CN105205319A - Improved amplitude-undamped linear interpolation method for synchronization of sampled data - Google Patents

Abstract

The invention discloses an improved amplitude-undamped linear interpolation method for synchronization of sampled data. The method comprises steps as follows: (1), a current interpolation position k is calculated; (2), sampled-data signals x(n-1) and xn before and after a to-be-interpolated moment are acquired; (3), a calculation result y(n-1) of previous interpolation is acquired; (4), an output result yn of current interpolation is calculated; (5), sampled data are updated, the step (1) is performed again under the condition that y(n-1) is equal to yn, and an output result of the next interpolation is calculated. The improved amplitude-undamped linear interpolation method for synchronization of the sampled data guarantees that gains of amplitudes of the sampled data at different frequencies of a sampling system in the linear interpolation process are 1, consistency of the amplitudes is maintained, the accuracy of the sampled data is improved, and the method has good application prospect.

Description

A kind of undamped linear interpolation method of modified amplitude for sampling data synchronization

Technical field

The present invention relates to power system of data acquisition technical field, be specifically related to a kind of undamped linear interpolation method of modified amplitude for sampling data synchronization.

Background technology

Intelligent grid adopts the mode of digitized sampling to carry out data acquisition usually, its sampling system is distributed, need carry out synchronously to the sampled data from distinct device, at present, widely using synchronous method is linear interpolation method, but, amplitude attenuation to a certain degree can be produced in linear Interpolation Process, especially, for higher hamonic wave, affect the accuracy of sampled data.But, because the gain of each harmonic is different, cannot be compensated with coefficient simply.Therefore, for amplitude attenuation problem, improving existing linear interpolation method, to improve the accuracy of sampled data, is current urgent problem.

Summary of the invention

Technical matters solved by the invention is existing linear interpolation method, and the meeting for sampled data produces amplitude attenuation to a certain degree, affects the problem of the accuracy of sampled data.The undamped linear interpolation method of modified amplitude for sampling data synchronization of the present invention, ensure that the amplitude gain of the sampled data (DC component, first-harmonic, harmonic wave, m-Acetyl chlorophosphonazo etc.) of sampling system each frequency in linear Interpolation Process is 1, keep the consistance of amplitude, improve the accuracy of sampled data, have a good application prospect.

In order to achieve the above object, the technical solution adopted in the present invention is:

For the undamped linear interpolation method of modified amplitude of sampling data synchronization, it is characterized in that: comprise the following steps,

Step (1), according to formula (1), calculates current location of interpolation k,

$k=\frac{\mathrm{\Δ}t}{T}---\left(1\right)$

Wherein, Δ t is the mistiming of interpolation moment and last point sampling data, and T is data sampling period;

Step (2), in the moment residing for location of interpolation k, obtains the interpolation moment sampled data signal x of forward and backward 2 _n-1, x _n;

Step (3), obtains the result of calculation y of last interpolation _n-1, y _n-1initial value be set to zero;

Step (4), according to formula (2), calculates the Output rusults y of current interpolation _n, guarantee that the amplitude gain perseverance of sampled data is 1,

$y_n=x_{n-1}+\frac{k}{2-k}\·x_n-\frac{k}{2-k}\·y_{n-1}---\left(2\right);$

Step (5), upgrades sampled data, and makes y _n-1=y _n, repeat step (1), the Output rusults carrying out interpolation next time calculates, and the computation period of interpolation and data sampling period T-phase are together.

The invention has the beneficial effects as follows: the undamped linear interpolation method of modified amplitude for sampling data synchronization of the present invention, ensure that the amplitude gain of the sampled data (DC component, first-harmonic, harmonic wave, m-Acetyl chlorophosphonazo etc.) of sampling system each frequency in linear Interpolation Process is 1, keep the consistance of amplitude, improve the accuracy of sampled data, have a good application prospect.

Accompanying drawing explanation

Fig. 1 is the process flow diagram of the undamped linear interpolation method of modified amplitude for sampling data synchronization of the present invention.

Embodiment

Below in conjunction with Figure of description, the present invention is further illustrated.

