Insulation impedance testing methods, controllers, DC equipment and storage media

Abstract

This application provides a method, controller, DC device, and storage medium for detecting insulation impedance. The method is applied to a detection system connected to a DC bus, which is connected to a load via a feeder. It includes modulating the DC bus's ground signal into an AC signal based on a preset PWM signal, thereby generating an AC current to ground in the feeder; acquiring the AC current to ground; and calculating the insulation impedance of the feeder based on the AC current to ground. This application can accurately detect the insulation impedance of the feeder.

Description

Technical Field

[0001] This application relates to the field of insulation resistance detection technology, and in particular to an insulation resistance detection method, controller, DC device and storage medium. Background Technology

[0002] Currently, most traditional feeder branches use DC Hall effect sensors to collect leakage current and calculate the insulation impedance of a single feeder DC current using corresponding formulas. This method is suitable for single feeder branches. However, for multi-feeder branches, continuing to use DC Hall effect sensors to collect leakage current may lead to inaccurate leakage current measurements due to circulating currents generated in the multi-feeder branches. This can result in incorrect insulation impedance calculations and affect the safety of the load operation. Summary of the Invention

[0003] This application provides a method, controller, DC device, and storage medium for detecting insulation impedance, in order to solve the problem that existing methods using DC Hall effect sensors to collect leakage current from multi-feeder branches are inaccurate and lead to incorrect insulation impedance calculations.

[0004] In a first aspect, embodiments of this application provide a method for detecting insulation impedance, applied to a detection system, wherein the detection system is connected to a DC bus, and the DC bus is connected to a load via a feeder;

[0005] The detection method may include:

[0006] The DC bus ground signal is modulated into an AC signal according to the preset PWM signal so that the feeder generates an AC current to ground.

[0007] Collect the AC current to ground and calculate the insulation impedance of the feeder based on the AC current to ground.

[0008] In one possible implementation, the detection system includes an insulation detection module equipped with a switch and an AC transformer;

[0009] The insulation detection module is connected to the DC bus, and an AC transformer is installed on the feeder, which is connected to the insulation detection module.

[0010] In one possible implementation, the insulation detection module includes a signal generator and an unbalanced bridge circuit with a switch, the signal generator being connected to the unbalanced bridge circuit, and the unbalanced bridge circuit being connected to a DC bus.

[0011] Modulate the DC bus's ground signal into an AC signal according to a preset PWM signal, including:

[0012] The control signal generator generates a preset PWM signal and controls the switching of the unbalanced bridge circuit according to the preset PWM signal to modulate the DC bus to ground signal into an AC signal.

[0013] In one possible implementation, the insulation detection module includes a control unit connected to an AC transformer;

[0014] Collect the AC current to ground and calculate the insulation impedance of the feeder based on the AC current to ground, including:

[0015] The AC transformer collects the AC current to ground on the feeder and sends the AC current to ground to the control unit so that the control unit can calculate the insulation impedance of the feeder based on the AC current to ground.

[0016] In one possible implementation, the insulation impedance of the feeder is calculated based on the alternating current to ground, including:

[0017] Calculate the current difference between the AC current to ground and the reference AC current to ground, and calculate the insulation impedance of the feeder based on the current difference;

[0018] Among them, the reference AC current to ground is the AC current obtained by modulating the DC bus to ground electrical signal according to the preset PWM signal when the feeder is in normal condition.

[0019] In one possible implementation, after calculating the insulation impedance of the feeder based on the AC current to ground, the detection method further includes:

[0020] If the insulation impedance of the feeder is greater than or equal to the first impedance and less than the preset standard impedance, a first-level alarm signal will be output. The first-level alarm signal is used to indicate that the feeder needs to be repaired within a first preset time period.

[0021] If the insulation impedance of the feeder is greater than or equal to the second impedance and less than the first impedance, a second-level alarm signal is output. The second-level alarm signal is used to indicate that the feeder needs to be repaired within a second preset time period.

[0022] If the insulation impedance of the feeder is greater than or equal to the third impedance and less than the second impedance, a third-level alarm signal is output. The third-level alarm signal is used to indicate that the feeder should be repaired within a third preset time period.

