An insulation monitoring circuit and an insulation monitoring method

Abstract

The present application discloses an insulation monitoring circuit and an insulation monitoring method. The insulation monitoring circuit includes: a control module, a voltage dividing circuit, a signal acquisition circuit, and a calibration circuit. The first input end of the voltage dividing circuit is used to access a DC signal, the second input end of the voltage dividing circuit is used to access an AC excitation signal, the voltage dividing circuit is provided with a voltage dividing access port, and the voltage dividing access port is used to be connected to a device under test; the input end of the signal acquisition circuit is connected to the voltage dividing end of the voltage dividing circuit, and the acquisition end of the voltage acquisition module is connected to the input end of the control module; the calibration circuit includes a calibration resistor, and the calibration circuit is used to control whether the calibration resistor is connected to the voltage dividing access port according to the first level received by its control end; the control module is used to obtain the insulation impedance of the device under test through a preset calculation model according to the sampling signal obtained from the acquisition end of the voltage sampling circuit, or update the parameters of the calculation model. The present application can improve the accuracy of insulation impedance monitoring.

Description

Technical Field

[0001] This application relates to the technical field of monitoring circuits, and particularly to an insulation monitoring circuit and an insulation monitoring method. Background Art

[0002] In the fields of power systems and industrial automation, the insulation performance of electrical equipment is one of the key factors to ensure the safe and stable operation of the system. The monitoring of insulation resistance is of great significance for preventing electrical faults, reducing equipment damage, and ensuring personnel safety. Traditional insulation monitoring technologies mainly rely on regular power outage detection, which is not only inefficient but also unable to reflect the insulation status of equipment in real time. In addition, with the aging of equipment, changes in the operating environment, and the increase in power load, the insulation performance will gradually decline, and it is difficult for traditional methods to detect these potential problems in a timely manner. Summary of the Invention

[0003] This application aims to at least solve one of the technical problems existing in the prior art. For this purpose, this application proposes an insulation monitoring circuit and an insulation monitoring method, which can improve the accuracy of insulation impedance monitoring.

[0004] In a first aspect, this application provides an insulation monitoring circuit, including:

[0005] A control module;

[0006] A voltage division circuit, the first input terminal of the voltage division circuit is used to access a DC signal, the second input terminal of the voltage division circuit is used to access an AC excitation signal, the voltage division circuit is provided with a voltage division access port, and the voltage division access port is used to connect with the device under test;

[0007] A signal acquisition circuit, the input terminal of the signal acquisition circuit is connected to the voltage division terminal of the voltage division circuit, and the acquisition terminal of the voltage acquisition module is connected to the input terminal of the control module;

[0008] A calibration circuit, the control terminal of the calibration circuit is connected to the output terminal of the control module, the calibration circuit includes a calibration resistor, and the calibration circuit is used to control the calibration resistor to be connected to or disconnected from the voltage division access port according to the first level received by its control terminal;

[0009] Wherein, the control module is used for:

[0010] According to the sampling signal obtained from the acquisition terminal of the voltage sampling circuit, the insulation impedance of the device under test is obtained through a preset calculation model, or the parameters of the calculation model are updated.

[0011] The insulation monitoring circuit according to the embodiments of the first aspect of the present application has at least the following beneficial effects: When the insulation monitoring circuit provided by the present application is used to monitor the insulation of the device under test, a DC signal is sent to the first input terminal of the voltage dividing circuit, and an AC excitation signal is sent to the second input terminal. The DC signal and the AC excitation signal enter the signal acquisition circuit after passing through the voltage dividing circuit. Subsequently, the control module is used to obtain the sampling signal from the acquisition terminal of the signal acquisition circuit, and combined with the sampling signal through a preset calculation model, so as to calculate the insulation impedance of the device under test connected to the voltage dividing access port, realizing real-time and accurate monitoring of the insulation state of the electrical equipment. In addition, when it is necessary to correct the parameters of the calculation model, the control module outputs a first level to the control terminal of the correction circuit, so that the correction circuit controls the correction circuit to be connected to the voltage dividing access port. Subsequently, the control module obtains the sampling signal from the acquisition terminal of the signal acquisition circuit again, and corrects the parameters of the calculation model according to the sampling signal to improve the accuracy of the insulation impedance monitoring of the insulation monitoring circuit.

[0012] According to some embodiments of the first aspect of the present application, the voltage dividing circuit includes a second resistor, a third resistor, and a fourth resistor. One end of the second resistor is used to connect to the DC signal, and the other end is connected to the input terminal of the voltage dividing access port. One end of the third resistor is used to connect to the AC excitation signal, and the other end is connected to the input terminal of the voltage dividing access port. One end of the fourth resistor is connected to the output terminal of the voltage dividing access port, and the other end is grounded. The input terminal of the voltage sampling circuit is connected between the fourth resistor and the voltage dividing access port.

[0013] According to some embodiments of the first aspect of the present application, the signal acquisition circuit includes an operational amplifier, a fifth resistor, a sixth resistor, and a first capacitor. The non-inverting input terminal of the operational amplifier is connected between the fourth resistor and the voltage dividing access port through the fifth resistor. The output terminal of the operational amplifier is connected to the inverting input terminal. The output terminal of the operational amplifier is connected to one end of the first capacitor through the sixth resistor. The other end of the first capacitor is grounded. The input terminal of the control module is connected between the sixth resistor and the first capacitor.

