Harmonic detection method, device and equipment based on dynamic fundamental frequency and storage medium

Abstract

The invention relates to the technical field of electric energy quality analysis, in particular to a harmonic detection method, device and equipment based on dynamic fundamental frequency and a storage medium. Then determining a first approximate fundamental frequency signal according to the minimum calculation time length and the zero crossing number of the sampling signals in the minimum calculation time length; performing Fourier transform on the plurality of first voltage sampling signals according to the first approximate fundamental frequency signal to obtain a maximum amplitude, and determining a first fundamental frequency signal; and finally, according to the first fundamental frequency signal, performing Fourier transform on the plurality of first voltage sampling signals for multiple times to obtain a plurality of low-frequency harmonic amplitudes, a plurality of low-frequency harmonic phases, a plurality of high-order harmonic amplitudes and a plurality of high-order harmonic phases. According to the invention, the fundamental frequency signal is dynamically detected, so that the harmonic quantity detection is more accurate, and the harmonic analysis result is more reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of power quality analysis, and in particular to a harmonic detection method, device, equipment and storage medium based on dynamic fundamental frequency. Background Art

[0002] As rectification technology continues to mature, the operating frequencies of devices such as speed drives, air conditioners, and energy storage converters are adjusted in real time according to application needs. Taking speed drives as an example, they are mainly used in induction motor adjustment and control. The frequency of speed drive operation is related to load processing and inverter equipment. At this time, the base frequency of the speed drive is not the commonly believed 50Hz.

[0003] The detection method used by the existing power quality detection device still uses the set frequency as the base frequency. For example, countries around the world mainly design based on IEC 61000-4-7 and 61000-4-30 issued by IEC (International Electrotechnical Commission). According to this standard, the harmonic test is performed using discrete Fourier transform, specifically, 50Hz (or 60Hz) is used as the base frequency for calculation.

[0004] When the fundamental frequency of the test object is no longer 50Hz, the harmonics detected and calculated are no longer correct. When harmonic analysis and harmonic suppression measures are formulated based on incorrect data, the results will be biased to a certain extent.

[0005] Based on this, it is necessary to develop a harmonic detection method based on dynamic fundamental frequency. The use of a variable fundamental frequency harmonic detection method can improve the accuracy of harmonic measurement and the reliability of analysis. Summary of the invention

[0006] The embodiments of the present invention provide a harmonic detection method, device, equipment and storage medium based on a dynamic fundamental frequency, which are used to solve the problem of inaccurate harmonic detection results when a fixed fundamental frequency is used for harmonic detection in the prior art.

[0007] In a first aspect, an embodiment of the present invention provides a harmonic detection method based on a dynamic fundamental frequency, comprising:

[0008] Acquire a plurality of first voltage sampling signals;

[0009] Determine a first approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time;

[0010] Determine a first baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal;

[0011] According to the first baseband signal, the multiple first voltage sampling signals are subjected to multiple Fourier transforms to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes, and multiple high-order harmonic phases.

[0012] In a possible implementation, determining the first approximate baseband signal according to the minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time includes:

[0013] Get the minimum calculation time;

[0014] Determining the number of zero-crossing sampling signals in the plurality of first voltage sampling signals according to the sampling frequency of the first voltage sampling signal and the minimum calculation time;

[0015] The first approximate baseband signal is determined according to a first formula, wherein the first formula is:

[0016]

[0017] Wherein, Fn0 is the first approximate baseband signal, N is the number of zero crossings of the sampling signal within the minimum calculation time, and tw is the minimum calculation time.

[0018] In a possible implementation, determining the first baseband signal according to the maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal includes:

[0019] Get the step adjustment amount;

[0020] Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length;

[0021] Performing Fourier transform on the first sampling array according to the first approximate baseband signal;

[0022] Add the amplitude obtained by Fourier transform to the amplitude queue;

[0023] If the first approximate baseband signal does not exceed the baseband threshold, adjusting the first approximate baseband signal according to the step adjustment amount, and jumping to the step of performing Fourier transform on the first sampling array according to the first approximate baseband signal;

[0024] Otherwise, selecting the maximum amplitude from the amplitude queue as the target amplitude;

[0025] A first approximate baseband signal corresponding to the target amplitude is used as the first baseband signal.

