converting the polar coordinate system to the rectangular coordinate system adopted by the present invention can effectively convert the disk image into a straight line segment image.

[0051] Step 3, substitute the pixel coordinate value of the temperature pointer into the straight line linear fitting equation corresponding to the thermometer 4 to obtain the current temperature reading of the thermometer 4; the straight line linear fitting equation is used to characterize the mathematical relationship between the pixel coordinate value of the temperature pointer and the reading of the thermometer 4. The expression of the straight line linear fitting equation is as follows:

[0052] Y = k·X + b;

[0053] Wherein, Y represents the reading of the thermometer 4, X represents the current pixel coordinate value of the temperature pointer, and b represents a constant. In this specific embodiment, k=0.66, b=0.85.

[0054] In this specific embodiment, X=43, so Y=0.66*43+0.85=29.23(°C) is read.

[0055] The pointer of the dial thermometer 4 of the present invention performs template matching, and obtains the X coordinate value in the method of the present invention through high-precision edge recognition at the pixel level, thereby achieving temperature recognition at the 0.1°C level.

[0056] The image processing unit of the present invention is already equipped with a straight line linear fitting equation calculation software program before executing the thermometer 4 reading process.

[0057] Specifically, the process of establishing the straight line linear fitting equation in the straight line linear fitting equation calculation software program includes: before starting the formal temperature measurement process, first, based on the image of the thermometer 4, the circular scale of the thermometer 4 is stretched into a straight line segment; the pixel coordinate position of each scale line in the straight line segment is identified; according to the scale range and scale line position of the thermometer 4, the corresponding relationship between the pixel coordinate value and the temperature reading is established.

[0058] The process of stretching the circular scale of the thermometer 4 into a straight line segment includes: identifying the outer circle of the circular image of the thermometer 4, fitting the edge line of the outer circle of the thermometer 4 with a square frame, and intercepting the image inside the square, establishing a polar coordinate system with pixels as units, and setting the center of the square as the polar coordinate origin; converting the polar coordinate system into a rectangular coordinate system, so that the circular scale image of the thermometer 4 is stretched into a straight line segment image of the rectangular coordinate system.

[0059] Preferably, the process of pulling the circular scale image of the thermometer 4 up to a straight line segment image of a rectangular coordinate system also includes: identifying the starting point position of the circular scale of the thermometer 4 by a template matching algorithm; generating a straight line segment of a rectangular coordinate system based on the starting point position of the circular scale. Since the circular scale of the circular dial of the thermometer 4 is not a full circle, the starting point position of the circular scale is determined as the starting position of the straight line segment image. In this specific embodiment, according to the range of 0 to 160°C of the circular dial temperature scale, image templates are established for 0°C, 160°C and the dial pointer, and the starting point of the straight line segment of 0 to 160°C in the rectangular coordinate system is determined by template matching.

[0060] Preferably, the process of pulling the circular scale of the thermometer 4 up to the straight line segment of the rectangular coordinate system also includes: performing multi-point uneven calibration on the fitted straight line segment scale of the rectangular coordinate system, so that the scale lines in the thermometer 4 are linear in the calibrated thermometer 4 image. In the corrected image, the position of each scale line is detected using Hough transform or other line detection algorithms. In this specific embodiment, the scale of 0 to 160°C is adjusted between the starting points of the straight line segment to minimize the distribution distortion of the linear conversion scale, thereby achieving the highest recognition accuracy;

[0061] Preferably, the polar coordinate system is converted to a rectangular coordinate system using the following formula:

[0062]

[0063] Among them, (r1,∠θ) represents any point in the polar coordinate system, (X1,Y1) represents a point in the plane rectangular coordinate system; R represents the outer radius of the circular dial thermometer scale value.

[0064] Specifically, a straight-line linear fitting method is used to determine the temperature reading represented by each scale line based on the scale range of the thermometer 4, and based on the coordinate position of the scale line, a straight-line linear fitting equation is solved:

[0065] Y = k·X + b;

[0066] Wherein, Y represents the reading of the thermometer 4, X represents the current pixel coordinate value of the temperature pointer, and b represents a constant. In this specific embodiment, k=0.66, b=0.85.

