Method and apparatus for detecting faults in a frequency converter system

Abstract

The application discloses a frequency converter system fault detection method and device, and relates to the technical field of frequency converters. The application acquires an insulation monitoring resistance value of a frequency converter system. If the insulation monitoring resistance value is lower than a preset resistance threshold value, it indicates that a motor grounding fault occurs. The frequency converter system can be further judged according to a three-phase current vector of the frequency converter to determine whether a motor single-phase or two-phase grounding fault occurs, and the frequency converter system can be judged according to an actual running current of the motor to determine whether a motor three-phase grounding fault occurs. Thus, the detection of the motor grounding fault is realized, and meaningless acquisition and judgment of the three-phase current vector and the actual running current can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of frequency converter, and in particular to a frequency converter system fault detection method and device. BACKGROUND

[0002] A cold rolling transmission system is hung with various devices, such as tension rollers, uncoilers, loop hoists, coil loading trolleys, roll changing trolleys, medium circulating variable frequency pumps, etc. A fault of a frequency converter system of the transmission system will cause a production line to stop, and thus affect the production. Therefore, it is necessary to detect the fault of the frequency converter system in production, so as to find the fault in time and repair it. SUMMARY

[0003] The present application provides a frequency converter system fault detection method and device, which solves the technical problem of how to detect the fault of the frequency converter system.

[0004] In one aspect, the present application provides the following technical solutions:

[0005] A frequency converter system fault detection method, comprising:

[0006] Obtaining an insulation monitoring resistance value of a frequency converter system;

[0007] If the insulation monitoring resistance value is lower than a preset resistance threshold, obtaining a three-phase current vector sum of a frequency converter in the frequency converter system and an actual operating current of a motor;

[0008] Determining whether a motor single-phase or two-phase ground fault occurs in the frequency converter system according to the three-phase current vector sum;

[0009] Determining whether a motor three-phase ground fault occurs in the frequency converter system according to the actual operating current.

[0010] Preferably, the determination of whether the motor single-phase or two-phase ground fault occurs in the frequency converter system according to the three-phase current vector sum comprises:

[0011] If the three-phase current vector sum is greater than a first preset threshold, it is determined that the motor single-phase or two-phase ground fault occurs in the frequency converter system.

[0012] Preferably, the determination of whether the motor three-phase ground fault occurs in the frequency converter system according to the actual operating current comprises:

[0013] Obtaining a current rotating speed of the motor;

[0014] Determining a target operating current corresponding to the current rotating speed according to a preset corresponding relationship between the motor rotating speed and the operating current;

[0015] determine a current threshold according to the target operating current, the current threshold being greater than the target operating current;

[0016] if the actual operating current is greater than the current threshold, determine that the motor three-phase ground fault occurs in the frequency converter system.

[0017] Preferably, the frequency converter system fault detection method further comprises:

[0018] acquire the three-phase offset current of the frequency converter, and if the offset current of at least one phase is greater than a second preset threshold, determine that the internal element of the frequency converter is damaged.

[0019] In another aspect, the embodiments of the present application also provide the following technical solutions:

[0020] A frequency converter system fault detection device comprises:

[0021] a resistance acquisition module configured to acquire an insulation monitoring resistance value of the frequency converter system;

[0022] a current acquisition module configured to acquire a three-phase current vector sum of a frequency converter in the frequency converter system and an actual operating current of a motor if the insulation monitoring resistance value is lower than a preset resistance threshold;

[0023] a first fault determination module configured to determine whether a motor single-phase or two-phase ground fault occurs in the frequency converter system according to the three-phase current vector sum;

[0024] a second fault determination module configured to determine whether a three-phase ground fault occurs in the frequency converter system according to the actual operating current.

[0025] Preferably, the first fault determination module determines whether a motor single-phase or two-phase ground fault occurs in the frequency converter system according to the three-phase current vector sum, comprising:

[0026] if the three-phase current vector sum is greater than a first preset threshold, determine that the motor single-phase or two-phase ground fault occurs in the frequency converter system.

[0027] Preferably, the second fault determination module determines whether a three-phase ground fault occurs in the frequency converter system according to the actual operating current, comprising:

[0028] acquire a current rotating speed of the motor;

[0029] determine a target operating current corresponding to the current rotating speed according to a preset corresponding relationship between the rotating speed and the operating current;

[0030] determine a current threshold according to the target operating current, the current threshold being greater than the target operating current;

[0031] If the actual running current is greater than the current threshold, it is determined that the frequency converter system has a three-phase grounding fault.

