A substation secondary circuit test system capable of self-switching test circuit

Abstract

The application provides a substation secondary circuit test system capable of automatically switching a test circuit, comprising a test circuit switching module connected between a secondary circuit of a substation and a meter device, a meter reading module for obtaining a display screen picture of the meter device, and a control module; the recognition strategy in the control module comprises binarizing the display screen picture, separately accumulating each column and each row of pixel values to form an accumulated column sequence and an accumulated row sequence, dividing the display screen picture based on the accumulated column sequence and the accumulated row sequence, a plurality of divided column coordinates and a plurality of divided row coordinates corresponding to wave troughs, to divide out a character image recording only a single digital character; extracting a character feature of the character image based on the on-off state of a seven-segment LED, and matching the character feature with a standard feature corresponding to a plurality of digital characters to determine a recognized character. The application can automatically switch the test circuit connected with the secondary circuit, realize continuous testing of the secondary circuit, and collect test results.

Description

Technical Field

[0001] This invention relates to the field of intelligent secondary circuit testing technology, specifically to a substation secondary circuit testing system with self-switching test circuits. Background Technology

[0002] With the continuous advancement of the State Grid Corporation's new power system construction and the ongoing deployment of new-generation high-reliability substations, the workload of substation secondary maintenance personnel has further increased. Each new substation commissioning requires nearly a thousand sets of secondary circuit tests, including DC resistance, insulation, and polarity tests. Currently, these tests are conducted by one person continuously switching between single-phase and phase-to-phase connections on the secondary side, while another person records and analyzes the data. A single three-phase circuit requires 18 sets of tests. This process consumes 50% of the time required for new substation commissioning and acceptance, is inefficient, prone to manual wiring errors, increases power outage time, introduces potential faults, and reduces grid reliability. In accordance with the State Grid Corporation's requirements for promoting the transformation and upgrading of operational models and improving work efficiency, there is an urgent need to propose an intelligent testing method for substation secondary circuits to achieve automatic switching and testing of secondary circuits, thereby improving the efficiency and reliability of substation secondary circuit testing. Summary of the Invention

[0003] In view of this, the problem to be solved by the present invention is to provide a substation secondary circuit testing system with self-switching test circuits, which can automatically switch the test circuits connected to the secondary circuits, realize continuous testing of the secondary circuits and acquisition of test results, and improve the efficiency and reliability of substation secondary circuit testing.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A substation secondary circuit testing system with self-switching test circuits includes a test circuit switching module connected between the substation's secondary circuits and metering equipment, and a meter reading module that acquires images from the display screen of the metering equipment. Both the test circuit switching module and the meter reading module are electrically connected to a control module. The control module includes a recognition strategy: Character segmentation: The display image is binarized, and the pixel values ​​of each column and each row are accumulated individually to form an accumulated column sequence and an accumulated row sequence. Based on the troughs of the accumulated column sequence and accumulated row sequence, the display image is segmented to extract character images that record only a single numeric character. ; Character recognition: Extracting character images based on the on / off status of a seven-segment LED display. Character features Character features Standard features corresponding to several numeric characters Matching to determine the recognized characters Furthermore, the recognition strategy includes a character verification function. , Where N represents the character image. Quantity, Indicates and The recognition structure corresponds to the standard features, where D is the set of digits 0-9. for The reciprocal of the Hamming distance between them; like If the image is captured, the recognition is successful; otherwise, the image on the display screen is re-captured and the recognition strategy is executed.

[0005] Furthermore, the test circuit switching module includes: three phase access ports corresponding to the three phases of the transformer, a zero access port corresponding to the neutral line, a positive port and a negative port connected to the positive and negative poles of the metering equipment, arranged in sequence, a positive conduction switch connected in series between each phase access port and the positive port, a negative conduction switch connected in series between the zero access port and the negative port, and adjacent conduction switches connected in series between two adjacent ports of the two phase access ports and the zero access port.

[0006] Furthermore, both the positive and negative conduction switches are MOSFET devices.