[0023] Among them, the first impedance is less than the preset standard impedance, the second impedance is less than the first impedance, the third impedance is less than the second impedance, the first preset duration is greater than the second preset duration, and the second preset duration is greater than the third preset duration.

[0024] Secondly, this application provides an insulation resistance detection device for use in a detection system. The detection system is connected to a DC bus, and the DC bus is connected to a load via multiple feeders.

[0025] The detection device may include:

[0026] The first control module is used to modulate the DC bus's ground electrical signal into an AC signal according to a preset PWM signal, so that the feeder generates an AC current to ground.

[0027] The second control module is used to collect the AC current to ground and calculate the insulation impedance of the feeder based on the AC current to ground.

[0028] Thirdly, embodiments of this application provide a controller, including a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the steps of the insulation impedance detection method as described in the first aspect or any possible implementation of the first aspect.

[0029] Fourthly, this application provides a DC device including the controller described in the third aspect above.

[0030] Fifthly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the insulation impedance detection method as described in the first aspect or any possible implementation of the first aspect.

[0031] This application provides a method, controller, DC device, and storage medium for detecting insulation impedance. The method modulates the DC bus's ground signal into an AC signal based on a preset PWM signal, thereby generating an AC current to ground in the feeder. Subsequently, by acquiring this AC current, the presence of leakage current can be accurately determined, and the feeder's insulation impedance can be calculated based on the ground current. This method eliminates the need for a DC Hall effect sensor, is unaffected by circulating current in the feeder, and accurately calculates the insulation impedance on the feeder. This facilitates timely maintenance of insulation impedance anomalies and ensures the normal operation of the load. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart illustrating the implementation of the insulation impedance detection method provided in this application embodiment;

[0034] Figure 2 This is a schematic diagram of the structure of a detection system provided in an embodiment of this application;

[0035] Figure 3 This is a schematic diagram of an unbalanced bridge circuit provided in an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of the insulation resistance detection device provided in the embodiments of this application;

[0037] Figure 5 This is a schematic diagram of the controller provided in an embodiment of this application;

[0038] Figure 6 This is a connection diagram of a DC device provided in an embodiment of this application. Detailed Implementation

[0039] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0041] See Figure 1 The diagram illustrates the implementation flowchart of the insulation resistance detection method provided in this application embodiment. Figure 1 As shown, an insulation resistance detection method is applied to a detection system. The detection system is connected to a DC bus, and the DC bus is connected to a load through a feeder. The detection method may include S101 and S102.

[0042] S101 modulates the DC bus's ground signal into an AC signal according to a preset PWM signal, so that the feeder generates an AC current to ground.

[0043] In the embodiments of this application, at least one feeder can be connected between the DC bus and the load. For ordinary loads, the DC bus can be connected to the ordinary load through one feeder to ensure that the ordinary load operates normally. For critical loads, the DC bus can be connected to the critical load through two or more feeders to ensure that the critical load operates normally through redundant power supply. Ordinary loads and critical loads can be distinguished according to actual usage.

[0044] For example, in nuclear power applications, double-feeder branches are required. These branches may generate circulating currents. In such scenarios, if insulation impedance detection still uses the traditional DC Hall effect sensor method, problems such as damaged DC Hall sensors and false alarms may occur. Therefore, the application scenarios described in this application can be used for single-feeder, double-feeder, or multi-feeder branch scenarios.

[0045] In the embodiments of this application, the detection system can generate a preset PWM signal and modulate the DC bus's ground electrical signal according to the preset PWM signal to obtain an AC signal, thereby causing the feeder to generate an AC current to ground. The ground electrical signal may include a ground voltage signal or a ground current signal, which can be selected and modulated according to actual conditions.

[0046] For example, the detection system may include a switching module connected to the DC bus. The switching unit controls the operation of each switch according to a preset PWM signal, thereby modulating the DC bus's ground signal to generate an AC current to ground in the feeder. The switching unit can be selected and configured according to actual conditions.

[0047] S102 collects the AC current to ground and calculates the insulation impedance of the feeder based on the AC current to ground.