[0014] According to some embodiments of the first aspect of the present application, the correction circuit further includes a switching tube and a five-pin relay. The control terminal of the switching tube is connected to the output terminal of the control module. The output terminal of the switching tube is grounded. The input terminal of the switching tube is connected to the negative control terminal of the five-pin relay. The positive control terminal of the five-pin relay is used to connect to the voltage source. The common terminal of the five-pin relay is connected to the input terminal of the voltage dividing access port. The normally closed terminal of the five-pin relay is left open. The normally open terminal of the five-pin relay is connected to the output terminal of the voltage dividing access port through the correction resistor.

[0015] According to some embodiments of the first aspect of the present application, the calibration circuit further includes a diode, a second capacitor, and a seventh resistor. The anode terminal of the diode is connected to the positive control terminal of the five-pin relay. The cathode terminal of the diode is respectively connected to a voltage source and one end of the second capacitor. The other end of the second capacitor is grounded. The control terminal of the switching tube is connected to the output terminal of the control module through the seventh resistor.

[0016] In a second aspect, the present application also provides an insulation monitoring method, which is applied to the control module of the insulation monitoring circuit according to any one of the embodiments of the first aspect. The insulation monitoring method includes:

[0017] Obtaining a sampling signal from the acquisition terminal of the signal acquisition circuit;

[0018] Performing Fourier transform processing on the sampling signal to obtain a fundamental wave component;

[0019] According to the fundamental wave component, the resistance values of the resistors in the voltage division circuit, and a preset calculation model, obtaining the insulation impedance value of the device under test;

[0020] When the insulation impedance value is less than a preset impedance threshold, generating a first abnormal signal; wherein, the first abnormal signal is used to indicate that the insulation impedance of the device under test is abnormal.

[0021] According to the insulation monitoring method of the embodiments of the second aspect of the present application, it has at least the following beneficial effects: When performing insulation monitoring on the device under test, a DC signal is respectively sent to the first input terminal of the voltage division circuit, and an AC excitation signal is sent to the second input terminal. The DC signal and the AC excitation signal enter the signal acquisition circuit after passing through the voltage division circuit. Subsequently, the control module is used to obtain the sampling signal from the acquisition terminal of the signal acquisition circuit, and perform Fourier transform processing on the sampling signal to obtain the fundamental wave component. The fundamental wave component is the sine wave component with the lowest frequency in the signal, which contains the main energy and information of the signal. Then, according to the fundamental wave component, the resistance values of the resistors in the voltage division circuit, and a preset calculation model, the insulation impedance value of the device under test is obtained. Through the above method, the real-time and accurate monitoring of the insulation state of electrical equipment can be realized. In addition, through the real-time monitoring of the insulation impedance value and comparison with the preset impedance threshold, the situation of abnormal insulation impedance can be discovered in time. When the insulation impedance value is less than the preset impedance threshold, the system will generate a first abnormal signal, which is used to indicate that the insulation impedance of the device under test is abnormal, which can help maintenance personnel discover and handle potential safety hazards in time, prevent equipment failures or accidents, improve the reliability and stability of the equipment, and extend the service life of the equipment.

[0022] According to some embodiments of the second aspect of the present application, after the step of obtaining the sampling signal from the acquisition terminal of the signal acquisition circuit, it further includes:

[0023] Perform Fourier transform processing on the sampling signal to obtain a DC component;

[0024] According to the DC component, the resistance values of the resistors in the voltage division circuit, and the calculation model, obtain the equivalent resistance value of the device under test;

[0025] When the equivalent resistance value is less than or equal to a preset first resistance threshold, determine that the grounding type of the device under test is metallic grounding;

[0026] When the equivalent resistance value is greater than the first resistance threshold and less than or equal to a preset second resistance threshold, determine that the grounding type of the device under test is high-resistance grounding.

[0027] According to some embodiments of the second aspect of the present application, after the step of obtaining the equivalent resistance value of the device under test according to the DC component, the resistance values of the resistors in the voltage division circuit, and the calculation model, further include:

[0028] According to the insulation impedance value, the equivalent resistance value, and the calculation model, obtain the target capacitive reactance value of the device under test;

[0029] Obtain the AC frequency of the AC excitation signal at the second input terminal of the voltage division circuit;

[0030] According to the target capacitive reactance value and the AC frequency, obtain the distributed capacitance value of the device under test;

[0031] When the distributed capacitance value is greater than or equal to a preset capacitance threshold, generate a second abnormal signal; wherein, the second abnormal signal is used to characterize the abnormal line length of the device under test.

[0032] According to some embodiments of the second aspect of the present application, further include:

[0033] Send a first level to the control terminal of the calibration circuit to control the calibration resistor in the calibration circuit to be connected to the voltage division access port of the voltage division circuit;

[0034] Obtain the sampling signal from the acquisition terminal of the signal acquisition circuit;

[0035] Obtain a calibration fundamental wave component and a calibration DC component according to the sampling signal;

[0036] According to the calibration fundamental wave component, the calibration DC component, the resistance value of the calibration resistor, and the resistance values of the resistors in the voltage division circuit, update the original parameters of the calculation model.

