CN103575988A - Method for measuring phase difference of alternating current in digital mode - Google Patents
Method for measuring phase difference of alternating current in digital mode Download PDFInfo
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- CN103575988A CN103575988A CN201210260874.1A CN201210260874A CN103575988A CN 103575988 A CN103575988 A CN 103575988A CN 201210260874 A CN201210260874 A CN 201210260874A CN 103575988 A CN103575988 A CN 103575988A
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Abstract
The invention discloses a method for measuring the phase difference of alternating current in a digital mode. Continuous digital sampling signals are processed in a digital integration and interpolation mode, and zero points of electric signals are calculated according to an integration beginning point P1 and the visual generation time of an integration ending point k acquired in a difference mode; frequency or periods of the electric signals are calculated according to the zero crossing points of the electric signals; finally, the phase difference of acquired signals is calculated according to the zero crossing point time difference and periods of different signals. By means of the method for measuring the phase difference of the alternating current in the digital mode, it is not needed that low-frequency signals are converted into square waves, the defect that traditional zero crossing point detection is poor in interference resisting performance is overcome, phase difference measurement of low-frequency signals is particularly facilitated, system detection is convenient to carry out, hardware expenses are small, and interference resisting performance of a system is good; the method is easy and reasonable to achieve and has wide application prospect, and data are accurate and reliable.
Description
Technical field
The present invention relates to a kind of technology of phase differential of digitized measurement alternating current, also can be for the phase difference measurement of other low-frequency signals.
Background technology
In daily life, production run, usually need to measure the phase differential of ac signal, the phase differential of measurement is more accurate, and the effect of application is often better.In existing method for measuring phase difference, great majority adopt signal are transformed into square wave, then measure the mistiming of rising edge between two square waves, thereby draw the phase differential of two signals, but this algorithm is easy to realize but needs extra hardware, and the impact being easily interfered.
Summary of the invention
Technical matters to be solved by this invention is not accurate enough for the Phase Difference Measuring Precision of ac signal in prior art, has proposed a kind of method of phase differential of digitized measurement alternating current.
The present invention is for solving the problems of the technologies described above by the following technical solutions:
A method for the phase differential of alternating current, comprises the following steps:
Step 1), samples to tested electric signals, obtains the sampled value of tested electric signals, then generates sampled signal;
Step 2), in the sampled signal of tested electric signals, select m the sampled point discharging in order after tested electric signals is crossed negative peak in a cycle on the sampling time, the sampling time of establishing this m sampled point is respectively t
1, t
2... t
i, t
i+1... t
m, sampled value is respectively x
1, x
2... x
i, x
i+1... x
m, wherein i, m are natural number and 1≤i<m;
Step 3), makes S
ifor from the 1st sampled point (x
1, t
1) to i sampled point (x
i, t
i) digital integration, S
i+1for from the 1st sampled point (x
1, t
1) to i+1 sampled point (x
i+1, t
i+1) digital integration; Work as S
iand S
i+1product be less than or equal at 0 o'clock, between i sampled point and i+1 sampled point, by the mode of interpolation, obtain a digital integration end point k, make from the 1st sampled point (x
1, t
1) to integration end point (x
k, t
k) digital integration be zero, calculate the virtual time of origin t of integration end point k
k;
Step 4), calculate the zero crossing time:
Step 5), repeating step 2) obtain successively several zero crossing time: T to step 4)
z1, T
z2... T
zj, T
z (j+1)... T
zn, wherein, j=1,2 ... n, n is positive integer, the cycle of tested electric signals: T
pj=T
z (j+1)-T
zj, the cycle that therefore obtains tested electric signals is followed successively by T
p1, T
p2, T
p3... T
p (n-1);
Step 6), for two tested electric signals that frequency is identical, obtains respectively the zero crossing time of two tested electric signals according to step 1) to step 5); Again according to the difference of the zero crossing time of two tested electric signals, and the cycle of the tested electric signals that obtains of step 5), calculate two phase differential between tested electric signals.
Further, the method for the phase differential of a kind of digitized measurement alternating current of the present invention, tested electric signals being sampled described in step 1) is constant duration sampling or not constant duration sampling.
Further, the method for the phase differential of a kind of digitized measurement alternating current of the present invention, being sampled as described in step 1) sampled to the complete cycle ripple of tested electric signals.
Further, the method for the phase differential of a kind of digitized measurement alternating current of the present invention, the Choice of described the 1st sampled point is: while not arriving zero point after the cycle of tested electric signals is crossed negative peak, select a sampled point as the 1st sampled point.