[0048] After the feeder generates an AC current to ground, the detection system can collect this AC current and calculate the leakage current of the feeder. Finally, the insulation impedance of the feeder can be calculated based on the leakage current and the current test voltage. Specifically, if the AC current to ground exceeds a preset current, it can be determined that the feeder has a leakage current. In this case, the difference between the AC current to ground and the preset current is the leakage current, calculated using effective values.

[0049] In embodiments of this application, the detection system may include a current acquisition circuit or an AC transformer, which can acquire the AC current to ground of the feeder.

[0050] The detection system may include a control module that can calculate the insulation impedance of the feeder based on the AC current to ground.

[0051] This application embodiment modulates the ground signal of the DC bus using a PWM signal to generate a corresponding AC current to ground in the feeder. The insulation impedance of the feeder is then calculated based on this AC current. This method eliminates the need for DC Hall effect devices, is unaffected by the circulating current in the feeder, and can accurately calculate the insulation impedance, reducing calculation errors and improving the reliability of the load to a certain extent.

[0052] Figure 2 This is a schematic diagram of the structure of a detection system provided in an embodiment of this application. Figure 2 As shown, in some embodiments of this application, the detection system includes an insulation detection module equipped with a switch and an AC transformer;

[0053] The insulation detection module is connected to the DC bus, and an AC transformer is installed on the feeder, which is connected to the insulation detection module.

[0054] like Figure 2As shown, the DC bus and the load may include at least one feeder, and each feeder is equipped with an AC transformer. The insulation detection module can generate a preset PWM signal and control the switch in the insulation detection module according to the preset PWM signal to modulate the DC bus's ground signal and generate an AC ground signal, so that each feeder generates an AC current to ground.

[0055] The AC current transformer can collect the AC current to ground on the feeder and send it to the insulation detection module, so that the insulation detection module can calculate the insulation impedance of the feeder based on the AC current to ground. Each feeder has one AC current transformer, and the AC current to ground collected by each transformer is independent of the others.

[0056] This application embodiment can utilize the characteristic that AC transformers can only sample AC signals to obtain a modulated sine wave signal.

[0057] Furthermore, AC transformers exhibit magnetic bias. A fixed magnetic field can cause this bias, and if it reaches a certain level, it can lead to transformer saturation, resulting in a clipped positive half of the waveform and a downward shift in the negative half. This is equivalent to the hysteresis loop deflecting in one direction. Because this bias varies with the load, the circulating current has a magnitude, so the relationship between the transformer's range and the circulating current must be considered. Taking into account the circulating current generated by the feeder, the AC transformer's range must be greater than the maximum circulating current value. For example, if the maximum circulating current is 5A, the range might need to be 20A to avoid magnetic bias.

[0058] In this embodiment, the DC bus is modulated by an insulation detection module to generate an AC current to ground on the feeder. The AC current to ground is collected by an AC transformer, and the insulation detection module calculates the insulation impedance of the feeder based on the AC current to ground. This is unaffected by the circulating current in the feeder and can improve the accuracy of the insulation impedance calculation.

[0059] In some embodiments of this application, the insulation detection module includes a signal generator and an unbalanced bridge circuit with a switch, wherein the signal generator is connected to the unbalanced bridge circuit and the unbalanced bridge circuit is connected to the DC bus.

[0060] Modulate the DC bus's ground signal into an AC signal according to a preset PWM signal, including:

[0061] The control signal generator generates a preset PWM signal and controls the switching of the unbalanced bridge circuit according to the preset PWM signal to modulate the DC bus to ground signal into an AC signal.

[0062] Figure 3 This is a schematic diagram of an unbalanced bridge circuit provided in an embodiment of this application, as shown below. Figure 3As shown, the unbalanced bridge circuit consists of multiple resistors and multiple switches.

[0063] In the embodiments of this application, the signal generator can generate a preset PWM signal and control each switch in the unbalanced bridge circuit according to the preset PWM signal, so as to modulate the DC bus to ground signal through the unbalanced bridge circuit, modulate the DC bus to ground signal into an AC signal, and thereby make the feeder generate an AC current to ground.

[0064] This application embodiment modulates the DC bus ground signal using a signal generator and an unbalanced bridge circuit to generate an AC ground signal, which is unaffected by the feeder circulating current and can improve the accuracy of feeder insulation impedance calculation.

