Circuit breaker rigid opening and closing point positioning method based on non-contact measurement

Abstract

The invention provides a circuit breaker rigid opening and closing point positioning method, system and device based on non-contact measurement, and relates to the technical field of power equipment testing methods. According to the invention, a traditional measurement mode of installing a sensor on the circuit breaker operating mechanism is abandoned, and non-contact measurement is carried out by adopting the high-speed camera, so that the damage to the high-voltage circuit breaker operating mechanism is avoided, and meanwhile, the cost is low, the operation is simple, and the method is suitable for circuit breakers with multiple voltage grades and multiple models. Compared with the situation that a sensor needs to be installed at the fixed position of the circuit breaker, the KCF algorithm updated by the fusion template is adopted, and an appropriate target can be freely selected on the operating mechanism of the circuit breaker for tracking. Different from different sensor types and installation positions, different measured stroke curve results lead to inaccurate positioning of the just-open and just-close points, the non-contact measurement method is accurate in measurement result, high in precision and accurate in positioning of the just-open and just-close points.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment testing methods, and particularly relates to a method, a system and a device for positioning the opening and closing points of a circuit breaker based on non-contact measurement. Background Art

[0002] High-voltage circuit breakers play an important control and protection role in the power system, and are also switch devices that can handle the most diverse tasks and requirements in the power system. In addition to interrupting the load current during normal operation of the system, high-voltage circuit breakers also need to cooperate with automatic protection devices to promptly cut off the fault current in a timely manner. The reliability of their actions is an important guarantee for the safe and stable operation of the electrical system. Measuring the opening and closing points of the circuit breaker is the premise for measuring the opening distance, contact distance and over-travel of the circuit breaker, which plays an important role in judging the reliability of the circuit breaker's actions and affects the safe operation of the power.

[0003] The existing judgment of the opening and closing points of the circuit breaker directly detects and identifies the switching quantity of the circuit breaker. In actual field applications, the acquisition of switching quantity information is difficult and complex, and there are inherent errors that cannot be eliminated by using the auxiliary contacts of the auxiliary switch, resulting in inaccurate judgment of the opening and closing points. Chinese Patent with Publication No. CN102901622B provides a method for calculating the opening and closing points by wavelet analysis and Hilbert transform. This method can realize the calculation of the opening and closing points, but it is necessary to first collect displacement signals using a displacement sensor, then extract displacement characteristics using wavelet analysis, and then extract the signal envelope through Hilbert transform, and the calculation is relatively complex; Chinese Patent with Publication No. CN110686888A provides a method for judging the opening and closing states by collecting the AC current on the secondary side of the circuit breaker and calculating the action threshold. This method is cumbersome to operate and has low measurement accuracy. Chinese Patent with Publication No. CN102778346A proposes a method for installing a displacement sensor to collect the stroke of the circuit breaker and then using the acceleration method to determine the opening and closing points of the three-phase displacement of the circuit breaker. This method requires the sensor to be installed on the operating mechanism of the circuit breaker. Different installation positions result in different test results, with large errors, and improper installation will cause irreversible harm to the operating mechanism of the circuit breaker.

[0004] The above test methods have their own advantages and disadvantages, and can basically complete the detection of the opening and closing points of the circuit breaker. However, due to different working methods, the detection results of the same circuit breaker may be different, and it is impossible to judge which method or device is more accurate in detection. Moreover, the detection is slow, the steps are cumbersome, and more equipment is required, which is a waste of manpower, material resources and financial resources. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides a method, system, and device for positioning the just-separation and just-closing points of a circuit breaker based on non-contact measurement, which solves the technical problems of inaccurate detection results, slow detection speed, cumbersome steps, and the need for a large number of devices.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0009] A method for positioning the just-separation and just-closing points of a circuit breaker based on non-contact measurement includes:

[0010] Collecting video images of the opening and closing movements of the circuit breaker containing the operating mechanism of the circuit breaker through a high-speed camera;

[0011] Using the inter-frame difference method to screen the video images of the opening and closing actions of the circuit breaker to obtain a number of image frames;

[0012] Selecting the target area of the operating mechanism of the circuit breaker on the first image frame obtained by screening, and using the KCF algorithm with fused template update for frame-by-frame tracking to obtain the center coordinates of the target area on each image frame, so as to obtain the opening and closing stroke curves of the circuit breaker;

[0013] Performing denoising processing on the opening and closing stroke curves of the circuit breaker to obtain smooth opening and closing stroke curves of the circuit breaker;

[0014] For the smooth opening and closing stroke curves of the circuit breaker, using the cumulative derivative method to obtain the stroke cumulative derivative curve;

[0015] Performing key point positioning on the smooth opening and closing stroke curves of the circuit breaker and the stroke cumulative derivative curve, querying the just-separation and just-closing points, and calculating the opening distance and overtravel during the opening and closing processes.