[0037] According to some embodiments of the second aspect of the present application, updating the original parameters of the calculation model according to the corrected fundamental wave component, the corrected DC component, the resistance value of the corrected resistor, and the resistance values of the resistors in the voltage dividing circuit includes:

[0038] Obtaining target parameters according to the corrected fundamental wave component, the corrected DC component, the resistance value of the corrected resistor, and the resistance values of the resistors in the voltage dividing circuit;

[0039] When the difference between the target parameters and the original parameters of the calculation model is less than or equal to a preset correction threshold, do not process the original parameters of the calculation model;

[0040] When the difference between the target parameters and the original parameters of the calculation model is greater than the correction threshold, replace the original parameters with the target parameters.

[0041] Additional aspects and advantages of the present application will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present application. Description of the Drawings

[0042] Additional aspects and advantages of the present application will become apparent and be easily understood in conjunction with the following description of the embodiments with reference to the accompanying drawings, where:

[0043] Figure 1 is a circuit block diagram of the insulation monitoring circuit provided in the first aspect of the present application;

[0044] Figure 2 is a circuit diagram of the insulation monitoring circuit provided in the first aspect of the present application;

[0045] Figure 3 is a circuit diagram of the correction circuit in the insulation monitoring circuit provided in the first aspect of the present application;

[0046] Figure 4 is a circuit diagram of the device under test provided in one embodiment of the first aspect of the present application;

[0047] Figure 5 is a circuit diagram of the function signal generator chip provided in one embodiment of the first aspect of the present application;

[0048] Figure 6 is a flowchart of the insulation monitoring method provided in one embodiment of the second aspect of the present application;

[0049] Figure 7 For the present application Figure 6 is the flowchart after step S110;

[0050] Figure 8 For the present application Figure 7Flow chart after step S220 in [the present application]

[0051] Figure 9 Flow chart of the insulation monitoring method provided by another embodiment of the second aspect of the present application

[0052] Figure 10 For the present application Figure 9 Flow chart of step S440 in [the present application] Detailed implementation manners

[0053] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application.

[0054] In the description of the present application, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present application.

[0055] In the description of the present application, if the first and second are described only for the purpose of distinguishing technical features, they should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0056] In the description of the present application, unless otherwise clearly defined, words such as "set", "installed", "connected", etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above words in the present application in combination with the specific content of the technical solution.

[0057] In the fields of power systems and industrial automation, the insulation performance of electrical equipment is one of the key factors to ensure the safe and stable operation of the system. Monitoring the insulation resistance is of great significance for preventing electrical faults, reducing equipment damage, and ensuring personnel safety. Traditional insulation monitoring technologies mainly rely on regular power outage detection. This method is not only inefficient but also unable to reflect the insulation state of the equipment in real time. In addition, with the aging of the equipment, the change of the operating environment, and the increase of the power load, the insulation performance will gradually decline, and it is difficult for traditional methods to detect these potential problems in a timely manner.

[0058] Based on this, the present application provides an insulation monitoring circuit and an insulation monitoring method to solve the above technical problems. The technical solutions provided by the present application will be described in detail one by one below.

[0059] In a first aspect, referring to Figure 1 , the present application provides an insulation monitoring circuit, including: a control module, a voltage dividing circuit, a signal acquisition circuit, and a calibration circuit. The first input terminal of the voltage dividing circuit is used to connect to a DC signal, the second input terminal of the voltage dividing circuit is used to connect to an AC excitation signal, the voltage dividing circuit is provided with a voltage dividing access port, and the voltage dividing access port is used to connect to a device under test; the input terminal of the signal acquisition circuit is connected to the voltage dividing terminal of the voltage dividing circuit, and the acquisition terminal of the voltage acquisition module is connected to the input terminal of the control module; the control terminal of the calibration circuit is connected to the output terminal of the control module, the calibration circuit includes a calibration resistor R1, and the calibration circuit is used to control the calibration resistor R1 to be connected to or disconnected from the voltage dividing access port according to the first level received by its control terminal; the control module is used to: obtain the insulation impedance of the device under test through a preset calculation model according to the sampling signal obtained from the acquisition terminal of the voltage sampling circuit, or update the parameters of the calculation model. The specific processing flow of the control module is as follows: obtain a sampling signal from the acquisition terminal of the signal acquisition circuit; perform Fourier transform processing on the sampling signal to obtain a fundamental wave component; obtain the insulation impedance value of the device under test according to the fundamental wave component, the resistance values of the resistors in the voltage dividing circuit, and the preset calculation model; when the insulation impedance value is less than a preset impedance threshold, generate a first abnormal signal; wherein, the first abnormal signal is used to indicate that the insulation impedance of the device under test is abnormal.

[0060] When the insulation monitoring circuit provided by the present application is used to monitor the insulation of the device under test, a DC signal is sent to the first input terminal of the voltage dividing circuit, and an AC excitation signal is sent to the second input terminal. The DC signal and the AC excitation signal enter the signal acquisition circuit after passing through the voltage dividing circuit. Subsequently, the control module is used to obtain a sampling signal from the acquisition terminal of the signal acquisition circuit, and combine it with the preset calculation model, so as to calculate the insulation impedance of the device under test connected to the voltage dividing access port, realizing real-time and accurate monitoring of the insulation state of the electrical equipment. In addition, when it is necessary to correct the parameters of the calculation model, the control module outputs a first level to the control terminal of the calibration circuit, so that the calibration circuit controls the calibration circuit to be connected to the voltage dividing access port. Subsequently, the control module obtains a sampling signal from the acquisition terminal of the signal acquisition circuit again, and corrects the parameters of the calculation model according to the sampling signal to improve the accuracy of the insulation impedance monitoring of the insulation monitoring circuit.

