CN103713198A - Method for measuring phase to phase mutual impedance of long-distance extra-high voltage common-tower double-circuit transmission line - Google Patents

Abstract

The invention discloses a method for measuring phase to phase mutual impedance of a long-distance extra-high voltage common-tower double-circuit transmission line. The method comprises the first step that the head end of a measured phase is in an open circuit, the tail end of the measured phase is in ground connection, the head ends of other phases are in an open circuit, the tail ends of other phases are in ground connection, voltages are applied to the head end of the measured phase, currents are injected into the head end of the measured phase, and the current signal of the head end of the measured phase and the induction voltage signals of the head ends of other phases under two frequencies are synchronously measured; the second step that the voltage signals and the current signals under the two frequencies are obtained through an FFT filtering algorithm; the third step that phase to phase mutual impedance values under the two frequencies are respectively calculated according to the voltage signals and the current signals under the two frequencies, and a phase to phase mutual impedance value under the frequency of 50Hz is obtained by averaging the two phase to phase mutual impedance values. According to the method, a traditional measurement method is changed, the influence of line distribution parameter characteristics and induction voltage phases and the existence of power frequency interference are considered in the line connection mode and the algorithm, and especially in the long-distance transmission line, the errors of the phase to phase mutual impedance value measured through the method are reduced, and engineering needs are met.

Description

A kind of length is apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity

Technical field

The invention belongs to power transmission and transformation test, particularly a kind of length is apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, and the method can realize Measurement accuracy length apart from the alternate transimpedance of extra-high voltage same tower double circuit transmission line of electricity.

Background technology

For the long measurement apart from the alternate transimpedance of same tower double back transmission line, traditional measurement method is because circuit phase conductor electric capacity and impedance influences each other and existence that power frequency is disturbed, tend to produce larger error, the longer error of circuit distance is larger, and this kind of error may can not put up with in engineering application.

Summary of the invention

The object of the invention is to propose a kind of length apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity technical scheme for the problems referred to above, in scheme, utilize alien frequencies power supply to solve power frequency interference problem, utilize the alternate transimpedance correction algorithm of long distance line to overcome capacitive coupling and the impact of ground capacitance on alternate transimpedance, the method is applicable to the measurement of the alternate transimpedance of different length circuit.

To achieve these goals, technical scheme of the present invention is: a kind of length is apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, it is the measuring method of 240 kilometers of above common-tower double-return A1, B1, C1, A2, B2, the alternate transimpedance of C2 six-phase transmission lines 50Hz frequency, wherein, described method comprises:

The first step: obtain respectively the alternate transimpedance value of take under two frequencies that absolute error value up and down that 50Hz frequency is mid point equates;

Second step: two alternate transimpedance values are averaged and obtain alternate transimpedance mean value under two frequencies, and described mean value is alternate transimpedance value under 50Hz frequency.

Further, described absolute error value is 1.5Hz to 3Hz to scheme.

Further, the alternate transimpedance value under two frequencies that the absolute error value up and down that described 50Hz frequency is mid point equates, is the alternate transimpedance value under two frequencies eliminating after 50Hz frequency interferences to scheme, and concrete step is:

The first step, tested phase head end open circuit end ground connection, other phase head end open circuit end ground connection, applies voltage Injection Current at tested phase head end, the tested phase head end current signal under two frequencies of synchro measure and other phase head end induced voltage signal;

Second step, adopts FFT Fourier Transform Filtering algorithm to obtain the voltage and current signal under two frequencies;

The 3rd step, by the voltage and current signal under two frequencies, obtains respectively the alternate transimpedance value under two frequencies.

Further, the obtaining step of described alternate transimpedance value is scheme:

The first step: meter is calculated the self-impedance of A1, B1, C1, A2, B2, C2 phase conductor first respectively, self-admittance, determines electric current correction factor and voltage correction factor by self-impedance and self-admittance;

Second step, A1, B1, C1, A2, B2, C2 mutually in one of select progressively A1, B1, C1, A2, B2 be a tested phase, by tested phase head end and other induced voltage phase head end open circuit, tested phase end and other induced voltage phase end ground connection, at tested phase head end Injection Current, measure respectively tested phase head end injected value of current and other induced voltage phase head end voltage;

The 3rd step: list alternate transimpedance equation expression formula according to described electric current correction factor and voltage correction factor the tested phase head end source current being obtained by second step, induced voltage phase head end voltage;

The 4th step: solving equation expression formula obtains A1, B1, C1, A2, the alternate transimpedance value of B2, C2.

Further, described alternate transimpedance equation expression formula is scheme:

$Z_M=\frac{{\stackrel{\·}{U}}_j}{k_1{k}_2{\stackrel{\·}{I}}_i}={\stackrel{\·}{U}}_j/(\frac{\tanh \sqrt{Z_i{Y}_i}}{\sqrt{Z_i{Y}_i}}\·\frac{\tanh \sqrt{Z_j{Y}_j}}{\sqrt{Z_j{Y}_j}}{i}_i);$

Described electric current correction factor is:

Described voltage correction factor is:

Wherein: k ₁for electric current correction factor, k ₂for voltage correction factor, subscript j is induced voltage phase, and subscript i is Injection Current phase; Y _jfor the zero sequence resultant admittance of induced voltage phase, Z _iand Z _jbe respectively the self-impedance of Injection Current phase and induced voltage phase, Y _ifor the self-admittance of Injection Current phase.Wherein

y _jjfor the self-admittance of induced voltage j phase, Y _jkfor transadmittance.