[0026] In a possible implementation, performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of low-frequency harmonic amplitudes and a plurality of low-frequency harmonic phases includes:

[0027] Determine a plurality of frequency-multiplied signals according to the first baseband signal, wherein the frequency-multiplied signals are integer multiples of the frequency of the first baseband signal;

[0028] Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length;

[0029] erroneously extracting a frequency-multiplied signal from the plurality of frequency-multiplied signals as a frequency-multiplied signal to be processed;

[0030] Performing Fourier transform on multiple sampling arrays except the first sampling array according to the frequency-doubled signal to be processed to obtain low-frequency harmonic amplitude and low-frequency harmonic phase;

[0031] If the traversal of the multiple frequency-multiplied signals is not completed, the process jumps to the step of traversingly taking out a frequency-multiplied signal from the multiple frequency-multiplied signals as the frequency-multiplied signal to be processed.

[0032] In a possible implementation, performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of high-order harmonic amplitudes and a plurality of high-order harmonic phases includes:

[0033] Get frequency interval;

[0034] Determine a plurality of high-frequency signals according to the first baseband signal and the frequency interval, wherein the high-frequency signals are two adjacent high-frequency signals separated by the frequency interval;

[0035] Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length;

[0036] erroneously extracting high-frequency signals from the plurality of high-frequency signals as high-frequency-multiplied signals to be processed;

[0037] Performing Fourier transform on multiple sampling arrays except the first sampling array according to the high-frequency signal to be processed to obtain high-frequency harmonic amplitude and high-frequency harmonic phase;

[0038] If the traversal of the multiple high-frequency signals is not completed, the process jumps to the step of traversally extracting a high-frequency signal from the multiple high-frequency signals as the high-frequency signal to be processed.

[0039] In a possible implementation, after performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of low-frequency harmonic amplitudes, a plurality of low-frequency harmonic phases, a plurality of high-order harmonic amplitudes, and a plurality of high-order harmonic phases, the method includes:

[0040] Acquire a plurality of second voltage sampling signals, wherein the time periods corresponding to the plurality of second voltage sampling signals are connected to the time periods corresponding to the plurality of first voltage sampling signals;

[0041] Determine a second approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time;

[0042] Determine a second baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of second voltage sampling signals using the second approximate baseband signal;

[0043] If the deviation between the second baseband signal and the first baseband signal is less than a threshold, performing multiple Fourier transforms on the multiple second voltage sampling signals according to the first baseband signal to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes, and multiple high-order harmonic phases;

[0044] Otherwise, the harmonic root mean square of multiple harmonic sampling values ​​is calculated to obtain the steady-state harmonic amplitude.

[0045] In a possible implementation, calculating the harmonic root mean square of a plurality of harmonic sampling values ​​to obtain a steady-state harmonic amplitude includes:

[0046] The steady-state harmonic amplitude is determined according to a second formula, wherein the second formula is:

[0047]

[0048] Where U h,Fn1 is the hth steady-state harmonic amplitude, M is the total number of multiple second voltage sampling signals, u m is the mth harmonic sampling value.

[0049] In a second aspect, an embodiment of the present invention provides a harmonic detection device based on a dynamic fundamental frequency, which is used to implement the harmonic detection method based on a dynamic fundamental frequency as described in the first aspect or any possible implementation of the first aspect, and the harmonic detection device based on a dynamic fundamental frequency includes:

[0050] A sampling signal acquisition module, used to acquire a plurality of first voltage sampling signals;

[0051] A baseband signal initial determination module, used to determine a first approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time;

[0052] A baseband signal determination module, configured to determine a first baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal;

[0053] as well as,

[0054] The harmonic detection module is used to perform multiple Fourier transforms on the multiple first voltage sampling signals according to the first baseband signal to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes and multiple high-order harmonic phases.

[0055] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the computer program, it implements the steps of the method described in the first aspect or any possible implementation method of the first aspect.

[0056] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in the first aspect or any possible implementation of the first aspect are implemented.