[0032] Preferably, the frequency converter system fault detection device further comprises:

[0033] The third fault determination module is configured to acquire a three-phase offset current of the frequency converter, and if the offset current of at least one phase is greater than a second preset threshold, it is determined that an internal element of the frequency converter is damaged.

[0034] In another aspect, the embodiments of the present application also provide the following technical solutions:

[0035] An electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor implements any of the above frequency converter system fault detection methods when executing the program.

[0036] In another aspect, the embodiments of the present application also provide the following technical solutions:

[0037] A computer readable storage medium has a computer program stored thereon, and the computer program implements any of the above frequency converter system fault detection methods when executed by a processor.

[0038] The one or more technical solutions provided by the present application have at least the following technical effects or advantages:

[0039] The present application acquires the insulation monitoring resistance value of the frequency converter system, and if the insulation monitoring resistance value is lower than a preset resistance threshold, it is determined that a motor grounding fault has occurred. The frequency converter system can be further determined whether a motor single-phase or two-phase grounding fault has occurred according to the three-phase current vector of the frequency converter, and whether a motor three-phase grounding fault has occurred according to the actual running current of the motor, so as to realize the detection of the motor grounding fault, and to avoid meaningless acquisition and determination of the three-phase current vector and the actual running current. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0041] Figure 1 The flow chart of the frequency converter system fault detection method in the embodiments of the present application;

[0042] Figure 2 The structural schematic diagram of the frequency converter system fault detection device in the embodiments of the present application. DETAILED DESCRIPTION

[0043] The embodiment of the present application provides a variable frequency converter system fault detection method and device, and solves the technical problem of how to detect the variable frequency converter system fault.

[0044] In order to better understand the technical scheme of the present application, the technical scheme of the present application will be described in detail below in combination with the drawings of the specification and specific embodiments.

[0045] As shown in the figure, the variable frequency converter system fault detection method of the embodiment comprises: Figure 1

[0046] Step S1, obtaining an insulation monitoring resistance value of the variable frequency converter system;

[0047] Step S2, if the insulation monitoring resistance value is lower than a preset resistance threshold value, obtaining a three-phase current vector sum of the variable frequency converter in the variable frequency converter system and an actual running current of the motor;

[0048] Step S3, judging whether the variable frequency converter system has a motor single-phase or two-phase grounding fault according to the three-phase current vector sum;

[0049] Step S4, judging whether the variable frequency converter system has a motor three-phase grounding fault according to the actual running current.

[0050] In the embodiment, the variable frequency converter is used to control the motor to work. It is found in production that the skin of a certain phase of the motor is broken and soaked, which will cause the phase to be grounded, and then cause the insulation value of the phase to be reduced, and then cause the insulation monitoring resistance value of the variable frequency converter system to be reduced, which is usually lower than 40kΩ. If the preset resistance threshold value is set to 40kΩ. Then in step S2, if the insulation monitoring resistance value of the variable frequency converter system is lower than the preset resistance threshold value, it indicates that a motor grounding fault has occurred, and the motor grounding fault includes two cases of a motor single-phase or two-phase grounding fault and a motor three-phase grounding fault, and it is necessary to further judge which grounding fault.

[0051] It is also found in production that under normal circumstances or when the motor is three-phase grounded, the three-phase current vector sum of the variable frequency converter is basically equal to zero, and when the motor is single-phase or two-phase grounded, the three-phase current vector sum of the variable frequency converter will significantly increase, which is manifested as: before the variable frequency converter is enabled, the three-phase current vector sum is usually greater than 6%; after the variable frequency converter is enabled, the three-phase current vector sum is usually greater than 16%, so that whether the variable frequency converter system has a motor single-phase or two-phase grounding fault can be judged according to the three-phase current vector sum. Therefore, step S3 can comprise: if the three-phase current vector sum is greater than a first preset threshold value, it is judged that the variable frequency converter system has a motor single-phase or two-phase grounding fault; wherein before the variable frequency converter is enabled, the first preset threshold value can be 6%; after the variable frequency converter is enabled, the first preset threshold value can be 16%.

