Contact ablation evaluation method and system in SF6 circuit breaker on-off test

Abstract

The invention discloses a contact ablation assessment method and system in an SF6 circuit breaker breaking test, and relates to the field of contact ablation assessment, and the method comprises the steps: connecting an arc voltage divider in parallel at two ends of an SF6 circuit breaker, deploying a displacement sensor, and starting a main contact and arc contact breaking test; in the test process, arc voltage, current magnitude, contact displacement and voltage waveform data are acquired in real time through a high-frequency data acquisition system, denoising processing is performed on the voltage waveform data, and starting time, duration time and peak voltage of the arc are extracted; establishing a regression relation model between the arc duration time and the current magnitude according to the arc duration time and the current magnitude; and evaluating the ablation degree of the main contact through the regression relation model between the arc duration and the current magnitude, evaluating the ablation degree of the arc contact through the contact displacement, and generating a real-time contact health evaluation report according to the ablation evaluation result. And the evaluation efficiency is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of contact erosion assessment, and in particular to a method and system for assessing contact erosion during SF6 circuit breaker breaking tests. Background Technology

[0002] SF6 circuit breakers typically employ a dual-contact system consisting of main contacts and arc contacts. The main contact surfaces are usually silver-plated and are responsible for carrying the rated current and short-circuit current in the system. The arc contact tips are typically made of copper-tungsten material and are responsible for withstanding arc erosion between the contacts during opening and closing. In the design, testing, and operation of SF6 circuit breakers, attention must be paid to the coordination relationship and real-time status of the dual contacts, as this has a crucial impact on the successful interruption of the test current. In the breaking test of SF6 circuit breakers, since the double contacts are in parallel structure, when the contacts are closed, most of the test current flows through the main contacts, and a small portion flows through the arc contacts. When the main contacts separate, most of the current is transferred to the arc contacts through the conductive path inside the arc-extinguishing chamber. During this process, a brief electric arc phenomenon will appear on the main contacts. Its duration is related to the current phase, the contact surface condition of the main contacts, vibration, contact resistance and length of the arc contacts, and will leave ablation scars on the surface of the main contacts, affecting the current carrying capacity. When the arc contacts separate, the electric arc generated between the contacts will ablate the ends of the arc contacts, making the rod-shaped contacts shorter and the inner diameter of the quincunx-shaped contacts larger, further affecting the current transfer process. In severe cases, the current transfer will fail, resulting in the inability to break the test current. Summary of the Invention

[0003] In view of the aforementioned existing problems, the present invention is proposed.

[0004] Therefore, this invention provides a method for evaluating contact erosion in SF6 circuit breaker breaking tests to solve the problems of cumbersome measurement and evaluation processes and low test efficiency.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for evaluating contact erosion during an SF6 circuit breaker breaking test, comprising: An arc voltage divider is connected in parallel across both ends of the SF6 circuit breaker, and a displacement sensor is deployed to initiate the main contact and arc contact breaking test. During the breaking test, the arc voltage, current magnitude, contact displacement and voltage waveform data are collected in real time through a high-frequency data acquisition system. The voltage waveform data is then denoised to extract the arc start time, duration and peak voltage. Based on the arc duration and current magnitude, a regression model is established between the arc duration and current magnitude. The degree of ablation of the main contact is assessed by using the regression model between the arc duration and the current magnitude, and the degree of ablation of the arc contact is assessed by the contact displacement. A real-time contact health assessment report is generated based on the ablation assessment results.

[0006] As a preferred embodiment of the contact erosion assessment method in the breaking test of an SF6 circuit breaker according to the present invention, the arc voltage divider includes an arc voltage divider with a withstand voltage level of 550kV, which measures the voltage when an electric arc is generated between the contacts. The displacement sensor includes a function to measure the mechanical stroke curve and obtain the displacement during the contact opening process.

[0007] As a preferred embodiment of the contact erosion evaluation method in the SF6 circuit breaker breaking test of the present invention, the breaking test of the main contact includes testing the performance of the main contact when disconnecting the circuit under rated load, so that the current is successfully interrupted when the contacts are separated, and cyclically simulating multiple breaking operations. The arc contact breaking test includes generating a large current using a short-circuit test power supply under short-circuit conditions to produce an electric arc during the breaking process, and breaking the circuit multiple times under different currents to test the arc extinguishing capability and ablation of the arc contact.

