CN115575706B - Frequency continuous tracking measurement system and method suitable for electric energy meter calibrator - Google Patents
Frequency continuous tracking measurement system and method suitable for electric energy meter calibrator Download PDFInfo
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- CN115575706B CN115575706B CN202211451855.7A CN202211451855A CN115575706B CN 115575706 B CN115575706 B CN 115575706B CN 202211451855 A CN202211451855 A CN 202211451855A CN 115575706 B CN115575706 B CN 115575706B
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Abstract
The invention discloses a frequency continuous tracking measurement system and a frequency continuous tracking measurement method suitable for an electric energy meter calibrator. The frequency continuous tracking measurement method suitable for the electric energy meter calibrator is based on the theory of zero crossing points, has a breakpoint continuous calculation function, adds a self-created anti-interference restriction algorithm, does not need a complex filtering algorithm, directly carries out operation analysis on sampling data, has the characteristics of good instantaneity, strong anti-interference, high accuracy, less occupied resources, short calculation time and the like, provides a basis for real-time continuous tracking measurement, has applicability to a plurality of spike waves, pulse waves, waveforms with multiple zero crossing points, waveforms with high harmonic content, inter-harmonic waveforms and the like, and ensures the accuracy of electric parameter and electric energy measurement of the electric energy meter calibrator under various working conditions.
Description
Technical Field
The invention belongs to the technical field of electric power measurement, and particularly relates to a frequency continuous tracking measurement system and method suitable for an electric energy meter calibrator.
Background
There are three ways of calculating the frequency of the existing power system: in the method 1, a phase-locked loop circuit is adopted to realize phase locking, the interval time calculation frequency of a fixed number of sampling points is monitored, the hardware circuit of the method is slightly complex, and the situation that the harmonic wave is large and the signal is small can cause the failure of phase locking; mode 2, calculating the frequency by adopting a basic zero crossing method, wherein the method is not applicable to waveforms with large harmonic waves and multiple zero crossing points; the method 3 is characterized in that the fundamental wave signals are restored through a complex filtering algorithm, and the frequency is calculated through a zero crossing method, so that the method has high requirements on the memory and the operation capability of the MCU, and the real-time performance and the continuity are difficult to ensure.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a frequency continuous tracking measurement system and method suitable for an electric energy meter calibrator, which have the advantages of solving various problems existing in the existing calculation frequency of an electric energy meter calibrator, simplifying a hardware design circuit of the electric energy meter calibrator by adopting fixed-point sampling, simplifying the frequency continuous tracking measurement method with high real-time anti-interference performance, having a breakpoint continuous calculation function, adding a self-created anti-interference limiting algorithm, directly carrying out operation analysis on sampling data without a complex filtering algorithm, and having the characteristics of high real-time performance, strong anti-interference performance, high accuracy, less occupied resources, short calculation time and the like, thereby providing guarantee for the measurement error of the electric energy meter calibrator, the accuracy of electric parameter measurement, and having applicability to a plurality of spike waves, pulse waves, waveforms with multiple zero crossing points, waveforms with high harmonic content, inter-harmonic waveforms and the like.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the frequency continuous tracking measurement system suitable for the electric energy meter calibrator comprises a fixed point acquisition module, an anti-interference zero continuous tracking analysis module and a frequency calculation module; the fixed-point acquisition module acquires voltage and current signals of each phase in the power system according to a fixed high-frequency sampling frequency to obtain a sampling point sequence with a fixed number of each phase per second; the anti-interference zero continuous tracking analysis module has a breakpoint continuous calculation function based on zero crossing theory, performs real-time acquisition of sampling point sequences, performs tracking analysis in real time, finds a zero position, sets a preset zero after finding the zero position, and confirms the zero position as an effective zero after meeting anti-interference limiting conditions; the frequency calculation module calculates the period of the power waveform through the positions of two adjacent effective zero points, so that the frequency of the power system is calculated.
