Power supply system insulation fault monitoring method and device

Abstract

The invention provides a power supply system insulation fault monitoring method and device, and belongs to the technical field of insulation monitoring, and the method comprises the steps: carrying out the insulation monitoring of a cable based on a multi-frequency signal, and obtaining a first cable signal; compensating the first cable signal based on the compensation information to obtain a second cable signal; and obtaining a cable insulation monitoring result based on the second cable signal. According to the power supply system insulation fault monitoring method and device provided by the invention, the accuracy and reliability of power supply system insulation monitoring can be improved.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of insulation monitoring, and more specifically, to a method and device for monitoring insulation faults in a power supply system. Background Art

[0002] As a key carrier for power transmission and communication signal transmission, cables play a vital role in all fields of modern society. The insulation performance of cables is the core factor to ensure their safe and stable operation. During long-term operation, the insulation performance of cables will be affected by various factors and gradually decline. Once the insulation performance of cables declines to a certain extent, it may cause various faults, which will not only affect the power supply and communication quality, but also cause serious safety accidents, such as fires, electric shock accidents, etc., causing huge losses to social production and life.

[0003] Today, monitoring of cable insulation is not accurate or reliable enough. Summary of the invention

[0004] The purpose of the present disclosure is to provide a method and device for monitoring insulation faults in a power supply system, so as to improve the accuracy and reliability of cable insulation monitoring.

[0005] A first aspect of an embodiment of the present disclosure provides a method for monitoring insulation faults in a power supply system, comprising: Performing insulation monitoring on the cable based on the multi-frequency signal to obtain a first cable signal; Compensating the first cable signal based on the compensation information to obtain a second cable signal; A cable insulation monitoring result is obtained based on the second cable signal.

[0006] A second aspect of the embodiments of the present disclosure provides a power supply system insulation fault monitoring device, comprising: A signal acquisition module, used to perform insulation monitoring on the cable based on the multi-frequency signal to obtain a first cable signal; A signal compensation module, configured to compensate the first cable signal based on compensation information to obtain a second cable signal; A signal monitoring module is used to obtain a cable insulation monitoring result based on the second cable signal.

[0007] According to a third aspect of an embodiment of the present disclosure, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of the above-mentioned power supply system insulation fault monitoring method when executing the computer program.

[0008] According to a fourth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned method for monitoring insulation faults in a power supply system are implemented.

[0009] The beneficial effects of the power supply system insulation fault monitoring method and device provided by the embodiments of the present disclosure are: The present disclosure utilizes multi-frequency signals for insulation monitoring, which can monitor the insulation state of the cable in real time, and is helpful to timely discover potential insulation problems. The present disclosure injects multi-frequency signals into the cable without directly disconnecting the cable or physically contacting it, thereby avoiding interference with the normal operation of the cable. The present disclosure compensates the first cable signal through compensation information, and can obtain a more accurate second cable signal. The above-mentioned compensation mechanism takes into account the influence of cable environmental factors and other factors on signal transmission, thereby reducing the signal attenuation and phase shift caused by these factors, and improving the accuracy of the signal. The present disclosure introduces a compensation mechanism, so that the present disclosure can more accurately reflect the insulation state of the cable, which is helpful to timely discover potential insulation problems, such as insulation aging, moisture, etc., thereby enhancing the reliability of the monitoring system. By comparing or matching the second cable signal with the standard signal characteristics, the insulation state of the tested cable can be more accurately judged, and the accuracy and reliability of insulation monitoring of the power supply system are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 A schematic diagram of a flow chart of a method for monitoring insulation faults in a power supply system provided in an embodiment of the present disclosure; Figure 2 A schematic diagram of a signal generation and injection circuit provided in one embodiment of the present disclosure; Figure 3 A schematic diagram of a signal sampling circuit provided by an embodiment of the present disclosure; Figure 4 A schematic diagram of the structure of a power supply system insulation fault monitoring device provided by an embodiment of the present disclosure; Figure 5 A structural block diagram of a power supply system insulation fault monitoring device provided by an embodiment of the present disclosure; Figure 6 A schematic block diagram of an electronic device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0012] In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present disclosure. However, it should be clear to those skilled in the art that the present disclosure may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obstructing the description of the present disclosure with unnecessary details.

[0013] In order to make the purpose, technical solutions and advantages of the present disclosure more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0014] Please refer to Figure 1 , Figure 1 A flow chart of a method for monitoring insulation faults in a power supply system provided by an embodiment of the present disclosure, the method comprising: S101: Perform insulation monitoring on a cable based on a multi-frequency signal to obtain a first cable signal.

[0015] In this embodiment, the multi-frequency signal is a signal of known frequency, including signals of multiple frequencies. The multi-frequency signal can be input at one end of the cable under test, and the output signal can be monitored at the other end of the cable under test to obtain a first cable signal. The multi-frequency signal is connected to the cable through a coupling device using the principles of capacitive coupling and inductive coupling. The insulation state of the cable under test can be monitored in real time without affecting the operation of the cable under test, and potential insulation problems such as insulation aging, moisture, partial discharge, etc. can be discovered in time.

[0016] Multi-frequency signals can be generated by a function generator and then connected to the cable injection point through a signal amplifier. The function generator can accurately set the frequency, amplitude and phase of each frequency component.

[0017] The first cable signal is the signal obtained after the multi-frequency signal is transmitted in the tested cable. The output information of the multi-frequency signal in the cable can be indirectly obtained by monitoring the changes in the electromagnetic field around the cable through Hall sensors, Rogowski coils, etc. These sensors can monitor the changes in the current or magnetic field in the cable without direct contact with the cable, avoiding interference with the normal operation of the cable.