Scheme is further: described meter is calculated A1, B1, C1, A2, B2, the self-impedance of C2 phase conductor, the method for self-admittance is:

Described phase self-admittance measurement comprises the following steps:

The first step: by tested phase head end and terminal open circuit, all the other not tested phase head end and end shorted to earths;

Second step: add alternating voltage at tested phase head end, first and last end synchro measure obtains tested phase head end voltage, head end electric current, terminal voltage, end current, wherein end current is measured as zero, and the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: obtain phase self-admittance by following formula:

$\left[\begin{array}{c}{\stackrel{\·}{U}}_1\\ {\stackrel{\·}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\λl}& Z_c\sinh \mathrm{\λl}\\ \frac{\sin \mathrm{\λl}}{Z_c}& \cosh \mathrm{\λl}\end{array}\right]\left[\begin{array}{c}{\stackrel{\·}{U}}_2\\ {\stackrel{\·}{I}}_2\end{array}\right]$

In formula

represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\λ}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor phase wave impedance, λ is phase circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length phase self-capacitance, phase self-resistance, from reactance, phase self-conductance with from susceptance, z is phase self-impedance, y is phase self-admittance;

The measurement of described phase self-impedance comprises the following steps:

The first step: by tested phase head end open circuit, tested phase end shorted to earth, all the other not tested phase head end and terminal open circuits;

Second step: add alternating voltage at tested phase head end, first and last end synchro measure obtains tested phase head end voltage, head end electric current, terminal voltage, end current, and the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: obtain phase self-impedance by following formula:

$\left[\begin{array}{c}{\stackrel{\·}{U}}_1\\ {\stackrel{\·}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\λl}& Z_c\sinh \mathrm{\λl}\\ \frac{\sin \mathrm{\λl}}{Z_c}& \cosh \mathrm{\λl}\end{array}\right]\left[\begin{array}{c}{\stackrel{\·}{U}}_2\\ {\stackrel{\·}{I}}_2\end{array}\right]$

In formula

represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\λ}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor phase wave impedance, λ is phase circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length phase self-capacitance, phase self-resistance, from reactance, phase self-conductance with from susceptance, z is phase self-impedance, y is phase self-admittance.

The present invention compared with prior art tool has the following advantages: the present invention has changed traditional measurement method, in the mode of connection, adopted head end open circuit, the whole ground connection of end, on metering system, adopt and measure the head end Injection Current of tested phase and the induced voltage of other phase head end, on algorithm, introduced the concept of electric current correction factor and voltage correction factor, therefore on the mode of connection and algorithm, consider the existence that circuit characteristics of distributed parameters and impact and the power frequency of induced voltage phase are disturbed, particularly in long distance transmission line, by the inventive method, measure the alternate transimpedance value of coming and reduced error, the needs of engineering have been met.

Below in conjunction with drawings and Examples, the present invention is described in detail.

Accompanying drawing explanation

Fig. 1 is that common-tower double-return circuit is equivalent to π lumped parameter model schematic diagram;

Circuit π type schematic equivalent circuit when Fig. 2 is test;

Fig. 3 is the circuit equivalent electrical circuit that applies current return electric current;

Fig. 4 is for producing the distribution parameter isoboles of induced voltage circuit.

Embodiment

Length, apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, is the measuring method of 240 kilometers of above common-tower double-return A1, B1, C1, A2, B2, the alternate transimpedance of C2 six-phase transmission lines 50Hz frequency, and wherein, described method comprises:

The first step: obtain respectively the alternate transimpedance value of take under two frequencies that absolute error value up and down that 50Hz frequency is mid point equates;

Second step: two alternate transimpedance values are averaged and obtain alternate transimpedance mean value under two frequencies, and described mean value is alternate transimpedance value under 50Hz frequency.

In embodiment, described absolute error value is 1.5Hz to 3Hz.

In embodiment: the alternate transimpedance value under two frequencies that the absolute error value up and down that described 50Hz frequency is mid point equates is the alternate transimpedance value under two frequencies eliminating after 50Hz frequency interferences, and concrete step is:

The first step, tested phase head end open circuit end ground connection, other phase head end open circuit end ground connection, applies voltage Injection Current at tested phase head end, the tested phase head end current signal under two frequencies of synchro measure and other phase head end induced voltage signal;

Second step, adopts FFT Fourier Transform Filtering algorithm to obtain the voltage and current signal under two frequencies;

The 3rd step, by the voltage and current signal under two frequencies, obtains respectively the alternate transimpedance value under two frequencies.

For avoiding the interference of power frequency component in test, alternate transimpedance is measured and is used alien frequencies power supply, supply frequency selects to approach alien frequencies 47.5Hz and the 52.5Hz of 50Hz, use respectively two frequency measurements, because actual measurement environment mesohigh aerial power transmission line is not to only have separately test line, also have the 50Hz circuit that other is moving, the interference that can bring 50Hz simultaneously.Therefore, if there is power frequency to disturb in measuring-signal, the voltage and current signal of surveying by alien frequencies signal and the interference of 50Hz power frequency, formed, utilize FFT Fourier transform extraction alien frequencies signal wherein, then calculate the alternate transimpedance R under alien frequencies _47.5, X _47.5and R _52.5, X _52.5, the transimpedance under 50Hz frequency obtains in accordance with the following methods:

R ₅₀=(R _47.5+R _52.5)÷2

$X_{50}=(X_{47.5}\×\frac{50}{47.5}+X_{52.5})\÷2$

In embodiment: the obtaining step of described alternate transimpedance value is:

The first step: meter is calculated the self-impedance of A1, B1, C1, A2, B2, C2 phase conductor first respectively, self-admittance, determines electric current correction factor and voltage correction factor by self-impedance and self-admittance;

Second step, A1, B1, C1, A2, B2, C2 mutually in one of select progressively A1, B1, C1, A2, B2 be a tested phase, by tested phase head end and other induced voltage phase head end open circuit, tested phase end and other induced voltage phase end ground connection, at tested phase head end Injection Current, measure respectively tested phase head end injected value of current and other induced voltage phase head end voltage;

The 3rd step: list alternate transimpedance equation expression formula according to described electric current correction factor and voltage correction factor the tested phase head end source current being obtained by second step, induced voltage phase head end voltage;

The 4th step: solving equation expression formula obtains A1, B1, C1, A2, the alternate transimpedance value of B2, C2.