The invention also provides a measuring method of the frequency continuous tracking measuring system suitable for the electric energy meter calibrator, which comprises the following steps:
step 1: collecting voltage and current signals of each phase in the power system according to a fixed high-frequency sampling frequency of 25.6kHz, and obtaining a sequence of 25600 sampling points fixed per phase per second through A/D conversion of the voltage and current signals to obtain a sequence of 25600 sampling points, wherein the interval time t=1/25600 seconds between the sampling points;
step 2: every 256 sampling points are collected and are analyzed by the anti-interference zero continuous tracking analysis module, the zero position found by point-by-point analysis is set as a preset zero point, and V is met n <0,V n+1 Conditions of ≡0, representing that the predetermined zero point is between the nth and the n+1th sampling points, and recording the precise time t:
t=(|V n |÷(V n+1 －V n )+n)×∆t
wherein V is n The value of the sampling point before the zero point; v (V) n+1 The value of the sampling point after the zero point; n is the serial number of the sampling point;
step 3: entering an anti-interference limit analysis algorithm, wherein if the condition is met, the effective zero point is the effective zero point, otherwise, the ineffective zero point is the ineffective zero point;
step 4: executing the step 5, if the number of the effective zero points is more than 1, otherwise executing the step 2;
step 5: after confirmation of two adjacent effective zero positions, the frequency fn is calculated.
Further, in the step 3, the content determined by the antijam restriction analysis algorithm includes:
(1) The value V of the 1 st to 100 th sampling points after the preset zero point m Positive, i.e. V m >0, wherein n+1 is not less than m is not more than n+100;
(2) The 1 st to 100 th sampling points after the preset zero point have a characteristic of a sine wave rising trend, namely
Wherein, V is m Is V (V) m+1 -V m ；n+1≤m≤n+100；
(3) Ignoring waveforms of dc character in parallel, i.e. without effective zero point and
wherein, V is n Is V (V) n+1 -V n ，0≤n≤∞；
(4) And searching for zero points in parallel, and updating the preset zero points when the preset zero point conditions are met.
Further, in the step 5, the frequency fn=1++t (t n+1 -t n ），t n Is the effective zero point accurate time of the nth, t n+1 The effective zero point accurate time is n+1th.
Further, the real-time continuous tracking measurement is suitable for measuring a plurality of spike waves, pulse waves, multi-zero crossing point waveforms, waveforms with high harmonic content and inter-harmonic waveforms.
The beneficial effects are that:
the invention solves various problems existing in the existing calculation frequency of the electric power system, has higher applicability to a plurality of spike waves, pulse waves, multi-zero crossing point waveforms, waveforms with high harmonic content, inter-harmonic waveforms and the like, simplifies a hardware design circuit of the electric energy meter calibrator by adopting fixed-point sampling, provides guarantee for the electric energy pulse accuracy of the electric power system, and ensures the accuracy of metering errors and electric parameter measurement of the electric energy meter calibrator under various working conditions.
Drawings
Fig. 1 is a main module frame diagram of the frequency continuous tracking measurement system suitable for the electric energy meter calibrator.
FIG. 2 is a flow chart of an algorithm analysis process of the present invention.
Fig. 3 is a table of voltage signal a/D conversion sampling data according to the present invention.
Fig. 4 is a waveform diagram of one cycle of the voltage signal of the present invention.
Fig. 5 is a table of a voltage signal a/D conversion sampling data of the present invention superimposed with multiple harmonics.
Fig. 6 is a waveform diagram of a voltage signal superimposed with multiple harmonics according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
As shown in FIG. 1, the frequency continuous tracking measurement system suitable for the electric energy meter calibrator comprises a fixed-point acquisition module, an anti-interference zero continuous tracking analysis module and a frequency calculation module. The fixed-point acquisition module acquires the signals subjected to A/D conversion according to a fixed sampling frequency to obtain a sampling point sequence; the anti-interference zero continuous tracking analysis module has a breakpoint continuous calculation function based on the theory of zero crossing points, can ensure that sampling data are analyzed in real time, and whether sampling points after a preset zero point are effective zero points is determined after the sampling points are analyzed by an anti-interference limiting algorithm; the frequency calculation module determines the period of one periodic wave according to the interval time of two adjacent effective zero points, and finally calculates the frequency.
As shown in fig. 2, the frequency continuous tracking measurement method suitable for the electric energy meter calibrator of the present invention specifically includes the following steps:
step 1: the voltage and current signals of each phase in the power system are acquired according to the fixed high-frequency sampling frequency of 25.6kHz, and are converted into digital signals through A/D (analog-to-digital) conversion, so that a sequence of 25600 sampling points per second are fixed per phase, and the interval time t=1 and 25600 seconds between the sampling points is shortened.