[0018] S102: Compensate the first cable signal based on the compensation information to obtain a second cable signal.

[0019] In this embodiment, the compensation information may include a length compensation value, a temperature compensation value, and a humidity compensation value. This embodiment takes into account that the cable length has a significant impact on signal attenuation and causes a phase shift of the signal, so a length compensation mechanism is set.

[0020] Taking into account the influence of the ambient temperature of the environment where the tested cable is located on the monitoring results, the resistivity of the cable insulation material changes with temperature. When the temperature rises, the resistivity of the insulation material will decrease. Therefore, when the ambient temperature of the tested cable is greater than or equal to the preset temperature threshold, the temperature compensation value can be determined by a certain step size or according to a formula.

[0021] Increased humidity will cause the cable insulation to get damp. Considering the impact of the ambient humidity of the environment where the tested cable is located on the monitoring results, when the cable insulation gets damp, its insulation resistance will drop significantly. For example, for an insulated cable, if the insulation layer gets damp, water molecules will form a conductive path inside the insulation material, reducing the insulation resistance. This will cause the injected multi-frequency signal to attenuate more during the transmission process, which can easily be mistaken for signal attenuation caused by other problems such as insulation aging. Therefore, when the humidity value of the tested cable is greater than or equal to the preset humidity threshold, the humidity compensation value is determined by a certain step size or according to a formula.

[0022] The length compensation information can be determined according to the length of the measured cable, the temperature compensation information can be determined according to the ambient temperature of the environment where the measured cable is located, and the humidity compensation information can be determined according to the ambient humidity of the environment where the measured cable is located. The second cable signal is a signal obtained after the first cable signal is length compensated, temperature compensated, and humidity compensated.

[0023] In this embodiment, the method for monitoring insulation faults in a power supply system further includes: Acquiring compensation information based on the first neural network model; Acquiring compensation information based on the first neural network model includes: inputting cable length information, ambient temperature information, and ambient humidity information into the first neural network module to obtain compensation information; Before obtaining compensation information based on the first neural network model, the method further includes: The second neural network model is trained based on historical cable length information, ambient temperature information, ambient humidity information and corresponding loss values ​​to obtain the first neural network model.

[0024] For example, the first neural network model can be a convolutional neural network model, which collects historical cable length information, ambient temperature information, ambient humidity information and corresponding loss values, including signal attenuation value and signal phase shift value, which can be obtained by monitoring the signal loss value in an intact cable. In this process, the length, ambient temperature and ambient humidity of the intact cable must be obtained. A data set is obtained through a large number of experiments or historical records for training the second neural network model (convolutional neural network model).

[0025] S103: Obtaining a cable insulation monitoring result based on the second cable signal.

[0026] In this embodiment, the second cable signal is a signal obtained after the first cable signal is compensated, and can reflect the signal characteristics of the input multi-frequency signal after being transmitted in the tested cable.

[0027] The signal attenuation characteristics, phase shift characteristics and reflection signal characteristics of the second cable signal can be extracted and compared or matched with the standard signal attenuation characteristics, phase shift characteristics and reflection signal characteristics. The standard signal includes: a normal standard signal and an abnormal standard signal, that is, a signal when the cable has no insulation fault and a signal when the cable has an insulation fault. The abnormal standard signal can be obtained by collecting characteristic signals of historical cable insulation faults.

[0028] If the above characteristics match the normal characteristics, it is determined that the tested cable has no insulation fault. If the above characteristics match the fault characteristics, it is determined that the tested cable has a corresponding fault.

[0029] In this embodiment, the method for monitoring insulation faults in a power supply system further includes: Obtaining cable insulation monitoring results based on the third neural network model and the second cable signal; Obtaining a cable insulation monitoring result based on the third neural network model includes: inputting the second cable signal into the third neural network model to obtain a cable insulation monitoring result; Before obtaining the cable insulation monitoring result based on the third neural network model and the second cable signal, it also includes: The fourth neural network model is trained based on historical signal characteristics or signal waveforms when the cable has insulation faults and when it does not have insulation faults, to obtain the third neural network model.

[0030] For example, the third neural network model can be a convolutional neural network model, which collects signal features or signal waveforms when the insulation fault occurs and when the insulation fault does not occur in the historical cable, and the signal features or signal waveforms include: signal attenuation features, signal phase shift features, signal attenuation waveforms and signal phase shift waveforms. At the same time, during training, the signal features or signal waveforms should be input into the fourth neural network model together with their corresponding fault types. A data set is obtained through a large number of experiments or historical records for training the second neural network model (convolutional neural network model).

[0031] In this embodiment, the capacitance value and the resistance value of the cable to ground may also be obtained based on the second cable signal; The insulation fault detection result of the cable is obtained based on the ground capacitance value and ground resistance value of the cable.

[0032] In this embodiment, the insulation fault detection result of the cable is obtained based on the ground capacitance value and ground resistance value of the cable, including: In response to the absolute value of the difference between the ground capacitance value and the standard ground capacitance value being greater than a first capacitance threshold, the cable is at risk of insulation failure; In response to the absolute value of the difference between the ground capacitance value and the standard ground capacitance value being greater than a second capacitance threshold, an insulation fault occurs in the cable; In response to the absolute value of the difference between the ground resistance value and the standard ground resistance value being greater than a first resistance threshold, the cable is at risk of insulation failure; In response to the absolute value of the difference between the ground resistance value and the standard ground resistance value being greater than a second resistance threshold, an insulation fault occurs in the cable; The location where the insulation fault occurs in the cable is obtained based on the second cable signal.