[0057] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0058] The embodiment of the present invention discloses a harmonic detection method based on dynamic fundamental frequency, which first obtains multiple first voltage sampling signals; then determines the first approximate fundamental frequency signal according to the minimum calculation time and the number of zero crossings of the sampling signal within the minimum calculation time; then determines the first fundamental frequency signal according to the maximum amplitude obtained by Fourier transforming the multiple first voltage sampling signals with the first approximate fundamental frequency signal; finally, according to the first fundamental frequency signal, performs multiple Fourier transforms on the multiple first voltage sampling signals to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes and multiple high-order harmonic phases. The embodiment of the present invention segments the voltage sampling signal, determines the approximate fundamental frequency signal based on the number of zero crossing sampling signals within a preset time, and then determines a more accurate fundamental frequency signal by Fourier transforming the approximate fundamental frequency signal, extracts the harmonic amplitude and phase by segmenting the fundamental frequency signal, and because the fundamental frequency signal is dynamically detected, the harmonic quantity detection is more accurate and the harmonic analysis result is more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0060] Figure 1 is a flow chart of a harmonic detection method based on dynamic fundamental frequency provided by an embodiment of the present invention;

[0061] Figure 2 is a schematic diagram of a first baseband signal determination process provided by an embodiment of the present invention;

[0062] Figure 3 It is a functional block diagram of a harmonic detection device based on dynamic fundamental frequency provided by an embodiment of the present invention;

[0063] Figure 4 It is a functional block diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0064] In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, and methods are omitted so as not to obscure the description of the present invention with unnecessary details.

[0065] In order to make the purpose, technical solutions and advantages of the present invention more clear, a specific implementation method will be described below in conjunction with the accompanying drawings.

[0066] The following is a detailed description of an embodiment of the present invention. This example is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0067] Figure 1 A flow chart of a harmonic detection method based on dynamic fundamental frequency provided in an embodiment of the present invention.

[0068] like Figure 1 As shown, it shows a flowchart of the implementation of the harmonic detection method based on dynamic fundamental frequency provided by an embodiment of the present invention, which is described in detail as follows:

[0069] In step 101, a plurality of first voltage sampling signals are acquired.

[0070] Exemplarily, in order to detect harmonic data, the signal is first sampled by an AD (analog-to-digital conversion) chip, and the chip sampling frequency is set to Fs. Fs is usually 1024 or 512 sampling points / cycle. Taking a 50Hz system as an example, each cycle is 1 / 50s, that is, 1024 or 512 sampling points can be used every 0.02s. According to IEC 61000-4-7 and 61000-4-30, for low-frequency signals, 40th harmonics can be calculated by discrete Fourier transform, and the maximum frequency of the low-frequency harmonics to be detected is set to Fsup1. Those exceeding Fsup1 are usually called ultra-high harmonics, and are calculated using the harmonic group method, and the highest frequency exceeding the subharmonic group is set to Fsup2.

[0071] Then the sampling calculation is carried out, and the calculation steps are discussed in detail later.

[0072] In step 102, a first approximate baseband signal is determined according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time.

[0073] In some implementations, determining the first approximate baseband signal according to the minimum calculation duration and the number of zero crossings of the sampled signal within the minimum calculation duration includes:

[0074] Get the minimum calculation time;

[0075] Determining the number of zero-crossing sampling signals in the plurality of first voltage sampling signals according to the sampling frequency of the first voltage sampling signal and the minimum calculation time;

[0076] The first approximate baseband signal is determined according to a first formula, wherein the first formula is:

[0077]

[0078] Wherein, Fn0 is the first approximate baseband signal, N is the number of zero crossings of the sampling signal within the minimum calculation time, and tw is the minimum calculation time.

[0079] Exemplarily, the minimum calculation time tw is determined:

[0080] In one application scenario, the recommended method of IEC 61000-4-7 is used to take 10 cycles as the minimum calculation length. When the base frequency is 50 Hz, the duration of 10 cycles is 0.2 s. Considering that in most industrial applications, the change from one mode to another can be completed in 0.2 s, that is, small changes can be captured, so tw is set to 0.2 s.

[0081] Determine the approximate baseband signal Fn0 of the detection object:

[0082] Since the electrical signal is a sinusoidal signal, each cycle has two zero-value points. Assuming that the number of zero-value points detected in the first tw period is N within TW (TW is the time length of multiple sampling voltage signals), the approximate baseband signal Fn0 is obtained by the following formula:

[0083]

[0084] Wherein, Fn0 is the first approximate baseband signal, N is the number of zero crossings of the sampling signal within the minimum calculation time, and tw is the minimum calculation time.

[0085] In step 103, a first baseband signal is determined according to a maximum amplitude obtained by performing Fourier transform on the plurality of first voltage sampling signals using the first approximate baseband signal.

