Insulation monitoring circuit and insulation monitoring method

Abstract

The invention discloses an insulation monitoring circuit and an insulation monitoring method, the insulation monitoring circuit comprises a control module, a voltage division circuit, a signal acquisition circuit and a correction circuit, a first input end of the voltage division circuit is used for accessing a direct current signal, a second input end of the voltage division circuit is used for accessing an alternating current excitation signal, the voltage division circuit is provided with a voltage division access port, and the voltage division access port is connected with the correction circuit. The partial pressure access port is used for being connected with to-be-tested equipment; the input end of the signal acquisition circuit is connected with the voltage division end of the voltage division circuit, and the acquisition end of the voltage acquisition module is connected with the input end of the control module; the correction circuit comprises a correction resistor and is used for controlling whether the correction resistor is connected to the partial pressure access port or not according to a first level received by a control end of the correction circuit; and the control module is used for obtaining the insulation resistance of the to-be-tested equipment through a preset calculation model according to a sampling signal obtained from the acquisition end of the voltage sampling circuit, or updating the parameters of the calculation model. According to the invention, the accuracy of insulation resistance monitoring can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of monitoring circuits, and in particular to an insulation monitoring circuit and an insulation monitoring method. Background Art

[0002] In the field of power systems and industrial automation, the insulation performance of electrical equipment is one of the key factors to ensure safe and stable operation of the system. Monitoring insulation resistance is of great significance for preventing electrical failures, reducing equipment damage, and ensuring personnel safety. Traditional insulation monitoring technology mainly relies on regular power outage detection, which is not only inefficient but also unable to reflect the insulation status of the equipment in real time. In addition, as the equipment ages, the operating environment changes, and the power load increases, the insulation performance will gradually decline, and traditional methods are difficult to detect these potential problems in a timely manner. Summary of the invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present 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, the present application provides an insulation monitoring circuit, comprising:

[0005] Control module;

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

[0007] A signal acquisition circuit, wherein 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;

[0008] A correction circuit, wherein the control end of the correction circuit is connected to the output end of the control module, the correction circuit comprises a correction resistor, and the correction circuit is used to control the correction resistor to connect to or disconnect from the voltage divider access port according to a first level received by the control end thereof;

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

[0010] According to the sampling signal obtained from the collection end of the voltage sampling circuit, the insulation impedance of the device to be tested is obtained through a preset calculation model, or the parameters of the calculation model are updated.

[0011] According to the insulation monitoring circuit of the embodiment of the first aspect of the present application, at least the following beneficial effects are achieved: when the insulation monitoring circuit provided by the present application is used to monitor the insulation of the device to be tested, a DC signal is sent to the first input end of the voltage divider circuit, and an AC excitation signal is sent to the second input end, and the DC signal and the AC excitation signal enter the signal acquisition circuit after passing through the voltage divider circuit, and then the sampling signal is obtained from the acquisition end of the signal acquisition circuit by using the control module, and the sampling signal is combined with the preset calculation model to calculate the insulation impedance of the device to be tested connected to the voltage divider access port, thereby achieving 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 end of the correction circuit so that the correction circuit controls the correction circuit to access the voltage divider access port, and then the control module obtains the sampling signal from the acquisition end of the signal acquisition circuit again, and corrects the parameters of the calculation model according to the sampling signal, so as 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 divider 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, and the other end is connected to the input end of the voltage divider access port, one end of the third resistor is used to access an AC excitation signal, and the other end is connected to the input end of the voltage divider access port, one end of the fourth resistor is connected to the output end of the voltage divider access port, and the other end is grounded, and the input end of the voltage sampling circuit is connected between the fourth resistor and the voltage divider 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-phase input terminal of the operational amplifier is connected between the fourth resistor and the voltage divider 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, and 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 also includes a switching tube and a five-pin relay, the control end of the switching tube is connected to the output end of the control module, the output end of the switching tube is grounded, the input end of the switching tube is connected to the negative control end of the five-pin relay, the positive control end of the five-pin relay is used to connect to a voltage source, the common end of the five-pin relay is connected to the input end of the voltage divider access port, the normally closed end of the five-pin relay is unconnected, and the normally open end of the five-pin relay is connected to the output end of the voltage divider access port through the correction resistor.