[0008] As a preferred embodiment of the contact erosion assessment method in the SF6 circuit breaker breaking test described in this invention, the high-frequency data acquisition system comprises a sensor, a signal conditioning module, a data sampling module, a synchronization module, and a storage and transmission module. After the test begins, the physical quantities of the main contact and the arc contact are simultaneously acquired through the synchronization module, and the output signal data is acquired through the sensor. Each output signal is amplified and filtered before being sent to the data sampling module for digitization, and then transmitted to the data processing system through a high-speed interface for real-time processing and analysis. The data processing system performs noise reduction, analysis, and storage on the acquired data. The physical quantities include test current, mechanical stroke curve, and arc voltage; The output signals include the start time, end time, start displacement, and end displacement of the main contact opening arc, the current phase at the moment the main contact opens, the start time and start displacement of the arc contact opening arc, and are electrically isolated by an opto-isolation module.

[0009] As a preferred embodiment of the contact erosion assessment method in the SF6 circuit breaker breaking test described in this invention, the noise reduction process includes detecting and removing outliers in the data using a Kalman filtering algorithm. The Kalman filter algorithm includes two stages: prediction and update. The formula for the prediction stage is expressed as follows:

[0010]

[0011] in, express The predicted state at any given moment; express The state transition matrix at time t; express State estimation at time; express Control input matrix at any given time; express Time-based control input; express The prediction error covariance matrix at time 1; express The transpose of the state transition matrix at each time step; Represents the process noise covariance matrix; The formula for the update phase is expressed as follows:

[0012]

[0013]

[0014] in, express Kalman gain matrix at time step; express The prediction error covariance matrix at time 1; express The observation matrix at each time point; express The transpose of the observation matrix at each moment; express The observation noise covariance matrix at time step; express State estimation after each update; express State estimation for time-predicted events; express The observed value at time; This represents the error covariance matrix updated at time t; Represents the identity matrix.

[0015] As a preferred embodiment of the contact erosion assessment method in the SF6 circuit breaker breaking test described in this invention, the regression relationship model formula between the arc duration and the current magnitude is expressed as follows:

[0016] in, Indicates the duration of the electric arc; Indicates the magnitude of the current; Indicates the coefficient of linear relationship; express .

[0017] As a preferred embodiment of the contact erosion assessment method in the SF6 circuit breaker breaking test described in this invention, the method for analyzing and assessing the degree of erosion of the main contacts includes: using a machine learning method, taking the instantaneous current value and arc duration when the main contacts separate in the first breaking test, and using a regression relationship model between the arc duration and the current magnitude, calculating the theoretical value of the arc duration of other current phase angles as a benchmark; in subsequent tests, comparing the actual arc duration of each test with the benchmark to obtain the ratio k1, and evaluating it according to a preset main contact status evaluation table; The method for analyzing and evaluating the degree of arc contact erosion includes using machine learning to take the displacement of the contact during the time period from the moment the main contact extinguishes the arc to the moment the arc contact ignites the arc as the evaluation input parameter for the amount of arc contact erosion; and using the length difference between the arc contact and the main contact in the first breaking test as a benchmark, comparing the actual length difference with the benchmark in subsequent tests to obtain the ratio k2, and evaluating it according to a preset arc contact state evaluation table.

[0018] Secondly, the present invention provides a contact erosion assessment system for SF6 circuit breaker breaking tests, comprising: The test unit connects an arc voltage divider in parallel across the two ends of the SF6 circuit breaker and deploys a displacement sensor to initiate the main contact and arc contact breaking test. The data acquisition unit, during the breaking test, acquires arc voltage, current magnitude, contact displacement and voltage waveform data in real time through a high-frequency data acquisition system, and performs noise reduction processing on the voltage waveform data to extract the arc start time, duration and peak voltage. The analysis unit establishes a regression model between the arc duration and the current magnitude based on the arc duration and the current magnitude. The evaluation unit assesses the degree of ablation of the main contact through a regression model between the arc duration and the current magnitude, and assesses the degree of ablation of the arc contact through contact displacement. Based on the ablation assessment results, it generates a real-time contact health assessment report.

[0019] Thirdly, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, it implements any step of the contact erosion assessment method in the SF6 circuit breaker breaking test as described in the first aspect of the present invention.