[0086] Exemplarily, determining the first baseband signal according to the maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal includes:

[0087] Get the step adjustment amount;

[0088] Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length;

[0089] Performing Fourier transform on the first sampling array according to the first approximate baseband signal;

[0090] Add the amplitude obtained by Fourier transform to the amplitude queue;

[0091] If the first approximate baseband signal does not exceed the baseband threshold, adjusting the first approximate baseband signal according to the step adjustment amount, and jumping to the step of performing Fourier transform on the first sampling array according to the first approximate baseband signal;

[0092] Otherwise, selecting the maximum amplitude from the amplitude queue as the target amplitude;

[0093] A first approximate baseband signal corresponding to the target amplitude is used as the first baseband signal.

[0094] Exemplarily, the minimum calculation duration number J of the sampling signal is determined:

[0095] The voltage signal is sampled by the AD (analog-to-digital conversion) chip. Assuming the sampling voltage signal time length is TW, the minimum calculation time length J of the sampling signal is calculated by the following formula:

[0096]

[0097] Then, discrete Fourier transform is performed with the fundamental frequency Fn0, and the amplitude of harmonics lower than Fsup1 can be calculated by discrete Fourier transform. Since the fundamental frequency Fn1 is the main frequency of work, the amplitude corresponding to the fundamental frequency Fn1 after discrete Fourier transform is the largest, and Fn1 is determined by this method.

[0098] Specifically, if Figure 2 As shown, the plurality of first voltage sampling signals are divided into a plurality of sampling arrays 202 according to the minimum calculation time, and then, the first sampling array 202 is Fourier transformed according to the first approximate baseband signal 201; then, the amplitude obtained by the Fourier transform is added to the amplitude queue 203; if the first approximate baseband signal 201 does not exceed the baseband threshold 204, the first approximate baseband signal 201 is adjusted according to the step adjustment amount 205 (for example, the first approximate baseband signal 201 is increased according to the step adjustment amount 205), and the process jumps to the step of performing Fourier transform on the first sampling array 202 according to the first approximate baseband signal 201; otherwise, the amplitude with the largest value is selected from the amplitude queue 203 as the target amplitude; and the first approximate baseband signal corresponding to the target amplitude is used as the first baseband signal.

[0099] Through the above steps, a relatively accurate baseband signal that meets actual usage requirements is obtained.

[0100] In step 104, multiple Fourier transforms are performed on the multiple first voltage sampling signals according to the first baseband signal to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes, and multiple high-order harmonic phases.

[0101] In some implementations, performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of low-frequency harmonic amplitudes and a plurality of low-frequency harmonic phases includes:

[0102] Determine a plurality of frequency-multiplied signals according to the first baseband signal, wherein the frequency-multiplied signals are integer multiples of the frequency of the first baseband signal;

[0103] Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length;

[0104] erroneously extracting a frequency-multiplied signal from the plurality of frequency-multiplied signals as a frequency-multiplied signal to be processed;

[0105] Performing Fourier transform on multiple sampling arrays except the first sampling array according to the frequency-multiplied signal to be processed to obtain low-frequency harmonic amplitude and low-frequency harmonic phase;

[0106] If the traversal of the multiple frequency-multiplied signals is not completed, the process jumps to the step of traversingly taking out a frequency-multiplied signal from the multiple frequency-multiplied signals as the frequency-multiplied signal to be processed.

[0107] In some implementations, performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of high-order harmonic amplitudes and a plurality of high-order harmonic phases includes:

[0108] Get frequency interval;

[0109] Determine a plurality of high-frequency signals according to the first baseband signal and the frequency interval, wherein the high-frequency signals are two adjacent high-frequency signals separated by the frequency interval;

[0110] Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length;

[0111] erroneously extracting high-frequency signals from the plurality of high-frequency signals as high-frequency-multiplied signals to be processed;

[0112] Performing Fourier transform on multiple sampling arrays except the first sampling array according to the high-frequency signal to be processed to obtain high-frequency harmonic amplitude and high-frequency harmonic phase;

[0113] If the traversal of the multiple high-frequency signals is not completed, the process jumps to the step of traversally extracting a high-frequency signal from the multiple high-frequency signals as the high-frequency signal to be processed.