In embodiment, described alternate transimpedance equation expression formula is:

$Z_M=\frac{{\stackrel{\·}{U}}_j}{k_1{k}_2{\stackrel{\·}{I}}_i}={\stackrel{\·}{U}}_j/(\frac{\tanh \sqrt{Z_i{Y}_i}}{\sqrt{Z_i{Y}_i}}\·\frac{\tanh \sqrt{Z_j{Y}_j}}{\sqrt{Z_j{Y}_j}}{i}_i);$

Described electric current correction factor is:

Described voltage correction factor is:

Wherein: k ₁for electric current correction factor, k ₂for voltage correction factor, subscript j is induced voltage phase, and subscript i is Injection Current phase; Y _jfor the zero sequence resultant admittance of induced voltage phase, Z _iand Z _jbe respectively the self-impedance of Injection Current phase and induced voltage phase, Y _ifor the self-admittance of Injection Current phase.Wherein

y _jjfor the self-admittance of induced voltage j phase, Y _jkfor phase transadmittance.

Wherein, described phase transadmittance Y _jkto obtain by following method:

The first step: meter is calculated self-impedance and the self-admittance of the unit length of A1, B1, C1, A2, B2, C2 phase conductor first respectively, determines by self-impedance and self-admittance the constant that each calculates for mutual capacitance value;

Second step: A1, B1, C1, A2, B2, C2 mutually in select progressively A1, B1, C1, A2, B2 one be a tested phase mutually, opened a way in tested phase two ends, at tested phase head end, apply described frequency supply voltage, other phase terminal open circuit, other phase head end shorted to earth, the respectively tested phase head end of synchro measure and terminal voltage, other phase head end earth current and other phase terminal voltage;

The 3rd step: sequentially list mutual admittance equations expression formula tested and other phase according to described constant the tested phase head end supply voltage being obtained by second step, tested phase terminal voltage, other phase head end earth current and other phase terminal voltage;

The 4th step: solving equation expression formula obtains A1, B1, C1, A2, the mutual admittance value of B2, C2;

The mutual admittance equations expression formula of described tested and other phase is respectively: when measuring the phase transadmittance expression formula that A1 phase time is A1 phase and B1 phase, C1 phase, A2 phase, B2 phase, C2 phase, when measuring B1 phase time, it is B1 phase and the phase transadmittance expression formula of C1 phase, A2 phase, B2 phase, C2 phase, when measuring C1 phase time, it is C1 phase and the phase transadmittance expression formula of A2 phase, B2 phase, C2 phase, when measuring A2 phase time, be A2 phase and the phase transadmittance expression formula of B2 phase, C2 phase, when the phase transadmittance expression formula of measurement B2 phase time B2 phase with C2 phase;

Described constant is by formula $k_i=\frac{\tanh ({\mathrm{\λ}}_{i}l/2)}{{\mathrm{\λ}}_{i}l/2}=\frac{\tanh (\sqrt{z_i{y}_i}l/2)}{\sqrt{z_i{y}_i}l/2}$

Definite constant, κ in formula _ifor constant,

λ _ifor phase conductor propagation constant,

z _iand y _ibe respectively unit length self-impedance and the self-admittance of each phase conductor; L is line length;

Subscript i=1,2,3,4,5,6,1,2,3,4,5,6 represents respectively A1, B1, C1, A2, B2, C2 phase;

Described A1 phase with the phase transadmittance expression formula of B1 phase, C1 phase, A2 phase, B2 phase, C2 phase is:

$\frac{{\stackrel{\·}{I}}_{i1}+{\stackrel{\·}{E}}_{i1}*Y_i^{\′}/2}{({\stackrel{\·}{U}}_{11}+{\stackrel{\·}{U}}_{12})/2}=\frac{{\stackrel{\·}{I}}_{i1}+{\stackrel{\·}{E}}_{i1}*(k_i{Y}_i-\underset{j=1}{\overset{6}{\mathrm{\Σ}}}{Y}_{\mathrm{ij}})/2}{({\stackrel{\·}{U}}_{11}+{\stackrel{\·}{U}}_{12})/2}=Y_{1i}$ Expression formula one

Wherein, subscript i ≠ j, i is that coupling phase=2,3,4,5,6,2,3,4,5,6 represent respectively B1, C1, A2, B2, C2 phase; Y ' _ifor i phase conductor changes the relatively resultant admittance of equivalence of lumped parameter, Y into _ifor i corresponding distribution parameter self-admittance mutually, Y ₁i is A1 phase and the transadmittance of i phase,

a1 phase head end voltage,

not terminal voltage of A1 phase,

a1 i phase head end earth current while applying voltage mutually,

it is A1 i phase terminal voltage while applying voltage mutually; By i=2,3,4,5,6,5 equations are listed in substitution respectively;

Described B1 phase with the phase transadmittance expression formula of C1 phase, A2 phase, B2 phase, C2 phase is:

$\frac{\stackrel{\&CenterDot;}{I_{i2}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="2"\; label="E\; i"\; filenames="140107142023.png,140107142027.png"\; state="\{\{state\}\}">E</figure-callout>}}_i}*Y_i^{\&prime;}/2}{(\stackrel{\&CenterDot;}{U_{21}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="22"\; label="U"\; filenames="140107142023.png,140107142027.png"\; state="\{\{state\}\}">U</figure-callout>}}_{22}})/2}=\frac{\stackrel{\&CenterDot;}{I_{i2}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="2"\; label="E\; i"\; filenames="140107142023.png,140107142027.png"\; state="\{\{state\}\}">E</figure-callout>}}_i}*(k_i{Y}_i-\underset{j=1}{\overset{6}{\mathrm{\&Sigma;}}}{Y}_{\mathrm{ij}})/2}{(\stackrel{\&CenterDot;}{U_{21}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="22"\; label="U"\; filenames="140107142023.png,140107142027.png"\; state="\{\{state\}\}">U</figure-callout>}}_{22}})/2}=Y_{2i}$ Expression formula two

