CN115792600A - Automatic alarm method and device for three-phase current measurement errors of motor - Google Patents
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Abstract
The invention discloses an automatic alarm method for measuring errors of three-phase current of a motor, which comprises the following steps: sampling three-phase current data by using a motor, and performing Fourier transform on the three-phase current data which are synchronously acquired; calculating a Fourier sequence module value after three-phase current transformation, and calculating to obtain a complex phase quantity of three-phase power frequency according to the sequence module value; and judging whether the current error of the complex phasor is within an error range or not, and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time. According to the method for detecting the error of the motor three-phase stator current synchronously acquired, the inferior data with the measurement error exceeding the limit can be rejected, the fault misdiagnosis condition caused by the inferior data is avoided, the severity of the measurement error is quantitatively described, the automatic detection before the diagnosis of each section of real-time acquired data is realized on line, the machine halt manual detection which is time-consuming and labor-consuming is avoided, the extra hardware investment is not needed, and the operation cost is reduced.
Description
Technical Field
The invention relates to the technical field of fault detection, in particular to an automatic alarm method and device for a three-phase current measurement error of a motor.
Background
Three-phase stator currents of the motor are converted into weak currents by the current transformers respectively, then converted into voltage signals by the transmitters, converted into digital signals and synchronously transmitted to the database in a 5G communication mode, and a database background program conducts fault diagnosis on corresponding data, so that the method has important significance for fault early warning of equipment.
The existing three-phase stator current is synchronously measured by three sets of measuring devices with the same model, and data in a database is read without judging any measuring error, so that fault misdiagnosis and missed diagnosis are finally caused by data pollution caused by the measuring error of the device.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The present invention has been made in view of the above-mentioned conventional problems.
Therefore, the invention provides an automatic alarm method and device for the three-phase current measurement error of the motor, which solve the problems of data pollution, misdiagnosis and missed diagnosis of the fault caused by the current measurement error of the three-phase stator.
In order to solve the technical problems, the invention provides the following technical scheme:
in a first aspect, an embodiment of the present invention provides an automatic alarm method for a three-phase current measurement error of a motor, including:
carrying out data sampling on three-phase current by using a motor, and carrying out Fourier transform on the three-phase current data which are synchronously acquired;
calculating the Fourier sequence module value after the three-phase current transformation, and calculating to obtain the complex phase quantity of the three-phase power frequency according to the sequence module value;
and judging whether the current error of the complex phasor is within an error range or not, and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time.
The invention relates to a preferable scheme of an automatic alarm method for a three-phase current measurement error of a motor, which comprises the following steps:
converting a large primary side current into a small secondary side current through a current transformer, sending the small secondary side current into a data acquisition card through a wire, and transmitting data to a server through 5G communication by the data acquisition card;
when the transformation ratio between the current transformers is equal and the wiring of the secondary side lead is reliable, the automatic detection is carried out before the fault diagnosis of the three-phase current data collected in real time, otherwise, the measurement error exceeds the design precision.
As a preferred scheme of the automatic alarm method for the three-phase current measurement error of the motor, the method comprises the following steps: performing Fourier transform on the synchronously acquired three-phase current data comprises:
for discrete data, the fourier transform yields a spectrum, represented as:
where f is the independent variable whose frequency is a function of the spectrum, I (f) is a functional expression whose independent variable is a real dependent variable and is a complex number, and T s The sampling period being the sampling frequency f s I (n) is the distance obtained by collectionN data of the discrete current sequence i (1), i (2), i (3),.. N.i (N), N is the data length of the discrete current sequence i (1), i (2), i (3),.. N.i (N), j is an imaginary unit, i.e., j 2 = -1,e is a natural constant, pi is a circumferential ratio.
As a preferred scheme of the automatic alarm method for the three-phase current measurement error of the motor, the method comprises the following steps: and the complex number I (f) corresponds to the frequency f, and the modulus | I (f) | of the complex number I (f) is the amplitude of a component with the frequency f in the current of the discrete data sequence I (0), I (1), I (2), …, I (N).
The invention relates to a preferable scheme of an automatic alarm method for a three-phase current measurement error of a motor, which comprises the following steps: calculating the Fourier sequence module value after three-phase current transformation, comprising:
and the I (f) is a complex sequence, and the maximum value of the modulus value is obtained by the complex sequence I (f) and is represented as:
max{|I(f)|}＝|I(f 1 )|
wherein f is 1 A complex number I (f) of the current at the power frequency 1 ) Spoke angle arg (I (f) 1 ) Is the phase of the current.