[0020] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the contact erosion assessment method in an SF6 circuit breaker breaking test as described in the first aspect of the present invention.

[0021] The beneficial effects of this invention are as follows: In the daily testing process, by adding an arc voltage measurement channel, the measurement can be performed under energized conditions while connected to the main circuit. By measuring the change in arc voltage between the circuit breaker contacts, the state of the arc contact can be reflected. The measurement is convenient and quick, does not affect daily testing work, and the data can better reflect the actual breaking conditions. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart of a method for evaluating contact erosion during an SF6 circuit breaker breaking test.

[0024] Figure 2 This is a flowchart of an evaluation method for assessing contact erosion during an SF6 circuit breaker breaking test.

[0025] Figure 3 This is a schematic diagram of the current transfer process in a contact erosion assessment method for an SF6 circuit breaker breaking test.

[0026] Figure 4 This is a schematic diagram of the arc pressure morphology of the main and arc contacts in an SF6 circuit breaker breaking test, which is used to evaluate contact erosion.

[0027] Figure 5 This is a schematic diagram comparing the arc voltage morphology of the main contacts at different stages in a contact erosion assessment method for an SF6 circuit breaker breaking test.

[0028] Figure 6 This is a schematic diagram of the dynamic resistance test voltage waveform for a method to evaluate contact erosion during an SF6 circuit breaker breaking test.

[0029] Figure 7This is a schematic diagram illustrating the definition of contact tripping parameters in a method for evaluating contact erosion during an SF6 circuit breaker breaking test. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0033] Reference Figures 1-7 As one embodiment of the present invention, this embodiment provides a method for evaluating contact erosion during an SF6 circuit breaker breaking test, comprising the following steps: S1. Connect an arc voltage divider in parallel across both ends of the SF6 circuit breaker and deploy a displacement sensor to initiate the main contact and arc contact breaking test.

[0034] The arc voltage divider includes an arc voltage divider with a withstand voltage level of 550kV, used to measure the voltage when an electric arc is generated between the contacts.

[0035] The displacement sensor includes a function to measure the mechanical stroke curve and obtain the displacement during the contact opening process.

[0036] It is important to know that an arc voltage divider is connected to both ends of the bushings of the SF6 circuit breaker under test. Its withstand voltage level is 550kV, which can withstand the high recovery voltage applied to both ends of the SF6 circuit breaker under test after interruption. The low voltage arm measurement range is selected as 100:1. Since the arc voltage divider itself has a limiting device, the maximum output voltage is 5kV.

[0037] The secondary output of the arc voltage divider is connected to an analog-to-digital-to-optical converter module with opto-isolation. The module is placed on a 35kV insulated platform to prevent overvoltage caused by ground potential rise, which could damage the downstream measurement system. The opto-isolation module transmits data to a 14-bit resolution data acquisition system via optical fiber.

[0038] The arc voltage test channel of the data acquisition software is set to a range of ±5kV. Based on the bit depth of the data acquisition system, it can identify waveform changes of about 10V. The sampling rate is set to 10MHz to meet the requirements of microsecond-level waveform characteristic testing.

[0039] A linear displacement sensor was used to measure the mechanical stroke curve of the hydraulic mechanism's tie rod, and the stroke test channel of the data acquisition software was set to 120% of the maximum stroke range.

[0040] The breaking test of the main contact includes testing the performance of the main contact when breaking the circuit under rated load, ensuring that the current is successfully interrupted when the contacts separate, and simulating multiple breaking operations in a loop. The arc contact breaking test includes generating a large current using a short-circuit test power supply under short-circuit conditions to produce an electric arc during the breaking process, and breaking the circuit multiple times under different currents to test the arc extinguishing capability and ablation of the arc contact.

[0041] It is important to understand that an SF6 circuit breaker includes: a mechanical switching device capable of closing, carrying, and interrupting current under normal circuit conditions; carrying a specified overcurrent for a specified time and capable of closing and interrupting current under abnormal circuit conditions (such as various short-circuit conditions); main contacts including contacts in the main circuit of the switching device that carry the current of the main circuit when in the closed position; arc contacts including contacts in the switching device designed to form an electric arc; and current transfer including the process of current transfer from the main contacts to the arc contacts when the SF6 circuit breaker interrupts current, during which a brief electric arc may occur between the main contacts, the duration of which is related to the product structure design, the current phase when the main contacts separate, and the contact state.

