CN1955745A - Phase measuring method in on-line monitoring of high-voltage electric equipment - Google Patents

Abstract

A method for measuring phase in on-line detection of high voltage device includes sampling any two routes of signals containing harmonic wave to obtain finite length sampling series, calculating its average value to obtain DC components in signals, deducting DC component to obtain finite length series only containing AC signal, carrying out multiplication operation on corresponding points of two-route finite length series, carrying out integration operation on multiplication operation result and dividing obtained result by magnitude of signal base wave component to obtain reverse tangent then obtaining angle difference.

Description

The method of the phase measurement in a kind of on-line monitoring of high-voltage electric equipment

Technical field

The present invention relates to the method for the phase measurement of voltage or electric current, particularly relate to the method for the phase measurement of voltage in a kind of on-line monitoring of high-voltage electric equipment or electric current.

Background technology

In the insulating of electric measurement of high pressure on-line monitoring field of power industry, need the real-time dielectric loss to capacitance type equipment, electric capacity to carry out on-line measurement.The phase place (also can be referred to as angular difference) that dielectric loss measurement needs comparison system voltage and end to shield electric current, precision prescribed reaches more than 1 '.At present, the on-line monitoring field mainly adopts the zero passage relative method to calculate, and promptly utilizes two AC signal zero crossing point mistimings to calculate phase differential, this method is only utilized zero crossing and near information thereof, being limited in scope of data acquisition, and be interfered easily, effect is unsatisfactory in the practicality.In addition, also have a kind of method (FFT is the abbreviation of fast fourier transform) that adopts hardware phase-locked-loop+FFT, FFT has used the whole of image data, calculates effect and obviously is better than the zero crossing relative method.Yet because phaselocked loop is feedback-type control, FFT is applied to finite interval in addition, and the error of calculation and stability are still not ideal enough.

Summary of the invention

The method that the purpose of this invention is to provide the phase measurement in the on-line monitoring of high-voltage electric equipment that a kind of calculated amount is little and computational accuracy is high.

The method of the measurement of phase place in a kind of on-line monitoring of high-voltage electric equipment that can achieve the above object includes following steps:

(1) comprises signal x (t), the y (t) of harmonic wave for any two-way, sample, obtained limit for length's sampled value sequence row;

x(k)＝{x(1)，x(2)，…，x(n)}；

y(k)＝{y(1)，y(2)，…，y(n)}；

1＜k＜n wherein, n=fkT;

N is a sampling number, and f is a sample frequency, and T is the cycle of power frequency component, and k is sampling complete cycle issue;

(2) calculate arithmetic mean, obtain DC component a, b in the signal; Formula is as follows:

$a=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{x}_i}{n}$

$b=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i}{n}$

N=fkT wherein;

(3) cut after the DC component, only comprised the finite length sequence of AC signal; Formula is as follows:

x′(k)＝x(k)-a＝{x(0)-a，x(1)-a，…，x(n)-a}＝{x′(0)，x′(1)，…，x′(n)}；

y′(k)＝y(k)-b＝{y(0)-b，y(1)-b，…，y(n)-b}＝{y′(0)，y′(1)，…，y′(n)}；

1＜k＜n wherein, n=fkT;

(4) two-way finite length sequence corresponding point are carried out multiplying; Formula is as follows:

z(k)＝x′(k)×y′(k)＝{x′(1)×y′(1)，x′(2)×y′(2)，…，x′(n)×y′(n}＝{z(1)，z(2)，…，z(n)}

(5) operation result with the 4th step carries out integral operation, can obtain the value that is directly proportional with the differential seat angle δ sine value of two paths of signals, falls the result again divided by signal fundametal compoment amplitude, and the negate sine, obtains differential seat angle δ; Formula is as follows:

$\mathrm{\δ}={\sin }^{-1}\left(\frac{1}{X\·Y}\underset{0}{\overset{\mathrm{kT}}{\∫}}z\left(k\right)\mathrm{dk}\right)={\sin }^{-1}(\frac{1}{X\·Y}\underset{i=1}{\overset{\mathrm{fkT}-1}{\mathrm{\Σ}}}\frac{z\left(i\right)+z(i+1)}{2}\×\frac{1}{f})\·$

In practical operation, the signal of sampling in the described step 1 is the end screen current signal of system voltage signal or equipment.And the signal of sampling carries out the A/D conversion according to higher frequency and gathers according to power frequency complete cycle (as 40 cycles), has obtained limit for length's sampled value sequence row.