[0052] ​As mentioned above, when the motor is three-phase grounded, the sum of the three-phase current vectors of the frequency converter is also substantially equal to zero. Therefore, if the sum of the three-phase current vectors is less than the first preset threshold value, it only indicates that the motor single-phase or two-phase grounding fault does not occur in the frequency converter system, and it cannot be confirmed whether the motor three-phase grounding fault occurs, that is, the sum of the three-phase current vectors cannot be used to determine whether the motor three-phase grounding fault occurs at this time. In the production, it is also found that under normal circumstances, the actual running current of the motor is certain when the load and working condition of the motor are good, and when the motor is three-phase grounded, more current is needed to maintain the balance of the electromagnetic force of the motor because part of the current leaks to the ground, so that the actual running current of the motor will significantly increase when the motor is three-phase grounded, and thus the actual running current of the motor can be used to determine whether the motor three-phase grounding fault occurs in the frequency converter system. For the motor, the actual running current of the motor corresponds to the speed of the motor, and thus step S4 can include: obtaining the current speed of the motor; determining the target running current corresponding to the current speed according to the preset corresponding relationship between the speed of the motor and the running current; determining the current threshold value according to the target running current, and the current threshold value is greater than the target running current; if the actual running current is greater than the current threshold value, it is determined that the motor three-phase grounding fault occurs in the frequency converter system. The target running current is the normal running current that the motor should have under normal circumstances at the current speed of the motor, and the current threshold value can be N times of the target running current, N is a natural number greater than 1, and the actual running current of the motor is greater than the current threshold value, which indicates that the motor three-phase grounding fault occurs. The process of determining the preset corresponding relationship between the speed of the motor and the running current can be: 10 motor speeds between 0-100% and the motor running current corresponding to each motor speed under normal working conditions can be obtained, and 10 pairs of (motor speed, running current) coordinates are fitted to obtain the relationship between the speed of the motor and the running current.

[0053] Of course, the embodiment can also not determine whether the grounding fault occurs according to the insulation monitoring resistance value, but directly determine whether the single-phase or two-phase grounding fault occurs according to the sum of the three-phase current vectors of the frequency converter, and directly determine whether the three-phase grounding fault occurs according to the actual running current of the motor, but meaningless judgment will be performed when no grounding fault occurs, and the specific grounding fault is determined after the insulation monitoring resistance value is lower than the preset resistance threshold value, which can avoid meaningless acquisition of the sum of the three-phase current vectors and the actual running current and meaningless fault judgment.

[0054] In the embodiment, the failure of the frequency converter system also includes damage of an internal element of the frequency converter. When the motor is a book motor, the internal element is a linear optocoupler element for measuring three-phase output current of the motor. In practice, it is found that after the internal element is damaged, at least one phase of the offset current of the frequency converter will significantly increase, usually by more than 100%. Therefore, the frequency converter system failure detection method of the embodiment can further include: obtaining three-phase offset currents of the frequency converter, and if at least one phase of the offset current is greater than a second preset threshold, determining that an internal element of the frequency converter is damaged; wherein the second preset threshold can be 100%.

[0055] As shown in Figure 2 the embodiment also provides a frequency converter system failure detection device, which can include:

[0056] a resistance obtaining module configured to obtain an insulation monitoring resistance value of the frequency converter system;

[0057] a current obtaining module configured to obtain a three-phase current vector sum of the frequency converter and an actual operating current of the motor if the insulation monitoring resistance value is lower than a preset resistance threshold;

[0058] a first failure judgment module configured to determine whether the frequency converter system has a single-phase or two-phase ground fault of the motor according to the three-phase current vector sum;

[0059] a second failure judgment module configured to determine whether the frequency converter system has a three-phase ground fault according to the actual operating current.

[0060] The first failure judgment module configured to determine whether the frequency converter system has a single-phase or two-phase ground fault of the motor according to the three-phase current vector sum can include: if the three-phase current vector sum is greater than a first preset threshold, determining that the frequency converter system has a single-phase or two-phase ground fault of the motor.

[0061] The second failure judgment module configured to determine whether the frequency converter system has a three-phase ground fault according to the actual operating current can include: obtaining a current speed of the motor; determining a target operating current corresponding to the current speed according to a preset corresponding relationship between the motor speed and the operating current; determining a current threshold according to the target operating current, the current threshold being greater than the target operating current; and if the actual operating current is greater than the current threshold, determining that the frequency converter system has a three-phase ground fault.

[0062] Further, the frequency converter system failure detection device can further include a third failure judgment module configured to obtain three-phase offset currents of the frequency converter, and if at least one phase of the offset current is greater than a second preset threshold, determining that an internal element of the frequency converter is damaged.

[0063] Based on the same inventive concept as the variable frequency converter system fault detection method described above, the embodiment also provides an electronic device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of any of the variable frequency converter system fault detection methods described above when executing the program.