[0067] Specifically, the image processing unit calculates the temperature change rate of the bus conductor 2 according to the temperature of the bus conductor 2 in a continuous time, and issues a warning signal when the temperature change rate of the bus conductor 2 exceeds a set threshold. The present invention can further obtain the obtained temperature data and perform deep learning to obtain the long-term state change trend of the conductor temperature inside the bus, and provide over-threshold temperature state forecast and warning. The present invention is also equipped with a status display device, which issues a warning signal when the temperature change rate of the bus conductor 2 exceeds a set threshold.

[0068] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A temperature measurement system for internal conductors of a phase-isolated enclosed busbar based on machine vision, characterized in that: Includes thermometer, observation window, industrial camera and image processing unit; The thermometer is a dial thermometer, which is arranged on the surface of the bus conductor and is used to collect the current temperature of the bus conductor; The observation window is arranged on the surface of the busbar housing and faces the thermometer; The industrial camera is arranged outside the busbar housing and is used to capture the thermometer image through the observation window and send it to the image processing unit; The image processing unit is used to identify the current temperature of the bus conductor according to the thermometer image.

2. According to the machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 1, it is characterized in that: The image processing unit identifies the pixel coordinate value of the temperature pointer in the current thermometer image; substitutes the pixel coordinate value of the temperature pointer into the straight line linear fitting equation corresponding to the thermometer to obtain the current temperature reading of the thermometer; the straight line linear fitting equation is used to characterize the mathematical relationship between the pixel coordinate value of the temperature pointer and the thermometer reading.

3. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 2, characterized in that: The process of establishing the linear fitting equation of the straight line includes: based on the image of the thermometer, stretching the circumferential scale of the thermometer into a straight line segment; identifying the pixel coordinate position of each scale line in the straight line segment; and establishing a corresponding relationship between the pixel coordinate value and the temperature reading according to the scale range and scale line position of the thermometer.

4. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 3 is characterized in that: The process of the image processing unit identifying the pixel coordinate value of the temperature pointer in the current thermometer image includes: pulling the circular scale image of the thermometer into a straight line segment image, and using a template matching algorithm to identify the pixel coordinate value of the temperature pointer in the straight line segment image.

5. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 4, characterized in that: The process of stretching the circular scale image of the thermometer into a straight line segment image includes: identifying the outer circle of the circular image of the thermometer, fitting the edge line of the outer circle of the thermometer with a square frame, intercepting the image inside the square, establishing a polar coordinate system with pixels as units, and setting the center of the square as the polar coordinate origin; converting the polar coordinate system into a rectangular coordinate system, so that the circular scale image of the thermometer is stretched into a straight line segment image of the rectangular coordinate system.

6. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 5, characterized in that: Use the following formula to convert polar coordinates to rectangular coordinates: Among them, (r1,∠θ) represents any point in the polar coordinate system, (X1,Y1) represents a point in the plane rectangular coordinate system; R represents the outer circle radius of the dial thermometer scale value.

7. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 3, characterized in that: The linear fitting method is used to determine the temperature reading represented by each scale line based on the scale range of the thermometer, and the linear fitting equation of the straight line is solved based on the coordinate position of the scale line: Y = k·X + b; Among them, Y represents the thermometer reading, X represents the current pixel coordinate value of the temperature pointer, b represents a constant, and k represents a coefficient.

8. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 5, characterized in that: The process of pulling the thermometer's circular scale image up to a straight line segment image also includes: identifying the starting point position of the thermometer's circular scale through a template matching algorithm; and generating a straight line segment image of a rectangular coordinate system based on the starting point position of the circular scale.

9. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 5, characterized in that: The process of pulling the circular scale image of the thermometer into a straight line segment image also includes: performing multi-point uneven calibration on the straight line segment scale of the fitted rectangular coordinate system so that the middle scale line is linear in the calibrated thermometer image.

10. The machine vision-based temperature measurement system for internal conductors of a phase-isolated enclosed busbar according to claim 1, characterized in that: The image processing unit calculates the bus conductor temperature change rate based on the temperature of the bus conductor in a continuous period of time, and issues a warning signal when the bus conductor temperature change rate exceeds a set threshold.

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