The advantage of method provided by the present invention is: 1, utilize all sampled values to calculate, can carry out tens power frequency period high sampling rate data computing, do not need hardware phase-locked-loop, utilize the multicycle data average, reduce frequency change and bring to such an extent that influence.2, overcome FFT and will reach the drawback that the same needed sampling rate of precision, data volume, operand sharply increases, can overcome the influence of rugged change of waveform and the drift of a few amplifying circuit direct current of influence of harmonic, data stability height, resolution height, can satisfy the requirement of insulating of electric measurement of high pressure on-line monitoring measurement range precision in 3 ' ~ 20 ' scope, and operand is starkly lower than the FFT that carries out the same quantity of data computing.After the phase place of the voltage that 3, calculates and equipment end screen electric current, can directly calculate the dielectric loss of equipment, very easy and be widely used.

Embodiment

The invention provides the method for phase measurement in a kind of on-line monitoring of high-voltage electric equipment, this method mainly includes following steps:

(1) comprises signal x (t), the y (t) of harmonic wave for any two-way, sample, obtained limit for length's sampled value sequence row;

x(k)＝{x(1)，x(2)，…，x(n)}；

y(k)＝{y(1)，y(2)，…，y(n)}；

1＜k＜n wherein, n=fkT;

N is a sampling number, and f is a sample frequency, and T is the cycle of power frequency component, and k is sampling complete cycle issue;

(2) calculate arithmetic mean, obtain DC component a, b in the signal; Formula is as follows:

$a=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{x}_i}{n}$

$b=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i}{n}$

N=fkT wherein;

(3) cut after the DC component, only comprised the finite length sequence of AC signal (power frequency 50Hz component and harmonic component); Formula is as follows:

x′(k)＝x(k)-a＝{x(0)-a，x(1)-a，…，x(n)-a}＝{x′(0)，x′(1)，…，x′(n)}；

y′(k)＝y(k)-b＝{y(0)-b，y(1)-b，…，y(n)-b}＝{y′(0)，y′(1)，…，y′(n)}；

1＜k＜n wherein, n=fkT;

(4) two-way finite length sequence corresponding point are carried out multiplying; Formula is as follows:

z(k)＝x′(k)×y′(k)＝{x′(1)×y′(1)，x′(2)×y′(2)，…，x′(n)×y′(n}＝{z(1)，z(2)，…，z(n)}

(5) operation result with the 4th step carries out integral operation, can obtain the value that is directly proportional with the differential seat angle δ sine value of two paths of signals, falls the result again divided by signal fundametal compoment amplitude, and the negate sine, obtains differential seat angle δ; Formula is as follows:

$\mathrm{\δ}={\sin }^{-1}\left(\frac{1}{X\·Y}\underset{0}{\overset{\mathrm{kT}}{\∫}}z\left(k\right)\mathrm{dk}\right)={\sin }^{-1}(\frac{1}{X\·Y}\underset{i=1}{\overset{\mathrm{fkT}}{\mathrm{\Σ}}}\frac{z\left(i\right)+z(i+1)}{2}\×\frac{1}{f})\·$

Sampling in the above-mentioned step 1 can the acquisition system voltage signal, also can gather the end screen current signal of a certain equipment.The higher frequency of signal of sampling is carried out the A/D conversion and is gathered according to power frequency complete cycle (as 40 cycles), has obtained limit for length's sampled value sequence row.

As the phase place δ that has both measured system voltage _U, the phase place δ of electric current is shielded at the end of having measured certain equipment again _IAfter, just can calculate the dielectric loss value of this equipment easily.