[0061] In the second input terminal of the voltage dividing circuit, an AC excitation signal can be generated by a function signal generator chip. Refer to Figure 5 , in the present application, a 50 Hz sine signal is output from the position of pin 2 of the function signal generator chip XR2206D to the second input terminal of the voltage dividing circuit. The above-mentioned generation method of the AC excitation signal is only an example of one implementation manner of the present application, and no specific limitation is made thereto.

[0062] Referring toFigure 4 , Figure 4 Schematic diagram of an isolation transformer for one embodiment of the present application. L1, L2, and L3 are the A-phase, B-phase, and C-phase of the circuit respectively, and N represents the neutral line, which can be equivalently a capacitor and a resistor in parallel to the ground, i.e., the part shown by the dashed line in the figure. The specific form of the device under test is not limited in the present application.

[0063] Referring to Figure 2 , it can be understood that the voltage dividing circuit includes a second resistor R2, a third resistor R3, and a fourth resistor R4. One end of the second resistor R2 is used to connect to a DC signal, and the other end is connected to the input end of the voltage dividing access port. One end of the third resistor R3 is used to connect to an AC excitation signal, and the other end is connected to the input end of the voltage dividing access port. One end of the fourth resistor R4 is connected to the output end of the voltage dividing access port, and the other end is grounded. The input end of the voltage sampling circuit is connected between the fourth resistor R4 and the voltage dividing access port. Thus, when monitoring the insulation impedance, the corresponding insulation impedance calculation formula in the calculation model is:

[0064] Z = k1 / s1 - R4 - R3;

[0065] where Z is the insulation impedance, k1 is the impedance compensation coefficient, and s1 is the fundamental wave component.

[0066] In addition, in the insulation monitoring circuit provided in the present application, in addition to monitoring the insulation impedance, the equivalent resistance value of the device under test can also be monitored. The specific monitoring method is: performing Fourier transform processing on the sampling signal to obtain the DC component; obtaining the equivalent resistance value of the device under test according to the DC component, the resistance values of the resistors in the voltage dividing circuit, and the calculation model. Thus, when monitoring the equivalent resistance, the corresponding equivalent resistance calculation formula in the calculation model is:

[0067] R 等 = k2 / d1 - R4 - R2;

[0068] where R 等 is the equivalent resistance, k2 is the resistance compensation coefficient, and d1 is the DC component.

[0069] Continuing to refer to Figure 2, It can be understood that the signal acquisition circuit includes an operational amplifier U1, a fifth resistor R5, a sixth resistor R6, and a first capacitor C1. The non-inverting input terminal of the operational amplifier U1 is connected between the fourth resistor R4 and the voltage division access port through the fifth resistor R5. The output terminal of the operational amplifier U1 is connected to the inverting input terminal. The output terminal of the operational amplifier U1 is connected to one end of the first capacitor C1 through the sixth resistor R6, and the other end of the first capacitor C1 is grounded. The input terminal of the control module is connected between the sixth resistor R6 and the first capacitor C1. By setting the operational amplifier U1 and connecting the output terminal of the operational amplifier U1 to the inverting input terminal, a negative feedback configuration enables the circuit to have stable gain and excellent linearity, capable of amplifying the weak signal output from the voltage division circuit for subsequent processing or measurement. Additionally, the RC filter network composed of the sixth resistor R6 and the first capacitor C1 is located at the output terminal of the operational amplifier U1. This network can further filter out high-frequency noise and ripples in the output signal, improve the signal-to-noise ratio and stability of the signal, enhance the anti-interference ability of the entire signal acquisition circuit, and enable it to maintain good performance in a complex electromagnetic environment.

[0070] Referring to Figure 3 , It can be understood that the calibration circuit further includes a switching transistor Q1 and a five-pin relay K1. The control terminal of the switching transistor Q1 is connected to the output terminal of the control module. The output terminal of the switching transistor Q1 is grounded. The input terminal of the switching transistor Q1 is connected to the negative control terminal of the five-pin relay K1. The positive control terminal of the five-pin relay K1 is used to connect to a voltage source. The common terminal of the five-pin relay K1 is connected to the input terminal of the voltage division access port. The normally closed terminal of the five-pin relay K1 is left unconnected. The normally open terminal of the five-pin relay K1 is connected to the output terminal of the voltage division access port through a calibration resistor R1. In this circuit, when normally conducting insulation monitoring on the device under test, the first level is low level, and the switching transistor Q1 is not conducting. Therefore, the positive control terminal and the negative control terminal of the five-pin relay K1 are not conducting, and the internal relay does not have magnetism. The common terminal and the normally closed terminal of the five-pin relay K1 are connected, that is, the calibration resistor R1 is not connected to the voltage division access port. Additionally, when it is necessary to calibrate the parameters of the calculation model, the first level output by the control module to the control terminal of the calibration circuit is converted to high level to make the switching transistor Q1 conduct. Therefore, the positive control terminal and the negative control terminal of the five-pin relay K1 are connected, and the internal relay has magnetism. The common terminal and the normally open terminal of the five-pin relay K1 are connected, thereby controlling the calibration resistor R1 to be connected to the voltage division access port.