[0042] It's also important to know that the main and arc contacts of an SF6 circuit breaker are arranged in parallel. The successful current interruption process is as follows: When the circuit breaker is in the closed position, the moving and stationary main contacts carry current, and no arc is generated; when the moving and stationary main contacts separate, a brief arc is generated between the main contacts, which extinguishes after a short time, and the current flows through the arc contact circuit; when the arc contacts separate, a continuous arc is generated between them, which extinguishes when the current crosses zero, as the contact gap increases and the arc-blowing effect intensifies. Figure 3 As shown.

[0043] Both the main contacts and the arcing contacts generate an electric arc upon separation, which erodes the contacts. The arcing time between the main contacts is usually short, but to ensure good current-carrying capacity, they are plated with a silver layer, which is often susceptible to arc erosion. Even a brief arc can leave noticeable burn marks on the surface, reducing current-carrying capacity and deteriorating the uniformity of the electric field distribution. Especially for structures with external insulating cylinders or supports, metal particles falling from the main contacts may adhere to the insulating components, reducing their insulation performance. The arcing time between the arcing contacts is longer, and copper-tungsten materials with strong arc erosion resistance are typically used at their ends. After severe contact erosion, the main contact surface has numerous scars, reducing the arcing contact's contact stroke. The main contacts may fail to transfer current successfully, leading to arc extinguishing failure. Furthermore, continuous arcing between the main contacts can easily cause flashover within the arc extinguishing chamber or even overheating, potentially leading to a circuit breaker explosion.

[0044] Regardless of length, an electric arc always presents a cathode voltage drop on the cathode surface, the amplitude of which varies depending on the material, typically ranging from a few volts to tens of volts. The arc duration between the main contacts is usually tens to hundreds of microseconds. Taking a switching speed of 10 mm / ms as an example, the calculated arc length is several millimeters. At this time, the measured arc voltage is essentially the cathode voltage drop of the electrode, and in terms of shape, it appears as a short-lived "protrusion". The duration of the arc is related to the current phase, the contact surface condition of the main contacts, vibration, the contact resistance of the arc contacts, and their length.

[0045] The arc duration between the contacts is generally long, typically tens of milliseconds. This invention focuses only on the initial position, where the arc forms at the location of the liquid bridge breakage, generally in a double-step pattern. Then, as the contact gap increases (before the contacts leave the nozzle), the arc voltage increases linearly. Figure 4 As shown.

[0046] After the contacts undergo a certain degree of ablation, multiple arc-induced ablation scars on the surface of the main contacts will generate multiple arcs during current transfer, manifesting as multiple protrusions in the arc voltage morphology. The ends of rod-shaped arc contacts will be shortened and their diameter reduced by arc erosion; the inner diameter of the ends of plum-shaped arc contacts will increase, the petals will become thinner, and the clamping force will decrease. The arc voltage morphology of these arc contacts indicates premature arcing. Combining this with the contact stroke curves tested in the experiment, the internal contact state can be comprehensively deduced from these waveforms, such as... Figure 5 As shown.

[0047] S2. During the breaking test, the arc voltage, current magnitude, contact displacement and voltage waveform data are collected in real time through a high-frequency data acquisition system, and the voltage waveform data is denoised to extract the arc start time, duration and peak voltage.

[0048] The high-frequency data acquisition system comprises a sensor, a signal conditioning module, a data sampling module, a synchronization module, and a storage and transmission module. After the test begins, the synchronization module simultaneously acquires the physical quantities of the main contact and the arc contact, and the sensor acquires the output signal data. Each output signal is amplified and filtered before being sent to the data sampling module for digitization and transmitted to the data processing system via a high-speed interface for real-time processing and analysis. The data processing system performs noise reduction, analysis, and storage on the acquired data.

[0049] The physical quantities include test current, mechanical stroke curve, and arc voltage.

[0050] The output signals include the start time, end time, start displacement, and end displacement of the main contact opening arc, the current phase at the moment the main contact opens, the start time and start displacement of the arc contact opening arc, and are electrically isolated by an opto-isolation module.

[0051] The opto-isolation module includes a function that uses the photoelectric effect to convert the electrical signal at the input end into an optical signal, and then uses the optical signal to drive the output end, so that there is no direct electrical connection between the input end and the output end.

