CN114034927A - Signal measurement method and system based on frequency-following interpolation sampling - Google Patents
Signal measurement method and system based on frequency-following interpolation sampling Download PDFInfo
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Abstract
The invention discloses a signal measurement method and a system for sampling with frequency interpolation, which comprises the following steps: acquiring analog signals which are continuous in time and amplitude, and converting the analog signals into discrete digital signals which are discrete in time but continuous in amplitude; calculating the direct current component of the discrete digital signal by using the maximum value and the minimum value of the discrete digital signal, determining the estimation frequency range of the discrete digital signal after removing the direct current component, and obtaining the accurate measurement signal frequency; determining an interpolation pulse time according to a preset interpolation frequency, and interpolating discrete digital signals into frequency-following discrete sampling data based on the accurate measurement signal frequency at the interpolation pulse time; and performing Fourier transform on the frequency-following discrete sampling data to obtain the amplitude and the phase of the analog signal, and combining with the accurate measurement signal frequency to obtain the final analog signal characteristic quantity. The advantages are that: the method has the advantages of high precision, strong real-time performance and low computational power requirement on the system, can be applied to various protection devices sensitive to system signal frequency, and provides data support for a protection algorithm.
Description
Technical Field
The invention relates to a signal measurement method and a signal measurement system for frequency-following interpolation sampling, and belongs to the technical field of power systems.
Background
The signal frequency of the power system is generally power frequency 50Hz, but non-power frequency signals often appear in the system, which affects the stability of the system. The protective device taking the signal frequency as a judgment basis in the system comprises a low-cycle load shedding protective device of a power transmission and distribution system, a stable control protective device, a generator protective device of a power generation system, a distributed energy grid-connected interface protective device of a distributed energy system, a motor protective device and the like. These protection devices are sensitive to the frequency of the system and require the frequency, amplitude and phase of the signal as the basis for protection determination.
(1) The signal frequency variation amplitude of the power transmission and distribution system is small, and is basically about 0.5Hz at the power frequency of 50 Hz. The sampling system firstly adopts a comparator to change periodic sinusoidal signals into square signals with the same frequency period through a hardware frequency measuring device to obtain signal frequency, then adopts high-frequency pulses to measure the signal period of the square signals, and finally determines the original signal frequency. Meanwhile, the sampling system calculates the amplitude and the phase of the signal based on the power frequency of 50Hz and uses the signal amplitude and the phase as the approximate amplitude and the phase of the original signal. Thereby obtaining the characteristic information of the frequency, amplitude, phase and the like of the original signal.
(2) The frequency of the power generation and distributed energy system usually varies greatly. The sampling system firstly calculates the signal phase based on the power frequency of 50Hz, and then conjectures the frequency of the original signal by detecting the signal phase offset of each power frequency period time point. And finally, calculating the amplitude of the signal by a Fourier algorithm of frequency offset compensation.
(3) The high-precision frequency measurement method comprises wavelet analysis method, signal demodulation method, function analysis method, function approximation algorithm (such as least square method and Kalman filtering algorithm) and artificial neural network method.
The technical method (1) needs frequency measurement and hardware support, and a special hardware loop needs to be designed in practical application, so that the design cost is high. Meanwhile, an estimation mode is introduced, and the accuracy of signal characteristic information is not high.
According to the technical method (2), multi-period measurement is needed in a frequency measurement stage, the real-time performance is low, and meanwhile, the frequency calculation is based on the phase of power frequency, and the precision is lost, so that the precision of signal characteristic information calculation in the later period is not high.
The technical method (3) has large calculation amount, high requirement on the calculation capacity of device hardware and simultaneously has a defect in the real-time performance of frequency measurement.
Disclosure of Invention
The invention provides a signal measurement method and a signal measurement system for frequency-following interpolation sampling, aiming at the problems of low acquisition precision and poor real-time performance of the characteristic quantity of a power system signal in a frequency conversion state.