[0114] Exemplarily, low frequency harmonics are calculated:

[0115] In the J-1 tws following TW, with Fn as the fundamental frequency, discrete Fourier transform is used to calculate the harmonic amplitudes and phases of 2*Fn, 3*Fn.....Fsup1 with Fn as the interval.

[0116] Calculate higher harmonics:

[0117] In the subsequent J-1 tws of TW, with Fn as the fundamental frequency, discrete Fourier transform is used to calculate Fsup1 at fixed intervals within the frequency band from Fsup1 to Fsup2. For example, the fixed interval is 200 Hz, and the harmonic amplitudes and phases of Fsup1+200, Fsup1+400.....Fsup2 are obtained.

[0118] In some embodiments, after performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of low-frequency harmonic amplitudes, a plurality of low-frequency harmonic phases, a plurality of high-order harmonic amplitudes, and a plurality of high-order harmonic phases, the method includes:

[0119] Acquire a plurality of second voltage sampling signals, wherein the time periods corresponding to the plurality of second voltage sampling signals are connected to the time periods corresponding to the plurality of first voltage sampling signals;

[0120] Determine a second approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time;

[0121] Determine a second baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of second voltage sampling signals using the second approximate baseband signal;

[0122] If the deviation between the second baseband signal and the first baseband signal is less than a threshold, performing multiple Fourier transforms on the multiple second voltage sampling signals according to the first baseband signal to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes, and multiple high-order harmonic phases;

[0123] Otherwise, the harmonic root mean square of multiple harmonic sampling values ​​is calculated to obtain the steady-state harmonic amplitude.

[0124] In some implementations, calculating the harmonic root mean square of a plurality of harmonic sampling values ​​to obtain a steady-state harmonic amplitude includes:

[0125] The steady-state harmonic amplitude is determined according to a second formula, wherein the second formula is:

[0126]

[0127] Where U h,Fn1 is the hth steady-state harmonic amplitude, M is the total number of multiple second voltage sampling signals, u m is the mth harmonic sampling value.

[0128] Exemplarily, after sampling the next voltage signal TW1, the fundamental frequency Fn2 is calculated according to steps 102 and 103. If the difference meets the requirements of the third formula, the harmonics of the TW1 period are calculated according to step 104 using Fn1. It can be 0.5, or adjusted according to the signal fluctuation. The third formula is:

[0129] |Fn1-Fn1|<ζ

[0130] When the above formula is not satisfied in the subsequent period, refer to the IEC 61000-4-7 method to calculate the hth steady-state harmonic amplitude U by RMS h,Fn1 .

[0131] It should be noted that if the continuous calculation time with Fn1 as the fundamental frequency exceeds 1 minute, a harmonic steady-state value is counted at intervals of 1 minute. Assuming that the continuous calculation time with Fn1 as the fundamental frequency is 5 minutes, 5 steady-state harmonic values ​​can be obtained.

[0132]

[0133] Where U h,Fn1 is the hth steady-state harmonic amplitude, M is the total number of multiple second voltage sampling signals, u m is the mth harmonic sampling value.

[0134] If the subsequent time period does not satisfy the third formula, the harmonics are calculated according to step 104 and subsequent steps using the new fundamental frequency Fn2.

[0135] The harmonic detection method implementation method based on dynamic fundamental frequency of the present invention first obtains multiple first voltage sampling signals; then determines the first approximate fundamental frequency signal according to the minimum calculation time and the number of zero crossings of the sampling signal within the minimum calculation time; then determines the first fundamental frequency signal according to the maximum amplitude obtained by Fourier transforming the multiple first voltage sampling signals with the first approximate fundamental frequency signal; finally, according to the first fundamental frequency signal, performs multiple Fourier transforms on the multiple first voltage sampling signals to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes and multiple high-order harmonic phases. The implementation method of the present invention segments the voltage sampling signal, determines the approximate fundamental frequency signal based on the number of zero-crossing sampling signals within a preset time, and then determines a more accurate fundamental frequency signal by Fourier transforming the approximate fundamental frequency signal. By extracting the harmonic amplitude and phase by segmenting the fundamental frequency signal, since the fundamental frequency signal is dynamically detected, the harmonic quantity detection is more accurate and the harmonic analysis result is more reliable.

[0136] It should be understood that the size of the serial numbers of the steps in the above implementation does not mean 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 implementation method of the present invention.

[0137] The following is an implementation of the device of the present invention. For details not described in detail, reference may be made to the corresponding method implementation described above.