[0016] Preferably, the step of using the inter-frame difference method to screen the video images of the opening and closing actions of the circuit breaker to obtain a number of image frames includes:

[0017] Calculating the pixel difference value between two consecutive image frames, and the calculation formula is as follows:

[0018] D(t) = |I(t) - I(t - 1)|

[0019] where D(t) is the pixel difference value, I(t) is the pixel value of the t-th frame image, and I(t - 1) is the pixel value of the (t - 1)-th frame image;

[0020] Setting a threshold ω. If D(t) is less than the threshold ω, it is determined that the target does not move between the two image frames; otherwise, it is determined that the target moves at the t-th frame.

[0021] Eliminate all image frames in which the target does not move from the video images of the opening and closing operations of the circuit breaker, and screen to obtain the several image frames.

[0022] Preferably, on the first image frame obtained by screening, select the target area of the operating mechanism of the circuit breaker, and use the KCF algorithm with fused template update to perform frame-by-frame tracking to obtain the center coordinates of the target area in each image frame, so as to obtain the opening and closing stroke curve of the circuit breaker, including:

[0023] Select the tracking target on the first image frame, determine the position and size of the target area where the tracking target is located, so as to construct the first target appearance template and filter model;

[0024] Read the next image frame, use the entire image as the search area, and based on the target appearance template of the previous image frame, obtain the set of samples to be detected in the current image frame;

[0025] Multiply the set of samples to be detected in the current image frame by the filter model of the previous image frame to obtain the response value of the current image frame, and use the maximum response value as the target area of the current image frame;

[0026] Based on the target area of the current image frame, update the filter model, and combine the preset template update method to update the target appearance template;

[0027] Use the updated filter model and target appearance template to track the target position of subsequent image frames until all image frames are traversed;

[0028] Based on the center coordinates of the target area in each image frame, calculate frame by frame to obtain the opening and closing stroke curve of the circuit breaker.

[0029] Preferably, the response value of the current image frame is expressed as:

[0030]

[0031] Where is the response value, z is the set of samples to be detected in the current image frame, is the frequency domain space kernel matrix obtained by calculating the similarity between the sample set and the target appearance template, x t-1 is the target appearance template of the (t - 1)-th frame image, is matrix multiplication, is the filter model of the (t - 1)-th frame image;

[0032] The preset template update method includes:

[0033] Calculate the average peak correlation energy of the current image frame:

[0034]

[0035] Among them, are the maximum response value and the minimum response value of this frame respectively, and n is all the response values of this frame;

[0036] Set the threshold η. If f x > η, update the target appearance template, otherwise cancel the template update and continue to use the target appearance template of the previous frame.

[0037] Preferably, the denoising process of the opening and closing stroke curve of the circuit breaker to obtain a smooth opening and closing stroke curve of the circuit breaker includes:

[0038] Perform wavelet decomposition on the opening and closing stroke curve of the circuit breaker:

[0039]

[0040] Among them, s(t) is the opening and closing stroke curve of the circuit breaker, a is the scale factor of the wavelet function, controlling the contraction of the function, a > 0; b is the translation factor, controlling the movement of the wavelet function, and ψ(t) is the wavelet basis;

[0041] Select dB4 as the wavelet basis and perform threshold processing on the wavelet decomposition. The threshold function expression is:

[0042]

[0043] Among them, sign is the sign function, ω is the wavelet coefficient after wavelet decomposition of the opening and closing stroke curve of the circuit breaker, and ρ is the threshold;

[0044] After performing threshold processing and filtering denoising on the opening and closing stroke curve of the circuit breaker, finally obtain the smooth opening and closing stroke curve of the circuit breaker.

[0045] A non-contact measurement-based circuit breaker opening and closing point positioning system includes:

[0046] An acquisition module for acquiring video images of the opening and closing movement of a circuit breaker including a circuit breaker operating mechanism through a high-speed camera;

[0047] A screening module for screening the video images of the opening and closing actions of the circuit breaker by using the inter-frame difference method to obtain several image frames;

[0048] A tracking module for selecting the target area of the circuit breaker operating mechanism on the first image frame obtained by screening, and performing frame-by-frame tracking by using the KCF algorithm with fused template update to obtain the center coordinates of the target area on each image frame, so as to obtain the opening and closing stroke curve of the circuit breaker;

[0049] A denoising module, which is used to perform denoising processing on the opening and closing stroke curves of the circuit breaker to obtain smooth opening and closing stroke curves of the circuit breaker;

[0050] A derivative calculation module, which is used to adopt the cumulative derivative method to obtain a stroke cumulative derivative curve for the smooth opening and closing stroke curves of the circuit breaker;

[0051] A solution module, which is used to perform key point positioning on the smooth opening and closing stroke curves of the circuit breaker and the stroke cumulative derivative curve, query the instant of contact separation and instant of contact closure points, and calculate the opening distance and overtravel during the opening and closing processes.