The invention relates to a preferable scheme of an automatic alarm method for a three-phase current measurement error of a motor, which comprises the following steps: and calculating to obtain the complex phase quantity of the three-phase power frequency according to the sequence modulus, wherein the calculation comprises the following steps:
when the three phases are symmetrical, the complex phase quantity of the power frequency is expressed as:
wherein, I A (f 1 ) Is a complex phase of the A-phase current power frequency, I B (f 1 ) Is a complex phase of the power frequency of the phase B current, I C (f 1 ) Is the complex phase of the C-phase current power frequency, f 1 The power frequency is, e is a natural constant, j is an imaginary unit, and pi is a circumferential rate.
The invention relates to a preferable scheme of an automatic alarm method for a three-phase current measurement error of a motor, which comprises the following steps: judging whether the current error of the complex phasor is within an error range or not, and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time, wherein the automatic detection comprises the following steps:
if the currents between the measurement loops do not coincide, a small amount of error ε is allowed to exist, expressed as:
wherein, I A (f 1 ) Is a complex phase of the A-phase current power frequency, I B (f 1 ) Is a complex phase of the power frequency of the phase B current, I C (f 1 ) Is the complex phase quantity of the C-phase current power frequency, f 1 Representing power frequency, wherein e is a natural constant, j is an imaginary number unit, pi is a circumferential rate, and epsilon is a given allowable error;
when the measurement error is larger than epsilon, sending out a measurement device error overrun alarm to remind to check the corresponding measurement device, and refusing to use the data to carry out fault diagnosis;
and when the measurement error is not more than epsilon, the measured current error is within the error range, and the data is continuously sampled to realize fault detection.
In a second aspect, an embodiment of the present invention provides an automatic alarm device for a three-phase current measurement error of a motor, including:
the data acquisition module is used for sampling three-phase current data by using the motor and performing Fourier transform on the synchronously acquired three-phase current data;
the data processing module is used for calculating the Fourier sequence modulus after the three-phase current transformation and calculating to obtain the complex phase quantity of the three-phase power frequency according to the sequence modulus;
and the fault diagnosis module is used for judging whether the current error of the complex phasor is within an error range or not and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time.
In a third aspect, an embodiment of the present invention provides a computing device, including:
a memory and a processor;
the memory is configured to store computer-executable instructions, and the processor is configured to execute the computer-executable instructions, so that when the one or more programs are executed by the one or more processors, the one or more processors implement the event-driven configuration-based scene management method according to any embodiment of the present invention.
In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, the method for managing a configuration scene based on event driving is implemented.
Compared with the prior art, the invention has the beneficial effects that: according to the method for detecting the error of the synchronously acquired motor three-phase stator current, the inferior data with the over-limit measurement error can be eliminated, the fault misdiagnosis condition caused by the inferior data is avoided, the severity of the measurement error is quantitatively described, the automatic detection before the diagnosis of each section of real-time acquired data is realized on line, the shutdown manual detection which wastes time and labor is avoided, the additional hardware investment is not needed, and the operation cost is reduced.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
fig. 1 is a schematic flow chart of a method and an apparatus for automatically alarming measurement errors of three-phase currents of a motor according to an embodiment of the present invention;
fig. 2 is a complex-phase representation diagram of three-phase stator currents of a method and an apparatus for automatic alarming of three-phase current measurement errors of a motor according to an embodiment of the present invention;
fig. 3 is a schematic diagram of the method and apparatus for automatically alarming measurement error of three-phase current of an electric motor according to an embodiment of the present invention for collecting three-phase current of the electric motor on line;
fig. 4 is a fast fourier transform spectrum diagram of an automatic alarm method and device for three-phase current measurement errors of a motor according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as specifically described herein, and it will be appreciated by those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the present invention and that the present invention is not limited by the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
The present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially in general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected" and "connected" in the present invention are to be construed broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
Referring to fig. 1 to 2, a first embodiment of the present invention provides an automatic alarm method for three-phase current measurement errors of a motor, including:
s1, sampling three-phase current data by using a motor, and performing Fourier transform on the three-phase current data which are synchronously acquired;
furthermore, a large current on the primary side is converted into a small current on the secondary side through a current transformer, the small current is sent into a data acquisition card through a lead, and the data is transmitted to a server through 5G communication by the data acquisition card;
when the transformation ratio between the current transformers is equal and the wiring of the secondary side lead is reliable, the automatic detection is carried out before the fault diagnosis of the three-phase current data collected in real time, otherwise, the measurement error exceeds the design precision.