[0033] For example, for multiple frequencies For multi-frequency signals, multiple formulas can be obtained. For example, for frequency have , for frequency have , and so on, we can get the equation system

[0034] The above equations can be solved by the least square method to obtain the capacitance value to ground. And the resistance to ground ,in is the current value, is the number of different frequencies, is the voltage value.

[0035] The first capacitance threshold, the second capacitance threshold, the first resistance threshold and the second resistance threshold can be set manually, and the standard capacitance value to ground and the standard resistance value to ground can be obtained from the factory manual of the cable. The larger the absolute value of the difference between the capacitance value to ground and the standard capacitance value to ground, the greater the degree of aging of the cable, and the larger the absolute value of the difference between the resistance value to ground and the standard resistance value to ground, the greater the degree of aging of the cable.

[0036] When a cable fails, a fault warning can be issued. For example, when the absolute value of the difference between the ground capacitance value and the standard ground capacitance value is greater than the first capacitance threshold and / or the absolute value of the difference between the ground resistance value and the standard ground resistance value is greater than the first resistance threshold, the screen of the executing entity displays: The tested cable is at risk of insulation failure. Please check it in time. For another example, when the absolute value of the difference between the ground capacitance value and the standard ground capacitance value is greater than the second capacitance threshold and / or the absolute value of the difference between the ground resistance value and the standard ground resistance value is greater than the second resistance threshold, the screen of the executing entity displays: The tested cable has an insulation failure. Please handle it in time.

[0037] The second cable signal includes a reflected signal. When a multi-frequency signal propagates in a cable and encounters a fault point (such as insulation damage, short circuit, etc., which causes a change in line characteristics), a reflected signal is generated. For a normal cable, its characteristic impedance is relatively stable, but the equivalent impedance of the fault point is often different from the normal cable characteristic impedance, which causes signal reflection.

[0038] The time difference between the incident signal and the reflected signal can be measured , according to the formula , to determine the distance between the fault point and the signal injection end, where, is the speed at which the signal travels in the cable, is the distance between the fault point and the signal injection end.

[0039] It can be concluded from the above that the present disclosure utilizes multi-frequency signals for insulation monitoring, which can monitor the insulation state of the cable in real time, and is helpful to timely discover potential insulation problems. The present disclosure injects multi-frequency signals into the cable without directly disconnecting the cable or physically contacting it, thereby avoiding interference with the normal operation of the cable. The present disclosure compensates the first cable signal through compensation information to obtain a more accurate second cable signal. The above compensation mechanism takes into account the influence of cable environmental factors and other factors on signal transmission, thereby reducing the signal attenuation and phase shift caused by these factors, and improving the accuracy of the signal. The present disclosure introduces a compensation mechanism, so that the present disclosure can more accurately reflect the insulation state of the cable, which is helpful to timely discover potential insulation problems, such as insulation aging, moisture, etc., thereby enhancing the reliability of the monitoring system. By comparing or matching the second cable signal with the standard signal characteristics, the insulation state of the tested cable can be more accurately judged, and the accuracy and reliability of insulation monitoring of the power supply system are improved.

[0040] In one embodiment of the present disclosure, compensating the first cable signal based on the compensation information to obtain the second cable signal includes: Obtaining a first length compensation value and a second length compensation value based on the length of the cable; Obtaining a first temperature compensation value based on the ambient temperature of the cable; Obtaining a first humidity compensation value based on the humidity of the environment in which the cable is located; The first cable signal is compensated based on the first length compensation value, the first temperature compensation value and the first humidity compensation value to obtain a second cable signal.

[0041] In one embodiment of the present disclosure, obtaining a first length compensation value and a second length compensation value based on the length of the cable includes: Obtaining a first length compensation value based on the length of the cable and a first formula; A second length compensation value is obtained based on the length of the cable and a second formula.

[0042] In this embodiment, the first length compensation value can be obtained by a first formula: ,in, is the signal attenuation compensation value (first length compensation value), The frequency is The signal attenuation coefficient is is the length of the cable under test.

[0043] The second formula can be: ,in, is the phase shift compensation value of the signal (second length compensation value), is the frequency of the signal, is the length of the cable under test, is the phase velocity.

[0044] Length of the cable under test The signal attenuation coefficient can be obtained according to the meter mark and number on the cable. The signal frequency can be obtained from the instruction manual that comes with the tested cable when it leaves the factory. It is a signal of known frequency set by humans, the phase velocity , can be calculated by the third formula, the third formula: ,in, is the magnetic permeability of the cable insulation medium, is the dielectric constant of the cable insulation medium, which can be obtained from the cable's factory instruction manual.

[0045] In this embodiment, the influence of the ambient temperature and ambient humidity of the cable environment on the monitoring signal and the monitoring result is taken into account. The temperature threshold and the humidity threshold can be determined according to historical records or experience. If the temperature of the tested cable is higher than the predetermined temperature threshold, compensation can be performed according to a certain step length. If the humidity of the corresponding tested cable is higher than the predetermined humidity threshold, compensation can be performed according to a certain step length. The ambient temperature and ambient humidity of the tested cable can be obtained by a temperature sensor and a humidity sensor.

[0046] It can be concluded from the above that the present disclosure calculates the signal attenuation compensation value (first length compensation value) and the signal phase shift compensation value (second length compensation value) respectively through the first formula and the second formula. The present disclosure comprehensively considers multiple factors such as cable length, ambient temperature and humidity. The method provides a comprehensive compensation mechanism for cable signal transmission, which helps to reduce signal distortion and attenuation during transmission, thereby improving the reliability and stability of signal transmission and the accuracy and reliability of cable insulation monitoring.