[0071] During calibration, the control module continuously obtains sampling signals from the acquisition end of the voltage acquisition module, then obtains the calibrated fundamental component and the calibrated DC component according to the sampling signals, and then updates the original parameters of the calculation model according to the calibrated fundamental component, the calibrated DC component, the resistance value of the calibration resistor R1, and the resistance values of the resistors in the voltage division circuit. Specifically, the original parameters k1 and k2 of the calculation model are updated as follows:

[0072] k1' = s2 * (R3 + R4 + R1);

[0073] k2' = d2 * (R2 + R4 + R1);

[0074] Where k1' and k2' are the updated impedance compensation coefficients respectively, s2 is the calibrated fundamental component, and d2 is the calibrated DC component.

[0075] Continuing to refer to Figure 3 , it can be understood that the calibration circuit further includes a diode D1, a second capacitor C2, and a seventh resistor R7. The anode terminal of the diode D1 is connected to the positive control terminal of the five-pin relay K1. The cathode terminal of the diode D1 is respectively connected to the voltage source and one end of the second capacitor C2. The other end of the second capacitor C2 is grounded. The control terminal of the switching transistor Q1 is connected to the output terminal of the control module through the seventh resistor R7. Among them, the diode D1 mainly plays a protective role. When the voltage source is suddenly disconnected or the polarity is reversed, the diode D1 can conduct and absorb the reverse voltage, thereby protecting the five-pin relay K1, the switching transistor Q1, and the subsequent circuit from being damaged. The second capacitor C2 mainly plays a filtering and voltage stabilizing role. By filtering out the high-frequency noise and ripple in the voltage source, it provides a more stable and smooth voltage input for the five-pin relay K1 and the subsequent circuit. The seventh resistor R7 is connected between the control terminal of the switching transistor Q1 and the output terminal of the control module, mainly playing a current limiting and voltage dividing role, restricting the magnitude of the current flowing from the control module to the control terminal of the switching transistor Q1, and preventing the switching transistor Q1 or other components from being damaged due to excessive current.

[0076] It should be noted that the switching transistor Q1 here can be an NPN-type triode. The input terminal of the switching transistor Q1 corresponds to the collector of the NPN-type triode, the control terminal of the switching transistor Q1 corresponds to the base of the NPN-type triode, and the output terminal of the switching transistor Q1 corresponds to the emitter of the NPN-type triode. The specific form of the switching transistor Q1 is not specifically limited in this application.

[0077] In a second aspect, referring to Figure 6 , the present application also provides an insulation monitoring method, which is applied to the control module in the insulation monitoring circuit in any one of the embodiments in the first aspect. The insulation monitoring method may include but is not limited to the following steps:

[0078] Step S110: Obtain a sampling signal from the acquisition end of the signal acquisition circuit;

[0079] Step S120: Perform Fourier transform processing on the sampling signal to obtain a fundamental wave component;

[0080] Step S130: According to the fundamental wave component, the resistance values of each resistor in the voltage division circuit, and a preset calculation model, obtain the insulation impedance value of the device under test;

[0081] Step S140: When the insulation impedance value is less than a preset impedance threshold, generate a first abnormal signal; wherein, the first abnormal signal is used to indicate that the insulation impedance of the device under test is abnormal.

[0082] In steps S110 to S140, when monitoring the insulation of the device under test, a DC signal is respectively sent to the first input end of the voltage division circuit, and an AC excitation signal is sent to the second input end. The DC signal and the AC excitation signal enter the signal acquisition circuit after passing through the voltage division circuit. Subsequently, the control module is used to obtain a sampling signal from the acquisition end of the signal acquisition circuit, and perform Fourier transform processing on the sampling signal to obtain a fundamental wave component. The fundamental wave component is the sine wave component with the lowest frequency in the signal, which contains the main energy and information of the signal. Then, according to the fundamental wave component, the resistance values of each resistor in the voltage division circuit, and a preset calculation model, the insulation impedance value of the device under test is obtained. Through the above method, the real-time and accurate monitoring of the insulation state of electrical equipment can be realized. In addition, through the real-time monitoring of the insulation impedance value and comparison with the preset impedance threshold, the situation of abnormal insulation impedance can be found in time. When the insulation impedance value is less than the preset impedance threshold, the system will generate a first abnormal signal, which is used to indicate that the insulation impedance of the device under test is abnormal, and can help maintenance personnel discover and handle potential safety hazards in time, prevent equipment failures or accidents, improve the reliability and stability of the equipment, and extend the service life of the equipment.

[0083] Specifically, the voltage division circuit includes a second resistor, a third resistor, and a fourth resistor. One end of the second resistor is used to connect to the DC signal, and the other end is connected to the input end of the voltage division access port. One end of the third resistor is used to connect to the AC excitation signal, and the other end is connected to the input end of the voltage division access port. One end of the fourth resistor is connected to the output end of the voltage division access port, and the other end is grounded. The input end of the voltage sampling circuit is connected between the fourth resistor and the voltage division access port. Thus, when monitoring the insulation impedance, the corresponding insulation impedance calculation formula in the calculation model is:

[0084] Z = k1 / s1 - R4 - R3;

[0085] Wherein, Z is the insulation impedance, k1 is the impedance compensation coefficient, and s1 is the fundamental wave component.