It should be noted that, data stored in the database through synchronous sampling and transmission is actually secondary side current obtained by measuring three-phase current of a motor stator with three symmetrical phases through a current transformer, the three-phase current is measured through three sets of different devices with the same model, if the three-phase synchronous data stored in the database is also three-phase symmetrical, the transformation ratio among the three sets of current transformers is equal, the sampling of the current transformers is credible, otherwise, the sampling is not credible, and the sampling device needs to be checked.
Further, the fourier transforming the synchronously acquired three-phase current data comprises:
for discrete data, the fourier transform yields a spectrum, represented as:
where f is the independent variable whose frequency is a function of the spectrum, I (f) is a functional expression whose independent variable is a real dependent variable and is a complex number, and T s The sampling period being the sampling frequency f s The reciprocal of (i) is the nth data of the discrete current sequence i (1), i (2), i (3),.. The N, N is the data length of the discrete current sequence i (1), i (2), i (3),. The N, j is the imaginary unit, i.e. j 2 = -1,e is a natural constant, pi is a circumferential ratio.
It should be noted that the frequency spectrum visually displays the transformation result data, which facilitates further judgment. In circuit theory, for convenience of expression, three elements (amplitude, frequency, phase) are generally expressed as phasors, and further, phasors are expressed as complex numbers:
wherein, the first and the second end of the pipe are connected with each other,
are A, B, C three-phase stator current phasors, I m Is the amplitude of the alternating current, pi is the circumferential rate, f is the power frequency, t is the time,
the phase of the a-phase alternating current at t =0, j being an imaginary unit.
It should also be noted that the instantaneous value i of the phase A current A (t) corresponds to the phase A current complex phase
In the projection of a real axis, B, C two-phase implementation method is the same as A phase; due to the fact that
The three current complex phasors rotate around the origin on the complex plane at the same angular velocity ω =2 π f, so that the projections on the real axis each constitute an alternating three-phase stator current.
Furthermore, the complex I (f) corresponds to the frequency f, and the modulus | I (f) | of the complex I (f) is the amplitude of the component with the frequency f in the discrete data sequence I (0), I (1), I (2), …, I (N) current.
S2, calculating Fourier sequence module values after three-phase current transformation, and calculating to obtain complex phase of three-phase power frequency according to the sequence module values;
further, calculating a Fourier sequence module value after three-phase current transformation comprises the following steps:
i (f) is a complex sequence, and the modulus is maximized for complex sequence I (f) as:
max{|I(f)|}＝|I(f 1 )|
wherein f is 1 A complex number I (f) of the current at the power frequency 1 ) Spoke angle arg (I (f) 1 ) Is the phase of the current.
Note that, for the complex number I (f) 1 ) Let us express it in a triangular manner as I (f) 1 ) = I (cos θ + jssin θ), where I = | I (f) 1 ) In which θ is defined as the complex number I (f) 1 ) The argument of (d) is denoted arg (I (f) 1 ))。
Furthermore, the calculation of the complex phasor of the three-phase power frequency according to the sequence modulus includes:
when the three phases are symmetrical, the complex phase quantity of the power frequency is expressed as:
wherein, I A (f 1 ) Is a complex phase of the A-phase current power frequency, I B (f 1 ) Is a complex phase quantity of the power frequency of the phase B current, I C (f 1 ) Power frequency of C-phase currentComplex phase of (a), (b), (c) and (d) 1 The power frequency is, e is a natural constant, j is an imaginary unit, and pi is a circumferential rate.
S3, judging whether the current error of the complex phasor is within an error range or not, and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time;
furthermore, judging whether the current error of the complex phasor is within an error range, and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time, wherein the automatic detection comprises the following steps:
if the currents between the measurement loops do not coincide, a small amount of error ε is allowed to exist, expressed as:
wherein, I A (f 1 ) Is a complex phase of the A-phase current power frequency, I B (f 1 ) Is a complex phase of the power frequency of the phase B current, I C (f 1 ) Is the complex phase quantity of the C-phase current power frequency, f 1 Representing power frequency, wherein e is a natural constant, j is an imaginary number unit, pi is a circumferential rate, and epsilon is a given allowable error;
when the measurement error is larger than epsilon, sending out a measurement device error overrun alarm to remind the corresponding measurement device to be checked, and refusing to use data to carry out fault diagnosis;
and when the measurement error is not more than epsilon, the measured current error is within the error range, and the data is continuously sampled to realize fault detection.
It should be noted that when there is a relative error in the measurement loop, three-phase perfect symmetry is no longer satisfied. The current phasors of different phases have different amplitudes, and the phase difference is not equal to 120 degrees or both.