Further, the method for the phase differential of a kind of digitized measurement alternating current of the present invention, the concrete steps of described step 6) are as follows:
If the zero crossing time of the first via tested electric signals being calculated respectively by step 1) to step 5) is T1
zj, the second tunnel tested electric signals the zero crossing time be T2
zj, the value of the phase differential of two-way tested electric signals is expressed as with the number of degrees:
or be expressed as with radian:
wherein, T
pthe instantaneous value in tested electric signals cycle of calculating according to step 5), or the mean value of front several periodic quantities of the tested electric signals calculating according to step 5).
Further, the method for the phase differential of a kind of digitized measurement alternating current of the present invention, described digital integration mode comprises: trapezoidal integration or rectangular integration; Described interpolation method comprises: rectangle interpolation or trapezoidal interpolation.
The present invention adopts above technical scheme compared with prior art, has following technique effect:
1) traditional two contrary continuity points of zero friendship method symbolization are determined zero point, although algorithm clear physics conception is easily subject to the interference of harmonic wave, measuring error etc., measuring accuracy is low.Only have accurate location zero point, just can calculate accurate phase differential.For electric signal great majority, are symmetrical features, tested electric signals is crossed to the laggard row digital integration of peak value, by the mode of interpolation, obtain an integration end point, making the digital integration from integration starting point to integration end point is zero, by the zero point of integration start time and integration end time calculating electric signal.After having determined the zero crossing of signal, can calculate frequency and the cycle of electric signal.Last according to difference and the signal period of the zero crossing time of unlike signal, calculate and obtain the phase differential between signal.Traditional zero friendship method of comparing, operand increases to some extent, but precision, the anti-interference measured are greatly improved.
2) sampling involved in the present invention can be constant duration sampling, can be also not constant duration sampling.
Accompanying drawing explanation
Fig. 1 adopts the mode of rectangular integration, rectangle interpolation to calculate the virtual time of origin of integration end point, and obtains the schematic diagram of zero crossing;
Fig. 2 adopts the mode of trapezoidal integration, trapezoidal interpolation to calculate the virtual time of origin of integration end point, and obtains the schematic diagram of zero crossing;
Fig. 3 adopts the mode of trapezoidal integration, rectangle interpolation to calculate the virtual time of origin of integration end point, and obtains the schematic diagram of zero crossing;
Fig. 4 adopts the mode of rectangular integration, rectangle interpolation to obtain a series of zero crossings and calculates the schematic diagram of ac period;
Fig. 5 adopts the mode of trapezoidal integration, trapezoidal interpolation to obtain a series of zero crossings and calculates the schematic diagram of ac period;
Fig. 6 adopts the mode of trapezoidal integration, rectangle interpolation to obtain a series of zero crossings and calculates the schematic diagram of ac period;
Fig. 7 adopts the mode of rectangular integration, rectangle interpolation to obtain a series of zero crossings and calculate the schematic diagram that two paths of signals calculates phase differential;
Fig. 8 adopts the mode of trapezoidal integration, trapezoidal interpolation to obtain a series of zero crossings and calculate the schematic diagram that two paths of signals calculates phase differential;
Fig. 9 adopts the mode of trapezoidal integration, rectangle interpolation to obtain a series of zero crossings and calculate the schematic diagram that two paths of signals calculates phase differential.
Embodiment
Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:
Essence of the present invention is to adopt the mode of digital integration interpolation to process continuous digital sampled signal, chooses a sampled point P after signal is crossed positive negative peak
1as integration starting point, in follow-up sampled point, can there are two continuous like this some P
iand P
i+1if, from P
1to P
idigital integration numerical value and from P
1to P
i+1the product of digital integration numerical value be less than or equal at 0 o'clock, can be at P
iand P
i+1between by the mode of interpolation, obtain an integration end point k, the condition of obtaining of k is from P
1digital integration to k is 0.Can be by P
1sampling time of origin and the virtual time of origin of k zero point of calculating electric signal, frequency or the cycle of by the zero crossing of series of electrical signals, being calculated electric signal.Here so-called digital integration has following several mode: trapezoidal integration, rectangular integration mode; Here so-called interpolation has rectangle interpolation, trapezoidal interpolation method.Last according to difference and the signal period of the zero crossing time of unlike signal, calculate and obtain the phase differential between signal.The P choosing
1should not too approach zero point, if approach the interference that is easily subject to noise zero point, cause measurement result not accurate enough.
For obtaining comparatively accurate measurement result, the Choice of the sampled point P1 of suggestion is: should not too approach zero point.
The features and advantages of the invention will be elaborated by reference to the accompanying drawings by example.Principle of the present invention describes by measuring the phase differential of low frequency signal, and along with the raising of sample rate, the sampling number of the generation in a cycle is also more and more.Specific embodiment of the invention process is as follows:
1. pair measured signal is sampled, and described here is sampled as the sampling that complete cycle ripple is carried out.Can be constant duration sampling, can be also not constant duration sampling.