[0138] Figure 3 is a functional block diagram of a harmonic detection device based on dynamic fundamental frequency provided by an embodiment of the present invention, referring to Figure 3 The harmonic detection device based on dynamic fundamental frequency includes: a sampling signal acquisition module 301, a fundamental frequency signal initial determination module 302, a fundamental frequency signal determination module 303 and a harmonic detection module 304, wherein:

[0139] A sampling signal acquisition module 301 is used to acquire a plurality of first voltage sampling signals;

[0140] A baseband signal initial determination module 302 is used to determine a first approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time;

[0141] A baseband signal determination module 303, configured to determine a first baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal;

[0142] The harmonic detection module 304 is used to perform multiple Fourier transforms on the multiple first voltage sampling signals according to the first baseband signal to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes and multiple high-order harmonic phases.

[0143] Figure 4 is a functional block diagram of an electronic device provided by an embodiment of the present invention. Figure 4 As shown, the electronic device 4 of this embodiment includes: a processor 400 and a memory 401, wherein the memory 401 stores a computer program 402 that can be run on the processor 400. When the processor 400 executes the computer program 402, the above-mentioned harmonic detection method based on dynamic fundamental frequency and the steps in the embodiment are implemented, for example Figure 1 Steps 101 to 104 are shown.

[0144] Exemplarily, the computer program 402 may be divided into one or more modules / units, and the one or more modules / units are stored in the memory 401 and executed by the processor 400 to implement the present invention.

[0145] The electronic device 4 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The electronic device 4 may include, but is not limited to, a processor 400 and a memory 401. Those skilled in the art will appreciate that Figure 4 It is only an example of the electronic device 4 and does not constitute a limitation of the electronic device 4. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 4 may also include input and output devices, network access devices, buses, etc.

[0146] The processor 400 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), 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, etc.

[0147] The memory 401 may be an internal storage unit of the electronic device 4, such as a hard disk or memory of the electronic device 4. The memory 401 may also be an external storage device of the electronic device 4, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 4. Further, the memory 401 may also include both an internal storage unit and an external storage device of the electronic device 4. The memory 401 is used to store the computer program 402 and other programs and data required by the electronic device 4. The memory 401 may also be used to temporarily store data that has been output or is to be output.

[0148] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned function allocation can be completed by 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 implementation method can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method implementation method, which will not be repeated here.

[0149] In the above-mentioned embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0150] Those skilled in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0151] In the embodiments provided by the present invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0152] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0153] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0154] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned implementation method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, it can implement the steps of the above-mentioned various methods and device implementation methods. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium.

[0155] The above-described embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A harmonic detection method based on dynamic fundamental frequency, characterized in that: include: Acquire a plurality of first voltage sampling signals; Determine a first approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time; Determine a first baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal; According to the first baseband signal, the multiple first voltage sampling signals are subjected to multiple Fourier transforms to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes, and multiple high-order harmonic phases.

2. The harmonic detection method based on dynamic fundamental frequency according to claim 1, characterized in that: The step of determining the first approximate baseband signal according to the minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time comprises: Get the minimum calculation time; Determining the number of zero-crossing sampling signals in the plurality of first voltage sampling signals according to the sampling frequency of the first voltage sampling signal and the minimum calculation time; The first approximate baseband signal is determined according to a first formula, wherein the first formula is: Wherein, Fn0 is the first approximate baseband signal, N is the number of zero crossings of the sampling signal within the minimum calculation time, and tw is the minimum calculation time.

3. The harmonic detection method based on dynamic fundamental frequency according to claim 1, characterized in that: The determining of the first baseband signal according to the maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal comprises: Get the step adjustment amount; Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length; Performing Fourier transform on the first sampling array according to the first approximate baseband signal; Add the amplitude obtained by Fourier transform to the amplitude queue; If the first approximate baseband signal does not exceed the baseband threshold, adjusting the first approximate baseband signal according to the step adjustment amount, and jumping to the step of performing Fourier transform on the first sampling array according to the first approximate baseband signal; Otherwise, selecting the maximum amplitude from the amplitude queue as the target amplitude; A first approximate baseband signal corresponding to the target amplitude is used as the first baseband signal.