Step 2: every 256 sampling points (requiring 10 ms) are collected, the sampling points are analyzed by the anti-interference zero continuous tracking analysis module, the zero position found by point-by-point analysis is set as a preset zero point, and V is met n <0,V n+1 Conditions of ≡0, representing that the predetermined zero point is between the nth and the n+1th sampling points, and recording the precise time t:
t=(|V n |÷(V n+1 －V n )+n)×∆t
wherein V is n The value of the sampling point before the zero point; v (V) n+1 The value of the sampling point after the zero point; n is a sampling point serial number and indicates the sampling point; t is the interval time between sampling points, fixed 1/25600 seconds;
step 3: and entering an anti-interference limit analysis algorithm, wherein if the condition is met, the effective zero point is the effective zero point, and otherwise, the ineffective zero point is the ineffective zero point.
The judgment content of the anti-interference limit analysis algorithm comprises the following steps:
(1) The value V of the 1 st to 100 th sampling points after the preset zero point m Positive, i.e. V m >0, wherein n+1 is not less than m is not more than n+100;
(2) The 1 st to 100 th sampling points after the preset zero point have the characteristic of the rising trend of the sine wave, namely
Wherein, V is m Is V (V) m+1 -V m ；n+1≤m≤n+100；
(3) Ignoring waveforms of dc character in parallel, i.e. without effective zero point and
wherein, V is n Is V (V) n+1 -V n ，0≤n≤∞；
(4) And searching for zero points in parallel, and updating the preset zero points when the preset zero point conditions are met.
Step 4: and (5) executing the step (5) by the number of the effective zeros being greater than 1, otherwise executing the step (2).
Step 5: after two adjacent effective zero positions are confirmed, the frequency can be calculated, for example, the 1 st effective zero accurate time is t1, the 2 nd effective zero accurate time is t2, then the frequency f1=1 (t 2-t 1), the calculated frequency fn is updated in sequence, and the frequency fn=1 (t) n+1 -t n ），t n Is the effective zero point accurate time of the nth, t n+1 The effective zero point accurate time is n+1th.
The present invention will be described in detail with reference to the following examples.
Embodiment one:
s1, acquiring voltage and current signals of each phase in the power system according to a fixed high-frequency sampling frequency of 25.6kHz, and obtaining a sequence of 25600 sampling points per second per phase through A/D conversion to digital signals. The sine wave signal of the voltage and the current of the power system can be simulated, and the formula is as follows:
where ω=2pi f.50, u is the amplitude, ω is the angular frequency,
phase, f is frequency, and n is sample point sequence number.
S2, simulating a voltage signal with the frequency of 52Hz, wherein an acquired original sampling point is shown in a figure 3, a waveform of one cycle drawn according to the acquired original sampling point is shown in a figure 4, and the position of an effective zero point is marked in the figure.
S3, by analyzing the original sampling points, the effective zero point position Z1 is located between n=1 and n=2, and Z2 is located between n=493 and n=494.
The precise moment of Z1 is:
t1=(|V 1 |÷(V 2 －V 1 )+1)×∆t=(|－12|÷(22－(－12))+1)×(1÷25600)=5.284926470588235e－5；
the precise moment of Z2 is:
t2=(|V494|÷(V494－V493)+493)×∆t=(|－22|÷(11－(－22))+493)×(1÷25600)=0.0192838541666667。
wherein, t is the interval between each sampling point and each sampling point, and is fixed to be 1/25600; v1 is the sampling value of the 1 st sampling point, V2 is the sampling value of the 2 nd sampling point, V493 is the sampling value of the 493 th sampling point, and V494 is the sampling value of the 494 th sampling point.
S4, the step of performing the step of, calculating the frequency f=1++1 (t 2-t 1) =1++5 (0.0192838541666667-5.284926470588235 e-5)
=51.999Hz。
Frequency error e= (51.999-52)/(52×100= -0.0019%).
Embodiment two:
s1, superposing harmonic waves on the basis of a sine wave signal Un of a voltage and a current of the power system in the first embodiment. The waveform Unh after the voltage and current signals of the power system are superimposed and harmonic can be simulated, and the formula is as follows:
wherein Uh is a harmonic effective value, h is harmonic frequency,
is a harmonic phase.
S2, superposing harmonic waves on a voltage signal with the simulation frequency of 55Hz to generate waveforms of a plurality of zero crossings, wherein the superposed harmonic waves are shown in the following table:
the collected original sampling points are shown in a table in fig. 5, a waveform of one cycle drawn according to the collected original sampling points is shown in fig. 6, and the positions of effective zero points are marked in the graph.
S3, by analyzing the original sampling points, the effective zero point position Z1 is located between n=29 and n=30, and Z2 is located between n=495 and n=496.