Embodiment 1

Lifting a specific embodiment below is described in detail as follows:

Dielectric loss measurement in the capacitance type equipment monitoring means, is gathered 4 road signals with 16k Sps sampling rate in using simultaneously, and acquisition length is 40 power frequency periods, and every passage image data length is 12.8k.Wherein one the tunnel is reference signal, and other 3 the tunnel is the end screen electric current of device A, B, C three-phase; Utilize method of the present invention, calculate the phase place δ of the end screen electric current of device A, B, C three-phase _IA, δ _IB, δ _IC

Now enumerate the computation process that the A phase current is equivalent to the sampled data in two cycles

The sampled value A of A phase current is

Columns?1 through?7 0.0002 0.0394 0.0786 0.1177 0.1566 0.1953 0.2336

Columns?8 through?14 0.2716 0.3092 0.3463 0.3828 0.4188 0.4541 0.4888

Columns?15 through?21 0.5226 0.5557 0.5879 0.6192 0.6496 0.6789 0.7072

Columns?22 through?28 0.7344 0.7605 0.7854 0.8091 0.8316 0.8527 0.8726

Columns?29 through?35 0.8911 0.9082 0.9239 0.9383 0.9511 0.9625 0.9724

Columns?36 through?42 0.9808 0.9877 0.9931 0.9969 0.9992 1.0000 0.9992

Columns?43 through?49 0.9969 0.9930 0.9877 0.9808 0.9723 0.9624 0.9510

Columns?50 through?56 0.9381 0.9238 0.9081 0.8909 0.8724 0.8525 0.8314

Columns?57 through?63 0.8089 0.7852 0.7603 0.7342 0.7070 0.6787 0.6493

Columns?64 through?70 0.6190 0.5876 0.5554 0.5223 0.4885 0.4538 0.4185

Columns?71 through?77 0.3825 0.3460 0.3089 0.2713 0.2333 0.1949 0.1563

Columns?78 through?84 0.1174 0.0783 0.0391 -0.0002 -0.0394 -0.0786 -0.1177

Columns?85 through?91 -0.1566 -0.1953 -0.2336 -0.2716 -0.3092 -0.3463 -0.3828

Columns?92 through?98 -0.4188 -0.4541 -0.4888 -0.5226 -0.5557 -0.5879 -0.6192

Columns?99 through?105 -0.6496 -0.6789 -0.7072 -0.7344 -0.7605 -0.7854 -0.8091

Columns?106?through?112 -0.8316 -0.8527 -0.8726 -0.8911 -0.9082 -0.9239 -0.9383

Columns?113?through?119 -0.9511 -0.9625 -0.9724 -0.9808 -0.9877 -0.9931 -0.9969

Columns?120?through?126 -0.9992 -1.0000 -0.9992 -0.9969 -0.9930 -0.9877 -0.9808

Columns?127?through?133 -0.9723 -0.9624 -0.9510 -0.9381 -0.9238 -0.9081 -0.8909

Columns?134?through?140 -0.8724 -0.8525 -0.8314 -0.8089 -0.7852 -0.7603 -0.7342

Columns?141?through?147 -0.7070 -0.6787 -0.6493 -0.6190 -0.5876 -0.5554 -0.5223

Columns?148?through?154 -0.4885 -0.4538 -0.4185 -0.3825 -0.3460 -0.3089 -0.2713

Columns?155?through?161 -0.2333 -0.1949 -0.1563 -0.1174 -0.0783 -0.0391 0.0002

Columns?162?through?168 0.0394 0.0786 0.1177 0.1566 0.1953 0.2336 0.2716

Columns?169?through?175 0.3092 0.3463 0.3828 0.4188 0.4541 0.4888 0.5226

Columns?176?through?182 0.5557 0.5879 0.6192 0.6496 0.6789 0.7072 0.7344