[0064] The bus architecture (represented by the bus) can include any number of interconnected buses and bridges, and the bus links various circuits including one or more processors represented by the processor and the memory represented by the memory. The bus can also link various other circuits such as peripheral devices, voltage stabilizers, and power management circuits, which are well known in the art, and therefore, will not be further described herein. The bus interface provides an interface between the bus and the receiver and the transmitter. The receiver and the transmitter can be the same element, i.e., the transceiver, which provides a unit for communicating with various other devices on the transmission medium. The processor is responsible for managing the bus and general processing, while the memory can be used to store data used by the processor when performing operations.

[0065] Since the electronic device introduced in the embodiment is the electronic device used to implement the variable frequency converter system fault detection method in the embodiment, based on the variable frequency converter system fault detection method introduced in the embodiment, those skilled in the art can understand the specific implementation of the electronic device in the embodiment and its various forms, so the implementation of the method in the embodiment by the electronic device will not be described in detail. As long as those skilled in the art implement the electronic device used to implement the variable frequency converter system fault detection method in the embodiment, it belongs to the scope of the present application.

[0066] Based on the same inventive concept as the variable frequency converter system fault detection method described above, the present application also provides a computer readable storage medium, which stores a computer program, and the computer program implements any of the variable frequency converter system fault detection methods when executed by a processor.

[0067] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0068] The present application is described in reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0069] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0070] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0071] While the preferred embodiments of the application have been described, additional variations and modifications can be made to the embodiments by those of skill in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, the attached claims are intended to embrace all such variations and modifications as fall within the scope of the present application.

[0072] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A method for fault detection in a frequency converter system, characterized in that, include: Obtain the insulation monitoring resistance value of the frequency converter system; If the insulation monitoring resistance value is lower than the preset resistance threshold, then the three-phase current vector sum of the inverter in the inverter system and the actual operating current of the motor are obtained; Based on the sum of the three-phase current vectors, determine whether the inverter system has experienced a single-phase or two-phase grounding fault in the motor; Determine whether a three-phase ground fault has occurred in the inverter system based on the actual operating current. The step of determining whether a three-phase ground fault has occurred in the inverter system based on the actual operating current includes: Obtain the current speed of the motor; Based on the preset correspondence between motor speed and operating current, the target operating current corresponding to the current speed is determined; A current threshold is determined based on the target operating current, and the current threshold is greater than the target operating current; If the actual operating current is greater than the current threshold, it is determined that a three-phase grounding fault has occurred in the inverter system.

2. The inverter system fault detection method as described in claim 1, characterized in that, The step of determining whether a single-phase or two-phase ground fault has occurred in the inverter system based on the sum of the three-phase current vectors includes: If the sum of the three-phase current vectors is greater than the first preset threshold, it is determined that the inverter system has experienced a single-phase or two-phase grounding fault.

3. The inverter system fault detection method as described in claim 1, characterized in that, Also includes: The three-phase offset current of the frequency converter is obtained. If the offset current of at least one phase is greater than a second preset threshold, it is determined that the internal components of the frequency converter are damaged.

4. A fault detection device for a frequency converter system, characterized in that, include: The resistance acquisition module is used to acquire the insulation monitoring resistance value of the inverter system; The current acquisition module is used to acquire the three-phase current vector sum of the inverter in the inverter system and the actual operating current of the motor if the insulation monitoring resistance value is lower than a preset resistance threshold. The first fault judgment module is used to determine whether a single-phase or two-phase grounding fault has occurred in the inverter system based on the sum of the three-phase current vectors. The second fault judgment module is used to determine whether a three-phase grounding fault has occurred in the inverter system based on the actual operating current. The second fault determination module determines whether a three-phase ground fault has occurred in the inverter system based on the actual operating current, including: Obtain the current speed of the motor; Based on the preset correspondence between motor speed and operating current, the target operating current corresponding to the current speed is determined; A current threshold is determined based on the target operating current, and the current threshold is greater than the target operating current; If the actual operating current is greater than the current threshold, then the inverter system is determined to have a three-phase ground fault.

5. The inverter system fault detection device as described in claim 4, characterized in that, The first fault judgment module determines whether a single-phase or two-phase ground fault has occurred in the inverter system based on the sum of the three-phase current vectors, including: If the sum of the three-phase current vectors is greater than the first preset threshold, it is determined that the inverter system has experienced a single-phase or two-phase grounding fault.

6. The inverter system fault detection device as described in claim 4, characterized in that, Also includes: The third fault judgment module is used to obtain the three-phase offset current of the frequency converter. If the offset current of at least one phase is greater than the second preset threshold, it is determined that the internal components of the frequency converter are damaged.

7. An electronic device, characterized in that, The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the inverter system fault detection method according to any one of claims 1-3.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the inverter system fault detection method according to any one of claims 1-3.

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