[0007] Furthermore, the meter reading module is a camera device.

[0008] Furthermore, the substation secondary circuit testing system includes a Bluetooth communication module for wireless communication with external devices.

[0009] The beneficial effects of this invention are: By setting up a test circuit switching module, a meter reading module, and a control module with an identification strategy, the test circuit switching module can automatically switch the test circuit connected to the secondary circuit. The meter reading module is used to automatically collect the display screen images that record the test results. The identification strategy is used to automatically identify the test results recorded in the display screen images. Through the coordinated operation of the above three modules, the test circuit connected to the secondary circuit can be automatically switched, realizing continuous testing of the secondary circuit and acquisition of test results, thereby improving the efficiency and reliability of substation secondary circuit testing. Attached Figure Description

[0010] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a circuit diagram of the test circuit switching module in a substation secondary circuit test system with self-switching test circuit according to the present invention. Figure 2 This is a histogram showing the test verification effect of a substation secondary circuit test system with self-switching test circuit according to the present invention. Detailed Implementation

[0011] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0012] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed terms.

[0013] This invention provides a substation secondary circuit testing system with self-switching test circuits, such as... Figure 1 As shown, it includes a test circuit switching module connected between the secondary circuit of the substation and the metering equipment, and a meter reading module that acquires information from the display screen of the metering equipment. Both the test circuit switching module and the meter reading module are electrically connected to the control module.

[0014] The test circuit switching module includes a control circuit that switches the conduction of any two measuring points within the secondary circuit to the metering device. The conduction circuit includes several positive and negative switches. All measuring points within the secondary circuit are connected to the positive and negative terminals of the metering device via these switches. The control terminals of the positive and negative switches are connected to the control module to individually control the switches to open or close, thus switching the test circuit.

[0015] One embodiment of this application is as follows: both the positive and negative conduction switches are MOSFET devices, the control module is a microcontroller chip, and each IO port of the microcontroller is connected to the control terminal (gate) of a single MOSFET to control the MOSFET to conduct.

[0016] The secondary circuit of a transformer typically includes phase measurement points connected to the three phases a, b, and c, and a zero measurement point connected to the neutral line n. The corresponding conduction circuit includes n phase access ports corresponding one-to-one with the n phase measurement points, a zero access port connected to the zero measurement point, and positive and negative ports connected to the positive and negative poles of the metering equipment. A positive conduction switch is connected in series between each phase access port and the positive port, and a negative conduction switch is connected in series between the zero access port and the negative port. Adjacent conduction switches are connected in series between any two adjacent ports of the n-1 phase access ports and the zero access port arranged in sequence.

[0017] The working principle of the above-mentioned conducting circuit is as follows: In a transformer, a test circuit (including an, bn, cn, ab, bc, and ac) can be formed by connecting a meter in series between a phase measuring point and a zero measuring point, or between two phase measuring points. A test circuit is formed by simultaneously turning on the negative conducting switch corresponding to the zero measuring point and the positive conducting switch corresponding to a certain phase measuring point, connecting the meter in series between the zero measuring point and a certain phase measuring point. Alternatively, a test circuit is formed by simultaneously turning on the positive conducting switch corresponding to a phase measuring point farther from the zero measuring point, and all the negative conducting switches between another phase measuring point closer to the zero measuring point and the zero measuring point, connecting the meter in series between two phase measuring points.

[0018] The meter reading module is used to quickly acquire images from the display screens of metering devices, and can rapidly read the test information displayed by the metering devices in the test circuit. By controlling the continuous switching of the test circuit through the conduction circuit and the continuous acquisition by the meter reading module, the rapid and continuous testing and acquisition of the secondary circuit is completed.

[0019] One embodiment of this application is as follows: the meter reading module is a camera device, which is fixedly connected to the meter device via a fastening clamp and a fastening connector to accurately capture images from the meter device's display screen. The camera device is connected to a control module to control the camera device to start and receive the image data captured by the camera device.