Columns?183?through?189 0.7605 0.7854 0.8091 0.8316 0.8527 0.8726 0.8911

Columns?190?through?196 0.9082 0.9239 0.9383 0.9511 0.9625 0.9724 0.9808

Columns?197?through?203 0.9877 0.9931 0.9969 0.9992 1.0000 0.9992 0.9969

Columns?204?through?210 0.9930 0.9877 0.9808 0.9723 0.9624 0.9510 0.9381

Columns?211?through?217 0.9238 0.9081 0.8909 0.8724 0.8525 0.8314 0.8089

Columns?218?through?224 0.7852 0.7603 0.7342 0.7070 0.6787 0.6493 0.6190

Columns?225?through?231 0.5876 0.5554 0.5223 0.4885 0.4538 0.4185 0.3825

Columns?232?through?238 0.3460 0.3089 0.2713 0.2333 0.1949 0.1563 0.1174

Columns?239?through?245 0.0783 0.0391 -0.0002 -0.0394 -0.0786 -0.1177 -0.1566

Columns?246?through?252 -0.1953 -0.2336 -0.2716 -0.3092 -0.3463 -0.3828 -0.4188

Columns?253?through?259 -0.4541 -0.4888 -0.5226 -0.5557 -0.5879 -0.6192 -0.6496

Columns?260?through?266 -0.6789 -0.7072 -0.7344 -0.7605 -0.7854 -0.8091 -0.8316

Columns?267?through?273 -0.8527 -0.8726 -0.8911 -0.9082 -0.9239 -0.9383 -0.9511

Co1umns?274?through?280 -0.9625 -0.9724 -0.9808 -0.9877 -0.9931 -0.9969 -0.9992

Columns?281?through?287 -1.0000 -0.9992 -0.9969 -0.9930 -0.9877 -0.9808 -0.9723

Columns?288?through?294 -0.9624 -0.9510 -0.9381 -0.9238 -0.9081 -0.8909 -0.8724

Columns?295?through?301 -0.8525 -0.8314 -0.8089 -0.7852 -0.7603 -0.7342 -0.7070

Columns?302?through?308 -0.6787 -0.6493 -0.6190 -0.5876 -0.5554 -0.5223 -0.4885

Columns?309?through?315 -0.4538 -0.4185 -0.3825 -0.3460 -0.3089 -0.2713 -0.2333

Columns?316?through?321 -0.1949 -0.1563 -0.1174 -0.0783 -0.0391 0.0002

The sampled value B of reference current is

Columns?1 through 7 1.0000 0.9992 0.9969 0.9931 0.9877 0.9808 0.9724

Columns?8 through 14 0.9625 0.9511 0.9382 0.9239 0.9081 0.8910 0.8725

Columns?15?through 21 0.8526 0.8315 0.8090 0.7853 0.7604 0.7343 0.7071

Columns?22?through 28 0.6788 0.6494 0.6191 0.5878 0.5556 0.5225 0.4886

Columns?29?through 35 0.4540 0.4187 0.3827 0.3461 0.3090 0.2714 0.2334

Columns?36?through 42 0.1951 0.1564 0.1175 0.0785 0.0393 0.0000 -0.0393

Columns?43?through 49 -0.0785 -0.1175 -0.1564 -0.1951 -0.2334 -0.2714 -0.3090

Columns?50?through 56 -0.3461 -0.3827 -0.4187 -0.4540 -0.4886 -0.5225 -0.5556

Columns?57?through 63 -0.5878 -0.6191 -0.6494 -0.6788 -0.7071 -0.7343 -0.7604

Columns?64?through 70 -0.7853 -0.8090 -0.8315 -0.8526 -0.8725 -0.8910 -0.9081

Columns?71?through 77 -0.9239 -0.9382 -0.9511 -0.9625 -0.9724 -0.9808 -0.9877

Columns?78?through 84 -0.9931 -0.9969 -0.9992 -1.0000 -0.9992 -0.9969 -0.9931

Columns?85?through 91 -0.9877 -0.9808 -0.9724 -0.9625 -0.9511 -0.9382 -0.9239

Columns?92?through 98 -0.9081 -0.8910 -0.8725 -0.8526 -0.8315 -0.8090 -0.7853

Columns?99?through 105?-0.7604 -0.7343 -0.7071 -0.6788 -0.6494 -0.6191 -0.5878