[0047] In one embodiment of the present disclosure, before obtaining the first length compensation value and the second length compensation value based on the length of the cable, the method further includes: The cable length compensation value is obtained based on the ambient temperature of the cable; The cable length is obtained based on the cable length compensation value.

[0048] In this embodiment, the effect of ambient temperature on cable length is taken into consideration. When monitoring long-distance cables, the effect of temperature on length cannot be ignored.

[0049] The length compensation value of the cable can be determined by the fourth formula: ,in, is the cable length change value (cable length compensation value), is the initial length of the cable at the reference temperature, Is the linear expansion coefficient of the cable material, indicating the relative change in length caused by a unit temperature change. The difference between the current temperature and the reference temperature can be positive or negative. Similarly, the calculated cable length compensation value can also be positive or negative. The reference temperature is the standard temperature of the tested cable in the manual when it leaves the factory. The initial length of the cable at the reference temperature is and the linear expansion coefficient of the cable material It can be obtained from the factory instructions of the cable under test.

[0050] Cable length It can be obtained by adding the initial length of the cable at the reference temperature and the cable length change (cable length compensation value).

[0051] It can be concluded from the above that the present disclosure takes into account the influence of temperature on cable length. The present disclosure takes into account the important factor of ambient temperature by introducing a cable length compensation value, thereby improving the accuracy of cable length monitoring. The present disclosure is not only applicable to a specific type of cable, but can also be adjusted and applied according to different types of cables (with different linear expansion coefficients and initial lengths), thereby improving the accuracy, adaptability and reliability of cable length monitoring, thereby improving the accuracy and reliability of cable insulation monitoring.

[0052] In one embodiment of the present disclosure, obtaining a first temperature compensation value based on the ambient temperature of the cable includes: In response to the absolute value of the difference between the ambient temperature of the cable and the standard ambient temperature being greater than or equal to a first temperature threshold, taking a first temperature step as a first temperature compensation value; In response to the absolute value of the difference between the ambient temperature of the cable and the standard ambient temperature being greater than or equal to a second temperature threshold, using the second temperature step as a first temperature compensation value; The first temperature threshold is lower than the second temperature threshold.

[0053] In one embodiment of the present disclosure, obtaining a first humidity compensation value based on the humidity of the environment in which the cable is located includes: In response to the absolute value of the difference between the ambient humidity of the cable and the standard ambient humidity being greater than or equal to a first humidity threshold, taking a first humidity step as a first humidity compensation value; In response to the absolute value of the difference between the ambient humidity of the cable and the standard ambient humidity being greater than or equal to a second humidity threshold, taking the second humidity step as a first humidity compensation value; The first humidity threshold is less than the second humidity threshold.

[0054] In this embodiment, the ambient temperature of the cable environment can be obtained by a temperature sensor, and the ambient humidity of the cable environment can be obtained by a humidity sensor. The standard ambient temperature and standard ambient humidity can be obtained from the instructions attached to the cable when it leaves the factory, or can be set manually based on experience.

[0055] The first temperature threshold is less than the second temperature threshold, the first temperature step is less than the second temperature step, the first humidity threshold is less than the second humidity threshold, and the first humidity step is less than the second humidity step, wherein the first temperature step, the second temperature step, the first humidity step, and the second humidity step can be set manually or calculated by establishing a temperature and humidity influence model. The above-mentioned temperature and humidity influence model is a signal transmission model of the cable under different temperature and humidity conditions established through a large number of experiments and data analysis, and the ambient temperature and ambient humidity of the environment where the cable is located are input into the model, and the output value is the temperature compensation value and the humidity compensation value. The humidity referred to in the present disclosure is relative humidity.

[0056] In this embodiment, the first temperature step includes a first temperature attenuation step and a first temperature phase shift step, the second temperature step includes a second temperature attenuation step and a second temperature phase shift step, the first humidity step includes a first humidity attenuation step and a first humidity phase shift step, and the second humidity step includes a first humidity attenuation step and a first humidity phase shift step.

[0057] For example, the first temperature threshold is 5°C, the second temperature threshold is 10°C, the first humidity threshold is 10%, and the second humidity threshold is 20%. The standard ambient temperature is 20°C, the standard ambient humidity is 40%, the second temperature attenuation step is 8dB, the second temperature phase shift step is 12°, the first humidity attenuation step is 5dB, and the first humidity phase shift step is 5°. The ambient temperature of the cable environment monitored by the temperature sensor is 32°C, and the ambient humidity of the cable environment monitored by the humidity sensor is 53%. At this time, since the absolute value of the difference between the ambient temperature and the standard ambient temperature is 12°C, which is greater than or equal to the second temperature threshold (10°C), the monitoring signal is compensated with the second temperature attenuation step (8dB) and the second temperature phase shift step (12°). Since the absolute value of the difference between the ambient humidity and the standard ambient humidity is 13%, at this time, since the absolute value of the difference between the ambient humidity and the standard ambient humidity is greater than or equal to the first humidity threshold, the monitoring signal is compensated with the first humidity attenuation step (5dB) and the first humidity phase shift step (5°).

[0058] In this embodiment, the influence of temperature and humidity on the cable and the monitoring signal is taken into account. The increase in temperature will increase the attenuation of the signal when it is transmitted in the cable. The temperature change may also affect the capacitance and inductance parameters of the cable, further changing the attenuation characteristics of the signal. Under high-frequency signals, this influence is more obvious. At the same time, the higher the temperature and humidity, the greater the influence on the signal. Therefore, when the temperature and humidity are higher, the corresponding step size should also be increased accordingly.