Wherein, subscript i ≠ j, i is that coupling phase=3,4,5,6,3,4,5,6 represent respectively C1, A2, B2, C2 phase; Y ' _ifor i phase conductor changes the relatively resultant admittance of equivalence of lumped parameter, Y into _ifor i corresponding distribution parameter self-admittance mutually, Y ₂i is B1 phase and the transadmittance of i phase,

b1 phase head end voltage,

not terminal voltage of B1 phase,

b1 i phase head end earth current while applying voltage mutually,

it is B1 i phase terminal voltage while applying voltage mutually; By i=3,4,5,6,4 equations are listed in substitution respectively;

Described C1 phase with the phase transadmittance expression formula of A2 phase, B2 phase, C2 phase is:

$\frac{\stackrel{\&CenterDot;}{I_{i3}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="3"\; label="E\; i"\; filenames="140107142032.png"\; state="\{\{state\}\}">E</figure-callout>}}_i}*Y_i^{\&prime;}/2}{(\stackrel{\&CenterDot;}{U_{31}}+\stackrel{\&CenterDot;}{U_{32}})/2}=\frac{\stackrel{\&CenterDot;}{I_{i3}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="3"\; label="E\; i"\; filenames="140107142032.png"\; state="\{\{state\}\}">E</figure-callout>}}_i}*(k_i{Y}_i-\underset{j=1}{\overset{6}{\mathrm{\&Sigma;}}}{Y}_{\mathrm{ij}})/2}{(\stackrel{\&CenterDot;}{U_{31}}+\stackrel{\&CenterDot;}{U_{32}})/2}=Y_{3i}$ Expression formula three

Wherein, subscript i ≠ j, i is that coupling phase=4,5,6,4,5,6 represent respectively A2, B2, C2 phase; Y ' _ifor i phase conductor changes the relatively resultant admittance of equivalence of lumped parameter, Y into _ifor the self-admittance of the corresponding distribution parameter phase of i, Y ₃i is C1 phase and the transadmittance of i phase, c1 phase head end voltage,

not terminal voltage of C1 phase,

c1 i phase head end earth current while applying voltage mutually,

it is C1 i phase terminal voltage while applying voltage mutually; By i=4,5,6,3 equations are listed in substitution respectively;

Described A2 phase with the phase transadmittance expression formula of B2 phase, C2 phase is:

$\frac{\stackrel{\&CenterDot;}{I_{i4}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="4"\; label="E\; i"\; filenames="140107142027.png"\; state="\{\{state\}\}">E</figure-callout>}}_i}*Y_i^{\&prime;}/2}{(\stackrel{\&CenterDot;}{U_{41}}+\stackrel{\&CenterDot;}{U_{42}})/2}=\frac{\stackrel{\&CenterDot;}{I_{i4}}+\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="4"\; label="E\; i"\; filenames="140107142027.png"\; state="\{\{state\}\}">E</figure-callout>}}_i}*(k_i{Y}_i-\underset{j=1}{\overset{6}{\mathrm{\&Sigma;}}}{Y}_{\mathrm{ij}})/2}{(\stackrel{\&CenterDot;}{U_{41}}+\stackrel{\&CenterDot;}{U_{42}})/2}=Y_{4i}$ Expression formula four

Wherein, subscript i ≠ j, i is that coupling phase=5,6,5,6 represent respectively B2, C2 phase; Y ' _ifor i phase conductor changes the relatively resultant admittance of equivalence of lumped parameter, Y into _ifor the self-admittance of the corresponding distribution parameter phase of i, Y ₄i is A2 phase and the transadmittance of i phase,

a2 phase head end voltage,

not terminal voltage of A2 phase,

a2 i phase head end earth current while applying voltage mutually,

it is A2 i phase terminal voltage while applying voltage mutually; By i=5,6,2 equations are listed in substitution respectively;

Described B2 phase with the phase transadmittance expression formula of C2 phase is:

$\frac{\stackrel{\&CenterDot;}{I_{i5}}+\stackrel{\&CenterDot;}{E_{i5}}*Y_i^{\&prime;}/2}{(\stackrel{\&CenterDot;}{U_{51}}+\stackrel{\&CenterDot;}{U_{52}})/2}=\frac{\stackrel{\&CenterDot;}{I_{i5}}+\stackrel{\&CenterDot;}{E_{i5}}*(k_i{Y}_i-\underset{j=1}{\overset{6}{\mathrm{\&Sigma;}}}{Y}_{\mathrm{ij}})/2}{(\stackrel{\&CenterDot;}{U_{51}}+\stackrel{\&CenterDot;}{U_{52}})/2}=Y_{5i}$ Expression formula five

Wherein, subscript i ≠ j, i is coupling phase=6,6 represent C2 phase; Y ' _ifor i phase conductor changes the relatively resultant admittance of equivalence of lumped parameter, Y into _ifor i corresponding distribution parameter self-admittance mutually, Y ₅i is B2 phase and the transadmittance of i phase,

b2 phase head end voltage,

not terminal voltage of B2 phase,

b2 i phase head end earth current while applying voltage mutually, be B2 i phase terminal voltage while applying voltage mutually, i=6 substitution is listed to 1 equation;

15 yuan of solving equations of above-mentioned five expression formulas expansion are obtained to 15 alternate transadmittance Y _ij.