Columns?106?through?112 -0.5556 -0.5225 -0.4886 -0.4540 -0.4187 -0.3827 -0.3461

Columns?113?through?119 -0.3090 -0.2714 -0.2334 -0.1951 -0.1564 -0.1175 -0.0785

Columns?120?through?126 -0.0393 -0.0000 0.0393 0.0785 0.1175 0.1564 0.1951

Columns?127?through?133 0.2334 0.2714 0.3090 0.3461 0.3827 0.4187 0.4540

Columns?134?through?140 0.4886 0.5225 0.5556 0.5878 0.6191 0.6494 0.6788

Columns?141?through?147 0.7071 0.7343 0.7604 0.7853 0.8090 0.8315 0.8526

Columns?148?through?154 0.8725 0.8910 0.9081 0.9239 0.9382 0.9511 0.9625

Columns?155?through?161 0.9724 0.9808 0.9877 0.9931 0.9969 0.9992 1.0000

Columns?162?through?168 0.9992 0.9969 0.9931 0.9877 0.9808 0.9724 0.9625

Columns?169?through?175 0.9511 0.9382 0.9239 0.9081 0.8910 0.8725 0.8526

Columns?176?through?182 0.8315 0.8090 0.7853 0.7604 0.7343 0.7071 0.6788

Columns?183?through?189 0.6494 0.6191 0.5878 0.5556 0.5225 0.4886 0.4540

Columns?190?through?196 0.4187 0.3827 0.3461 0.3090 0.2714 0.2334 0.1951

Columns?197?through?203 0.1564 0.1175 0.0785 0.0393- 0.0000 -0.0393 -0.0785

Columns?204?through?210 -0.1175 -0.1564 -0.1951 -0.2334 -0.2714 -0.3090 -0.3461

Columns?211?through?217 -0.3827 -0.4187 -0.4540 -0.4886 -0.5225 -0.5556 -0.5878

Columns?218?through?224 -0.6191 -0.6494 -0.6788 -0.7071 -0.7343 -0.7604 -0.7853

Columns?225?through?231 -0.8090 -0.8315 -0.8526 -0.8725 -0.8910 -0.9081 -0.9239

Columns?232?through?238 -0.9382 -0.9511 -0.9625 -0.9724 -0.9808 -0.9877 -0.9931

Columns?239?through?245 -0.9969 -0.9992 -1.0000 -0.9992 -0.9969 -0.9931 -0.9877

Columns?246?through?252 -0.9808 -0.9724 -0.9625 -0.9511 -0.9382 -0.9239 -0.9081

Columns?253?through?259 -0.8910 -0.8725 -0.8526 -0.8315 -0.8090 -0.7853 -0.7604

Columns?260?through?266 -0.7343 -0.7071 -0.6788 -0.6494 -0.6191 -0.5878 -0.5556

Columns?267?through?273 -0.5225 -0.4886 -0.4540 -0.4187 -0.3827 -0.3461 -0.3090

Columns?274?through?280 -0.2714 -0.2334 -0.1951 -0.1564 -0.1175 -0.0785 -0.0393

Columns?281?through?287 0.0000 0.0393 0.0785 0.1175 0.1564 0.1951 0.2334

Columns?288?through?294 0.2714 0.3090 0.3461 0.3827 0.4187 0.4540 0.4886

Columns?295?through?301 0.5225 0.5556 0.5878 0.6191 0.6494 0.6788 0.7071

Columns?302?through?308 0.7343 0.7604 0.7853 0.8090 0.8315 0.8526 0.8725

Columns?309?through?315 0.8910 0.9081 0.9239 0.9382 0.9511 0.9625 0.9724

Columns?316?through?321 0.9808 0.9877 0.9931 0.9969 0.9992 1.0000

Two paths of signals is point-to-point to multiply each other and integration

d＝3.4907e-006

The sinusoidal computing of negate obtains angle

δ _IA＝0.01

Equally, in the system voltage unit, calculate the phase differential δ of three-phase system voltage signal equally with respect to same reference signal _UA, δ _UB, δ _UC