[0015] According to some embodiments of the first aspect of the present application, the correction circuit also includes a diode, a second capacitor and a seventh resistor, the anode end of the diode is connected to the positive control end of the five-pin relay, the cathode end 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, and the control end of the switch tube is connected to the output end of the control module through the seventh resistor.

[0016] In a second aspect, the present application further provides an insulation monitoring method, which is applied to a control module of the insulation monitoring circuit according to any one embodiment of the first aspect, and the insulation monitoring method comprises:

[0017] Acquire a sampling signal from a collection end of a signal collection circuit;

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

[0019] Obtaining the insulation impedance value of the device to be tested according to the fundamental wave component, the resistance value of each resistor in the voltage divider circuit and a preset calculation model;

[0020] When the insulation impedance value is less than a preset impedance threshold, a first abnormal signal is generated; 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 second aspect of the present application, there are at least the following beneficial effects: when the insulation monitoring of the device to be tested is performed, a DC signal is sent to the first input end of the voltage divider circuit, and an AC excitation signal is sent to the second input end, and the DC signal and the AC excitation signal enter the signal acquisition circuit after passing through the voltage divider circuit, and then the sampling signal is obtained from the acquisition end of the signal acquisition circuit by using the control module, and the sampling signal is Fourier transformed to obtain the fundamental component, the fundamental component is the sine wave component with the lowest frequency in the signal, and it contains the main energy and information of the signal, and then according to the fundamental component, the resistance value of each resistor in the voltage divider circuit and the preset calculation model, the insulation impedance value of the device to be tested is obtained, and the above method can realize the real-time and accurate monitoring of the insulation state of the electrical equipment. In addition, by real-time monitoring of the insulation impedance value and comparing it with the preset impedance threshold, the 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 to characterize the abnormal insulation impedance of the device to be tested, which can help maintenance personnel to timely discover and deal with potential safety hazards, 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 acquiring the sampling signal from the acquisition end of the signal acquisition circuit, the method further includes:

[0023] Performing Fourier transform processing on the sampled signal to obtain a DC component;

[0024] Obtaining an equivalent resistance value of the device under test according to the DC component, the resistance value of each resistor in the voltage divider circuit and the calculation model;

[0025] 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;

[0026] 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.

[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 value of each resistor in the voltage divider circuit and the calculation model, the method further includes:

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

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

[0030] Obtaining a distributed capacitance value of the device under test according to the target capacitive reactance value and the AC frequency;

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

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

[0033] Sending a first level to a control end of the correction circuit to control a correction resistor in the correction circuit to be connected to a voltage divider access port of the voltage divider circuit;

[0034] Acquire the sampling signal from the acquisition end of the signal acquisition circuit;

[0035] Obtaining a corrected fundamental wave component and a corrected DC component according to the sampling signal;

[0036] The original parameters of the calculation model are updated according to the corrected fundamental wave component, the corrected DC component, the resistance value of the correction resistor and the resistance value of each resistor in the voltage divider circuit.

[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 component, the corrected DC component, the resistance value of the correction resistor, and the resistance value of each resistor in the voltage divider circuit includes:

[0038] Obtaining a target parameter according to the corrected fundamental wave component, the corrected DC component, the resistance value of the corrected resistor, and the resistance value of each resistor in the voltage divider circuit;

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

[0040] When the difference between the target parameter and the original parameter of the calculation model is greater than the correction threshold, the original parameter is replaced by the target parameter.

[0041] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

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

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

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

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

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

[0048] Figure 6 A flowchart of an insulation monitoring method provided in an embodiment of the second aspect of the present application;

[0049] Figure 7 For this application Figure 6 The flowchart after step S110;

[0050] Figure 8 For this application Figure 7The flowchart after step S220;

[0051] Fig. 9 A flow chart of an insulation monitoring method provided in another embodiment of the second aspect of the present application;

[0052] Fig.10 For this application Fig. 9 Flowchart of step S440 in FIG. DETAILED DESCRIPTION

[0053] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0054] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 understood as a limitation on the present application.