Below further illustrating said method:

In Fig. 1, length is equivalent to π model, Y ' apart from common-tower double-return circuit _ifor i phase conductor changes the equivalence resultant admittance over the ground of lumped parameter, Y into _ijfor alternate transadmittance, Z _ifor phase conductor changes the self-impedance of lumped parameter, Z into _mfor alternate transimpedance.

The test connection method that the present embodiment proposes is as follows, when measuring A1 phase and other alternate transimpedance, circuit is equivalent to pi-network, and during measurement, equivalent electrical circuit as shown in Figure 2.Test method is that A1 phase head end applies power supply Injection Current, the equal ground connection of all 6 phase ends, and B1, C1, A2, B2, C2 phase head end are unsettled earth-free, measure Injection Current phase A1 phase head end electric current in test

with other phase head end voltage

While measuring other alternate transimpedance, method is same as described above, and the transimpedance between the two-phase of before having measured can no longer be measured.

For alternate transimpedance correction algorithm, we first consider two alternate transimpedance analyses, do not consider that other affects mutually, for the distribution parameter equivalent circuit that applies electric current phase as shown in Figure 3:

$\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1\\ {\stackrel{\&CenterDot;}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\mathrm{ch\&lambda;l}& Z_c\mathrm{sh\&gamma;l}\\ \frac{\mathrm{sh\&lambda;l}}{Z_C}& \mathrm{ch\&gamma;\&lambda;l}\end{array}\right]\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_2\\ {\stackrel{\&CenterDot;}{I}}_2\end{array}\right]---\left(1\right)$

Circuit unit length inductance l ₀, electric capacity c ₀, resistance r ₀, reactance x ₀, electricity is led g ₀, susceptance b ₀, Z _cfor surge impedance of a line (characteristic impedance),

λ is circuit propagation constant

circuit resistance R, inductance L, reactance completely, line length l, X=ω l ₀l=ω L, electricity are led G, admittance Y=l (g ₀+ j ω c ₀)=G+j ω C, capacitor C=c ₀l, impedance Z=l (r ₀+ jx ₀)=R+jX.

While measuring mutual inductance, apply electric current phase end ground connection, head end applies power supply, in above formula (1)

by formula (1), can be obtained along the line and first and last end current relationship is respectively,

$\stackrel{\&CenterDot;}{I}\left(l\right)={\stackrel{\&CenterDot;}{I}}_2\mathrm{ch\&lambda;l}---\left(2\right)$

$\stackrel{\&CenterDot;}{U}\left(l\right)=Z_c\mathrm{sh\&lambda;l}*{\stackrel{\&CenterDot;}{I}}_2---\left(3\right)$

${\stackrel{\&CenterDot;}{I}}_2=\frac{{\stackrel{\&CenterDot;}{U}}_1}{Z_c\mathrm{sh\&lambda;l}}=\frac{{\stackrel{\&CenterDot;}{I}}_1}{\mathrm{ch\&lambda;l}}---\left(4\right)$

For producing induced voltage phase, its distribution parameter isoboles as shown in Figure 4, has all been considered the induction electromotive force producing due to mutual inductance in the circuit of unit length

it is a controlled source, when its control parameter (applying the line current of electric current) is stablized, regards it as the steady voltage source of distribution.As can be seen from Figure 4, the voltage and current that phase conductor self-impedance and ground capacitance can be measured head end exerts an influence, and makes the head end measuring voltage of induced voltage phase be not equal to the induced potential producing due to mutual inductance effect between actual two phase conductors

circuit is longer, affects greatlyr, and according to traditional transimpedance concept, alternate transimpedance should be expressed as

therefore, make result produce larger error, this error is often difficult to tolerance in engineering.For any element circuit that is l apart from end, there is formula:

$\frac{d\stackrel{\&CenterDot;}{U}\left(l\right)}{\mathrm{dl}}=\stackrel{\&CenterDot;}{I}\left(l\right)*z+{\stackrel{\&CenterDot;}{e}}_M\left(l\right)---\left(5\right)$

$\frac{d\stackrel{\&CenterDot;}{I}\left(l\right)}{\mathrm{dl}}=\stackrel{\&CenterDot;}{U}\left(l\right)y---\left(6\right)$

And

the line current that is Injection Current is multiplied by two circuit transimpedance, and Zm is per unit length zero sequence mutual impedance between two circuits, and this electric current

because the characteristic of distribution parameter is not identical, be also not equal to the electric current that first and last end is surveyed, therefore along the line

be variable, at this, simplify computation model, think

constant,

also be constant (electric current is reduced to constant), equal:

${\stackrel{\&CenterDot;}{I}}^{\#}=\frac{1}{L}{\&Integral;}_0^L\stackrel{\&CenterDot;}{I}\left(l\right)\mathrm{dl}={\stackrel{\&CenterDot;}{I}}_2\frac{\mathrm{sh}\sqrt{\mathrm{ZY}}}{\sqrt{\mathrm{ZY}}}={\stackrel{\&CenterDot;}{I}}_1\frac{\mathrm{th}\sqrt{\mathrm{ZY}}}{\sqrt{\mathrm{ZY}}}---\left(7\right)$

According to formula (7), define an equivalent current correction factor:

(Z, Y is Injection Current phase resulting impedance and resultant admittance)

Definition is total induced potential completely:

${\stackrel{\&CenterDot;}{E}}_M={\stackrel{\&CenterDot;}{e}}_m\left(l\right)*L=z_m*{{\stackrel{\&CenterDot;}{I}}_1}^{\#}*L=Z_m*{{\stackrel{\&CenterDot;}{I}}_1}^{\#}---\left(8\right)$

: $Z_m=\frac{{\stackrel{\&CenterDot;}{E}}_M}{{{\stackrel{\&CenterDot;}{I}}_1}^{\#}}---\left(9\right)$