[0052] A device for positioning the instant of contact separation and instant of contact closure points of a circuit breaker based on non-contact measurement, comprising a high-speed camera, a single-chip microcomputer and a host computer;

[0053] The high-speed camera is directed at the operating mechanism of the circuit breaker;

[0054] The single-chip microcomputer is connected to the high-speed camera, the opening and closing control box of the circuit breaker, and the host computer, and is respectively used to control the triggering and closing of the high-speed camera, control the connection and disconnection of the opening and closing control box, and send the video images of the opening and closing movements of the circuit breaker captured by the high-speed camera to the host computer;

[0055] The host computer is used to execute the method for positioning the instant of contact separation and instant of contact closure points of the circuit breaker as described above.

[0056] (III) Beneficial effects

[0057] The present invention provides a method, a system and a device for positioning the instant of contact separation and instant of contact closure points of a circuit breaker based on non-contact measurement. Compared with the prior art, the following beneficial effects are achieved:

[0058] The present invention abandons the traditional measurement method of installing sensors on the operating mechanism of the circuit breaker, and adopts non-contact measurement with a high-speed camera, which not only avoids damage to the operating mechanism of the high-voltage circuit breaker, but also has low cost and simple operation, and is suitable for circuit breakers of multiple voltage levels and multiple models. Compared with the need to install sensors at fixed positions on the circuit breaker, the proposed KCF algorithm combined with template update can freely select a suitable target on the operating mechanism of the circuit breaker for tracking. Different from the different types and installation positions of sensors, the measured stroke curve results are different, which may lead to inaccurate positioning of the instant of contact separation and instant of contact closure points. By using the aforementioned non-contact measurement method, the measurement results are accurate, with high precision, and the positioning of the instant of contact separation and instant of contact closure points is accurate. Description of the drawings

[0059] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0060] Figure 1 It is a block diagram of a method for positioning the instant opening and closing points of a circuit breaker with non-contact measurement provided by an embodiment of the present invention;

[0061] Figure 2 It is a positioning diagram of the instant closing point of a circuit breaker provided by an embodiment of the present invention;

[0062] Figure 3 It is a positioning diagram of the instant opening point of a circuit breaker provided by an embodiment of the present invention;

[0063] Figure 4 It is a schematic structural diagram of a device for positioning the instant opening and closing points of a circuit breaker with contact measurement provided by an embodiment of the present invention. Specific Embodiments

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0065] By providing a method, system, and device for positioning the instant opening and closing points of a circuit breaker based on non-contact measurement in the embodiments of the present application, the technical problems of inaccurate detection results, slow detection speed, cumbersome steps, and the need for a large number of devices are solved.

[0066] First, it is necessary to explain several professional terms involved in the embodiments of the present invention:

[0067] Instant opening point: The moment when the moving and static contacts separate when the circuit breaker switches from the closed state to the open state;

[0068] Instant closing point: The moment when the moving and static contacts first touch when the circuit breaker switches from the open state to the closed state;

[0069] Closing opening distance: The distance between the moment of the closing action of the circuit breaker and the instant closing point;

[0070] Closing overtravel: The distance between the instant closing point of closing and the stable position of the moving contact of the circuit breaker;

[0071] Opening opening distance: The distance between the instant opening point and the stable position of the moving contact of the circuit breaker;

[0072] Opening overtravel: The distance from the moment of the circuit breaker opening operation to the just-opened point.

[0073] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners.

[0074] Embodiment 1:

[0075] As Figure 1 shown, an embodiment of the present invention provides a method for positioning the just-open and just-close points of a circuit breaker based on non-contact measurement, including:

[0076] S1. Collect video images of the opening and closing movements of the circuit breaker including the circuit breaker operating mechanism through a high-speed camera;

[0077] S2. Screen the video images of the opening and closing actions of the circuit breaker by using the inter-frame difference method to obtain several image frames;

[0078] S3. Select the target area of the circuit breaker operating mechanism on the first image frame obtained by screening, and perform frame-by-frame tracking by using the KCF algorithm with fused template update to obtain the center coordinates of the target area on each image frame, so as to obtain the opening and closing stroke curves of the circuit breaker;

[0079] S4. Denoise the opening and closing stroke curves of the circuit breaker to obtain smooth opening and closing stroke curves of the circuit breaker;

[0080] S5. For the smooth opening and closing stroke curves of the circuit breaker, use the cumulative derivative method to obtain the stroke cumulative derivative curve;

[0081] S6. Perform key point positioning on the smooth opening and closing stroke curves of the circuit breaker and the stroke cumulative derivative curve, query the just-open and just-close points, and calculate the opening distance and overtravel during the opening and closing processes.