[0065] In some embodiments of this application, the insulation detection module includes a control unit, which is connected to an AC transformer;

[0066] Collect the AC current to ground and calculate the insulation impedance of the feeder based on the AC current to ground, including:

[0067] The AC transformer collects the AC current to ground on the feeder and sends the AC current to ground to the control unit so that the control unit can calculate the insulation impedance of the feeder based on the AC current to ground.

[0068] In the embodiments of this application, the insulation detection module includes a control unit, which can control the signal generator to generate a preset PWM signal and calculate the AC current to ground collected by the AC transformer to obtain the insulation impedance of the feeder.

[0069] The insulation detection module provided in this application embodiment can accurately calculate the insulation impedance of the feeder based on the AC current to ground, and is not affected by the circulating current of the feeder, which can greatly improve the working reliability of the load.

[0070] In some embodiments of this application, the insulation impedance of the feeder is calculated based on the AC current to ground, including:

[0071] Calculate the current difference between the AC current to ground and the reference AC current to ground, and calculate the insulation impedance of the feeder based on the current difference;

[0072] Among them, the reference AC current to ground is the AC current obtained by modulating the DC bus to ground electrical signal according to the preset PWM signal when the feeder is in normal condition.

[0073] In the embodiments of this application, when the feeder is in a normal state, the detection system can modulate the DC bus to ground electrical signal according to a preset PWM signal to obtain an AC current, which can then be used as a reference AC current to ground.

[0074] In practical applications, the current difference between the AC current to ground and the reference AC current to ground can be calculated as the leakage current of the feeder, and then the insulation impedance of the feeder can be calculated based on this leakage current.

[0075] The embodiments of this application can accurately calculate the insulation impedance of the feeder by using the reference AC current to ground and the actual sampled AC current to ground, without being affected by the circulating current of the feeder.

[0076] In some embodiments of this application, after calculating the insulation impedance of the feeder based on the AC current to ground, the detection method further includes:

[0077] If the insulation impedance of the feeder is greater than or equal to the first impedance and less than the preset standard impedance, a first-level alarm signal will be output. The first-level alarm signal is used to indicate that the feeder needs to be repaired within a first preset time period.

[0078] If the insulation impedance of the feeder is greater than or equal to the second impedance and less than the first impedance, a second-level alarm signal is output. The second-level alarm signal is used to indicate that the feeder needs to be repaired within a second preset time period.

[0079] If the insulation impedance of the feeder is greater than or equal to the third impedance and less than the second impedance, a third-level alarm signal is output. The third-level alarm signal is used to indicate that the feeder should be repaired within a third preset time period.

[0080] Among them, the first impedance is less than the preset standard impedance, the second impedance is less than the first impedance, the third impedance is less than the second impedance, the first preset duration is greater than the second preset duration, and the second preset duration is greater than the third preset duration.

[0081] In the embodiments of this application, the first impedance, second impedance, third impedance, first preset duration, second preset duration, and third preset duration can be set according to actual conditions. The preset standard impedance is the minimum safe impedance of the feeder; if the insulation impedance is less than the preset standard impedance, it indicates a feeder malfunction.

[0082] In the embodiments of this application, the smaller the insulation resistance of the feeder, the higher the degree of feeder abnormality, and the more time is needed to repair the feeder.

[0083] This application embodiment sets a graded alarm strategy based on the insulation impedance of the feeder. Feeders with high alarm levels are subject to emergency repairs, while feeders with low alarm levels are subject to delayed repairs. This helps to rationally schedule maintenance personnel, improve maintenance efficiency, and further enhance the working reliability of the load.

[0084] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0085] The following are device embodiments of this application. For details not described in detail, please refer to the corresponding method embodiments described above.

[0086] Figure 4 A schematic diagram of the insulation resistance detection device provided in an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiment of this application are shown, and are described in detail below:

[0087] like Figure 4 As shown, the insulation resistance detection device 20 is used in the detection system. The detection system is connected to the DC bus, and the DC bus is connected to the load through multiple feeders.