Formula (5) is carried out to differential:

$\frac{d^2\stackrel{\&CenterDot;}{U}\left(l\right)}{{\mathrm{<figure-callout\; id="2"\; label="dl"\; filenames="140107142023.png,140107142027.png"\; state="\{\{state\}\}">dl</figure-callout>}}^2}=\mathrm{zy}\stackrel{\&CenterDot;}{U}\left(l\right)---\left(10\right)$

The solution of equation (10) is:

$\stackrel{\&CenterDot;}{U}\left(l\right)=C_1{e}^{\mathrm{\&lambda;l}}+C_2{e}^{-\mathrm{\&lambda;l}}---\left(11\right)$

(11) formula is got to micro-formula (5) of bringing into:

$\stackrel{\&CenterDot;}{I}\left(l\right)=\frac{C_1}{Z_C}{e}^{\mathrm{\&lambda;l}}-\frac{C_2}{Z_C}{e}^{-\mathrm{\&lambda;l}}-\frac{{\stackrel{\&CenterDot;}{E}}_M}{Z}---\left(12\right)$

Z=lz wherein, ${\stackrel{\&CenterDot;}{E}}_M=l{\stackrel{\&CenterDot;}{e}}_m\left(l\right),$

When l=0, have $\stackrel{\&CenterDot;}{U}\left(0\right)={\stackrel{\&CenterDot;}{U}}_2,\stackrel{\&CenterDot;}{I}\left(0\right)={\stackrel{\&CenterDot;}{I}}_2,$

Therefore, when l=0, equation (11), (12) are formed to system of equations, first solve C ₁, C ₂:

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="140107142037.png"\; state="\{\{state\}\}">C</figure-callout>}}_1=\frac{1}{2}{\stackrel{\&CenterDot;}{U}}_2+\frac{1}{2}{Z}_c{\stackrel{\&CenterDot;}{I}}_2+\frac{Z_c}{2Z}{\stackrel{\&CenterDot;}{E}}_M---\left(13\right)$

${\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="140107142023.png,140107142027.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=\frac{1}{2}{\stackrel{\&CenterDot;}{U}}_2-\frac{1}{2}{Z}_c{\stackrel{\&CenterDot;}{I}}_2-\frac{Z_c}{2Z}{\stackrel{\&CenterDot;}{E}}_M---\left(14\right)$

Finally: $\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1=\cosh \mathrm{\&gamma;l}*{\stackrel{\&CenterDot;}{U}}_2+Z_c\sinh \mathrm{\&gamma;l}*{\stackrel{\&CenterDot;}{I}}_2+\frac{Z_C\mathrm{sh\&lambda;l}}{Z}*{\stackrel{\&CenterDot;}{E}}_m\\ {\stackrel{\&CenterDot;}{I}}_1=\frac{\sinh \mathrm{\&gamma;l}}{Z_C}*{\stackrel{\&CenterDot;}{U}}_2+\cosh \mathrm{\&gamma;l}*{\stackrel{\&CenterDot;}{I}}_2+\frac{\mathrm{ch\&lambda;l}-1}{Z}*{\stackrel{\&CenterDot;}{E}}_m\end{array}---\left(15\right)$

Namely after former long-line equation, increased by one by

the item determining, this circuit (loop of induced voltage) end short circuit grounding, head end open circuit when conventional method is surveyed mutual inductance, have boundary condition: for people (15), can solve:

${\stackrel{\&CenterDot;}{U}}_1=E_m\frac{Z_C}{Z}\mathrm{th\&lambda;l}=E_m\frac{\mathrm{th}\sqrt{\mathrm{ZY}}}{\sqrt{\mathrm{ZY}}}$ The correction factor of induced potential can be defined as: ${\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="140107142023.png,140107142027.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=\frac{\mathrm{th}\sqrt{\mathrm{ZY}}}{\sqrt{\mathrm{ZY}}}$

Therefore, two alternate transimpedance are expressed as:

Here it is while not considering that other affects mutually, the analysis calculation method of two alternate transimpedance, wherein voltage correction factor

middle Z and Y are used self-impedance and the self-admittance of induced voltage phase, electric current correction factor

middle Z and Y are used self-impedance and the self-admittance of Injection Current phase.

The transimpedance that above method is applied to common-tower double-return 6 phase conductors is measured, and analysis calculation method is as follows.

The alternate transimpedance of common-tower double-return circuit 6: measurement and correction algorithm can be considered the impact of other relative measurement phase with reference to the Measurement Algorithm of two alternate transimpedance, stipulate the mode of connection of other phase, redefine correction factor.

Utilize measured two-phase head end voltage and current, the algorithm of the alternate transimpedance of this patent proposition common-tower double-return circuit is as follows:

$Z_M=\frac{{\stackrel{\&CenterDot;}{U}}_j}{k_1{k}_2{\stackrel{\&CenterDot;}{I}}_i}={\stackrel{\&CenterDot;}{U}}_j/(\frac{\tanh \sqrt{Z_i{Y}_i}}{\sqrt{Z_i{Y}_i}}\&CenterDot;\frac{\tanh \sqrt{Z_j{Y}_j}}{\sqrt{Z_j{Y}_j}}{i}_i)---\left(16\right)$

K wherein ₁for electric current correction factor

K ₂for voltage correction factor $k_{}$ ${}_2=\tanh \sqrt{Z_j{Y}_j}/\sqrt{Z_j{Y}_j},$