[0055] In the description of this application, if there is a description of first or second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0056] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0057] In the field of power systems and industrial automation, the insulation performance of electrical equipment is one of the key factors to ensure safe and stable operation of the system. Monitoring insulation resistance is of great significance for preventing electrical failures, reducing equipment damage, and ensuring personnel safety. Traditional insulation monitoring technology mainly relies on regular power outage detection, which is not only inefficient but also unable to reflect the insulation status of the equipment in real time. In addition, as the equipment ages, the operating environment changes, and the power load increases, the insulation performance will gradually decline, and traditional methods are difficult 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-mentioned technical problems. The technical solutions provided by the present application are described in detail one by one below.

[0059] First, refer to Figure 1 The present application provides an insulation monitoring circuit, including: a control module, a voltage divider circuit, a signal acquisition circuit and a correction circuit, wherein the first input end of the voltage divider circuit is used to access a DC signal, the second input end of the voltage divider circuit is used to access an AC excitation signal, the voltage divider circuit is provided with a voltage divider access port, and the voltage divider access port is used to connect to a device under test; the input end of the signal acquisition circuit is connected to the voltage divider end of the voltage divider circuit, and the acquisition end of the voltage acquisition module is connected to the input end of the control module; the control end of the correction circuit is connected to the output end of the control module, the correction circuit includes a correction resistor R1, and the correction circuit is used to control the correction resistor R1 to access or disconnect the voltage divider 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 specific processing flow of the control module is: 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 component; obtaining the insulation impedance value of the device under test according to the fundamental component, the resistance value of each resistor in the voltage divider circuit and a preset calculation model; 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 characterize the insulation impedance abnormality of the device under test.

[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 end of the voltage divider 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 divider circuit. Then, the control module is used to obtain the sampling signal from the acquisition end of the signal acquisition circuit, and the sampling signal is combined with the preset calculation model to calculate the insulation impedance of the device under test connected to the voltage divider access port, thereby 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 end of the correction circuit so that the correction circuit controls the correction circuit to access the voltage divider access port. Then, the control module obtains the sampling signal from the acquisition end 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] At the second input end of the voltage divider circuit, an AC excitation signal generated by a function signal generator chip can be used. Figure 5 In this application, a 50Hz sinusoidal signal is output from pin 2 to the second input end of the voltage divider circuit through the function signal generator chip XR2206D. The above-mentioned method of generating the AC excitation signal is only an example of one of the implementation methods of this application and is not specifically limited to this.

[0062] Reference Figure 4 , Figure 4 A schematic diagram of an isolation transformer in one embodiment is provided for this application, where L1, L2 and L3 are phase A, phase B and phase C of the circuit respectively, and N represents the neutral line, which can be equivalent to a capacitor and a resistor in parallel to the ground, i.e., the dotted line portion in the figure. The specific form of the device under test is not limited in this application.

[0063] Reference Figure 2 It can be understood that the voltage divider 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 access the DC signal, and the other end is connected to the input end of the voltage divider access port, one end of the third resistor R3 is used to access the AC excitation signal, and the other end is connected to the input end of the voltage divider access port, one end of the fourth resistor R4 is connected to the output end of the voltage divider access port, and the other end is grounded, and the input end of the voltage sampling circuit is connected between the fourth resistor R4 and the voltage divider access port. Therefore, when monitoring the insulation impedance, the corresponding insulation impedance calculation formula in the calculation model is:

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

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

[0066] In addition, in the insulation monitoring circuit provided by 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: Fourier transform the sampling signal to obtain the DC component; according to the DC component, the resistance value of each resistor in the voltage divider circuit and the calculation model, the equivalent resistance value of the device under test is obtained. Therefore, when monitoring the equivalent resistance, the corresponding equivalent resistance calculation formula in the calculation model is:

[0067] R 等 =k2 / d1-R4-R2;

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

[0069] Continue to refer to Figure 2It 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-phase input terminal of the operational amplifier U1 is connected between the fourth resistor R4 and the voltage divider 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, the other end of the first capacitor C1 is grounded, and 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, the circuit has a stable gain and excellent linearity through the negative feedback configuration, and can amplify the weak signal output from the voltage divider circuit for subsequent processing or measurement. In addition, 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, and enhance the anti-interference ability of the entire signal acquisition circuit, so that it can maintain good performance in a complex electromagnetic environment.

[0070] Reference Figure 3 It can be understood that the correction circuit also includes a switch tube Q1 and a five-pin relay K1. The control end of the switch tube Q1 is connected to the output end of the control module, the output end of the switch tube Q1 is grounded, the input end of the switch tube Q1 is connected to the negative control end of the five-pin relay K1, the positive control end of the five-pin relay K1 is used to connect to the voltage source, the common end of the five-pin relay K1 is connected to the input end of the voltage divider access port, the normally closed end of the five-pin relay K1 is unconnected, and the normally open end of the five-pin relay K1 is connected to the output end of the voltage divider access port through the correction resistor R1. In this circuit, when insulation monitoring is normally performed on the device to be tested, the first level is a low level, the switch tube Q1 is not turned on, so the positive control terminal and the negative control terminal of the five-pin relay K1 are not turned on, the internal relay is not magnetic, and the common terminal and the normally closed terminal of the five-pin relay K1 are connected, that is, the correction resistor R1 is not connected to the voltage divider access port; in addition, 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 correction circuit is converted to a high level to turn on the switch tube Q1, so the positive control terminal and the negative control terminal of the five-pin relay K1 are connected, the internal relay is magnetic, and the common terminal and the normally open terminal of the five-pin relay K1 are connected, thereby controlling the correction resistor R1 to be connected to the voltage divider access port.

[0071] During calibration, the control module continuously obtains sampling signals from the acquisition end of the voltage acquisition module, and then obtains the correction fundamental component and the correction DC component according to the sampling signal, and then updates the original parameters of the calculation model according to the correction fundamental component, the correction DC component, the resistance value of the correction resistor R1 and the resistance values ​​of each resistor in the voltage divider circuit, specifically, the original parameters k1 and k2 of the calculation model are updated:

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

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

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

[0075] Continue to refer to Figure 3 , it can be understood that the correction circuit also includes a diode D1, a second capacitor C2 and a seventh resistor R7, the anode end of the diode D1 is connected to the positive control end of the five-pin relay K1, the cathode end 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, and the control end of the switch tube Q1 is connected to the output end 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 be turned on and absorb the reverse voltage, thereby protecting the five-pin relay K1, the switch tube Q1 and the subsequent circuit from damage. The second capacitor C2 mainly plays the role of filtering and voltage stabilization, by filtering out the high-frequency noise and ripple in the voltage source, providing 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 end of the switch tube Q1 and the output end of the control module, and mainly plays the role of current limiting and voltage dividing, limiting the current size flowing from the control module to the control end of the switch tube Q1, and preventing the switch tube Q1 or other components from being damaged due to excessive current.

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

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

[0078] Step S110: acquiring a sampling signal from a collection end of a signal collection circuit;

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

[0080] Step S130: Obtaining the insulation impedance value of the device to be tested according to the fundamental wave component, the resistance value of each resistor in the voltage divider circuit and a preset calculation model;