As known from the equivalent circuit of the current transformer, for an ideal current transformer (various losses are 0), a primary side current (a certain phase stator current of the motor) and a secondary side current (the current is converted into a voltage digital signal by a transducer and then transmitted to a database for storage) are in the same phase, and a ratio is a constant, that is, a fixed parameter current ratio of the current transformer. And expressing the ratio by phasor, wherein the ratio of the current phasors of the first side and the second side is a real constant, and the ratio is the fixed parameter current ratio of the current transformer. In the implementation process, the current transformer cannot achieve 0 loss, in the operation process, the loss is increased due to factors such as oxidation and loose connection, the ratio of phasor representation is not real number but complex number, and the ratio of the imaginary part represents the transformation ratio distortion degree generated due to the loss.
It should also be noted that, considering that the measurement devices that are synchronously acquired cannot be completely identical, resulting in necessary error margins and measurement error allowance epsilon, epsilon =0.01 is generally taken, and actually, appropriate adjustment is performed according to the accuracy requirements and the overhaul feedback of the measurement devices.
The above is a schematic scheme of the automatic alarm method for the three-phase current measurement error of the motor in the embodiment. It should be noted that the technical scheme of the automatic alarm device for the three-phase current measurement error of the motor and the technical scheme of the automatic alarm method for the three-phase current measurement error of the motor belong to the same concept, and details of the technical scheme of the automatic alarm device for the three-phase current measurement error of the motor in the embodiment, which are not described in detail, can be referred to the description of the technical scheme of the automatic alarm method for the three-phase current measurement error of the motor.
The motor three-phase current measuring error automatic alarm device in this embodiment includes:
the data acquisition module is used for sampling the three-phase current data by using the motor and carrying out Fourier transform on the three-phase current data which are synchronously acquired;
the data processing module is used for calculating a Fourier sequence module value after three-phase current transformation and calculating to obtain complex phase quantity of three-phase power frequency according to the sequence module value;
and the fault diagnosis module is used for judging whether the current error of the complex phasor is within an error range or not and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time.
The embodiment further provides a computing device, which is suitable for the situation of the automatic alarm method for the three-phase current measurement error of the motor, and the method comprises the following steps:
a memory and a processor; the memory is used for storing computer executable instructions, and the processor is used for executing the computer executable instructions to realize the automatic alarm method for the three-phase current measurement errors of the motor provided by the embodiment.
The computer device may be a terminal comprising a processor, a memory, a communication interface, a display screen and an input means connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used for carrying out wired or wireless communication with an external terminal, and the wireless communication can be realized through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on a shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.
The present embodiment also provides a storage medium, on which a computer program is stored, which when executed by a processor, implements the method for implementing automatic alarm of measurement errors of three-phase currents of an electric motor as set forth in the above embodiments.
The storage medium proposed in this embodiment belongs to the same inventive concept as the data storage method proposed in the above embodiment, and the technical details that are not described in detail in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.
Example 2
Referring to fig. 3 to 4, a second embodiment of the present invention is shown, which is scientifically demonstrated according to different situations to verify the beneficial effects.
Taking a certain motor as an example, a large primary side current is converted into a small secondary side current through a current transformer, the small secondary side current is sent into a data acquisition card B1 through a lead, and the data is transmitted to a server through 5G communication by the B1. And (3) obtaining a frequency spectrum by FFT (fast Fourier transform) on the acquired data, setting the power frequency of the obtained result to be 50Hz, and respectively setting the moduli of the three-phase current phasors as follows:
the error result is:
errors are all smaller than 0.01, within an error allowable range, the complex number models are in accordance with the standard, as shown in a combined graph 3, amplitude-frequency curves visually display corresponding complex numbers through different frequencies, amplitude-frequency curves visually display corresponding argument through different frequencies, further judgment is carried out, a measuring device meets the precision requirement, no alarm is given, and one-time detection is completed.
If the A-phase current transformer of a certain motor is replaced by an old element with unqualified same type, the acquired data is processed by FFT to obtain a frequency spectrum, the power frequency of the obtained result is set to be 50Hz, and the modulus of three-phase current phasors of the obtained result is respectively as follows:
the error result is:
and the errors are all larger than 0.01, the criterion is not met, the judgment is unqualified, and the motor automatically alarms and measures an error overrun signal to finish primary detection.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (10)
1. An automatic alarm method for measuring errors of three-phase currents of a motor is characterized by comprising the following steps:
carrying out data sampling on three-phase current by using a motor, and carrying out Fourier transform on the three-phase current data which are synchronously acquired;
calculating a Fourier sequence modulus after the three-phase current transformation, and calculating to obtain a complex phase quantity of the three-phase power frequency according to the sequence modulus;
and judging whether the current error of the complex phasor is within an error range or not, and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time.