2. after tested electric signals is crossed negative peak, select several sampled points discharging in order on the sampling time, the sampling time of supposing each sampled point is t
i, sampled value is x
i, i>=1, makes S
ifor from point (x
1, t
1) digital integration of ordering to i; If S
iand S
i+1product be less than or equal to 0, can between i point and i+1 point, by the mode of interpolation, obtain an integration end point k, make from point (x
1, t
1) to the digital integration of some k, be zero, can calculate the virtual time of origin t of a k
k;
3. the process that obtains zero crossing is as follows, the calculating of the zero crossing time after selected peak value:
4. calculating the concrete operations of zero crossing time can be referring to Fig. 1, Fig. 2, Fig. 3.Fig. 1 adopts the mode of rectangular integration, rectangle interpolation to calculate the virtual time of origin of integration end point, and obtains the schematic diagram of zero crossing.In Fig. 1 from t
1start digital integration, t
kthe virtual time of origin of the integration end point obtained of interpolation, in figure from t
1to t
kdigital integration be 0.T
zto calculate the zero crossing obtaining.Fig. 2 adopts the mode of trapezoidal integration, trapezoidal interpolation to calculate the virtual time of origin of integration end point, and obtains the schematic diagram of zero crossing.In Fig. 2 from t
1start digital integration, t
kthe virtual time of origin of the integration end point obtained of interpolation, in figure from t
1to t
kdigital integration be 0.T
zto calculate the zero crossing obtaining.Fig. 3 adopts the mode of trapezoidal integration, rectangle interpolation to calculate the virtual time of origin of integration end point, and obtains the schematic diagram of zero crossing.In Fig. 3 from t
1start digital integration, t
kthe virtual time of origin of the integration end point obtained of interpolation, in figure from t
1to t
kdigital integration be 0.T
zto calculate the zero crossing obtaining.If purely adopt trapezoidal integration, when carrying out interpolation calculation, there is calculated amount situation bigger than normal.Fig. 3 adopts trapezoidal integration when starting integration, but when carrying out interpolation arithmetic, has adopted the method for rectangle interpolation, and the object of doing is like this to reduce the complexity of computing.For obtaining measurement result comparatively accurately, the height of establishing this rectangle in the calculating of accompanying drawing is the mean value of two sampled points of vicinity.
5. obtain several zero crossings and can carry out the calculating of signal period after the time, specifically can be referring to Fig. 4, Fig. 5, Fig. 6.Fig. 4 adopts the mode of rectangular integration, rectangle interpolation to obtain a series of zero crossings and calculates the schematic diagram of ac period.Fig. 5 adopts the mode of trapezoidal integration, trapezoidal interpolation to obtain a series of zero crossings and calculates the schematic diagram of ac period.Fig. 6 adopts the mode of trapezoidal integration, rectangle interpolation to obtain a series of zero crossings and calculates the schematic diagram of ac period.Low frequency signal one in Fig. 4, Fig. 5, Fig. 6 co-exists in 3 negative peaks, therefore after negative peak occurs, has carried out altogether 3 interpolation and has calculated, and on transverse axis, the time is respectively T
z1, T
z2, T
z3hollow round spot be 3 zero crossings that calculate, because cycle of measured signal can be expressed as: T
pj=T
zj+1-T
zj, so in Fig. 4, Fig. 5, Fig. 6 the signal period can be expressed as: T
p2=T
z3-T
z2, T
p1=T
z2-T
z1.
6. the calculating of phase differential can be referring to Fig. 7, Fig. 8, Fig. 9.Fig. 7 adopts the mode of rectangular integration, rectangle interpolation to obtain a series of zero crossings and calculate the schematic diagram that two paths of signals calculates phase differential.Fig. 8 adopts the mode of trapezoidal integration, trapezoidal interpolation to obtain a series of zero crossings and calculate the schematic diagram that two paths of signals calculates phase differential.Fig. 9 adopts the mode of trapezoidal integration, rectangle interpolation to obtain a series of zero crossings and calculate the schematic diagram that two paths of signals calculates phase differential.In Fig. 7, Fig. 8, Fig. 9, sinusoidal wave I has two zero crossings after negative peak occurs, the time of these two zero crossings is respectively T1
zjand T1
zj+1, sinusoidal wave II also has two zero crossings after negative peak occurs, and the time of these two zero crossings is respectively T2
zjand T2
zj+1, the phase differential of sinusoidal wave I and sinusoidal wave II can be expressed as:
or
t in formula
pthe cycle of signal, T
pcan be the instantaneous value of the current period that calculates, or the mean value of the front several periodic quantities that calculate.Formula also can be write as the form that radian is expressed.
Preferred version is that the described constant duration that is sampled as is sampled.