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

[0082] In step S110 to step S140, when the insulation monitoring of the device to be tested is performed, a DC signal is sent to the first input end of the voltage divider 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 divider circuit. Then, the sampling signal is obtained from the acquisition end of the signal acquisition circuit by using the control module, and the sampling signal is Fourier transformed to obtain the fundamental component. The fundamental 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 component, the resistance value of each resistor in the voltage divider circuit and the preset calculation model, the insulation impedance value of the device to be tested is obtained. The above method can realize real-time and accurate monitoring of the insulation state of the electrical equipment. In addition, by real-time monitoring of the insulation impedance value and comparing it with the preset impedance threshold, the 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 to characterize the abnormal insulation impedance of the device to be tested, which can help maintenance personnel to timely discover and deal with potential safety hazards, 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 divider 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, and the other end is connected to the input end of the voltage divider access port, one end of the third resistor is used to access an AC excitation signal, and the other end is connected to the input end of the voltage divider access port, one end of the fourth resistor is connected to the output end of the voltage divider access port, and the other end is grounded, and the input end of the voltage sampling circuit is connected between the fourth resistor and the voltage divider access port. Therefore, when monitoring the insulation impedance, the corresponding insulation impedance calculation formula in the calculation model is:

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

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

[0086] Reference Figure 7It is understandable that after step S110, the following steps are also included but not limited to:

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

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

[0089] Step S230: 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;

[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, it is determined that the grounding type of the device under test is high-resistance grounding.

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

[0092] R 等 =k2 / d1-R4-R2;

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

[0094] In step S230 to step 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 a corresponding maintenance strategy. For example, for metallic grounding, there may be a risk of leakage, and immediate measures need to be taken to repair it to prevent further damage to the equipment or cause a safety accident; and 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] Reference Figure 8 It is understandable that after step S220, the following steps are also included but not limited to:

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

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

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

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

[0100] In step S310 to step S340, distributed capacitance refers to a distributed parameter formed by a non-capacitive form. 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 pressure difference but are insulated from each other. It must be noted that capacitors are not the only ones with capacitance in electronic and electrical circuits. There is capacitance between any two energized conductors, such as between power transmission lines, between transmission lines and the earth, between the pins of transistors, and between components. This calculation model can not only monitor the insulation impedance and equivalent resistance value, but also monitor the target capacitive reactance value and distributed capacitance value, specifically:

[0101]

[0102] Where XC represents the target capacitance 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 promptly 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 insulation impedance, equivalent resistance and distributed capacitance, the system can more accurately determine the electrical status of the device under test. This multi-parameter joint analysis method is more reliable than single indicator analysis and can improve the accuracy and reliability of fault diagnosis.

[0104] Reference Fig. 9 It is understandable that the insulation monitoring method provided by the present application may also include but is not limited to the following steps:

[0105] Step S410: sending a first level to the control terminal of the correction circuit to control the correction resistor in the correction circuit to be connected to the voltage divider access port of the voltage divider circuit;

[0106] Step S420: acquiring a sampling signal from a collection end of a signal collection circuit;

[0107] Step S430: obtaining a corrected fundamental wave component and a corrected DC component according to the sampled signal;

[0108] Step S440: updating the original parameters of the calculation model according to the correction fundamental wave component, the correction DC component, the resistance value of the correction resistor and the resistance value of each resistor in the voltage divider circuit.

[0109] In step S410 to step S440, when the parameters of the calculation model need to be corrected, the first level output by the control module to the control end of the correction circuit is converted to a high level to turn on the switch tube, so that the positive control end and the negative control end of the five-pin relay are connected, the internal relay is magnetic, and the common end and the normally open end of the five-pin relay are connected, thereby controlling the correction resistor to be connected to the voltage divider access port. The sampling signal is obtained from the acquisition end of the voltage acquisition module, and then a Fourier transform is performed according to the sampling signal to obtain the correction fundamental component and the correction DC component. Then, according to the correction fundamental component, the correction DC component, the resistance value of the correction resistor and the resistance value of each resistor in the voltage divider 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] Among them, k1' and k2' are the updated impedance compensation coefficient and resistance compensation coefficient respectively, s2 is the correction fundamental component, and d2 is the correction DC component. Through the intervention of the correction circuit and the correction resistor, the output of the voltage divider circuit can be accurately adjusted to compensate for the errors introduced by the non-ideal characteristics of the voltage divider circuit components (such as the resistance temperature coefficient, aging, etc.). This helps to improve the accuracy of the sampled signal in subsequent measurements. Through the intervention of the correction circuit, the output of the voltage divider circuit can be accurately adjusted to compensate for the errors introduced by the non-ideal characteristics of the voltage divider circuit components (such as the resistance temperature coefficient, aging, etc.), which can improve the accuracy of the sampled signal in subsequent measurements.