[0059] It can be concluded from the above that the present disclosure can more accurately reflect the actual state of the cable under different environmental conditions by introducing a compensation mechanism for temperature and humidity, which helps to reduce measurement errors caused by changes in environmental factors and improve the accuracy of the data. The present disclosure can automatically adjust the compensation value according to different ambient temperature and humidity conditions, thereby adapting to a wider range of environmental changes, making the present disclosure more flexible and reliable, and able to maintain stable performance under various environmental conditions. The present disclosure can more finely control the compensation amount and improve the accuracy and reliability of the compensation by setting different thresholds and step sizes. For example, when the ambient temperature or humidity changes slightly, using a smaller compensation step size can save resources; when the changes are larger, a larger step size is used to ensure accuracy, thereby improving the accuracy and reliability of cable insulation monitoring.

[0060] In one embodiment of the present disclosure, obtaining a cable insulation monitoring result based on the second cable signal includes: Extracting features from the second cable signal to obtain a plurality of first features; A cable insulation monitoring result is obtained based on the plurality of first features.

[0061] In one embodiment of the present disclosure, obtaining a cable insulation monitoring result based on a plurality of first features includes: The plurality of first features are matched with standard features in a standard feature library to obtain a cable insulation monitoring result.

[0062] In this embodiment, the second cable signal is a signal obtained after the first cable signal is length compensated, temperature compensated and humidity compensated, and the first cable signal is a signal obtained after the multi-frequency signal is transmitted in the tested cable.

[0063] The first feature may include a signal attenuation feature, a signal phase shift feature, and a reflected signal feature. The standard feature library includes multiple normal standard features and multiple abnormal standard features. The normal standard feature is a feature when there is no insulation fault in the cable, and the abnormal standard feature includes a feature when there is a ground fault, a short circuit fault, a broken line fault, an insulation aging fault, etc. in the cable. The feature may be embodied in the form of a vector. The standard feature library can be continuously updated and improved with the accumulation of actual experience to meet the needs of more types of cable fault monitoring.

[0064] The matching degree of two features can be calculated by calculating the Euclidean distance or the cosine similarity.

[0065] In response to the first feature and the normal standard feature having a matching degree greater than or equal to a first matching threshold, the first feature is a normal feature; In response to the matching degree between the first feature and the abnormal standard feature being greater than or equal to the second matching threshold, the first feature is an abnormal feature.

[0066] In this embodiment, the smaller the Euclidean distance is, the higher the matching degree is. Both the first matching threshold and the second matching threshold can be set manually.

[0067] For example, the extracted signal attenuation feature vector , the normal standard eigenvector , insulation aging fault characteristic vector , respectively calculate the Euclidean distance between the extracted signal attenuation feature vector and the normal standard feature vector and the insulation aging fault feature vector:

[0068]

[0069] in, is the number of vector values, For the The vector value of the extracted signal attenuation feature vector, For the The vector value of the normal standard eigenvectors, For the The vector value of the insulation aging fault feature vector.

[0070] For example, the first matching threshold and the second matching threshold are equal, both are 2, and after calculation, we get The value of is 6, and we get The value of is 1. Since the smaller the Euclidean distance, the higher the corresponding matching degree, the extracted signal attenuation feature vector does not match the normal standard feature vector, and the extracted signal attenuation feature vector matches the insulation aging fault feature vector. It is determined that the cable has an insulation aging fault. From the above, it can be concluded that the present disclosure obtains multiple first features including signal attenuation features, signal phase shift features and reflected signal features by extracting features from the second cable signal, and these features can fully reflect the insulation status of the cable. By matching the above features with the standard features in the standard feature library, it is possible to accurately determine whether there is an insulation fault in the cable and the type of fault. The present disclosure can more accurately determine the insulation condition of the cable and reduce the possibility of misjudgment and missed judgment through feature extraction and matching mechanisms. The present disclosure further improves the accuracy of the signal through compensation technology, thereby enhancing the reliability of the monitoring results. The present disclosure can fully reflect the insulation condition of the cable by extracting multiple features, which helps to discover various potential insulation faults. The standard feature library of the present disclosure ensures that the monitoring can cover multiple fault types, improves the comprehensiveness of the monitoring, and thus improves the accuracy and reliability of cable insulation monitoring.

[0071] Figure 2 A schematic diagram of a signal generation and injection circuit provided by an embodiment of the present disclosure is shown in FIG. Figure 2 As shown, the signal generation and injection circuit includes: STM32MCU, voltage amplifier circuit, drive amplifier circuit and high voltage isolation circuit; The voltage amplifier circuit is connected to the STM32MCU and the drive amplifier circuit respectively; The driving amplifier circuit is connected to the high voltage isolation circuit.

[0072] The STM32 MCU is the core control unit of the entire signal generation. It can generate digital signals through internal timers and digital-to-analog converters and convert them into analog signals. For example, the STM32 timer can be used to generate square wave signals of different frequencies, and then the digital-to-analog converter can be used to convert the square wave signal into a multi-frequency signal of a sine wave or other waveform. Through programming, the frequency, amplitude, phase and other parameters of the signal can be accurately controlled to meet the needs of cable detection. When generating multi-frequency signals, the STM32 MCU can generate complex signals containing multiple frequency components according to the preset frequency combination and time sequence. For example, to generate a signal containing three frequency components of 1kHz, 5kHz and 10kHz, three timer interrupts with different frequencies can be set in the program, and the DAC output value can be updated in each interrupt service program to achieve the generation of multi-frequency signals.

[0073] The signal amplitude output from the STM32 MCU is usually small, generally within a few volts, which cannot meet the requirements of direct injection into the cable. The function of the voltage amplifier circuit is to amplify the small signal output by the MCU to reach a voltage level that can be effectively injected into the cable. It is mainly based on amplifier chips (such as operational amplifiers) to achieve this.