[0086] Refer to Figure 7, it can be understood that after step S110, the following steps are included but not limited to:

[0087] Step S210: Perform Fourier transform processing on the sampled signal to obtain the DC component;

[0088] Step S220: Obtain the equivalent resistance value of the device under test according to the DC component, the resistance values of each resistor in the voltage division circuit, and the calculation model;

[0089] Step S230: When the equivalent resistance value is less than or equal to the preset first resistance threshold, determine that the grounding type of the device under test is metallic grounding;

[0090] Step S240: When the equivalent resistance value is greater than the first resistance threshold and less than or equal to the preset second resistance threshold, determine that the grounding type of the device under test is high-resistance grounding.

[0091] In steps S210 to S220, the equivalent resistance value in the device under test can also be obtained through the calculation model. Specifically, the equivalent resistance calculation formula corresponding in the calculation model is:

[0092] R 等 = k2 / d1 - R4 - R2;

[0093] where, R 等 is the equivalent resistance, k2 is the resistance compensation coefficient, and d1 is the DC component.

[0094] In steps S230 to S240, the grounding type of the device under test can be reflected by the equivalent resistance value. By accurately judging the grounding type of the device under test, the system can formulate corresponding maintenance strategies. For example, for metallic grounding, there may be a risk of leakage, and immediate measures need to be taken for repair to prevent further damage to the device or the occurrence of safety accidents; while for high-resistance grounding, a second metallic grounding fault may occur, and a more detailed maintenance plan needs to be formulated according to the specific situation.

[0095] Referring to Figure 8 , it can be understood that after step S220, the following steps are included but not limited to:

[0096] Step S310: Obtain the target capacitive reactance value of the device under test according to the insulation impedance value, the equivalent resistance value, and the calculation model;

[0097] Step S320: Obtain the AC frequency of the AC excitation signal at the second input end of the voltage division circuit;

[0098] Step S330: Obtain the distributed capacitance value of the device under test according to the target capacitive reactance value and the AC frequency;

[0099] Step S340: When the distributed capacitance value is greater than or equal to a preset capacitance threshold, generate a second abnormal signal; wherein, the second abnormal signal is used to characterize the abnormal line length of the device under test.

[0100] In steps S310 to S340, the distributed capacitance refers to a distributed parameter formed by non-capacitive forms. Live cables and transformers have a certain distributed capacitance to the ground, and the size of the distributed capacitance depends on the geometric dimensions of the cable, the length of the cable, and the insulating material, etc. It is composed of two conductors that have a voltage difference and are insulated from each other. It must be noted that in electronic and electrical circuits, not only capacitors have capacitance. There is capacitance between any two energized conductors, such as between power transmission lines, between transmission lines and the ground, between the pins of transistors, and between components. This calculation model can not only monitor the insulation impedance and equivalent resistance values, but also monitor the target capacitive reactance value and the distributed capacitance value. Specifically:

[0101]

[0102] Among them, XC represents the target capacitive reactance value, C 分布 represents the distributed capacitance value, and f represents the AC frequency of the AC excitation signal. The size of the distributed capacitance value is closely related to the length of the line. When the line length changes, the distributed capacitance value will also change accordingly. Through the preset capacitance threshold, the system can timely detect whether the line length of the device under test is abnormal. This is of great significance for detecting problems such as line aging, damage, or poor connection, and helps prevent safety accidents caused by line problems.

[0103] By comprehensively considering multiple indicators such as the insulation impedance value, equivalent resistance value, and distributed capacitance value, the system can more accurately judge the electrical state of the device under test. This method of joint analysis of multiple parameters is more reliable than single-index analysis and can improve the accuracy and reliability of fault diagnosis.

[0104] Referring to Figure 9 , it can be understood that the insulation monitoring method provided by this application may also but is not limited to including the following steps:

[0105] Step S410: Send a first level to the control end of the calibration circuit to control the calibration resistor in the calibration circuit to be connected to the voltage division access port of the voltage division circuit;

[0106] Step S420: Obtain a sampling signal from the acquisition end of the signal acquisition circuit;

[0107] Step S430: Obtain a calibration fundamental component and a calibration DC component according to the sampling signal;

[0108] Step S440: Update the original parameters of the calculation model according to the corrected fundamental component, the corrected DC component, the resistance value of the correction resistor, and the resistance values of the resistors in the voltage division circuit.