[0082] The embodiment of the present invention abandons the traditional measurement method of installing sensors on the circuit breaker operating mechanism, and uses a high-speed camera for non-contact measurement, which not only avoids damaging the circuit breaker operating mechanism of high-voltage circuit breakers, but also has low cost, simple operation, and is suitable for circuit breakers of multiple voltage levels and multiple models.

[0083] Next, each step of the above technical solution will be introduced in detail:

[0084] In step S1, video images of the opening and closing movements of the circuit breaker including the circuit breaker operating mechanism are collected through a high-speed camera.

[0085] It is understandable that the high-speed camera can be pre-aligned with the tracking target on the breaker operating mechanism (for example, the ring on the crank arm of the breaker operating mechanism or the connection of the moving link), and the distance between the high-speed camera and the breaker operating mechanism can be adjusted according to the on-site test environment, so as to facilitate the acquisition of complete video images of the breaker opening and closing movements in this step.

[0086] In step S2, the frame difference method is used to screen the video images of the breaker opening and closing actions, and several image frames are obtained.

[0087] Since the video images of the breaker movement captured by the high-speed camera contain a large number of static images, which are not required in this solution. To reduce the calculation amount and improve the operation efficiency. Therefore, the frame difference method commonly used in the static background is selected to screen the moving image sequence. The frame difference method has good adaptability to environmental changes and fast movements, and does not require the establishment of a background module. It directly performs difference operations on adjacent images to determine whether the target has moved.

[0088] Correspondingly, this step specifically includes:

[0089] Calculate the pixel difference value between two consecutive image frames. The calculation formula is as follows:

[0090] D(t) = |I(t) - I(t - 1)|

[0091] Where D(t) is the pixel difference value, I(t) is the pixel value of the t-th frame image, and I(t - 1) is the pixel value of the (t - 1)-th frame image;

[0092] Set a threshold ω. If D(t) is less than the threshold ω, it is judged that the target has not moved between the two image frames; otherwise, it is judged that the target has moved at the t-th frame.

[0093] Delete all the image frames in which the target has not moved from the video images of the breaker opening and closing actions, and screen and obtain the several image frames.

[0094] In step S3, on the first image frame obtained by screening, select the target area of the breaker operating mechanism, and use the KCF algorithm with fused template update to perform frame-by-frame tracking to obtain the center coordinates of the target area on each image frame, so as to obtain the opening and closing stroke curve of the breaker.

[0095] It should be noted that the KCF (Kernelized Correlation Filters) algorithm is a typical correlation filtering algorithm: it uses ridge regression in the kernel space to transform the problem of solving the filter into an optimization problem of the classifier. The KCF algorithm sets (x i , y i) is the training sample set, then the target tracking task to be solved is converted into a ridge regression problem, that is, f(x i ) = y i .

[0096]

[0097] In the formula, x i represents the feature vector of the tracking target in the image, y i represents the response value corresponding to the feature vector of the tracking target, λ represents the regularization coefficient, w represents the parameter of the regression model. Transforming the above formula into the complex domain to solve for w, we get:

[0098] w = (X H X + λI) -1 X H y

[0099] In the formula, X is a circulant matrix, X H represents its complex conjugate transpose matrix; I is the identity matrix.

[0100] The KCF algorithm maps the feature space to a higher-dimensional space by introducing a kernel function, so that the mapped samples are linearly separable in the high-dimensional space. Then w is represented as:

[0101]

[0102] In the formula, Φ(x i ) represents the non-linear mapping function, a i is the weight coefficient.

[0103] Therefore, the problem of solving w is converted into the problem of solving a, and the expression of a is:

[0104]

[0105] In the formula, K represents the kernel matrix of the kernel space. Then transforming the above formula into the frequency domain to obtain the model of the final filter of the KCF algorithm:

[0106]

[0107] The KCF algorithm does not fix the first frame image as a template, but will update the template. Using the target position and size obtained from the previous frame as the test area of the current input frame, calculate the correlation between the test area of the current input frame and the filter. The maximum response value is the tracking result of the current frame, that is, the target area of the current image frame.

[0108]

[0109] In the formula, x t-1is the target region model for frame t-1, and z represents the set of samples to be detected in the current input frame. is the response value. is the frequency domain space kernel matrix obtained by calculating the similarity between the sample set and the target appearance template.

[0110] After determining the target position in the current frame, extract the target position in the current frame as the training sample. Calculate the filter parameters. And update the filter model and the target region model using linear interpolation:

[0111]

[0112] In the formula, γ is the learning rate.