In order to solve the above technical problem, the present invention provides a signal measurement method of frequency-following interpolation sampling, which includes:
acquiring analog signals which are continuous in time and amplitude, and converting the analog signals which are continuous in time and amplitude into discrete digital signals which are discrete in time but continuous in amplitude;
acquiring a maximum value and a minimum value of the discrete digital signal, calculating a direct current component of the discrete digital signal by using the maximum value and the minimum value of the discrete digital signal, removing the direct current component from the discrete digital signal, determining an estimation frequency range of the discrete digital signal after removing the direct current component by using a zero crossing point frequency measurement method, and quickly and real-timely obtaining an accurate measurement signal frequency by using a continuous point frequency measurement method in combination with the estimation frequency range;
determining interpolation pulse time according to the frequency of the accurate measurement signal and the number of predetermined sampling points, and interpolating the discrete digital signal into frequency-following discrete sampling data based on the frequency of the accurate measurement signal at the interpolation pulse time by utilizing a linear interpolation algorithm;
and performing Fourier transform calculation on the frequency-following discrete sampling data to obtain the amplitude and the phase of the analog signal, and combining with the accurate measurement signal frequency to obtain the final analog signal characteristic quantity.
Further, the acquiring an analog signal continuous in both time and amplitude, and converting the analog signal continuous in both time and amplitude into a discrete digital signal discrete in time but continuous in amplitude includes:
converting an analog signal which is continuous in time and amplitude into a discrete digital signal which is discrete in time and continuous in amplitude under the action of a sampling pulse according to a pre-acquired requirement, recording the time and the numerical value of each discrete signal as (x, y), and presetting the number of sampling points in a signal period as M points.
Further, when the direct current component of the discrete digital signal is calculated by using the maximum value and the minimum value of the discrete digital signal, and the direct current component is removed from the discrete digital signal, then the zero-crossing frequency measurement method is used to determine the estimation frequency range of the discrete digital signal after the direct current component is removed, and the continuous point frequency measurement method is used to combine the estimation frequency range to obtain the accurate measurement signal frequency in a fast real-time manner, the method includes:
step 3.1: the direct current component statistics comprises the following steps: counting the number m of sampling points with the sampling data more than 0 and less than 0 in the preset period T of the signal1And m2If m is1Or m2If the maximum value is greater than M, 4/5, step 3.2 is carried out, if not, step 3.3 is carried out, and the maximum value y of the sampling points is recorded during statisticsmaxAnd the minimum value yminWherein the predetermined period follows the frequency change;
step 3.2: obtaining a DC component yzThe method comprises the following steps: calculating and obtaining a direct current component value y according to the formula (1)zInitial yzStep 3.3 is performed when the value is 0;
step 3.3: removing the direct current component, including: raw discrete sampled data point y according to equation (2)sRemoving DC component value yzThen step 3.4 is carried out;
y＝ys-yz (2)
step 3.4: determining a positive zero crossing, comprising: find two consecutive sample points (x)1,y1) And (x)2,y2) Satisfy y1<0 and y2>0 and obtaining the time x of the positive zero crossing point by adopting the formula (3)01，tsStep 3.5 is carried out for sampling interval time;
step 3.5: determining a next negative-going zero-crossing, comprising: find a first set of two consecutive sample points (x)3,y3) And (x)4,y4) Satisfy y3>0 and y4<0 and obtaining the time x of the negative zero crossing point by adopting the formula (4)02，tsStep 3.6 is carried out for sampling interval time;
step 3.6: judging whether the signal is an interference signal or not, if the signal is an interference signal, judging whether the signal is an interference signal, if the signal is an interference signal, the signal is a signal at the moment x of a positive zero crossing point01And the time x of the negative zero crossing02Is greater than one sixth of the predetermined period T, step 3.7 is entered and the time difference (x) is calculated02-x01) Is expressed as a half period ThOtherwise, determining the result as the interference signal discarding calculation result, and re-entering the step 3.4;
step 3.7: obtaining a plurality of sets of half periods ThThe method comprises the following steps: the cumulative calculation obtains n +2 effective half periods ThRemoving the maximum and minimum of n +2 results, leaving n valid half-cycles ThEntering step 3.8;