[0109] In steps S410 to S440, when the parameters of the calculation model need to be corrected, the first level output by the control module to the control terminal of the correction circuit is converted to a high level, so that the switching tube is turned on. As a result, the positive control terminal and the negative control terminal of the five-pin relay are connected, and the internal relay has magnetism. The common terminal and the normally open terminal of the five-pin relay are connected, thereby controlling the correction resistor to be connected to the voltage division access port. A sampling signal is obtained from the acquisition terminal of the voltage acquisition module, and then a Fourier transform is performed according to the sampling signal to obtain the corrected fundamental component and the corrected DC component. Then, according to the corrected fundamental component, the corrected DC component, the resistance value of the correction resistor, and the resistance values of the resistors in the voltage division circuit, the original parameters of the calculation model are updated. Specifically, the original parameters k1 and k2 of the calculation model are updated:

[0110] k1' = s2 * (R3 + R4 + R1);

[0111] k2' = d2 * (R2 + R4 + R1);

[0112] Where k1’ and k2’ are the updated impedance compensation coefficient and resistance compensation coefficient respectively, s2 is the corrected fundamental component, and d2 is the corrected DC component. Through the intervention of the correction circuit and the correction resistor, the output of the voltage division circuit can be accurately adjusted to compensate for the errors introduced by the non-ideal characteristics of the voltage division circuit components (such as the resistance temperature coefficient, aging, etc.). This helps to improve the accuracy of the sampling signal in subsequent measurements. Through the intervention of the correction circuit, the output of the voltage division circuit can be accurately adjusted to compensate for the errors introduced by the non-ideal characteristics of the voltage division circuit components (such as the resistance temperature coefficient, aging, etc.), which can improve the accuracy of the sampling signal in subsequent measurements.

[0113] Refer to Figure 10 , it can be understood that in step S440, it may include but is not limited to the following steps:

[0114] Step S510: Obtain the target parameter according to the corrected resistance value, the correction resistor value, and the resistance values of the resistors in the voltage division circuit;

[0115] Step S520: When the difference between the target parameter and the original parameter of the calculation model is less than or equal to the preset correction threshold, do not process the original parameter of the calculation model;

[0116] Step S530: When the difference between the target parameter and the original parameter of the calculation model is greater than the correction threshold, replace the original parameter with the target parameter.

[0117] In steps S510 to S530, according to the calibrated resistance value, the calibrated resistance value, and the resistance values of the resistors in the voltage division circuit, target parameters are obtained, that is, the target impedance compensation coefficient k1' and the target resistance compensation coefficient k2' are obtained respectively. Subsequently, the differences between the target parameters and the original parameters of the calculation model are calculated, that is, the difference between the target impedance compensation coefficient k1' and the original impedance compensation coefficient k1, and the difference between the target resistance compensation coefficient k2' and the original resistance compensation coefficient k2. When the difference is less than or equal to the preset calibration threshold, the original parameters of the calculation model are not processed. Only when the difference is greater than the calibration threshold, the target parameters are used to replace the original parameters. If the change in the parameters is too small, this change may be caused only by random noise in the data or minor fluctuations during the training process. If every such minor change is accepted and used to update the model parameters, the model may overfit the noise in the training data. Additionally, if the parameters are frequently updated due to minor changes, the output of the model may become unstable. In this way, system instability or performance degradation caused by incorrect or unreasonable parameter updates is prevented.

[0118] In a third aspect, the present application further provides an electronic device, including: at least one memory, at least one processor, and at least one program, where the program is stored in the memory, and the processor executes one or more programs to implement the above insulation monitoring method.

[0119] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and signals, such as the program instructions / signals corresponding to the processing module in the embodiments of the present application. The processor executes various functional applications and data processing by running the non-transitory software programs, instructions, and signals stored in the memory, that is, implements the insulation monitoring method in the above method embodiments.

[0120] The memory may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store relevant data of the above insulation monitoring method, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely set relative to the processor, and these remote memories can be connected to the processing module through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0121] One or more signals are stored in the memory and, when executed by one or more processors, implement the insulation monitoring method in any of the above method embodiments.

[0122] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium storing computer-executable instructions, which when executed by one or more processors, enable the one or more processors to execute the insulation monitoring method in the above method embodiments.

[0123] The device embodiments described above are merely illustrative. 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 to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0124] Through the description of the above embodiments, those of ordinary skill in the art can understand that all or some of the steps and systems disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable signals, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory, or other memory technologies, CD-ROM, digital versatile disk (DVD), or other optical disk storage, magnetic cassette, tape, magnetic disk storage, or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, as is well known to those of ordinary skill in the art, a communication medium typically includes computer-readable signals, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and may include any information delivery medium.

[0125] It should be understood that in this application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (one)" or a similar expression below refers to any combination of these items, including any combination of single item (one) or plural items (ones). For example, at least one (one) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0126] In several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the above division of units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of devices or units can be in electrical, mechanical or other forms.

[0127] The units described above as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0128] In addition, each functional unit in each embodiment of this application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0129] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of various embodiments of this application. The aforementioned storage medium includes: various media that can store programs such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs.

[0130] The embodiments of this application have been described in detail above in conjunction with the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can also be made without departing from the purpose of this application.