The undamped linear interpolation method of modified amplitude for sampling data synchronization of the present invention, ensure that the amplitude gain of the sampled data (DC component, first-harmonic, harmonic wave, m-Acetyl chlorophosphonazo etc.) of sampling system each frequency in linear Interpolation Process is 1, keep the consistance of amplitude, improve the accuracy of sampled data, as shown in Figure 1, comprise the following steps

Step (1), according to formula (1), calculates current location of interpolation k,

$k=\frac{\mathrm{\Δ}t}{T}---\left(1\right)$

Wherein, Δ t is the mistiming of interpolation moment and last point sampling data, and T is data sampling period;

Step (2), in the moment residing for location of interpolation k, obtains the interpolation moment sampled data signal x of forward and backward 2 _n-1, x _n;

Step (3), obtains the result of calculation y of last interpolation _n-1, y here _n-1initial value be set to zero;

Step (4), according to formula (2), calculates the Output rusults y of current interpolation _n, guarantee that the amplitude gain perseverance of sampled data is 1,

$y_n=x_{n-1}+\frac{k}{2-k}\·x_n-\frac{k}{2-k}\·y_{n-1}---\left(2\right);$

Guarantee the amplitude gain perseverance of sampled data be 1 theory deduction as follows,

Transform is carried out to formula (2), obtains

$\[\frac{k}{2}{z}^{-1}+(1-\frac{k}{2})\]Y=\[(1-\frac{k}{2})z^{-1}+\frac{k}{2}\]X---\left(3\right)$

Then transport function is as follows,

$H\left(z\right)=\frac{(1-\frac{k}{2})z^{-1}+\frac{k}{2}}{\frac{k}{2}{z}^{-1}+(1-\frac{k}{2})}---\left(4\right)$

By z=e ^{j ω T}substitute into formula (4), obtain

$H\left(j\mathrm{\ω}\right)=\frac{(1-\frac{k}{2})e^{-j\mathrm{\ω}T}+\frac{k}{2}}{\frac{k}{2}{e}^{-j\mathrm{\ω}T}+(1-\frac{k}{2})}---\left(5\right)$

By Euler's formula, obtain

e ^-jωT＝cosωT-jsinωT(6)

Formula (6) is brought into and substitutes into formula (5),

$H\left(j\mathrm{\ω}\right)=\frac{\[(1-\frac{k}{2})\cos \mathrm{\ω}T+\frac{k}{2}\]-j(1-\frac{k}{2})\sin \mathrm{\ω}T}{\[\frac{k}{2}\cos \mathrm{\ω}T+(1-\frac{k}{2})\]-j\frac{k}{2}\sin \mathrm{\ω}T}---\left(7\right)$

Then amplitude gain is as follows

$\begin{array}{c}\left|H\left(j\mathrm{\ω}\right)\right|=\sqrt{\frac{{\[(1-\frac{k}{2})cos\mathrm{\ω}T+\frac{k}{2}\]}^2+{(1-\frac{k}{2})}^2{\sin }^2\mathrm{\ω}T}{{\[\frac{k}{2}cos\mathrm{\ω}T+(1-\frac{k}{2})\]}^2+{\left(\frac{k}{2}\right)}^2{\sin }^2\mathrm{\ω}T}}\\ =\sqrt{\frac{{(1-\frac{k}{2})}^2(1-\frac{k}{2}\]k\cos \mathrm{\ω}T+{\left(\frac{k}{2}\right)}^2}{{\left(\frac{k}{2}\right)}^2+(1-\frac{k}{2})k\cos \mathrm{\ω}T+{(1-\frac{k}{2})}^2}}=1\end{array}---\left(8\right)$

After visible employing formula (2) interpolation calculation, amplitude gain perseverance is 1;

Step (5), upgrades sampled data, and makes y _n-1=y _n, repeat step (1), the Output rusults carrying out interpolation next time calculates, and the computation period of interpolation and data sampling period T-phase are together.More than show and describe ultimate principle of the present invention and principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; what describe in above-described embodiment and instructions just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.Application claims protection domain is defined by appending claims and equivalent thereof.

Claims (1)

1., for the undamped linear interpolation method of modified amplitude of sampling data synchronization, it is characterized in that: comprise the following steps,

Step (1), according to formula (1), calculates current location of interpolation k,

$k=\frac{\mathrm{\Δ}t}{T}---\left(1\right)$

Wherein, Δ t is the mistiming of interpolation moment and last point sampling data, and T is data sampling period;

Step (2), in the moment residing for location of interpolation k, obtains the interpolation moment sampled data signal x of forward and backward 2 _n-1, x _n;

Step (3), obtains the result of calculation y of last interpolation _n-1, y _n-1initial value be set to zero;

Step (4), according to formula (2), calculates the Output rusults y of current interpolation _n, guarantee that the amplitude gain perseverance of sampled data is 1,

$y_n=x_{n-1}+\frac{k}{2-k}\·x_n-\frac{k}{2-k}\·y_{n-1}---\left(2\right);$

Step (5), upgrades sampled data, and makes y _n-1=y _n, repeat step (1), the Output rusults carrying out interpolation next time calculates, and the computation period of interpolation and data sampling period T-phase are together.