[0113] In addition, since there are many circuit breaker manufacturers and there are also many types of actuator designs. Sometimes it is impossible to select a tracking target that is completely unobstructed. When the selected tracking target is partially obstructed during movement, the tracking area will decrease. If the template is updated at this time, the template will still be updated to the characteristics of the current obstructed area, and these characteristics no longer represent the true appearance of the target. Positions that were originally highly matched with the target area may be wrongly considered to be matched, resulting in the tracking filter learning the wrong response pattern and mistakenly believing that the target appearance has changed. During subsequent tracking, the tracking area has been shifting, then problems such as tracking failure or tracking drift will occur, causing a significant decrease in tracking accuracy. Therefore, it is also necessary to introduce a method for determining template update of (target appearance) to overcome the aforementioned defects.

[0114] Correspondingly, this step specifically includes:

[0115] S31. Select a tracking target on the first image frame, determine the position and size of the target area where the tracking target is located, so as to construct the first target appearance template and the filter model;

[0116] S32. Read the next image frame, use the entire image as the search area, and obtain the set of samples to be detected in the current image frame based on the target appearance template of the previous image frame;

[0117] S33. Multiply the set of samples to be detected in the current image frame by the filter model of the previous image frame, obtain the response value of the current image frame, and use the maximum response value as the target area of the current image frame;

[0118] S34. Update the filter model based on the target area of the current image frame, and update the target appearance template in combination with the preset template update method;

[0119] S35. Use the updated filter model and the target appearance template to track the target position in subsequent image frames until all image frames are traversed;

[0120] S36. Based on the central coordinates of the target region on each image frame, calculate and obtain the opening and closing stroke curve of the circuit breaker frame by frame.

[0121] Among them, the preset template update method includes:

[0122] Calculate the average peak correlation energy of the current image frame:

[0123]

[0124] Among them, are the maximum response value and the minimum response value of this frame respectively, and n is all response values of this frame;

[0125] Set a threshold η. If f x > η, update the target appearance template, otherwise cancel the template update and continue to use the target appearance template of the previous frame.

[0126] Finally, use the KCF algorithm with the fused template to track the circuit breaker motion video image frame by frame to obtain the center coordinates (x t , y t ) of the tracking target, and then calculate the opening and closing stroke curve of the circuit breaker frame by frame for the extracted target center point coordinates, as shown in the following formula:

[0127]

[0128] In step S4, perform denoising processing on the opening and closing stroke curve of the circuit breaker to obtain a smooth opening and closing stroke curve of the circuit breaker.

[0129] In order to more accurately identify the opening and closing stroke curve of the circuit breaker, the embodiment of the present invention proposes an improved wavelet denoising method to filter and denoise the opening and closing stroke curve of the circuit breaker, making the stroke curve smoother and facilitating the opening and closing feature points.

[0130] Specifically:

[0131] First, perform wavelet decomposition on the opening and closing stroke curve of the circuit breaker:

[0132]

[0133] Among them, s(t) is the opening and closing stroke curve of the circuit breaker, a is the scale factor of the wavelet function, controlling the contraction of the function, a > 0; b is the translation factor, controlling the movement of the wavelet function, and ψ(t) is the wavelet basis.

[0134] Then, select dB4 as the wavelet basis and perform threshold processing on the wavelet decomposition. The expression of the threshold function is as follows:

[0135]

[0136] where sign is the sign function, ω is the wavelet coefficient after wavelet decomposition of the opening and closing stroke curve of the circuit breaker, and ρ is the threshold.

[0137] It should be noted that traditional thresholds are divided into soft thresholds and hard thresholds: for hard thresholds, the real number domain is discontinuous, changing from continuous to step at the threshold point, which is likely to cause signal reconstruction oscillation and generate the pseudo Gibbs phenomenon; for soft thresholds, although this function overcomes the defect of the discontinuous hard threshold function at the threshold point, there is a constant deviation from the original wavelet coefficient, reducing the similarity between the denoised signal and the original signal. The above improved wavelet threshold function effectively overcomes the shortcomings of soft and hard thresholds.

[0138] Finally, after performing threshold processing and filtering denoising on the opening and closing stroke curve of the circuit breaker, the smooth opening and closing stroke curve of the circuit breaker is finally obtained.

[0139] In step S5, for the smooth opening and closing stroke curve of the circuit breaker, the cumulative derivative method is used to obtain the cumulative derivative curve of the stroke, as shown in the following formula:

[0140]

[0141] where g(t) is the cumulative derivative curve of the stroke.

[0142] In step S6, key point positioning is performed on the smooth opening and closing stroke curve of the circuit breaker and the cumulative derivative curve of the stroke, the just-separated and just-closed points are queried, and the opening distance and overtravel during the opening and closing processes are calculated.