step 3.8: obtaining an estimated period TeThe method comprises the following steps: according to n valid half-cycles ThCalculating the preset period T of the average updating signal, wherein the updated preset period T of the signal is the estimation period Te，
According to an estimated period TeCalculating an estimated frequency FeEntering step 3.9 as formula (5) and formula (6);
step 3.9: the continuous point frequency measurement method comprises the following steps: acquiring 3 continuous sampling points in real time, wherein the phase difference of the 3 points is as shown in a formula (7), the continuously sampled data is as shown in a formula (8), the relation between numerical values can be known through the formula (9), the formula (10) is obtained through the formula (9), the formula (11) is obtained through the formula (7), the formula (12) is obtained through the formula (10) and the formula (11), the signal frequency is obtained through calculation of the formula (12), and the step is carried out in 3.10;
φ＝ωts (7)
wherein, y1、y2、y3For three consecutive samples, α is the initial phase of the first sample, and φ is tsPhase shift of time interval, A is signal amplitude, FfIs the signal frequency;
step 3.10: the original signal frequency is identified. The signal frequency is determined by equation (6) to be in the range of F ∈ [0.9F ]e，1.1Fe]Then is further prepared byF is obtained by calculation of formula (12)fIf F isfIn the frequency range 0.9Fe，1.1Fe]In, then F ═ FfUpdate the signal frequency, otherwise discard Ff；
Further, the determining an interpolation pulse according to the precision measurement signal frequency and the predetermined number of sampling points, and interpolating the discrete digital signal into frequency-following discrete sampling data based on the precision measurement signal frequency by using a linear interpolation algorithm and the interpolation pulse, includes:
obtaining a new signal period time T from the updated signal frequency F, and entering step 3.2;
updating the sampling interval time T by the new signal period time T and the number M of sampling pointss；
Generating t based on updatedsSampling the interpolated pulses of the interval time;
and interpolating the discrete digital signal into frequency following discrete sampling data based on the signal frequency by utilizing a linear interpolation algorithm and the interpolation pulse.
Further, the performing fourier transform calculation on the frequency-following discrete sampling data to obtain the amplitude and phase of the analog signal, and obtaining the final analog signal characteristic quantity by combining with the accurate measurement of the signal frequency includes:
obtaining y from the formulae (13), (14) and (15) in this orderxAnd yy；
In the formula, A is a signal amplitude, omega is a signal angular frequency, alpha is an initial phase of sampling data, and t is a signal time;
wherein, yxFor the Fourier calculation of the real part of the result, y, for M points of a signal periodyIs the imaginary part of the Fourier calculation result of M points of a signal period, and T is the reciprocal of the precise original signal frequency obtained by formula (12);
obtaining the amplitude amp, phase ang of the original signal according to equation (16) and the frequency F of the original signal according to equation (12)fAnd thus the final analog signal characteristic quantity is determined.
A system for frequency-tracking interpolated sampled signal measurement, comprising:
the acquisition module is used for acquiring analog signals which are continuous in time and amplitude and converting the analog signals which are continuous in time and amplitude into discrete digital signals which are discrete in time and continuous in amplitude;
the first determining module is used for acquiring the maximum value and the minimum value of the discrete digital signal, calculating the direct current component of the discrete digital signal by using the maximum value and the minimum value of the discrete digital signal, removing the direct current component from the discrete digital signal, determining the estimation frequency range of the discrete digital signal after removing the direct current component by using a zero crossing point frequency measurement method, and quickly and real-timely obtaining the frequency of the accurate measurement signal by using a continuous point frequency measurement method in combination with the estimation frequency range;
the interpolation processing module is used for determining interpolation pulse time according to the frequency of the accurate measurement signal and the number of predetermined sampling points, and interpolating the discrete digital signal into frequency-following discrete sampling data based on the frequency of the accurate measurement signal by utilizing a linear interpolation algorithm at the interpolation pulse time;
and the second determination module is used for performing Fourier transform calculation on the frequency-following discrete sampling data to obtain the amplitude and the phase of the analog signal, and determining the final analog signal characteristic quantity by combining with the frequency of the accurately measured signal.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the methods.