Electric current correction factor in formula (16)

with voltage correction factor

middle Z _iand Z _jget respectively the self-impedance of Injection Current phase and induced voltage phase conductor.For Injection Current phase correction factor k ₁in Y _iat this, can directly get the self-admittance of Injection Current phase, still can produce error herein in theory, because self-admittance comprises and other all alternate admittance, and in measuring process, the head end of induced voltage phase all can produce induced voltage, Injection Current phase and other each alternate capacitance current are reduced, be equivalent to Y _ireduce to some extent, herein due to k ₁affect littlely, ignore.For induced voltage phase correction factor k ₂in Y _j, because each mutually alternate transimpedance is basic identical, can think that in theory induced voltage equates, the induced voltage phase of surveying do not produce capacitance current mutually alternate with other induced voltage, therefore, Y ₂choose the transadmittance that should not comprise that surveyed induced voltage phase is mutually alternate with other induced voltage:

$Y_j=Y_{\mathrm{jj}}-\underset{k=1}{\overset{6}{\mathrm{\&Sigma;}}}{Y}_{\mathrm{jk}},k\&NotEqual;j,k\&NotEqual;i,$ (1)

Y wherein _jjfor the self-admittance of induced voltage j phase, Y _jkfor transadmittance mutually alternate with other induced voltage.

Therefore, any two alternate transimpedance are calculated and can be expressed as:

$Z_M=\frac{{\stackrel{\&CenterDot;}{U}}_j}{k_1{k}_2{\stackrel{\&CenterDot;}{I}}_i}={\stackrel{\&CenterDot;}{U}}_j/(\frac{\tanh \sqrt{Z_i{Y}_i}}{\sqrt{Z_i{Y}_i}}\&CenterDot;\frac{\tanh \sqrt{Z_j{Y}_j}}{\sqrt{Z_j{Y}_j}}{i}_i)$ (2)

Wherein

wherein j is induced voltage phase, and i is Injection Current phase, Z _iand Z _jbe respectively the self-impedance of Injection Current phase and induced voltage phase conductor, Y _ifor the self-admittance of Injection Current phase, Y _jthe zero sequence resultant admittance of induced voltage phase, Y _jjfor the self-admittance of induced voltage j phase, Y _jkfor the j phase transadmittance alternate with other phase k.

In embodiment, described meter is calculated A1, B1, C1, A2, B2, the self-impedance of C2 phase conductor and the method for self-admittance and is:

Described phase self-admittance measurement comprises the following steps:

The first step: by tested phase head end and terminal open circuit, all the other not tested phase head end and end shorted to earths;

Second step: add alternating voltage at tested phase head end, first and last end synchro measure obtains tested phase head end voltage, head end electric current, terminal voltage, end current, wherein end current is measured as zero, and the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: obtain phase self-admittance by following formula:

$\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1\\ {\stackrel{\&CenterDot;}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\&lambda;l}& Z_c\sinh \mathrm{\&lambda;l}\\ \frac{\sin \mathrm{\&lambda;l}}{Z_c}& \cosh \mathrm{\&lambda;l}\end{array}\right]\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_2\\ {\stackrel{\&CenterDot;}{I}}_2\end{array}\right]$

In formula represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\&lambda;}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor phase wave impedance, λ is phase circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length phase self-capacitance, phase self-resistance, from reactance, phase self-conductance with from susceptance, z is that (self-impedance is now for measuring the self-impedance of the mode of connection that phase self-admittance adopts to phase self-impedance, therefore large with actual self-impedance error, can not use), y is phase self-admittance, and phase self-admittance just can obtain the phase self-admittance of unit length divided by line length;

The measurement of described phase self-impedance comprises the following steps:

The first step: by tested phase head end open circuit, tested phase end shorted to earth, all the other not tested phase head end and terminal open circuits;

Second step: add alternating voltage at tested phase head end, first and last end synchro measure obtains tested phase head end voltage, head end electric current, terminal voltage, end current, and the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: obtain phase self-impedance by following formula:

$\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1\\ {\stackrel{\&CenterDot;}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\&lambda;l}& Z_c\sinh \mathrm{\&lambda;l}\\ \frac{\sin \mathrm{\&lambda;l}}{Z_c}& \cosh \mathrm{\&lambda;l}\end{array}\right]\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_2\\ {\stackrel{\&CenterDot;}{I}}_2\end{array}\right]$

In formula

represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\&lambda;}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor phase wave impedance, λ is phase circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length phase self-capacitance, phase self-resistance, from reactance, phase self-conductance with from susceptance, z is phase self-impedance, y is that (self-admittance is now for measuring the self-admittance of the mode of connection that phase self-impedance adopts in phase self-admittance, therefore large with actual self-admittance error, can not use), phase self-impedance just can obtain the phase self-impedance of unit length divided by line length.

In embodiment, while having other power frequency to disturb in A1, B1, C1, A2, B2, C2 six phase power transmission sequences:

The step that described phase self-admittance is measured is further:

The first step: by tested phase head end and terminal open circuit, all the other not tested phase head end and end shorted to earths;

Second step: add respectively the alternating voltage of take under two frequencies that absolute error value up and down that 50Hz frequency is mid point equates at tested phase head end, first and last end synchro measure obtains alternating voltage, head end electric current, terminal voltage, the end current under two frequencies of tested phase head end, wherein end current is measured as zero, and the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: adopt FFT Fourier Transform Filtering algorithm to obtain the voltage and current under two frequencies;

The 4th step: obtain respectively phase self-admittance under two frequencies by following formula:

$\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1\\ {\stackrel{\&CenterDot;}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\&lambda;l}& Z_c\sinh \mathrm{\&lambda;l}\\ \frac{\sin \mathrm{\&lambda;l}}{Z_c}& \cosh \mathrm{\&lambda;l}\end{array}\right]\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_2\\ {\stackrel{\&CenterDot;}{I}}_2\end{array}\right]$ Formula three;

In formula

represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\&lambda;}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor wave impedance, λ is circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length self-capacitance, self-resistance, from reactance, self-conductance with from susceptance, and propagation constant λ, z is phase self-impedance, y is phase self-admittance;