[0143] On the one hand, when the circuit breaker is closing, the closing spring provides energy to the operating mechanism, and the operating mechanism drives the moving contact to move through the transmission device. Since the movement of the moving contact is obtained indirectly, when the moving contact is stationary, the operating mechanism has already moved. Therefore, when the moving contact moves, there will be a large acceleration, and there will be a peak on the cumulative derivative curve; the moving contact continues to move. When the moving contact contacts the static contact and reaches the just-closed point, it is subjected to the resistance of the static contact, and the reverse acceleration reaches the maximum. As the moving contact continues to penetrate, the speed gradually decays, and the resistance also decreases. When the speed decays to zero, it reaches the maximum displacement. However, due to the spring device on the contact, the resistance compresses the spring, causing the moving contact to rebound, and it gradually stabilizes after the rebound to complete the closing operation.

[0144] Exemplarily, such as Figure 2As shown in the provided closing just-closing point positioning diagram of the circuit breaker. In the figure, point SH1 is the moment when the circuit breaker starts to operate, corresponding to point AH1 on the cumulative derivative curve, while SH2 is the moment when the circuit breaker just closes, corresponding to point AH2 on the cumulative derivative curve. At this point, the cumulative derivative curve reaches the maximum in the reverse direction, indicating that this point corresponds to the moment when the circuit breaker just closes, that is, the moving contact of the circuit breaker contacts the static contact. Since a spring device is equipped on the contact, the moving contact will not stop immediately, but continues to move forward to reach the maximum stroke, that is, SH3 on the stroke curve, and then is rebounded by the contact spring, resulting in bounce, and finally stabilizes at SH4. Then the total closing stroke of the circuit breaker is SH4, the opening distance is SH2, and the overtravel is SH4 - SH2.

[0145] On the other hand, when the circuit breaker is opening, the opening spring provides energy to the operating mechanism, and the operating mechanism drives the moving contact to move through the transmission device. Since the movement of the moving contact is obtained indirectly, when the moving contact is stationary, the operating mechanism has already moved. Therefore, when the moving contact operates, there will be a peak on the cumulative derivative curve; the moving contact continues to move, and the acceleration continues to increase. When the moving contact separates from the static contact and reaches the just-opening point, at this time, it is subject to resistance and the acceleration begins to decrease. When the speed decays to zero, it reaches the maximum displacement. However, due to the spring device on the contact, the resistance compresses the spring and causes the moving contact to rebound, and it gradually stabilizes after the rebound to complete the opening operation.

[0146] Exemplarily, as Figure 3 As shown in the provided opening just-opening point positioning diagram of the circuit breaker. In the figure, point SF1 is the moment when the circuit breaker starts to operate, corresponding to point AF1 on the cumulative derivative curve, while SF2 is the moment when the circuit breaker just opens, corresponding to point AF2 on the cumulative derivative curve. At this point, the moving contact and the static contact start to separate, and the cumulative derivative curve changes suddenly before and after, changing from rising to falling. After that, the moving contact will not stop immediately, but continues to move forward. SF3 corresponds to the maximum stroke of the moving contact of the circuit breaker, and then is rebounded by the contact spring, resulting in bounce, and finally stabilizes at SF4. Then the total opening stroke of the circuit breaker is SF4, the opening distance is SF2, and the overtravel is SF4 - SF2.

[0147] So far, the embodiment of the present invention has completed all the processes of the method for positioning the just-opening and just-closing points of the circuit breaker based on non-contact measurement.

[0148] Embodiment 2:

[0149] The embodiment of the present invention provides a system for positioning the just-opening and just-closing points of a circuit breaker based on non-contact measurement, including:

[0150] An acquisition module, configured to acquire video images of the opening and closing movements of the circuit breaker including the operating mechanism of the circuit breaker through a high-speed camera;

[0151] A screening module, which is used to screen the video images of the opening and closing actions of the circuit breaker by using the inter-frame difference method to obtain several image frames;

[0152] A tracking module, which is used to select the target area of the circuit breaker operating mechanism on the first image frame obtained by screening, and perform frame-by-frame tracking by using the KCF algorithm with fused template update to obtain the center coordinates of the target area on each image frame, so as to obtain the opening and closing stroke curves of the circuit breaker;

[0153] A denoising module, which is used to perform denoising processing on the opening and closing stroke curves of the circuit breaker to obtain smooth opening and closing stroke curves of the circuit breaker;

[0154] A derivative calculation module, which is used to obtain the cumulative derivative curve of the stroke for the smooth opening and closing stroke curves of the circuit breaker by using the cumulative derivative method;

[0155] A solution module, which is used to perform key point positioning on the smooth opening and closing stroke curves of the circuit breaker and the cumulative derivative curve of the stroke, query the just-separated and just-closed points, and calculate the opening distance and overtravel during the opening and closing processes.