[0020] The collaborative working principle of the meter reading module and the conduction circuit is as follows: the control chip controls the switch action in the conduction circuit to switch the test circuit, and within a set time after the test circuit is switched, the meter reading module receives a clear display screen image to complete the test and data acquisition of the test circuit; then the control chip controls the conduction circuit to switch to the next test circuit and receives the next display screen image.

[0021] The control module includes a recognition strategy, including character segmentation: binarizing the display image, accumulating the pixel values ​​of each column and row individually to form an accumulated column sequence and an accumulated row sequence, and segmenting the display image based on several segmentation column coordinates and segmentation row coordinates corresponding to the troughs of the accumulated column sequence and accumulated row sequence to segment the image into character images that record only a single digit character. .

[0022] Binarization processing includes: grayscale conversion and median filtering of the display image to convert the color image into a grayscale image, removing image noise while preserving image edge features. The display image is then subjected to adaptive binarization using Otsu's method to obtain a binary image. Binary image The binarization formula is: , in, The optimal segmentation threshold for the current display image is calculated using the OTSU algorithm (Otsu method).

[0023] When the meter's display screen shows only one line of numeric characters, and the display image does not include the screen border: Each column's pixel value is accumulated individually to form an accumulated column sequence. Several consecutive columns within the accumulated column sequence whose coordinates are below a set threshold serve as column dividing points (representing the interval between characters), accurately segmenting the character image containing only a single character. .

[0024] When the metering device displays only one line of numeric characters on its screen, and the screen image includes the screen border: Calculate the character image. The percentage of pixels with an inner value of 1 is used to remove edge character images whose percentage of pixels exceeds the percentage threshold.

[0025] When a meter displays multiple lines of numeric characters on its screen, and the screen image includes the screen border: First, the pixel values ​​of each line are accumulated individually to form an accumulated row sequence. Several consecutive column coordinates below a set threshold within the accumulated column sequence are used as row split points (representing line spacing). Based on these row split points, the character row image is accurately segmented. Then, the pixel values ​​of each column within the character row image are accumulated individually to form an accumulated column sequence. Several consecutive column coordinates below a set threshold within the accumulated column sequence are used as column split points, accurately segmenting the character image containing only a single character. .

[0026] Similarly, when the metering device displays multiple lines of numeric characters on its screen, and the screen image includes the screen border, the edge character image in the screen image is calculated. The percentage of pixels with an inner value of 1 is used to remove edge character images whose percentage of pixels exceeds the percentage threshold.

[0027] The formula for accumulating the pixels in each column is: , in, The height of each column of pixels, This represents the accumulated value of the pixel in column j.

[0028] Character recognition: Extracting character images based on the on / off status of a seven-segment LED display. Character features Character features Standard features corresponding to several numeric characters Matching to determine the recognized characters .

[0029] The digits 0-9 are displayed by individually controlling the brightness of the seven-segment LED display; therefore, the character characteristics... ,in, , i represents the i-th segment of the digital tube. A value of 1 indicates that the corresponding digital tube is lit. A value of 0 indicates that the corresponding digital tube is off.

[0030] Character recognition The formula for representing is: , Where D is the set of digits 0-9. The above formula represents the search for features that match the standard characteristics. The numbers with the smallest difference.

[0031] The character recognition function includes a character verification function. , , in, Indicates and Identify the corresponding standard features of the structure. for The reciprocal of the Hamming distance between them. If ( If the confidence threshold (usually 0.9) is met, the identification is successful; otherwise, a re-sampling mechanism is triggered to re-execute the identification strategy.

[0032] The substation secondary circuit testing system includes a Bluetooth communication module that enables wireless communication with external devices.

[0033] The specific implementation process and beneficial effects of this application plan are as follows: like Figure 1 As shown, there are 7 mode tubes in the conduction loop, indicating that the initial value of the switching number i is 1. The switching number i of the substation is 6. When i=7, the conduction loop stops switching.