A computing device, comprising, in combination,
one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods.
The invention achieves the following beneficial effects:
the method has high precision, strong real-time performance and low computational power requirement on the system, can be applied to various protection devices sensitive to system signal frequency, and provides data support for a protection algorithm; the method has low calculation force requirement and can be realized by a common singlechip.
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FIG. 1 is a schematic flow diagram of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, a signal measurement method with frequency-dependent interpolation sampling is divided into 4 processes. Firstly, a discrete sampling process, then a signal frequency measurement process, then a frequency following interpolation process, and finally an amplitude and phase solving process based on discrete Fourier transform, the method specifically comprises the following steps:
discrete sampling process:
according to the requirement, the analog signal which is continuous in time and amplitude is converted into a discrete digital signal which is discrete in time (fixed interval in time) but continuous in amplitude under the action of the sampling pulse. The time and value of each discrete signal is recorded as (x, y). The number of sampling points in one signal period is preset to be M points.
And (3) signal frequency measurement process:
according to the method, the characteristic that the frequency of the signal of the power system cannot be suddenly changed is utilized, the direct-current component of the filtered signal is firstly subjected to frequency measurement at the zero crossing point, the estimated frequency range of the signal is determined, and then the frequency of the accurately measured signal is quickly obtained in real time by adopting a continuous point frequency measurement method.
Step 2.1: counting the number m of sampling points with the sampling data more than 0 and less than 0 in a predetermined period T (the predetermined period changes along with the frequency)1And m2If m is1Or m2If M is greater than 4/5, step 2.2 is performed, and if not, step 2.3 is performed. Simultaneously recording the maximum value y of the sampling points during statisticsmaxAnd the minimum value ymin。
Step 2.2: calculating to obtain a zero drift value yz. Initial yz0. Step 2.3 is performed.
Step 2.3: removing direct current component y from subsequent sampling datazAnd then participate in the calculation. Step 2.4 is performed.
Step 2.4: determining the positive zero crossing point, and searching two continuous sampling points (x)1,y1) And (x)2,y2) Satisfy y1<0 and y2>0 and linear interpolation is used to obtain the time of zero. Is recorded as x01。tsIs the sampling interval time. Step 2.5 is performed.
Step 2.5: determining the next zero crossing point and searching for two consecutive sampling points (x)3,y3) And (x)4,y4) Satisfy y3>0 and y4<0 and linear interpolation is used to obtain the time of zero. Is recorded as x02。tsIs the sampling interval time. Step 2.6 is performed.
Step 2.6: if the time difference between two zero crossings (denoted as half period T)h) If the period is more than one sixth of the preset period T, the step 2.7 is entered, otherwise, the calculation result of the interference signal discarding is determined, and the step 2.4 is entered again.
Step 2.7: the cumulative calculation obtains n +2 effective half cycles ThRemoving the maximum and minimum values of n +2 results, leaving n valid half-cycles Th. Go to step 2.8.
Step 2.8: taking the average value to update the signal to preset a period T, wherein the period T is the estimation period TeAnd estimating the frequency Fe. Go to step 2.9.
Step 2.9: and (3) acquiring 3 continuous sampling points in real time, wherein the phase difference of the 3 points is as shown in a formula (7), the continuously sampled data is as shown in a formula (8), the relation between the numerical values can be known through the formula (9), and the formula (10) is obtained through the formula (9). From equation (7), equation (11) can be derived. From equations (10) and (11), equation (12) can be derived. As can be seen from equation (12), the frequency of the signal can be calculated from consecutive 3 sample data and the sampling interval time. Step 2.10 is entered.