[0052] The denoising process includes detecting and removing outliers in the data using a Kalman filter algorithm.

[0053] The Kalman filter algorithm consists of two stages: prediction and update.

[0054] The formula for the prediction stage is expressed as follows:

[0055]

[0056] in, express The predicted state at any given moment; express The state transition matrix at time t; express State estimation at time; express Control input matrix at any given time; express Time-based control input; express The prediction error covariance matrix at time 1; express The transpose of the state transition matrix at each time step; This represents the process noise covariance matrix.

[0057] The formula for the update phase is expressed as follows:

[0058]

[0059]

[0060] in, express Kalman gain matrix at time step; express The prediction error covariance matrix at time 1; express The observation matrix at each time point; express The transpose of the observation matrix at each moment; express The observation noise covariance matrix at time step; express State estimation after each update; express State estimation for time-predicted events; express The observed value at time; This represents the error covariance matrix updated at time t; Represents the identity matrix.

[0061] It's important to understand that in dynamic resistance testing, the current is supplied by an external DC power source, typically below 1000 amps and the voltage below 10 volts. In this invention, both the current and voltage are provided by the test circuit, typically tens of kiloamps and tens of kilovolts. Therefore, the obtained arc voltage waveform differs from the waveform obtained in dynamic resistance testing. Figure 5 As shown.

[0062] S3. Based on the arc duration and current magnitude, establish a regression model between the arc duration and current magnitude.

[0063] The regression model formula for the relationship between the arc duration and the current magnitude is expressed as follows:

[0064] in, Indicates the duration of the electric arc; Indicates the magnitude of the current; Indicates the coefficient of linear relationship; express .

[0065] S4. The degree of ablation of the main contact is assessed by the regression model between the arc duration and the current magnitude, and the degree of ablation of the arc contact is assessed by the contact displacement. A real-time contact health assessment report is generated based on the ablation assessment results.

[0066] The method for analyzing and evaluating the degree of ablation of the main contacts includes the following steps: Since the arc duration of the main contacts is linearly related to the current magnitude on the new prototype, a machine learning method is used to calculate the theoretical values ​​of the arc duration for other current phase angles using the instantaneous current value and arc duration during the main contact separation in the first breaking test, based on a regression model between the arc duration and the current magnitude. In subsequent tests, the actual arc duration is compared with the benchmark to obtain the ratio k1, and then the method is adjusted according to the preset main contact state. The evaluation table assesses the condition of the main contact. When 1 ≤ k1 < 1.2, the condition is assessed as normal; when 1.2 ≤ k1 < 1.4, the condition is assessed as good; when 1.4 ≤ k1 < 1.6, the condition is assessed as low risk; when 1.6 ≤ k1 < 1.8, the condition is assessed as medium risk; and when k1 ≥ 2, the condition is assessed as high risk. The k1 value reflects the deviation of contact erosion in actual tests. By combining different evaluation levels, the health status of the contacts can be determined, thereby predicting the risk of further wear or failure of the main contacts.

[0067] The k1 is represented as:

[0068] in, This represents the ratio of actual experimental data to baseline data; This represents actual experimental data; This represents the baseline data.

[0069] The method for analyzing and evaluating the degree of arc contact erosion includes using machine learning to take the displacement of the contact during the time period from the moment the main contact extinguishes the arc to the moment the arc contact ignites the arc as the input parameter for evaluating the amount of arc contact erosion. Using the length difference between the arc contact and the main contact in the first breaking test as a benchmark, in subsequent tests, the actual length difference is compared with the benchmark to obtain the ratio k2. An evaluation is then performed according to a preset arc contact condition evaluation table. When 0.8 ≤ k2 < 1, the arc contact condition is evaluated as normal; when 0.6 ≤ k2 < 0.8, the arc contact condition is evaluated as good; when 0.4 ≤ k2 < 0.6, the arc contact condition is evaluated as low risk; when 0.2 ≤ k2 < 0.4, the arc contact condition is evaluated as medium risk; and when 0 ≤ k2 < 0.2, the arc contact condition is evaluated as high risk. The value of k2 reflects the length difference between the arc contact and the main contact, indirectly reflecting the degree of arc contact erosion. These assessment results can be used to estimate the service life, wear level, and whether the arc contact needs to be replaced or repaired.