In sum, the method of the phase differential of a kind of digitized measurement alternating current involved in the present invention, do not need to convert low frequency signal to square wave, overcome the shortcoming that traditional zero crossing detects poor anti jamming capability, be particularly suitable for the phase difference measurement of low frequency signal, system is easy to detect, and hardware spending is little; The method has certain antijamming capability; Implement advantages of simple, data accurately, reliably; There is application prospect more widely.Certainly, the present invention also can be applied to phase difference measurement, measuring power angle of civilian three-phase alternating current etc.
Claims (6)
1. a method for the phase differential of digitized measurement alternating current, is characterized in that: comprise the following steps:
Step 1), samples to tested electric signals, obtains the sampled value of tested electric signals, then generates sampled signal;
Step 2), in the sampled signal of tested electric signals, select m the sampled point discharging in order after tested electric signals is crossed negative peak in a cycle on the sampling time, the sampling time of establishing this m sampled point is respectively t
1, t
2... t
i, t
i+1... t
m, sampled value is respectively x
1, x
2... x
i, x
i+1... x
m, wherein i, m are natural number and 1≤i<m;
Step 3), makes S
ifor from the 1st sampled point (x
1, t
1) to i sampled point (x
i, t
i) digital integration, S
i+1for from the 1st sampled point (x
1, t
1) to i+1 sampled point (x
i+1, t
i+1) digital integration; Work as S
iand S
i+1product be less than or equal at 0 o'clock, between i sampled point and i+1 sampled point, by the mode of interpolation, obtain a digital integration end point k, make from the 1st sampled point (x
1, t
1) to integration end point (x
k, t
k) digital integration be zero, calculate the virtual time of origin t of integration end point k
k;
Step 4), calculate the zero crossing time:
Step 5), repeating step 2) obtain successively several zero crossing time: T to step 4)
z1, T
z2... T
zj, T
z (j+1)... T
zn, wherein, j=1,2 ... n, n is positive integer, the cycle of tested electric signals: T
pj=T
z (j+1)-T
zj, the cycle that therefore obtains tested electric signals is followed successively by T
p1, T
p2, T
p3... T
p (n-1);
Step 6), for two tested electric signals that frequency is identical, obtains respectively the zero crossing time of two tested electric signals according to step 1) to step 5); Again according to the difference of the zero crossing time of two tested electric signals, and the cycle of the tested electric signals that obtains of step 5), calculate two phase differential between tested electric signals.
2. the method for the phase differential of a kind of digitized measurement alternating current according to claim 1, is characterized in that: described in step 1), tested electric signals being sampled is constant duration sampling or not constant duration sampling.
3. the method for the phase differential of a kind of digitized measurement alternating current according to claim 1, is characterized in that: being sampled as described in step 1) sampled to the complete cycle ripple of tested electric signals.
4. the method for the phase differential of a kind of digitized measurement alternating current according to claim 1, is characterized in that: the Choice of described the 1st sampled point is: while not arriving zero point after the cycle of tested electric signals is crossed negative peak, select a sampled point as the 1st sampled point.
5. the method for the phase differential of a kind of digitized measurement alternating current according to claim 1, is characterized in that: the concrete steps of described step 6) are as follows:
If the zero crossing time of the first via tested electric signals being calculated respectively by step 1) to step 5) is T1
zj, the second tunnel tested electric signals the zero crossing time be T2
zj, the value of the phase differential of two-way tested electric signals is expressed as with the number of degrees:
or be expressed as with radian:
wherein, T
pthe instantaneous value in tested electric signals cycle of calculating according to step 5), or the mean value of front several periodic quantities of the tested electric signals calculating according to step 5).
6. according to the method for the phase differential of a kind of digitized measurement alternating current described in any one in claim 1 to 5, it is characterized in that: described digital integration mode comprises: trapezoidal integration or rectangular integration; Described interpolation method comprises: rectangle interpolation or trapezoidal interpolation.
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| CN102095934A (en) * | 2010-12-17 | 2011-06-15 | 南京邮电大学 | Measuring method for phase difference of alternating current signals |
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| CN102539892A (en) * | 2012-01-16 | 2012-07-04 | 南京磐能电力科技股份有限公司 | Method for obtaining true effective values of AC (alternating current) signals |
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2012
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| US5321350A (en) * | 1989-03-07 | 1994-06-14 | Peter Haas | Fundamental frequency and period detector |
| CN101813725A (en) * | 2010-04-15 | 2010-08-25 | 南京邮电大学 | Method for measuring phase difference of low-frequency signals |
| CN102445600A (en) * | 2010-09-30 | 2012-05-09 | 上海华建电力设备股份有限公司 | Optimization method based on traditional phase difference measurement and circuit |
| CN102095934A (en) * | 2010-12-17 | 2011-06-15 | 南京邮电大学 | Measuring method for phase difference of alternating current signals |
| CN102539892A (en) * | 2012-01-16 | 2012-07-04 | 南京磐能电力科技股份有限公司 | Method for obtaining true effective values of AC (alternating current) signals |
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Application publication date: 20140212 |