[0074] The function of the drive amplifier circuit is to further increase the power of the signal on the basis of voltage amplification to meet the requirements of signal injection into the cable, which can be achieved by using a power amplifier. As a load, the cable has a low equivalent impedance and requires a large current to effectively inject the signal. The drive amplifier circuit can provide sufficient current driving capability to ensure that the signal can overcome the input impedance of the cable and enter the cable smoothly.

[0075] The main function of the high-voltage isolation circuit is to achieve electrical isolation between the signal source (including STM32 MCU, voltage amplifier circuit and drive amplifier circuit) and the cable, protecting the safety of the signal generating circuit and the operator.

[0076] Some signals are mixed-frequency signals, so the D / A function of the microprocessor is used to send signals, which are injected into the high-voltage transformer through the voltage follower circuit and the power amplifier circuit. According to the instructions sent by the data processing circuit, the signal generation circuit sends out low-frequency signals in the frequency range of 0.1-20Hz, high-frequency signals in the range of 2K-30KHz, and mixed-frequency signals stored in the processing circuit, and obtains the response characteristics of the line at different frequencies, which are then injected into the line using a high-frequency transformer, and the signals coupled from the line are consumed and absorbed at the same time.

[0077] Figure 3 A signal sampling circuit diagram is provided in accordance with an embodiment of the present disclosure. Figure 3As shown, the signal sampling circuit includes: a Rogowski coil, a notch filter circuit, a signal amplification circuit, a modulation and demodulation circuit and a low-pass filter circuit; The notch filter circuit is connected to the Rogowski coil and the signal amplification circuit respectively; The modulation and demodulation circuit is connected to the signal amplification circuit and the low-pass filtering circuit respectively.

[0078] In the signal sampling circuit, the Rogowski coil is used as a current sensor to obtain the current signal in the cable. It converts the current signal into a proportional voltage signal to provide input for subsequent signal processing. Since the current signal in the cable may contain various frequency components and noise, the wide bandwidth characteristics of the Rogowski coil can ensure that these signals are captured as completely as possible, while its linearity ensures the accuracy of the measurement.

[0079] The main function of the notch filter circuit is to suppress interference signals of specific frequencies. Interference signals will affect the accuracy of subsequent signal processing, so they need to be removed by the notch filter circuit.

[0080] The signal amplifier circuit is used to enhance the voltage signal output by the Rogowski coil. The amplifier circuit can be composed of an operational amplifier. The basic principle is to use the gain characteristics of the amplifier. According to the virtual short and virtual open characteristics of the amplifier, the output voltage amplification factor can be obtained.

[0081] In cable signal sampling, modulation can move the signal's spectrum to a high-frequency area with less interference, thereby improving the signal's transmission quality.

[0082] The low-pass filter circuit is used to filter out the high-frequency components in the signal and only allow the low-frequency signal to pass. In the signal sampling circuit, the cutoff frequency is determined according to the spectral characteristics of the signal and the requirements of subsequent processing. For example, if the useful components of the signal are mainly concentrated in the low-frequency band, and there is more noise in the high-frequency band, then the cutoff frequency can be set to be slightly higher than the highest useful frequency of the signal, which can effectively filter out the high-frequency noise while retaining the main components of the signal.

[0083] After the circuit uses a high-voltage Rogowski coil to obtain the current signal in the conductor, it is first converted into a voltage signal, and then passes through a trap circuit and a filter circuit to remove the industrial frequency current signal and high-frequency interference signal in the current signal. Then, the signal is amplified using an amplifier circuit. The amplified signal is processed using a modem and a low-pass filter to extract the current response with the same frequency as the generated signal. At this time, the current response includes the capacitive and resistive currents of the three-phase line to the ground.

[0084] This embodiment collects current signals through Rogowski coils, removes specific frequency interference through notch filter circuits, enhances signal amplitude through signal amplifier circuits, performs spectrum shifting and restoration on signals through modulation and demodulation circuits, and filters out high-frequency noise through low-pass filter circuits, thereby providing high-quality sampling signals for subsequent signal analysis and processing.

[0085] Figure 4 A schematic diagram of a power supply system insulation fault monitoring device provided by an embodiment of the present disclosure is shown in FIG. Figure 4 As shown, the insulation fault monitoring device of the power supply system includes: a power management module, an STM32 MCU, a minimum system, a connection terminal, an injection power generation module, a display circuit, a voltage acquisition module, a current acquisition module, a voltage signal processing module, a current signal processing module, a power monitoring module and an alarm circuit module; The STM32MCU is respectively connected with the power management module, the injection power generation module, the minimum system, the display circuit, the voltage signal processing module, the current signal processing module, the power monitoring module and the alarm circuit module; The connection terminal is connected to the injection power generation module; The voltage acquisition module is connected to the voltage signal processing module; The current acquisition module is connected to the current signal processing module.

[0086] In this embodiment, the power management module is the energy supply core of the insulation fault monitoring device of the entire power supply system, and is responsible for providing stable and appropriate power supply to each module in the device.

[0087] The STM32 MCU is the core of the entire monitoring device. It is responsible for controlling the coordination of various modules, processing and analyzing the collected data, and making corresponding decisions based on the results.

[0088] The minimum system is the basic circuit to ensure the normal operation of the STM32MCU, including the crystal oscillator circuit, reset circuit and power supply circuit. The crystal oscillator circuit provides a stable clock signal for the MCU, enabling it to work at the set frequency. The reset circuit is used to reset the MCU to the initial state when the device is powered on or an abnormal situation occurs, ensuring the stability and reliability of the system.