Claims

1. An insulation monitoring method, characterized in that, A control module applied to an insulation monitoring circuit, and the insulation monitoring circuit further includes: A voltage dividing circuit, the first input end of the voltage dividing circuit is used to access a DC signal, the second input end of the voltage dividing circuit is used to access an AC excitation signal, the voltage dividing circuit is provided with a voltage dividing access port, and the voltage dividing access port is used to connect with a device under test; A signal acquisition circuit, the input end of the signal acquisition circuit is connected to the voltage dividing end of the voltage dividing circuit, and the acquisition end of the signal acquisition circuit is connected to the input end of the control module; A calibration circuit, the control end of the calibration circuit is connected to the output end of the control module, the calibration circuit includes a calibration resistor, and the calibration circuit is used to control the calibration resistor to access or disconnect the voltage dividing access port according to the first level received by its control end; Wherein, the voltage dividing circuit includes a second resistor, a third resistor and a fourth resistor, one end of the second resistor is used to access a DC signal, the other end is connected to the input end of the voltage dividing access port, one end of the third resistor is used to access an AC excitation signal, the other end is connected to the input end of the voltage dividing access port, one end of the fourth resistor is connected to the output end of the voltage dividing access port, and the other end is grounded, and the input end of the signal acquisition circuit is connected between the fourth resistor and the voltage dividing access port; The insulation monitoring method includes: Obtaining a sampling signal from the acquisition end of the signal acquisition circuit; Performing Fourier transform processing on the sampling signal to obtain a fundamental wave component; According to the fundamental wave component, the resistance values of the resistors in the voltage dividing circuit and a preset calculation model, obtaining the insulation impedance value of the device under test; wherein, the calculation model corresponding to the insulation impedance value is: ； Where Z is the insulation impedance, k1 is the impedance compensation coefficient, s1 is the fundamental wave component, R3 is the third resistor, and R4 is the fourth resistor; When the insulation impedance value is less than a preset impedance threshold, generating a first abnormal signal; wherein, the first abnormal signal is used to indicate that the insulation impedance of the device under test is abnormal; Wherein, after the step of obtaining the sampling signal from the acquisition end of the signal acquisition circuit, it further includes: Performing Fourier transform processing on the sampling signal to obtain a DC component; According to the DC component, the resistance values of the resistors in the voltage dividing circuit and the calculation model, obtaining the equivalent resistance value of the device under test; wherein, the calculation model corresponding to the equivalent resistance value is: ； Among them, R 等 is the equivalent resistance, k2 is the resistance compensation coefficient, d1 is the DC component, and R2 is the second resistor; According to the insulation impedance value, the equivalent resistance value and the calculation model, obtaining the target capacitive reactance value of the device under test; wherein, the calculation model corresponding to the target capacitive reactance value is: ； Where XC represents the target capacitive reactance value; Obtaining the AC frequency of the AC excitation signal at the second input end of the voltage dividing circuit; According to the target capacitive reactance value and the AC frequency, obtaining the distributed capacitance value of the device under test; wherein, the distributed capacitance value is calculated according to the following formula: ； Among them, C 分布 represents the distributed capacitance value, and f represents the AC frequency of the AC excitation signal; When the distributed capacitance value is greater than or equal to a preset capacitance threshold, generating a second abnormal signal; wherein, the second abnormal signal is used to indicate that the line length of the device under test is abnormal.

2. The insulation monitoring method according to claim 1, wherein After the step of obtaining the equivalent resistance value of the device under test according to the DC component, the resistance values of the resistors in the voltage division circuit, and the calculation model, the following steps are further included: When the equivalent resistance value is less than or equal to a preset first resistance threshold, it is determined that the grounding type of the device under test is metallic grounding; When the equivalent resistance value is greater than the first resistance threshold and less than or equal to a preset second resistance threshold, it is determined that the grounding type of the device under test is high-resistance grounding.

3. The insulation monitoring method according to claim 2, characterized in that, The following steps are further included: Send a first level to the control end of the calibration circuit to control the calibration resistor in the calibration circuit to be connected to the voltage division access port of the voltage division circuit; Obtain the sampling signal from the acquisition end of the signal acquisition circuit; Obtain a calibrated fundamental component and a calibrated DC component according to the sampling signal; Update the original parameters of the calculation model according to the calibrated fundamental component, the calibrated DC component, the resistance value of the calibration resistor, and the resistance values of the resistors in the voltage division circuit; wherein, the original parameters are k1 and k2.

4. The insulation monitoring method according to claim 1, characterized in that, The signal acquisition circuit includes an operational amplifier, a fifth resistor, a sixth resistor, and a first capacitor. The positive input terminal of the operational amplifier is connected between the fourth resistor and the voltage division access port through the fifth resistor. The output terminal of the operational amplifier is connected to the inverting input terminal. The output terminal of the operational amplifier is connected to one end of the first capacitor through the sixth resistor. The other end of the first capacitor is grounded. The input terminal of the control module is connected between the sixth resistor and the first capacitor.

5. The insulation monitoring method according to claim 1, characterized in that The calibration circuit further includes a switching tube and a five-pin relay. The control terminal of the switching tube is connected to the output terminal of the control module. The output terminal of the switching tube is grounded. The input terminal of the switching tube is connected to the negative control terminal of the five-pin relay. The positive control terminal of the five-pin relay is used to be connected to a voltage source. The common terminal of the five-pin relay is connected to the input terminal of the voltage division access port. The normally closed terminal of the five-pin relay is left open. The normally open terminal of the five-pin relay is connected to the output terminal of the voltage division access port through the calibration resistor.

6. The insulation monitoring method according to claim 5, wherein The calibration circuit further includes a diode, a second capacitor, and a seventh resistor. The anode terminal of the diode is connected to the positive control terminal of the five-pin relay. The cathode terminal of the diode is respectively connected to the voltage source and one end of the second capacitor. The other end of the second capacitor is grounded. The control terminal of the switching tube is connected to the output terminal of the control module through the seventh resistor.

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