The precise moment of Z1 is:
t1=(|V 29 |÷(V 30 －V 29 )+29)×∆t=(|－60|÷(15－(－60))+29)×(1÷25600)=0.0011640625；
the precise moment of Z2 is:
t2=(|V 495 |÷(V 496 －V 495 )+495)×∆t=(|－19|÷(59－(－19))+495)×(1÷25600)=0.019345452724359。
wherein, t is the interval between each sampling point and each sampling point, and is fixed to be 1/25600; v29 is the sample value of the 29 th sample point, V30 is the sample value of the 30 th sample point, V495 is the sample value of the 495 th sample point, V496 is the sample value of the 496 th sample point.
S4, the step of performing the step of, the calculated frequency f=1++1 > (t 2-t 1) =1++ 0.019345452724359-0.0011640625) = 55.001Hz.
Frequency error e= (55.001-55)/(55×100=0.0018%).
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting; while the invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that: modifications may be made to the specific embodiments of the present invention or equivalents may be substituted for part of the technical features thereof; without departing from the spirit of the invention, it is intended to cover the scope of the invention as claimed.
Claims (3)
1. The measuring method of the frequency continuous tracking measuring system suitable for the electric energy meter calibrator is characterized by comprising the following steps of: the system comprises a fixed-point acquisition module, an anti-interference zero continuous tracking analysis module and a frequency calculation module; the fixed-point acquisition module acquires voltage and current signals of each phase in the power system according to a fixed high-frequency sampling frequency to obtain a sampling point sequence with a fixed number of each phase per second; the anti-interference zero continuous tracking analysis module has a breakpoint continuous calculation function based on zero crossing theory, performs real-time acquisition of sampling point sequences, performs tracking analysis in real time, finds a zero position, sets a preset zero after finding the zero position, and confirms the zero position as an effective zero after meeting anti-interference limiting conditions; the frequency calculation module calculates the period of the power waveform through the positions of two adjacent effective zero points, thereby calculating the frequency of the power system, and specifically comprises the following steps:
step 1: collecting voltage and current signals of each phase in the power system according to a fixed high-frequency sampling frequency of 25.6kHz, and obtaining a sequence of 25600 sampling points fixed per second per phase through A/D conversion to digital signals, wherein the interval time between the sampling points is equal to the interval time between the sampling points
Second, wherein the second is;
step 2: every 256 sampling points are collected and are analyzed by the anti-interference zero continuous tracking analysis module, the zero position found by point-by-point analysis is set as a preset zero point, and V is met n <0,V n+1 Conditions of ≡0, representing that the predetermined zero point is between the nth and the n+1th sampling points, and recording the precise time t:
wherein V is n The value of the sampling point before the zero point; v (V) n+1 The value of the sampling point after the zero point; n is the serial number of the sampling point;
step 3: entering an anti-interference limit analysis algorithm, wherein if the condition is met, the effective zero point is the effective zero point, otherwise, the ineffective zero point is the ineffective zero point; the judgment content of the anti-interference limit analysis algorithm comprises the following steps:
(1) The value V of the 1 st to 100 th sampling points after the preset zero point m Positive, i.e. V m >0, wherein n+1 is not less than m is not more than n+100;
(2) The 1 st to 100 th sampling points after the preset zero point have the characteristic of the rising trend of the sine wave, namely
Wherein->
Is V (V) m+1 -V m ；n+1≤m≤n+100；
(3) Ignoring waveforms of dc character in parallel, i.e. without effective zero point and
wherein->
Is V (V) n+1 -V n ，0≤n≤∞；
(4) Searching zero points in parallel, and updating the preset zero points when the preset zero point conditions are met;
step 4: executing the step 5, if the number of the effective zero points is more than 1, otherwise executing the step 2;
step 5: after confirmation of two adjacent effective zero positions, the frequency fn is calculated.
2. The method for measuring the frequency continuous tracking measurement system suitable for the calibrator of the electric energy meter according to claim 1, wherein in the step 5Frequency fn=1/(t) n+1 -t n ），t n Is the effective zero point accurate time of the nth, t n+1 The effective zero point accurate time is n+1th.
3. The method for measuring the frequency continuous tracking measurement system suitable for the electric energy meter calibrator according to claim 1, wherein the method is suitable for measuring a plurality of spike waves, pulse waves, multi-zero crossing point waveforms, waveforms with high harmonic content and inter-harmonic waveforms in real time.
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