[0070] The k2 is represented as:

[0071] in, This represents the ratio of the actual length difference between the arc contact and the main contact to the reference value of the first test. This represents the length difference between the actual arc contact and the main contact; This represents the baseline value for the first test.

[0072] The machine learning method involves analyzing and training historical test data and real-time sensor data using machine learning algorithms to establish a model capable of predicting the degree of contact erosion or assessing risk in real time. This data-driven process automatically calculates the health status of the contacts based on data such as arc duration and contact displacement during the test, and generates real-time assessment reports and early warning signals.

[0073] Machine learning models (such as support vector machines (SVM) and neural networks (ANN)) are trained using a large amount of historical data. During training, the model learns the latent patterns between each input feature and the target variable based on the relationship between the input features (arc duration, contact displacement, etc.) and the target variable (the degree of contact ablation).

[0074] Training set data typically includes known ablation degree labels, and the purpose of training is to enable the machine learning model to make accurate predictions on unseen data.

[0075] Based on the output of the machine learning model, the system can generate real-time contact health assessment reports. If the assessment results show that the contact erosion exceeds the set safety threshold, the system will automatically issue a warning signal. The warning signal can notify the operator of potential contact problems and prompt repair or replacement.

[0076] Example 2, an embodiment of the present invention, provides a contact erosion assessment system for SF6 circuit breaker breaking tests, comprising: The test unit connects an arc voltage divider in parallel across the two ends of the SF6 circuit breaker and deploys a displacement sensor to initiate the main contact and arc contact breaking test.

[0077] During the breaking test, the data acquisition unit uses a high-frequency data acquisition system to collect arc voltage, current magnitude, contact displacement, and voltage waveform data in real time, and performs noise reduction processing on the voltage waveform data to extract the arc start time, duration, and peak voltage.

[0078] The analysis unit establishes a regression model between the arc duration and the current magnitude based on the arc duration and the current magnitude.

[0079] The evaluation unit assesses the degree of ablation of the main contact through a regression model between the arc duration and the current magnitude, and assesses the degree of ablation of the arc contact through contact displacement. Based on the ablation assessment results, it generates a real-time contact health assessment report.

[0080] This embodiment also provides a computer device applicable to a method for evaluating contact erosion in an SF6 circuit breaker breaking test, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for evaluating contact erosion in an SF6 circuit breaker breaking test as proposed in the above embodiment.

[0081] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0082] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements a method for evaluating contact erosion in an SF6 circuit breaker breaking test as proposed in the above embodiment. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0083] In summary, this invention utilizes arc voltage testing technology to identify the arc characteristics during main contact separation and uses the start and end times and displacement of the main contact arc and the arc contact arc as input parameters for evaluating the contact system status. Based on the characteristics of the main contact and the arc contact, two different contact evaluation methods are defined. The measurement is convenient and quick, does not affect daily testing work, and the data better reflects the actual breaking situation.

[0084] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for evaluating contact erosion during an SF6 circuit breaker breaking test, characterized in that: include, An arc voltage divider is connected in parallel across both ends of the SF6 circuit breaker, and a displacement sensor is deployed to initiate the main contact and arc contact breaking test. During the breaking test, the arc voltage, current magnitude, contact displacement and voltage waveform data are collected in real time through a high-frequency data acquisition system. The voltage waveform data is then denoised to extract the arc start time, duration and peak voltage. Based on the arc duration and current magnitude, a regression model is established between the arc duration and current magnitude. The degree of ablation of the main contact is assessed by using the regression model between the arc duration and the current magnitude, and the degree of ablation of the arc contact is assessed by the contact displacement. A real-time contact health assessment report is generated based on the ablation assessment results.

2. The method for evaluating contact erosion during an SF6 circuit breaker breaking test as described in claim 1, characterized in that: The arc voltage divider includes an arc voltage divider with a withstand voltage level of 550kV, used to measure the voltage when an electric arc is generated between the contacts; The displacement sensor includes a function to measure the mechanical stroke curve and obtain the displacement during the contact opening process.

3. The method for evaluating contact erosion during an SF6 circuit breaker breaking test as described in claim 2, characterized in that: The breaking test of the main contact includes testing the performance of the main contact when breaking the circuit under rated load, ensuring that the current is successfully interrupted when the contacts separate, and simulating multiple breaking operations in a loop. The arc contact breaking test includes generating a large current using a short-circuit test power supply under short-circuit conditions to produce an electric arc during the breaking process, and breaking the circuit multiple times under different currents to test the arc extinguishing capability and ablation of the arc contact.