4. The harmonic detection method based on dynamic fundamental frequency according to claim 1, characterized in that: The method of performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of low-frequency harmonic amplitudes and a plurality of low-frequency harmonic phases includes: Determine a plurality of frequency-multiplied signals according to the first baseband signal, wherein the frequency-multiplied signals are integer multiples of the frequency of the first baseband signal; Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length; erroneously extracting a frequency-multiplied signal from the plurality of frequency-multiplied signals as a frequency-multiplied signal to be processed; Performing Fourier transform on multiple sampling arrays except the first sampling array according to the frequency-multiplied signal to be processed to obtain low-frequency harmonic amplitude and low-frequency harmonic phase; If the traversal of the multiple frequency-multiplied signals is not completed, the process jumps to the step of traversingly taking out a frequency-multiplied signal from the multiple frequency-multiplied signals as the frequency-multiplied signal to be processed.

5. The harmonic detection method based on dynamic fundamental frequency according to claim 1, characterized in that: The method of performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of high-order harmonic amplitudes and a plurality of high-order harmonic phases includes: Get frequency interval; Determine a plurality of high-frequency signals according to the first baseband signal and the frequency interval, wherein the high-frequency signals are two adjacent high-frequency signals separated by the frequency interval; Dividing the plurality of first voltage sampling signals into a plurality of sampling arrays according to the minimum calculation time, wherein the time length corresponding to the plurality of first voltage sampling signals in each sampling array is the minimum calculation time length; erroneously extracting high-frequency signals from the plurality of high-frequency signals as high-frequency-multiplied signals to be processed; Performing Fourier transform on multiple sampling arrays except the first sampling array according to the high-frequency signal to be processed to obtain high-frequency harmonic amplitude and high-frequency harmonic phase; If the traversal of the multiple high-frequency signals is not completed, the process jumps to the step of traversally extracting a high-frequency signal from the multiple high-frequency signals as the high-frequency signal to be processed.

6. The harmonic detection method based on dynamic fundamental frequency according to any one of claims 1 to 5, characterized in that: After performing a plurality of Fourier transforms on the plurality of first voltage sampling signals according to the first baseband signal to obtain a plurality of low-frequency harmonic amplitudes, a plurality of low-frequency harmonic phases, a plurality of high-order harmonic amplitudes, and a plurality of high-order harmonic phases, the method includes: Acquire a plurality of second voltage sampling signals, wherein the time periods corresponding to the plurality of second voltage sampling signals are connected to the time periods corresponding to the plurality of first voltage sampling signals; Determine a second approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time; Determine a second baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of second voltage sampling signals using the second approximate baseband signal; If the deviation between the second baseband signal and the first baseband signal is less than a threshold, performing multiple Fourier transforms on the multiple second voltage sampling signals according to the first baseband signal to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes, and multiple high-order harmonic phases; Otherwise, the harmonic root mean square of multiple harmonic sampling values ​​is calculated to obtain the steady-state harmonic amplitude.

7. The harmonic detection method based on dynamic fundamental frequency according to claim 6, characterized in that: The step of calculating the harmonic root mean square of a plurality of harmonic sampling values ​​to obtain a steady-state harmonic amplitude comprises: The steady-state harmonic amplitude is determined according to a second formula, wherein the second formula is: Where U h,Fn1 is the hth steady-state harmonic amplitude, M is the total number of multiple second voltage sampling signals, u m is the mth harmonic sampling value.

8. A harmonic detection device based on dynamic fundamental frequency, characterized in that: Used to implement the harmonic detection method based on dynamic fundamental frequency according to any one of claims 1 to 7, the harmonic detection device based on dynamic fundamental frequency comprises: A sampling signal acquisition module, used to acquire a plurality of first voltage sampling signals; A baseband signal initial determination module, used to determine a first approximate baseband signal according to a minimum calculation time and the number of zero crossings of the sampled signal within the minimum calculation time; A baseband signal determination module, configured to determine a first baseband signal according to a maximum amplitude obtained by Fourier transforming the plurality of first voltage sampling signals using the first approximate baseband signal; as well as, The harmonic detection module is used to perform multiple Fourier transforms on the multiple first voltage sampling signals according to the first baseband signal to obtain multiple low-frequency harmonic amplitudes, multiple low-frequency harmonic phases, multiple high-order harmonic amplitudes and multiple high-order harmonic phases.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method as claimed in any one of claims 1 to 7 are implemented.

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