φ＝ωts (7)
Wherein, y1: first sample data, y2: second sampled data, y3: third sample data, α: the initial phase of the first sampled data,
tsphase angle shift of time interval, a: amplitude of signal, Ff: the frequency of the signal.
Step 2.10: the method determines the signal frequency as the range of F epsilon [0.9F ] by the formula (6)e，1.1Fe]Then F is obtained by calculation of the formula (12)fIf F isfIn the frequency range 0.9Fe，1.1Fe]In, then F ═ FfUpdate the signal frequency, otherwise discard Ff。
And (3) frequency following interpolation process:
step 3.1: the signal period time T is obtained from the signal frequency F. Go to step 3.2.
Step 3.2: updating the sampling interval time T by the cycle time T and the number M of sampling pointss. Go to step 3.3. Step 3.3: generation is based on tsThe interpolated pulse of (2). Go to step 3.4.
Step 3.4: and (3) obtaining numerical data in the discrete sampling process by adopting a linear interpolation algorithm, and interpolating the numerical data into frequency-following discrete sampling data based on signal frequency.
Discrete Fourier transform process:
the continuous sampling data is set as formula (13).
As shown in formula (14), yx: real part of the result of a Fourier calculation of M points of a signal period, yy: the resulting imaginary part is calculated as a Fourier over M points of a signal period.
The amplitude (amp) and phase (ang) of the signal can be determined by y, as shown in equation (16)x，yyAnd T is obtained by calculation. Therefore, 3 characteristic quantities of frequency, amplitude and phase of the original signal can be measured and obtained.
Correspondingly, the invention also provides a signal measurement system of frequency-following interpolation sampling, which comprises:
the acquisition module is used for acquiring analog signals which are continuous in time and amplitude and converting the analog signals which are continuous in time and amplitude into discrete digital signals which are discrete in time and continuous in amplitude;
the first determining module is used for acquiring the maximum value and the minimum value of the discrete digital signal, calculating the direct current component of the discrete digital signal by using the maximum value and the minimum value of the discrete digital signal, removing the direct current component from the discrete digital signal, determining the estimation frequency range of the discrete digital signal after removing the direct current component by using a zero crossing point frequency measurement method, and quickly and real-timely obtaining the frequency of the accurate measurement signal by using a continuous point frequency measurement method in combination with the estimation frequency range;
the interpolation processing module is used for determining interpolation pulse time according to the frequency of the accurate measurement signal and the number of predetermined sampling points, and interpolating the discrete digital signal into frequency-following discrete sampling data based on the frequency of the accurate measurement signal by utilizing a linear interpolation algorithm at the interpolation pulse time;
and the second determination module is used for performing Fourier transform calculation on the frequency-following discrete sampling data to obtain the amplitude and the phase of the analog signal, and determining the final analog signal characteristic quantity by combining with the frequency of the accurately measured signal.
The present invention accordingly also provides a computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the methods described.
The invention also provides a computing device, comprising,
one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to 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 flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may 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 flow or flows and/or block diagram block or blocks.
These computer program instructions may 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 instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may 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 flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (8)
1. A method for signal measurement with frequency-dependent interpolated sampling, comprising:
acquiring analog signals which are continuous in time and amplitude, and converting the analog signals which are continuous in time and amplitude into discrete digital signals which are discrete in time but continuous in amplitude;
acquiring a maximum value and a minimum value of the discrete digital signal, calculating a direct current component of the discrete digital signal by using the maximum value and the minimum value of the discrete digital signal, removing the direct current component from the discrete digital signal, determining an estimation frequency range of the discrete digital signal after removing the direct current component by using a zero crossing point frequency measurement method, and quickly and real-timely obtaining an accurate measurement signal frequency by using a continuous point frequency measurement method in combination with the estimation frequency range;
determining interpolation pulse time according to the frequency of the accurate measurement signal and the number of predetermined sampling points, and interpolating the discrete digital signal into frequency-following discrete sampling data based on the frequency of the accurate measurement signal at the interpolation pulse time by utilizing a linear interpolation algorithm;
and performing Fourier transform calculation on the frequency-following discrete sampling data to obtain the amplitude and the phase of the analog signal, and combining with the accurate measurement signal frequency to obtain the final analog signal characteristic quantity.