[0156] Embodiment 3:

[0157] As Figure 4 shown, an embodiment of the present invention provides a device for positioning the just-separated and just-closed points of a circuit breaker based on non-contact measurement, including a high-speed camera 4, a single-chip microcomputer 5, and a host computer 6;

[0158] The high-speed camera 4 faces the circuit breaker operating mechanism 2 of the circuit breaker 1, and the distance between the high-speed camera 4 and the circuit breaker operating mechanism 2 can be adjusted according to the on-site test environment.

[0159] The single-chip microcomputer 5 is connected to the high-speed camera 4, the opening and closing control box 3 of the circuit breaker 1, and the host computer 6, and is respectively used to control the triggering and closing of the high-speed camera 4, control the connection and disconnection of the opening and closing control box 3, and send the video images of the opening and closing movements of the circuit breaker taken by the high-speed camera 4 to the host computer 6.

[0160] The host computer 6 is used to execute the method for positioning the just-separated and just-closed points of the circuit breaker as described in Embodiment 1.

[0161] In an optional implementation manner, in order to be able to collect all the moving images of the opening and closing actions, the single-chip microcomputer 5 is set to trigger the high-speed camera 4 first, and the circuit breaker action instruction is transmitted to the circuit breaker opening and closing control box with a delay of 500 ms.

[0162] Correspondingly, when the user issues a collection instruction to the single-chip microcomputer 5, and the single-chip microcomputer 5 issues a shooting instruction to the high-speed camera 4, after 500 ms, the breaker operation circuit is connected, the switching control box 3 receives the operation instruction, and the breaker 1 starts to perform the switching operation. After that, after the switching operation is completed, a shutdown instruction is issued, the high-speed camera 4 stops shooting, the breaker circuit is cut off again, and the video is transmitted to the host computer 6 via a coaxial cable for further processing.

[0163] It can be understood that the breaker closing and opening point positioning system and device based on non-contact measurement provided by the embodiments of the present invention correspond to the breaker closing and opening point positioning method based on non-contact measurement provided by the embodiments of the present invention. For the explanations, examples, beneficial effects, etc. of the relevant content, reference can be made to the corresponding parts in the breaker closing and opening point positioning method, and will not be elaborated here.

[0164] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0165] The embodiments of the present invention abandon the traditional measurement method of installing sensors on the breaker operating mechanism, and adopt a high-speed camera for non-contact measurement, which not only avoids damaging the breaker operating mechanism, but also has a low cost, simple operation, and is suitable for breakers of multiple voltage levels and multiple models. Compared with the sensors that need to be installed at fixed positions of the breaker, the proposed KCF algorithm with fused template update can freely select a suitable target on the breaker operating mechanism for tracking. Different from the different types and installation positions of sensors, the measured stroke curve results are different, which may lead to inaccurate positioning of the closing and opening points. By using the aforementioned non-contact measurement method, the measurement results are accurate, with high precision, and the closing and opening points are accurately positioned.

[0166] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0167] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for locating the closing and opening points of a circuit breaker based on non-contact measurement, characterized in that: include: The video images of the circuit breaker opening and closing movements including the circuit breaker operating mechanism are collected by a high-speed camera; Using an inter-frame difference method to screen the circuit breaker opening and closing action video image to obtain a number of image frames; Selecting a target area of ​​the circuit breaker operating mechanism on the first image frame obtained by screening, tracking frame by frame using the KCF algorithm updated by the fusion template, obtaining the center coordinates of the target area on each image frame, so as to obtain the circuit breaker opening and closing stroke curve; De-noising the circuit breaker opening and closing stroke curve to obtain a smooth circuit breaker opening and closing stroke curve; For the smooth circuit breaker opening and closing stroke curve, a cumulative derivative method is used to obtain a stroke cumulative derivative curve; The key points of the smooth circuit breaker opening and closing stroke curve and the stroke cumulative derivative curve are located, the just-opening and just-closing points are queried, and the open distance and over-distance in the opening and closing process are calculated.

2. The method for locating the circuit breaker opening and closing points according to claim 1, characterized in that: The inter-frame difference method is used to screen the circuit breaker opening and closing action video image to obtain a plurality of image frames, including: Calculate the pixel difference between two consecutive image frames. The calculation formula is as follows: D(t)=|I(t)-I(t-1)| Where D(t) is the pixel difference value, I(t) is the pixel value of the t-th frame image, and I(t-1) is the pixel value of the t-1-th frame image; Set a threshold ω. If D(t) is less than the threshold ω, it is judged that the target has not moved between the two image frames; otherwise, it is judged that the target has moved in frame t. All image frames in which the target does not move are eliminated from the circuit breaker opening and closing action video image, and the plurality of image frames are screened and obtained.