[0113] Reference Fig.10 It is understandable that step S440 may include but is not limited to the following steps:

[0114] Step S510: obtaining target parameters according to the calibrated impedance value, the calibrated resistance value and the resistance values ​​of each resistor in the voltage divider 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, the original parameter of the calculation model is not processed;

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

[0117] In step S510 to step S530, the target parameters are obtained according to the correction impedance value, the correction resistance value and the resistance value of each resistor in the voltage divider circuit, that is, the target impedance compensation coefficient k1' and the target resistance compensation coefficient k2' are obtained respectively, and then the difference between the target parameters and the original parameters of the calculation model is 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 correction threshold, the original parameters of the calculation model are not processed. Only when the difference is greater than the correction threshold, the target parameters replace the original parameters. If the change in the parameter is too small, this change may only be caused by random noise in the data or slight fluctuations in the training process. If each such slight change is accepted and used to update the model parameters, the model may overfit the noise in the training data. In addition, if the parameters are frequently updated due to slight changes, the output of the model may become unstable. In this way, system instability or performance degradation caused by parameter errors or unreasonable updates is prevented.

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

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

[0120] The memory may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required by at least one function; the data storage area may 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-transient memory, such as at least one disk storage device, a flash memory device or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processing module via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an 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, the insulation monitoring method in any of the above method embodiments is executed.

[0122] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores computer-executable instructions. The computer-executable instructions are executed by one or more processors, so that the one or more processors can execute the insulation monitoring method in the above method embodiment.

[0123] The device embodiments described above are merely illustrative, wherein 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, i.e., may be located in one place, or may be distributed over 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, it will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed methods 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, and the computer-readable medium can include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those skilled 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 a computer-readable signal, a data structure, a program module or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassette, magnetic tape, disk storage or other magnetic storage device, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media generally embodies computer readable signals, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0125] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least 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 the several embodiments provided in the present 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 schematic. For example, the division of the above units is only a logical function division. 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. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0127] The units described above 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 solution of this embodiment.

[0128] In addition, each functional unit in each embodiment of the present application 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.

[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 this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including multiple instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as ROM), random access memory (Random Access Memory, referred to as RAM), disk or optical disk and other media that can store programs.

[0130] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. An insulation monitoring circuit, characterized in that: include: Control module; A voltage divider circuit, wherein a first input end of the voltage divider circuit is used to access a DC signal, a second input end of the voltage divider circuit is used to access an AC excitation signal, and the voltage divider circuit is provided with a voltage divider access port, and the voltage divider access port is used to connect to a device under test; A signal acquisition circuit, wherein 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; A correction circuit, wherein the control end of the correction circuit is connected to the output end of the control module, the correction circuit comprises a correction resistor, and the correction circuit is used to control the correction resistor to connect to or disconnect from the voltage divider access port according to a first level received by the control end thereof; Wherein, the control module is used for: According to the sampling signal obtained from the collection end of the voltage sampling circuit, the insulation impedance of the device to be tested is obtained through a preset calculation model, or the parameters of the calculation model are updated.

2. The insulation monitoring circuit according to claim 1, characterized in that: The voltage divider 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, and the other end is connected to the input end of the voltage divider access port, one end of the third resistor is used to access an AC excitation signal, and the other end is connected to the input end of the voltage divider access port, one end of the fourth resistor is connected to the output end of the voltage divider access port, and the other end is grounded, and the input end of the voltage sampling circuit is connected between the fourth resistor and the voltage divider access port.