[0088] The detection device may include:

[0089] The first control module 201 is used to modulate the DC bus ground signal into an AC signal according to a preset PWM signal so that the feeder generates an AC current to ground.

[0090] The second control module 202 is used to collect the AC current to ground and calculate the insulation impedance of the feeder based on the AC current to ground.

[0091] In some embodiments of this application, the detection system includes an insulation detection module equipped with a switch and an AC transformer;

[0092] The insulation detection module is connected to the DC bus, and an AC transformer is installed on the feeder, which is connected to the insulation detection module.

[0093] In some embodiments of this application, the insulation detection module includes a signal generator and an unbalanced bridge circuit with a switch, wherein the signal generator is connected to the unbalanced bridge circuit and the unbalanced bridge circuit is connected to the DC bus.

[0094] The first control module 201 is also used to control the signal generator to generate a preset PWM signal, and to control the switching of the unbalanced bridge circuit according to the preset PWM signal, so as to modulate the DC bus to ground electrical signal into an AC signal.

[0095] In some embodiments of this application, the insulation detection module includes a control unit, which is connected to an AC transformer;

[0096] The second control module 202 is also used to control the AC transformer to collect the AC current to ground on the feeder and send the AC current to ground to the control unit so that the control unit can calculate the insulation impedance of the feeder based on the AC current to ground.

[0097] In some embodiments of this application, the second control module 202 is also used to calculate the current difference between the AC current to ground and the reference AC current to ground, and to calculate the insulation impedance of the feeder based on the current difference.

[0098] Among them, the reference AC current to ground is the AC current obtained by modulating the DC bus to ground electrical signal according to the preset PWM signal when the feeder is in normal condition.

[0099] In some embodiments of this application, the detection device may further include:

[0100] The third control module is used after calculating the insulation impedance of the feeder based on the AC current to ground:

[0101] If the insulation impedance of the feeder is greater than or equal to the first impedance and less than the preset standard impedance, a first-level alarm signal will be output. The first-level alarm signal is used to indicate that the feeder needs to be repaired within a first preset time period.

[0102] If the insulation impedance of the feeder is greater than or equal to the second impedance and less than the first impedance, a second-level alarm signal is output. The second-level alarm signal is used to indicate that the feeder needs to be repaired within a second preset time period.

[0103] If the insulation impedance of the feeder is greater than or equal to the third impedance and less than the second impedance, a third-level alarm signal is output. The third-level alarm signal is used to indicate that the feeder should be repaired within a third preset time period.

[0104] Among them, the first impedance is less than the preset standard impedance, the second impedance is less than the first impedance, the third impedance is less than the second impedance, the first preset duration is greater than the second preset duration, and the second preset duration is greater than the third preset duration.

[0105] Figure 5 This is a schematic diagram of the controller provided in an embodiment of this application. Figure 5 As shown, the controller 30 in this embodiment includes a processor 300 and a memory 301, wherein the memory 301 stores a computer program 302 that can run on the processor 300. When the processor 300 executes the computer program 302, it implements the steps in the above-described embodiments of the insulation impedance detection methods. Alternatively, when the processor 300 executes the computer program 302, it implements the functions of each module / unit in the above-described device embodiments.

[0106] For example, computer program 302 may be divided into one or more modules / units, one or more of which are stored in memory 301 and executed by processor 300 to complete this application. One or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 302 in controller 30.

[0107] The controller 30 may include, but is not limited to, a processor 300 and a memory 301. Those skilled in the art will understand that... Figure 5 This is merely an example of controller 30 and does not constitute a limitation on controller 30. It may include more or fewer components than shown, or combine certain components, or different components. For example, the controller may also include input / output devices, network access devices, buses, etc.

[0108] The processor 300 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0109] The memory 301 can be an internal storage unit of the controller 30, such as a hard disk or RAM of the controller 30. The memory 301 can also be an external storage device of the controller 30, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the controller 30. Furthermore, the memory 301 can include both internal and external storage units of the controller 30. The memory 301 is used to store computer programs and other programs and data required by the controller. The memory 301 can also be used to temporarily store data that has been output or will be output.

[0110] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0111] This application also provides a DC device, including the controller 30 described above.