2. The method of claim 1, wherein said obtaining an analog signal that is continuous in time and amplitude, and converting the analog signal that is continuous in time and amplitude into a discrete digital signal that is discrete in time but still continuous in amplitude, comprises:
converting an analog signal which is continuous in time and amplitude into a discrete digital signal which is discrete in time and continuous in amplitude under the action of a sampling pulse according to a pre-acquired requirement, recording the time and the numerical value of each discrete signal as (x, y), and presetting the number of sampling points in a signal period as M points.
3. The method for measuring a signal according to claim 2, wherein when the discrete digital signal is processed by using the maximum value and the minimum value of the discrete digital signal to calculate the dc component of the discrete digital signal, and the dc component is removed from the discrete digital signal, then the zero-crossing frequency measurement method is used to determine the estimated frequency range of the discrete digital signal after removing the dc component, and the continuous point frequency measurement method is used to combine the estimated frequency range to obtain the accurate measurement signal frequency in real time, comprising:
step 3.1:the direct current component statistics comprises the following steps: counting the number m of sampling points with the sampling data more than 0 and less than 0 in the preset period T of the signal1And m2If m is1Or m2If the maximum value is greater than M, 4/5, step 3.2 is carried out, if not, step 3.3 is carried out, and the maximum value y of the sampling points is recorded during statisticsmaxAnd the minimum value yminWherein the predetermined period follows the frequency change;
step 3.2: obtaining a DC component yzThe method comprises the following steps: calculating and obtaining a direct current component value y according to the formula (1)zInitial yzStep 3.3 is performed when the value is 0;
step 3.3: removing the direct current component, including: raw discrete sampled data point y according to equation (2)sRemoving DC component value yzThen step 3.4 is carried out;
y＝ys-yz (2)
step 3.4: determining a positive zero crossing, comprising: find two consecutive sample points (x)1,y1) And (x)2,y2) Satisfy y1<0 and y2>0 and obtaining the time x of the positive zero crossing point by adopting the formula (3)01，tsStep 3.5 is carried out for sampling interval time;
step 3.5: determining a next negative-going zero-crossing, comprising: find a first set of two consecutive sample points (x)3,y3) And (x)4,y4) Satisfy y3>0 and y4<0 and obtaining the time x of the negative zero crossing point by adopting the formula (4)02，tsStep 3.6 is carried out for sampling interval time;
step 3.6: judging whether the signal is an interference signal or not, if the signal is an interference signal, judging whether the signal is an interference signal, if the signal is an interference signal, the signal is a signal at the moment x of a positive zero crossing point01And the time x of the negative zero crossing02Is greater than one sixth of the predetermined period T, step 3.7 is entered and the time difference (x) is calculated02-x01) Is expressed as a half period ThOtherwise, determining the result as the interference signal discarding calculation result, and re-entering the step 3.4;
step 3.7: obtaining a plurality of sets of half periods ThThe method comprises the following steps: the cumulative calculation obtains n +2 effective half periods ThRemoving the maximum and minimum of n +2 results, leaving n valid half-cycles ThEntering step 3.8;
step 3.8: obtaining an estimated period TeThe method comprises the following steps: according to n valid half-cycles ThCalculating the preset period T of the average updating signal, wherein the updated preset period T of the signal is the estimation period Te，
According to an estimated period TeCalculating an estimated frequency FeEntering step 3.9 as formula (5) and formula (6);
step 3.9: the continuous point frequency measurement method comprises the following steps: acquiring 3 continuous sampling points in real time, wherein the phase difference of the 3 points is as shown in a formula (7), the continuously sampled data is as shown in a formula (8), the relation between numerical values can be known through the formula (9), the formula (10) is obtained through the formula (9), the formula (11) is obtained through the formula (7), the formula (12) is obtained through the formula (10) and the formula (11), the signal frequency is obtained through calculation of the formula (12), and the step is carried out in 3.10;