[0034] The specific process of automatic testing in a substation is as follows: Set the initial value of i to 1, and the waiting time after the test loop switch is t0.

[0035] Step 1: The microcontroller outputs the I / O level of the i-th round according to the table below. Taking i=1 as an example, the I / O level of the first round is 1000001, which means that the microcontroller I / O port corresponding to the 7th and 1st MOSFETs outputs a high level, and the rest are low levels. The order of I / O levels in the table is the same as Figure 2 The character order of the MOSFETs is reversed; the first I / O level corresponds to the 7th MOSFET, and the first I / O level corresponds to the 1st MOSFET.

[0036] Step two: During time t0, the control module continuously conducts the corresponding MOSFET combination for each round. Specifically, t0 is 4s for DC resistance measurement, 2s for polarity testing, and 5s for insulation testing. The metering module acquires a clear image on the display screen within the corresponding time t0 and transmits it to the control module. The recognition strategy within the control module identifies and stores the meter data recorded on the display screen image as the test result for the i-th round of data.

[0037] Determine if i is greater than 7. If it is less than 7, increment i by 1 and return to step one. If it is not less than 7, end all rounds of testing.

[0038] Step 3: The control module transmits the stored experimental data to mobile phones and other terminals via Bluetooth communication. Experimental reports can be generated directly through existing DC resistance, polarity, insulation and other analysis apps.

[0039] like Figure 2 As shown, the proposed solution was tested and verified. From June to October 2025, the intelligent testing method and device for secondary circuits of substations based on self-circulating control circuits were used in 21 substations in Tianjin to complete the DC resistance test of the secondary circuits of 500 transformers in the substations. It can be seen that the efficiency and accuracy of manual testing have been significantly improved, with the testing efficiency increasing by 70% and the testing accuracy increasing by 15%.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A substation secondary circuit testing system with self-switching test circuits, characterized in that, It includes a test circuit switching module that connects the secondary circuit of the substation to the metering equipment, and a meter reading module that acquires images from the display screen of the metering equipment. Both the test circuit switching module and the meter reading module are electrically connected to the control module. The control module includes a recognition strategy: Character segmentation: The display image is binarized, and the pixel values ​​of each column and each row are accumulated individually to form an accumulated column sequence and an accumulated row sequence. Based on the troughs of the accumulated column sequence and accumulated row sequence, the display image is segmented to extract character images that record only a single numeric character. ; Character recognition: Extracting character images based on the on / off status of a seven-segment LED display. Character features Character features Standard features corresponding to several numeric characters Matching to determine the recognized characters .

2. The substation secondary circuit testing system with self-switching test circuit according to claim 1, characterized in that, The recognition strategy includes a character verification function. ， Where N represents the character image. Quantity, Indicates and The recognition structure corresponds to the standard features, where D is the set of digits 0-9. for The reciprocal of the Hamming distance between them; like If the image is captured, the recognition is successful; otherwise, the image on the display screen is re-captured and the recognition strategy is executed.

3. The substation secondary circuit testing system with self-switching test circuit according to claim 1, characterized in that, The test circuit switching module includes: three phase access ports corresponding to the three phases of the transformer, a zero access port corresponding to the neutral line, a positive port and a negative port connected to the positive and negative poles of the metering equipment, arranged in sequence, a positive conduction switch connected in series between each phase access port and the positive port, a negative conduction switch connected in series between each zero access port and the negative port, and adjacent conduction switches connected in series between two adjacent ports of two phase access ports and the zero access port.

4. The substation secondary circuit testing system with self-switching test circuit according to claim 3, characterized in that, Both the positive and negative conduction switches are MOSFET devices.

5. A substation secondary circuit testing system with self-switching test circuits according to claim 1, characterized in that, The meter reading module is a camera device.

6. A substation secondary circuit testing system with self-switching test circuits according to claim 1, characterized in that, The substation secondary circuit testing system includes a Bluetooth communication module that can wirelessly communicate with external devices.

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