[0112] For example, Figure 6 This is a connection diagram of a DC device provided in an embodiment of this application, such as... Figure 6 As shown, the insulation detection module can be a DC grounding detector, and the other end of the acquisition module is connected to the DC grounding detector. This DC grounding detector can generate a PWM signal and modulate the DC bus, and can also calculate the insulation impedance based on the AC current of the feeder acquired by the AC transformer.

[0113] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0114] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0115] In the embodiments provided in this application, it should be understood that the disclosed devices / controllers and methods can be implemented in other ways. For example, the device / controller embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0116] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0117] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0118] If an integrated module / unit is implemented as 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, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various insulation impedance detection method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0119] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for detecting insulation resistance, characterized in that, An insulation detection system is applied to a device connected to a DC bus, which is connected to a load via a feeder. The system includes an insulation detection module with a switch and an AC transformer. The insulation detection module is connected to the DC bus, and the AC transformer is located on the feeder and connected to the insulation detection module. The insulation detection module includes a signal generator and an unbalanced bridge circuit with a switch; the signal generator is connected to the unbalanced bridge circuit, which is connected to the DC bus. The insulation detection module also includes a control unit connected to the AC transformer. The detection method includes: The signal generator is controlled to generate a preset PWM signal, and the switch of the unbalanced bridge circuit is controlled according to the preset PWM signal to modulate the DC bus to ground signal into an AC signal so that the feeder generates an AC current to ground. The AC transformer collects the AC current to ground on the feeder and sends the AC current to ground to the control unit, so that the control unit calculates the current difference between the AC current to ground and the reference AC current to ground, and calculates the insulation impedance of the feeder based on the current difference; wherein, the reference AC current to ground is the AC current obtained by modulating the DC bus to ground electrical signal according to a preset PWM signal when the feeder is in normal state.

2. The method for detecting insulation resistance according to claim 1, characterized in that, After calculating the insulation impedance of the feeder based on the current difference, the detection method further includes: If the insulation impedance of the feeder is greater than or equal to the first impedance and less than the preset standard impedance, a first-level alarm signal is output. The first-level alarm signal is used to indicate that the feeder should be repaired within a first preset time period. If the insulation impedance of the feeder is greater than or equal to the second impedance and less than the first impedance, a second-level alarm signal is output. The second-level alarm signal is used to indicate that the feeder should be repaired within a second preset time period. If the insulation impedance of the feeder is greater than or equal to the third impedance and less than the second impedance, a third-level alarm signal is output. The third-level alarm signal is used to indicate that the feeder should be repaired within a third preset time period. Wherein, the first impedance is less than the preset standard impedance, the second impedance is less than the first impedance, the third impedance is less than the second impedance, the first preset duration is greater than the second preset duration, and the second preset duration is greater than the third preset duration.

3. An insulation resistance detection device, characterized in that, An insulation detection system is applied to a DC bus, which is connected to a load via multiple feeders. The system includes an insulation detection module with a switch and an AC transformer. The insulation detection module is connected to the DC bus, and the AC transformer is located on each feeder and connected to the insulation detection module. The insulation detection module includes a signal generator and an unbalanced bridge circuit with a switch; the signal generator is connected to the unbalanced bridge circuit, which is connected to the DC bus. The insulation detection module also includes a control unit connected to the AC transformer. The detection device includes: The first control module is used to control the signal generator to generate a preset PWM signal, and to control the switching of the unbalanced bridge circuit according to the preset PWM signal, so as to modulate the DC bus to ground electrical signal into an AC signal, so as to generate an AC current to ground in the feeder. The second control module is used for the AC transformer to collect the AC current to ground on the feeder and send the AC current to ground to the control unit, so that the control unit can calculate the current difference between the AC current to ground and the reference AC current to ground, and calculate the insulation impedance of the feeder based on the current difference; wherein, the reference AC current to ground is the AC current obtained by modulating the DC bus to ground electrical signal according to a preset PWM signal when the feeder is in normal state.

4. A controller comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the insulation impedance detection method as described in any one of claims 1 to 2 above.

5. A DC device, characterized in that, Includes the controller as described in claim 4.

6. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the insulation impedance detection method as described in any one of claims 1 to 2 above.

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