2. The method for automatically alarming the measurement error of the three-phase current of the motor as claimed in claim 1, comprising the following steps:
converting a large current on the primary side into a small current on the secondary side through a current transformer, sending the small current into a data acquisition card through a lead, and transmitting data to a server through 5G communication by the data acquisition card;
when the transformation ratio between the current transformers is equal and the wiring of the secondary side lead is reliable, the automatic detection is carried out before the fault diagnosis of the three-phase current data collected in real time, otherwise, the measurement error exceeds the design precision.
3. The method as claimed in claim 2, wherein the fourier transform of the three-phase current data collected synchronously comprises:
for discrete data, the fourier transform yields a spectrum, represented as:
where f is the independent variable whose frequency is a function of the spectrum, I (f) is a functional expression whose independent variable is a real dependent variable and is a complex number, and T s The sampling period being the sampling frequency f s The reciprocal of (i) is the nth data of the discrete current sequence i (1), i (2), i (3),.. The N, N is the data length of the discrete current sequence i (1), i (2), i (3),. The N, j is the imaginary unit, i.e. j 2 = 1,e is a natural constant, and pi is the circumferential ratio.
4. The method for automatically alarming the measurement error of the three-phase current of the motor as claimed in claim 3, further comprising:
and the complex number I (f) corresponds to the frequency f, and the modulus | I (f) | of the complex number I (f) is the amplitude of a component with the frequency f in the current of the discrete data sequence I (0), I (1), I (2), …, I (N).
5. The automatic alarm method for the measurement errors of the three-phase current of the motor as claimed in claim 4, wherein the calculation of the modular values of the Fourier series after the transformation of the three-phase current comprises:
and the I (f) is a complex sequence, and the maximum value of the modulus value is obtained by the complex sequence I (f) and is represented as:
max{|I(f)|}＝|I(f 1 )|
wherein, f 1 A complex number I (f) of the current at the power frequency 1 ) Spoke angle arg (I (f) 1 ) Is the phase of the current.
6. The method as claimed in claim 5, wherein the calculating of the complex phase of the three-phase power frequency according to the sequence modulus comprises:
when three phases are symmetrical, the complex phase quantity of the power frequency is expressed as:
wherein, I A (f 1 ) Is a complex phase quantity of the power frequency of the A-phase current,I B (f 1 ) Is a complex phase of the power frequency of the phase B current, I C (f 1 ) Is the complex phase of the C-phase current power frequency, f 1 The power frequency is, e is a natural constant, j is an imaginary unit, and pi is a circumferential rate.
7. The method for automatically alarming the measurement error of the three-phase current of the motor as claimed in claim 6, wherein the step of judging whether the current error of the complex phasor is within an error range or not and realizing the automatic detection before the fault diagnosis of the three-phase current data collected in real time comprises the following steps:
if the currents between the measurement loops do not coincide, a small amount of error ε is allowed to exist, expressed as:
wherein, I A (f 1 ) Is a complex phase of the A-phase current power frequency, I B (f 1 ) Is a complex phase quantity of the power frequency of the phase B current, I C (f 1 ) Is the complex phase of the C-phase current power frequency, f 1 Representing power frequency, wherein e is a natural constant, j is an imaginary number unit, pi is a circumference ratio, and epsilon is a given allowable error;
when the measurement error is larger than epsilon, sending out a measurement device error overrun alarm to remind to check the corresponding measurement device, and refusing to use the data to carry out fault diagnosis;
and when the measurement error is not more than epsilon, the measured current error is within the error range, and the data is continuously sampled to realize fault detection.
8. An automatic alarm device for measuring errors of three-phase currents of a motor is characterized by comprising:
the data acquisition module is used for sampling the three-phase current data by using the motor and carrying out Fourier transform on the synchronously acquired three-phase current data;
the data processing module is used for calculating the Fourier sequence modulus after the three-phase current transformation and calculating to obtain the complex phase quantity of the three-phase power frequency according to the sequence modulus;
and the fault diagnosis module is used for judging whether the current error of the complex phasor is within an error range or not and realizing automatic detection before fault diagnosis of the three-phase current data acquired in real time.
9. A computing device, comprising:
a memory and a processor;
the memory is used for storing computer executable instructions, the processor is used for executing the computer executable instructions, and the computer executable instructions are executed by the processor to realize the steps of the automatic alarm method for the three-phase current measurement error of the motor according to any one of claims 1 to 7.
10. A computer readable storage medium storing computer executable instructions which, when executed by a processor, implement the steps of the method for automatic warning of errors in the measurement of three phase currents of an electric motor according to any one of claims 1 to 7.
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