[0089] The connection terminal is the interface component for connecting the insulation fault monitoring device of the power supply system with external equipment or cables. It provides various types of interfaces for connecting cables, injection power, host computers, etc.

[0090] The main function of the injection power generation module is to generate signals for detecting the insulation performance of cables. This module can realize signal generation based on a variety of principles, such as direct digital frequency synthesis technology or using the digital-to-analog converter inside the MCU combined with the timer function to generate signals. The signal source using direct digital frequency synthesis technology can generate high-precision and high-stability multi-frequency signals.

[0091] The display circuit is used to intuitively show the results of cable insulation monitoring and the operating status of the device to the user.

[0092] The voltage acquisition module is mainly composed of voltage sensors, which can be electromagnetic voltage transformers and capacitive voltage transformers. Based on the principle of electromagnetic induction, the electromagnetic voltage transformer converts the high voltage in the cable into a low voltage signal in proportion for subsequent acquisition and processing.

[0093] The current acquisition module can use Rogowski coil or current transformer as a sensor. The principle of Rogowski coil is based on the law of electromagnetic induction. It obtains current signals by measuring the changes in magnetic field. It has the advantages of wide bandwidth, high precision, and electrical isolation.

[0094] In the voltage signal processing module, the collected voltage signal will first be digitally filtered to remove noise interference.

[0095] The function of the current signal processing module is similar to that of the voltage signal processing module. It filters and extracts features from the collected current signal.

[0096] The power monitoring module is mainly responsible for monitoring the power status of the insulation fault monitoring device of the entire power supply system. It monitors the power supply voltage, current, power and other parameters, as well as the stability of the power supply and whether there are abnormal conditions such as overvoltage, overcurrent, undervoltage, etc. By connecting the voltage sensor and current sensor to the power line, the voltage and current signals of the power supply can be collected in real time, and then the relevant parameters of the power supply can be obtained through signal processing and analysis.

[0097] The alarm circuit module is triggered based on the results of cable insulation monitoring and the operating status of the device. When the insulation resistance value of the cable is lower than the set threshold, or the capacitance value exceeds the normal range, or the power monitoring module detects an abnormal situation, the alarm circuit will be triggered. The threshold for alarm triggering can be set in the STM32 MCU through software programming, and can be flexibly adjusted according to different cable types and monitoring requirements.

[0098] This embodiment is based on STM32 MCU, which can be an STM32F407 processor. The type of the output signal of the control signal generating device is controlled, and the DSP module in the chip is used to perform Fourier transform on the acquired time-varying signal to obtain the spectrum of the signal, and the current response signal obtained in the filter circuit is combined with Kalman filtering to obtain accurate capacitive and resistive currents. By changing the signal frequency, different capacitive and resistive currents are obtained, and a multivariate equation group is established. The resistance and capacitance values ​​of each phase line to the ground are obtained by solving the equations, and accurate insulation data is obtained.

[0099] Corresponding to the power supply system insulation fault monitoring method of the above embodiment, Figure 5 This is a structural block diagram of a power supply system insulation fault monitoring device provided by an embodiment of the present disclosure. For ease of description, only the parts related to the embodiment of the present disclosure are shown. Figure 5 The power supply system insulation fault monitoring device 20 includes: a signal acquisition module 21, a signal compensation module 22 and a signal monitoring module 23.

[0100] The signal acquisition module 21 is used to perform insulation monitoring on the cable based on the multi-frequency signal to obtain a first cable signal; A signal compensation module 22, configured to compensate the first cable signal based on the compensation information to obtain a second cable signal; The signal monitoring module 23 is used to obtain a cable insulation monitoring result based on the second cable signal.

[0101] In one embodiment of the present disclosure, the signal compensation module 22 is specifically configured to obtain a first length compensation value and a second length compensation value based on the length of the cable; Obtaining a first temperature compensation value based on the ambient temperature of the cable; Obtaining a first humidity compensation value based on the humidity of the environment in which the cable is located; The first cable signal is compensated based on the first length compensation value, the first temperature compensation value and the first humidity compensation value to obtain a second cable signal.

[0102] In one embodiment of the present disclosure, the signal compensation module 22 is further configured to obtain a first length compensation value based on the length of the cable and a first formula; A second length compensation value is obtained based on the length of the cable and a second formula.

[0103] In one embodiment of the present disclosure, the signal compensation module 22 is further configured to use a first temperature step as a first temperature compensation value in response to an absolute value of a difference between an ambient temperature of the cable and a standard ambient temperature being greater than or equal to a first temperature threshold; In response to the absolute value of the difference between the ambient temperature of the cable and the standard ambient temperature being greater than or equal to a second temperature threshold, using the second temperature step as a first temperature compensation value; The first temperature threshold is lower than the second temperature threshold.

[0104] In one embodiment of the present disclosure, the signal compensation module 22 is further configured to use a first humidity step as a first humidity compensation value in response to an absolute value of a difference between an ambient humidity of the cable and a standard ambient humidity being greater than or equal to a first humidity threshold; In response to the absolute value of the difference between the ambient humidity of the cable and the standard ambient humidity being greater than or equal to a second humidity threshold, taking the second humidity step as a first humidity compensation value; The first humidity threshold is less than the second humidity threshold.

[0105] In one embodiment of the present disclosure, the signal monitoring module 23 is specifically used to extract features from the second cable signal to obtain a plurality of first features; A cable insulation monitoring result is obtained based on the plurality of first features.

[0106] In an embodiment of the present disclosure, the signal monitoring module 23 is further configured to match the plurality of first features with standard features in a standard feature library to obtain a cable insulation monitoring result.