3. The insulation monitoring circuit according to claim 2, characterized in that: The signal acquisition circuit includes an operational amplifier, a fifth resistor, a sixth resistor and a first capacitor. The non-phase input terminal of the operational amplifier is connected between the fourth resistor and the voltage divider 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, and the input terminal of the control module is connected between the sixth resistor and the first capacitor.

4. The insulation monitoring circuit according to claim 1, characterized in that: The correction circuit also includes a switch tube and a five-pin relay. The control end of the switch tube is connected to the output end of the control module, the output end of the switch tube is grounded, the input end of the switch tube is connected to the negative control end of the five-pin relay, the positive control end of the five-pin relay is used to connect to a voltage source, the common end of the five-pin relay is connected to the input end of the voltage divider access port, the normally closed end of the five-pin relay is unconnected, and the normally open end of the five-pin relay is connected to the output end of the voltage divider access port through the correction resistor.

5. The insulation monitoring circuit according to claim 4, characterized in that: The correction circuit also includes a diode, a second capacitor and a seventh resistor. The anode end of the diode is connected to the positive control end of the five-pin relay, the cathode end 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, and the control end of the switch tube is connected to the output end of the control module through the seventh resistor.

6. An insulation monitoring method, characterized in that: A control module applied to the insulation monitoring circuit according to any one of claims 1 to 5, wherein the insulation monitoring method comprises: Acquire a sampling signal from a collection end of a signal collection circuit; Performing Fourier transform processing on the sampled signal to obtain a fundamental wave component; Obtaining the insulation impedance value of the device to be tested according to the fundamental wave component, the resistance value of each resistor in the voltage divider circuit and a preset calculation model; When the insulation impedance value is less than a preset impedance threshold, a first abnormal signal is generated; wherein the first abnormal signal is used to indicate that the insulation impedance of the device under test is abnormal.

7. The insulation monitoring method according to claim 6, characterized in that: After the step of acquiring the sampling signal from the acquisition end of the signal acquisition circuit, the method further includes: Performing Fourier transform processing on the sampled signal to obtain a DC component; Obtaining an equivalent resistance value of the device under test according to the DC component, the resistance value of each resistor in the voltage divider circuit and the calculation model; 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.

8. The insulation monitoring method according to claim 7, characterized in that: After the step of obtaining the equivalent resistance value of the device under test according to the DC component, the resistance values ​​of each resistor in the voltage divider circuit and the calculation model, the method further includes: Obtaining a target capacitive reactance value of the device under test according to the insulation impedance value, the equivalent resistance value and the calculation model; Acquiring the AC frequency of the AC excitation signal at the second input terminal of the voltage divider circuit; Obtaining a distributed capacitance value of the device under test according to the target capacitive reactance value and the AC frequency; When the distributed capacitance value is greater than or equal to a preset capacitance threshold, a second abnormal signal is generated; wherein the second abnormal signal is used to indicate that the line length of the device under test is abnormal.

9. The insulation monitoring method according to claim 7, characterized in that: Also includes: Sending a first level to a control end of the correction circuit to control a correction resistor in the correction circuit to be connected to a voltage divider access port of the voltage divider circuit; Acquire the sampling signal from the acquisition end of the signal acquisition circuit; Obtaining a corrected fundamental wave component and a corrected DC component according to the sampling signal; The original parameters of the calculation model are updated according to the corrected fundamental wave component, the corrected DC component, the resistance value of the correction resistor and the resistance value of each resistor in the voltage divider circuit.

10. The insulation monitoring method according to claim 9, characterized in that: The updating of the original parameters of the calculation model according to the corrected impedance value, the corrected resistance value and the resistance values ​​of each resistor in the voltage divider circuit includes: Obtaining a target parameter according to the corrected impedance value, the corrected resistance value, and the resistance value of each resistor in the voltage divider circuit; When the difference between the target parameter and the original parameter of the calculation model is less than or equal to a preset correction threshold, the original parameter of the calculation model is not processed; When the difference between the target parameter and the original parameter of the calculation model is greater than the correction threshold, the original parameter is replaced by the target parameter.

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