4. The method for evaluating contact erosion during an SF6 circuit breaker breaking test as described in claim 3, characterized in that: The high-frequency data acquisition system comprises a sensor, a signal conditioning module, a data sampling module, a synchronization module, and a storage and transmission module. After the test begins, the synchronization module simultaneously acquires the physical quantities of the main contact and the arc contact, and the sensor acquires output signal data. Each output signal is amplified and filtered before being sent to the data sampling module for digitization. The data is then transmitted to the data processing system via a high-speed interface for real-time processing and analysis. The data processing system denoises, analyzes, and stores the acquired data. The physical quantities include test current, mechanical stroke curve, and arc voltage; The output signals include the start time, end time, start displacement, and end displacement of the main contact opening arc, the current phase at the moment the main contact opens, the start time and start displacement of the arc contact opening arc, and are electrically isolated by an opto-isolation module.

5. The method for evaluating contact erosion during an SF6 circuit breaker breaking test as described in claim 4, characterized in that: The noise reduction process includes detecting and removing outliers in the data using a Kalman filter algorithm. The Kalman filter algorithm includes two stages: prediction and update. The formula for the prediction stage is expressed as follows: in, express The predicted state at any given moment; express The state transition matrix at time t; express State estimation at time; express Control input matrix at any given time; express Time-based control input; express The prediction error covariance matrix at time 1; express The transpose of the state transition matrix at each time step; Represents the process noise covariance matrix; The formula for the update phase is expressed as follows: in, express Kalman gain matrix at time step; express The prediction error covariance matrix at time 1; express The observation matrix at time points; express The transpose of the observation matrix at each moment; express The observation noise covariance matrix at time step; express State estimation after each update; express State estimation for time-predicted events; express The observed value at time; This represents the error covariance matrix updated at time t; Represents the identity matrix.

6. The method for evaluating contact erosion during an SF6 circuit breaker breaking test as described in claim 5, characterized in that: The regression model formula for the relationship between the arc duration and the current magnitude is expressed as follows: in, Indicates the duration of the electric arc; Indicates the magnitude of the current; Indicates the coefficient of linear relationship; express .

7. The method for evaluating contact erosion during an SF6 circuit breaker breaking test as described in claim 6, characterized in that: The method for analyzing and evaluating the degree of ablation of the main contact includes using machine learning methods to calculate the theoretical values ​​of the arc duration of other current phase angles based on the instantaneous current value and arc duration when the main contact separates during the first breaking test, using a regression model between the arc duration and the current magnitude. In subsequent tests, the actual arc duration of each test is compared with the benchmark to obtain the ratio k1, and the evaluation is performed according to a preset main contact status evaluation table. The method for analyzing and evaluating the degree of arc contact erosion includes using machine learning to take the displacement of the contact during the time period from the moment the main contact extinguishes the arc to the moment the arc contact ignites the arc as the evaluation input parameter for the amount of arc contact erosion; and using the length difference between the arc contact and the main contact in the first breaking test as a benchmark, comparing the actual length difference with the benchmark in subsequent tests to obtain the ratio k2, and evaluating it according to a preset arc contact state evaluation table.

8. A contact erosion assessment system for SF6 circuit breaker breaking tests, based on the method described in any one of claims 1 to 7, characterized in that: include, The test unit connects an arc voltage divider in parallel across the two ends of the SF6 circuit breaker and deploys a displacement sensor to initiate the main contact and arc contact breaking test. The data acquisition unit, during the breaking test, acquires arc voltage, current magnitude, contact displacement and voltage waveform data in real time through a high-frequency data acquisition system, and performs noise reduction processing on the voltage waveform data to extract the arc start time, duration and peak voltage. The analysis unit establishes a regression model between the arc duration and the current magnitude based on the arc duration and the current magnitude. The evaluation unit assesses the degree of ablation of the main contact through a regression model between the arc duration and the current magnitude, and assesses the degree of ablation of the arc contact through contact displacement. Based on the ablation assessment results, it generates a real-time contact health assessment report.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the contact erosion evaluation method in the breaking test of an SF6 circuit breaker as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the contact erosion evaluation method in the breaking test of an SF6 circuit breaker as described in any one of claims 1 to 7.

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