Utilize said method to calculate δ _UA=0.0005

Utilize these phase difference values, can calculate three-phase equipment and divide other dielectric loss

${\mathrm{tg\δ}}_A=\mathrm{tg}(\frac{\mathrm{\π}}{2}-({\mathrm{\δ}}_{\mathrm{IA}}-{\mathrm{\δ}}_{\mathrm{UA}}))$

${\mathrm{tg\δ}}_B=\mathrm{tg}(\frac{\mathrm{\π}}{2}-({\mathrm{\δ}}_{\mathrm{IB}}-{\mathrm{\δ}}_{\mathrm{UB}}))$

${\mathrm{tg\δ}}_C=\mathrm{tg}(\frac{\mathrm{\π}}{2}-({\mathrm{\δ}}_{\mathrm{IC}}-{\mathrm{\δ}}_{\mathrm{UC}}))$

Therefore

tgδ _A＝0.0165806％

Contrast 128 FFT, calculate the phase differential δ IA=0.010071 of current signal with respect to reference signal, the system voltage signal is with respect to the phase differential δ UA=0.0005391 of same reference signal

Therefore

tgδ _A＝0.0166363％

Both result of calculation is more approaching, but in the time need carrying out the calculating in many sampling periods, the fft algorithm operand will sharply increase.Practical application shows, adopts this algorithm numerical stability and the antijamming capability of multicycle sampling computing obviously to be better than fft algorithm.

Claims (4)

1, the method for the phase measurement in a kind of on-line monitoring of high-voltage electric equipment includes following steps:

(1) comprises signal x (t), the y (t) of harmonic wave for any two-way, sample, obtained limit for length's sampled value sequence row;

x(k)＝{x(1)，x(2)，…，x(n)}；

y(k)＝{y(1)，y(2)，…，y(n)}；

1＜k＜n wherein, n=fkT;

N is a sampling number, and f is a sample frequency, and T is the cycle of power frequency component, and k is sampling complete cycle issue;

(2) result in the step 1 is calculated arithmetic mean, obtain DC component a, b in the signal; Formula is as follows:

$a=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{x}_i}{n}$

$b=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i}{n}$

N=fkT wherein;

(3) cut after the DC component, only comprised the finite length sequence of AC signal; Formula is as follows:

x′(k)＝x(k)-a＝{x(0)-a，x(1)-a，…，x(n)-a}＝{x′(0)，x′(1)，…，x′(n)}；

y′(k)＝y(k)-b＝{y(0)-b，y(1)-b，…，y(n)-b}＝{y′(0)，y′(1)，…，y′(n)}；

1＜k＜n wherein, n=fkT;

(4) two-way finite length sequence corresponding point are carried out multiplying; Formula is as follows:

z(k)＝x′(k)×y′(k)＝{x′(1)×y′(1)，x′(2)×y′(2)，…，x′(n)×y′(n}＝{z(1)，z(2)，…，z(n)}

(5) operation result with step 4 carries out integral operation, falls the result again divided by signal fundametal compoment amplitude, and the negate tangent, obtains phase differential δ; Formula is as follows:

$\mathrm{\δ}={\mathrm{tg}}^{-1}\left(\frac{1}{X\·Y}\underset{0}{\overset{\mathrm{kT}}{\∫}}z\left(k\right)\mathrm{dk}\right)={\mathrm{tg}}^{-1}(\frac{1}{X\·Y}\underset{i=1}{\overset{\mathrm{fkT}-1}{\mathrm{\Σ}}}\frac{z\left(i\right)+z(i+1)}{2}\×\frac{1}{f}).$

2, method according to claim 1 is characterized in that: the signal of sampling in the described step 1 is the system voltage signal.

3, method according to claim 1 is characterized in that: the signal of sampling in the described step 1 is the end screen current signal of equipment.

4, according to claim 1 or 2 or 3 described methods, it is characterized in that: the higher frequency of the signal of sampling in the described step 1 is carried out the A/D conversion and is gathered complete cycle according to power frequency, has obtained limit for length's sampled value sequence row.