3. The method for locating the circuit breaker rigid opening and closing points according to claim 1, characterized in that: The target area of ​​the circuit breaker operating mechanism is selected on the first image frame obtained by screening, and the KCF algorithm updated by the fusion template is used for frame-by-frame tracking to obtain the center coordinates of the target area on each image frame to obtain the circuit breaker opening and closing stroke curve, including: Selecting a tracking target on a first image frame, determining a position and a size of a target area where the tracking target is located, so as to construct a first target appearance template and a filter model; Read the next image frame, use the entire image as the search area, and obtain the sample set to be detected in the current image frame based on the target appearance template of the previous image frame; Multiply the sample set to be detected of the current image frame by the filter model of the previous image frame to obtain the response value of the current image frame, and use the maximum response value as the target area of ​​the current image frame; Based on the target area of ​​the current image frame, the filter model is updated, and the target appearance template is updated in combination with a preset template updating method; The updated filter model and target appearance template are used to track the target position in subsequent image frames until all image frames are traversed; Based on the center coordinates of the target area on each image frame, the circuit breaker opening and closing stroke curve is calculated frame by frame.

4. The method for locating the circuit breaker opening and closing points according to claim 3, characterized in that: The response value of the current image frame is expressed as: in, is the response value, z is the sample set to be detected in the current image frame, is the frequency domain spatial kernel matrix obtained by calculating the similarity between the sample set and the target appearance template, x t-1 is the target appearance template of the t-1th frame image, is matrix multiplication, is the filter model of the t-1th frame image; The preset template updating method includes: Calculate the average peak correlation energy of the current image frame: in, are the maximum response value and the minimum response value of the frame respectively, and n is all the response values ​​of the frame; Set the threshold η, if f x >η, the target appearance template is updated; otherwise, the template update is canceled and the target appearance template of the previous frame continues to be used.

5. The method for locating the circuit breaker rigid opening and closing points according to claim 1, characterized in that: The denoising process is performed on the circuit breaker opening and closing stroke curve to obtain a smooth circuit breaker opening and closing stroke curve, including: The circuit breaker opening and closing stroke curve is subjected to wavelet decomposition: Among them, s(t) is the circuit breaker opening and closing stroke curve, a is the scale factor of the wavelet function, the contraction of the control function, a>0; b is the translation factor, which controls the movement of the wavelet function, and ψ(t) is the wavelet basis; Select dB4 as the wavelet basis and perform threshold processing on the wavelet decomposition, where the threshold function expression is: Among them, sign is the sign function, ω is the wavelet coefficient of the circuit breaker opening and closing stroke curve after wavelet decomposition, and ρ is the threshold value; After threshold processing, filtering and denoising are performed on the circuit breaker opening and closing stroke curve, the smooth circuit breaker opening and closing stroke curve is finally obtained.

6. A circuit breaker opening and closing point positioning system based on non-contact measurement, characterized in that: include: An acquisition module, used for acquiring a video image of the circuit breaker opening and closing movement including the circuit breaker operating mechanism through a high-speed camera; A screening module, used for screening the circuit breaker opening and closing action video image by using an inter-frame difference method to obtain a plurality of image frames; A tracking module is used to select a target area of ​​the circuit breaker operating mechanism on the first image frame obtained by screening, and use the KCF algorithm updated by the fusion template to perform frame-by-frame tracking to obtain the center coordinates of the target area on each image frame to obtain the circuit breaker opening and closing stroke curve; A denoising module, used for denoising the circuit breaker opening and closing stroke curve to obtain a smooth circuit breaker opening and closing stroke curve; A derivation module, for obtaining a stroke cumulative derivative curve by using a cumulative derivative method for the smoothed circuit breaker opening and closing stroke curve; The solution module is used to locate key points of the smooth circuit breaker opening and closing stroke curve and the stroke cumulative derivative curve, query the just-opening and just-closing points, and calculate the open distance and over-distance during the opening and closing process.

7. A circuit breaker opening and closing point positioning device based on non-contact measurement, characterized in that: Including high-speed camera, single-chip microcomputer and host computer; The high-speed camera is directed toward a circuit breaker operating mechanism of the circuit breaker; The single-chip microcomputer is connected to the high-speed camera, the opening and closing control box of the circuit breaker, and the host computer, and is respectively used to control the triggering and closing of the high-speed camera, control the connection and disconnection of the opening and closing control box, and send the circuit breaker opening and closing movement video images taken by the high-speed camera to the host computer; The host computer is used to execute the circuit breaker opening and closing point positioning method as described in any one of claims 1 to 5.

Images