[0107] See also Figure 6 , Figure 6 A schematic block diagram of an electronic device provided by an embodiment of the present disclosure. Figure 6 The electronic device 300 in the embodiment shown may include: one or more processors 301, one or more input devices 302, one or more output devices 303 and one or more memories 304. The processors 301, input devices 302, output devices 303 and memories 304 communicate with each other via a communication bus 305. The memory 304 is used to store computer programs, which include program instructions. The processor 301 is used to execute the program instructions stored in the memory 304. The processor 301 is configured to call the program instructions to execute the functions of each module / unit in the above-mentioned device embodiments, such as Figure 5 The functions of modules 21 to 23 are shown.

[0108] It should be understood that in the embodiment of the present disclosure, the processor 301 may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0109] The input device 302 may include a touch panel, a fingerprint collection sensor (for collecting the user's fingerprint information and fingerprint direction information), a microphone, etc., and the output device 303 may include a display (LCD, etc.), a speaker, etc.

[0110] The memory 304 may include a read-only memory and a random access memory, and provide instructions and data to the processor 301. A portion of the memory 304 may also include a non-volatile random access memory. For example, the memory 304 may also store information about the device type.

[0111] In a specific implementation, the processor 301, input device 302, and output device 303 described in the embodiments of the present disclosure can execute the implementation methods described in the first and second embodiments of the power supply system insulation fault monitoring method provided in the embodiments of the present disclosure, and can also execute the implementation methods of the electronic device described in the embodiments of the present disclosure, which will not be repeated here.

[0112] In another embodiment of the present disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, wherein the computer program includes program instructions, and when the program instructions are executed by the processor, all or part of the processes in the above-mentioned embodiment method are implemented, and the computer program can also be completed by instructing the relevant hardware through the computer program. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by the processor, the steps of each of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0113] The computer-readable storage medium may be an internal storage unit of the electronic device of any of the aforementioned embodiments, such as a hard disk or memory of the electronic device. The computer-readable storage medium may also be an external storage device of the electronic device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), etc. equipped on the electronic device. Furthermore, the computer-readable storage medium may also include both an internal storage unit of the electronic device and an external storage device. The computer-readable storage medium is used to store computer programs and other programs and data required by the electronic device. The computer-readable storage medium may also be used to temporarily store data that has been output or is to be output.

[0114] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this disclosure.

[0115] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the electronic devices and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here.

[0116] In the several embodiments provided in the present application, it should be understood that the disclosed electronic devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces or units, or it can be an electrical, mechanical or other form of connection.

[0117] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present disclosure.

[0118] In addition, each functional unit in each embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0119] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present disclosure, and these modifications or replacements should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for monitoring insulation faults in a power supply system, characterized in that: include: Performing insulation monitoring on the cable based on the multi-frequency signal to obtain a first cable signal; Compensating the first cable signal based on the compensation information to obtain a second cable signal; A cable insulation monitoring result is obtained based on the second cable signal.

2. The method for monitoring insulation faults in a power supply system according to claim 1, characterized in that: The compensating the first cable signal based on the compensation information to obtain the second cable signal includes: Obtaining a first length compensation value and a second length compensation value based on the length of the cable; Obtaining a first temperature compensation value based on the ambient temperature of the cable; Obtaining a first humidity compensation value based on the humidity of the environment in which the cable is located; The first cable signal is compensated based on the first length compensation value, the first temperature compensation value, and the first humidity compensation to obtain the second cable signal.

3. The method for monitoring insulation faults in a power supply system according to claim 2, characterized in that: The obtaining of a first length compensation value and a second length compensation value based on the length of the cable comprises: Obtaining the first length compensation value based on the length of the cable and a first formula; The second length compensation value is obtained based on the length of the cable and a second formula.

4. The method for monitoring insulation faults in a power supply system according to claim 2, wherein: The obtaining of a first temperature compensation value based on the ambient temperature of the cable comprises: In response to the absolute value of the difference between the ambient temperature of the cable and the standard ambient temperature being greater than or equal to a first temperature threshold, taking a first temperature step as a first temperature compensation value; In response to the absolute value of the difference between the ambient temperature of the cable and the standard ambient temperature being greater than or equal to a second temperature threshold, taking the second temperature step as a first temperature compensation value; The first temperature threshold is lower than the second temperature threshold.

5. The method for monitoring insulation faults in a power supply system according to claim 2, characterized in that: The obtaining of a first humidity compensation value based on the humidity of the environment in which the cable is located comprises: In response to the absolute value of the difference between the ambient humidity of the cable and the standard ambient humidity being greater than or equal to a first humidity threshold, taking a first humidity step as a first humidity compensation value; In response to the absolute value of the difference between the ambient humidity of the cable and the standard ambient humidity being greater than or equal to a second humidity threshold, taking the second humidity step as a first humidity compensation value; The first humidity threshold is lower than the second humidity threshold.

6. The method for monitoring insulation faults in a power supply system according to claim 1, characterized in that: The obtaining of the cable insulation monitoring result based on the second cable signal includes: Performing feature extraction on the second cable signal to obtain a plurality of first features; The cable insulation monitoring result is obtained based on the multiple first features.

7. The method for monitoring insulation faults in a power supply system according to claim 6, characterized in that: The obtaining the cable insulation monitoring result based on the multiple first features includes: The cable insulation monitoring result is obtained by matching the multiple first features with standard features in a standard feature library.

8. A power supply system insulation fault monitoring device, characterized in that: include: A signal acquisition module, used to perform insulation monitoring on the cable based on the multi-frequency signal to obtain a first cable signal; A signal compensation module, configured to compensate the first cable signal based on compensation information to obtain a second cable signal; A signal monitoring module is used to obtain a cable insulation monitoring result based on the second cable signal.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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