φ＝ωts (7)
wherein, y1、y2、y3For three consecutive samples, α is the initial phase of the first sample, and φ is tsPhase shift of time interval, A is signal amplitude, FfIs the signal frequency;
step 3.10: the original signal frequency is identified. The signal frequency is determined by equation (6) to be in the range of F ∈ [0.9F ]e，1.1Fe]Then F is obtained by calculation of the formula (12)fIf F isfIn the frequency range 0.9Fe，1.1Fe]In, then F ═ FfUpdate the signal frequency, otherwise discard Ff。
4. The method for signal measurement with frequency-following interpolation sampling according to claim 3, wherein the determining an interpolation pulse according to a precision measurement signal frequency and a predetermined number of sampling points, and interpolating a discrete digital signal into frequency-following discrete sampling data based on the precision measurement signal frequency by using a linear interpolation algorithm and the interpolation pulse comprises:
obtaining a new signal period time T from the updated signal frequency F, and entering step 3.2;
updating the sampling interval time T by the new signal period time T and the number M of sampling pointss；
Generating t based on updatedsSampling the interpolated pulses of the interval time;
and interpolating the discrete digital signal into frequency following discrete sampling data based on the signal frequency by utilizing a linear interpolation algorithm and the interpolation pulse.
5. The method according to claim 4, wherein the performing fourier transform calculation on the frequency-following discrete sampling data to obtain the amplitude and phase of the analog signal, and combining with the accurate measurement signal frequency to obtain the final analog signal characteristic quantity comprises:
obtaining y from the formulae (13), (14) and (15) in this orderxAnd yy；
In the formula, A is a signal amplitude, omega is a signal angular frequency, alpha is an initial phase of sampling data, and t is a signal time;
wherein, yxFor the Fourier calculation of the real part of the result, y, for M points of a signal periodyIs the imaginary part of the Fourier calculation result of M points of a signal period, and T is the reciprocal of the precise original signal frequency obtained by formula (12);
obtaining the amplitude amp, phase ang of the original signal according to equation (16) and the frequency F of the original signal according to equation (12)fAnd thus the final analog signal characteristic quantity is determined.
6. A system for signal measurement with frequency-dependent interpolated sampling, comprising:
the acquisition module is used for acquiring analog signals which are continuous in time and amplitude and converting the analog signals which are continuous in time and amplitude into discrete digital signals which are discrete in time and continuous in amplitude;
the first determining module is used for acquiring the maximum value and the minimum value of the discrete digital signal, calculating the direct current component of the discrete digital signal by using the maximum value and the minimum value of the discrete digital signal, removing the direct current component from the discrete digital signal, determining the estimation frequency range of the discrete digital signal after removing the direct current component by using a zero crossing point frequency measurement method, and quickly and real-timely obtaining the frequency of the accurate measurement signal by using a continuous point frequency measurement method in combination with the estimation frequency range;
the interpolation processing module is used for determining interpolation pulse time according to the frequency of the accurate measurement signal and the number of predetermined sampling points, and interpolating the discrete digital signal into frequency-following discrete sampling data based on the frequency of the accurate measurement signal by utilizing a linear interpolation algorithm at the interpolation pulse time;
and the second determination module is used for performing Fourier transform calculation on the frequency-following discrete sampling data to obtain the amplitude and the phase of the analog signal, and determining the final analog signal characteristic quantity by combining with the frequency of the accurately measured signal.
7. A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the methods of claims 1-5.
8. A computing device, comprising,
one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods of claims 1-5.
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