The 5th step: be averaged the phase self-admittance obtaining under 50Hz frequency by obtaining phase autoregressive parameter under two frequencies;

The step that described phase self-impedance is measured is further:

The first step: by tested phase head end open circuit, tested phase end shorted to earth, all the other not tested phase head end and terminal open circuits;

Second step: add respectively the alternating voltage of take under two frequencies that absolute error value up and down that 50Hz frequency is mid point equates at tested phase head end, first and last end synchro measure obtains alternating voltage, head end electric current, terminal voltage, the end current under two frequencies of tested phase head end, and the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: adopt FFT Fourier Transform Filtering algorithm to obtain the voltage and current under two frequencies;

The 4th step: obtain respectively phase self-impedance under two frequencies by following formula:

$\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1\\ {\stackrel{\&CenterDot;}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\&lambda;l}& Z_c\sinh \mathrm{\&lambda;l}\\ \frac{\sin \mathrm{\&lambda;l}}{Z_c}& \cosh \mathrm{\&lambda;l}\end{array}\right]\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_2\\ {\stackrel{\&CenterDot;}{I}}_2\end{array}\right]$ Formula four;

In formula

represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\&lambda;}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor wave impedance, λ is circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length self-capacitance, self-resistance, from reactance, self-conductance with from susceptance, and propagation constant λ, z is phase self-impedance, y is phase self-admittance;

The 5th step: be averaged the phase self-impedance obtaining under 50Hz frequency by obtaining phase self-impedance under two frequencies.

For above-described embodiment method validation:

For verifying above-mentioned algorithm, in PSCAD software, set up realistic model simulation actual measurement, line length is 336.6 kilometers, for making each alternate transimpedance distinguish to some extent model simultaneously, can provide alternate transimpedance true value, double-circuit line 6 is not replaced mutually, measure wherein two-phase.Simulation results sees the following form:

Table simulating, verifying

By table, can be found out, the alternate mutual resistance error 2.06% of method two that the present embodiment proposes, mutual reactance error 0.69%, with traditional algorithm

the error 14.34% of calculating is compared with 7.09%, has greatly reduced the error of calculation, can meet the needs of engineering completely.

Claims (6)

1. one kind long apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, it is the measuring method of 240 kilometers of above common-tower double-return A1, B1, C1, A2, B2, the alternate transimpedance of C2 six-phase transmission lines 50Hz frequency, it is characterized in that, described method comprises:

The first step: obtain respectively the alternate transimpedance value of take under two frequencies that absolute error value up and down that 50Hz frequency is mid point equates;

Second step: two alternate transimpedance values are averaged and obtain alternate transimpedance mean value under two frequencies, and described mean value is alternate transimpedance value under 50Hz frequency.

2. a kind of length according to claim 1, apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, is characterized in that, described absolute error value is 1.5Hz to 3Hz.

3. a kind of length according to claim 1 is apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, it is characterized in that, alternate transimpedance value under two frequencies that the absolute error value up and down that described 50Hz frequency is mid point equates, be the alternate transimpedance value under two frequencies eliminating after 50Hz frequency interferences, concrete step is:

The first step, tested phase head end open circuit end ground connection, other phase head end open circuit end ground connection, applies voltage Injection Current at tested phase head end, the tested phase head end current signal under two frequencies of synchro measure and other phase head end induced voltage signal;

Second step, adopts FFT Fourier Transform Filtering algorithm to obtain the voltage and current signal under two frequencies;

The 3rd step, by the voltage and current signal under two frequencies, obtains respectively the alternate transimpedance value under two frequencies.

According to a kind of length one of claim 1 or 3 Suo Shu apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, it is characterized in that, the obtaining step of described alternate transimpedance value is:

The first step: meter is calculated the self-impedance of A1, B1, C1, A2, B2, C2 phase conductor first respectively, self-admittance, determines electric current correction factor and voltage correction factor by self-impedance and self-admittance;

Second step, A1, B1, C1, A2, B2, C2 mutually in one of select progressively A1, B1, C1, A2, B2 be a tested phase, by tested phase head end and other induced voltage phase head end open circuit, tested phase end and other induced voltage are held end ground connection mutually, at tested phase head end Injection Current, measure respectively tested phase head end injected value of current and other induced voltage phase head end voltage;

The 3rd step: list alternate transimpedance equation expression formula according to described electric current correction factor and voltage correction factor the tested phase head end source current being obtained by second step, induced voltage phase head end voltage;

The 4th step: solving equation expression formula obtains A1, B1, C1, A2, the alternate transimpedance value of B2, C2.

5. a kind of length according to claim 4, apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, is characterized in that, described alternate transimpedance equation expression formula is:

$Z_M=\frac{{\stackrel{\&CenterDot;}{U}}_j}{k_1{k}_2{\stackrel{\&CenterDot;}{I}}_i}={\stackrel{\&CenterDot;}{U}}_j/(\frac{\tanh \sqrt{Z_i{Y}_i}}{\sqrt{Z_i{Y}_i}}\&CenterDot;\frac{\tanh \sqrt{Z_j{Y}_j}}{\sqrt{Z_j{Y}_j}}{i}_i);$

Described electric current correction factor is:

Described voltage correction factor is:

Wherein: k ₁for electric current correction factor, k ₂for voltage correction factor, subscript j is induced voltage phase, and subscript i is Injection Current phase; Y _jfor the zero sequence resultant admittance of induced voltage phase, Z _iand Z _jbe respectively the self-impedance of Injection Current phase and induced voltage phase, Y _ifor the self-admittance of Injection Current phase.Wherein

y _jjfor the self-admittance of induced voltage j phase, Y _jkfor transadmittance.

6. a kind of length according to claim 4, apart from the alternate transimpedance measuring method of extra-high voltage same tower double circuit transmission line of electricity, is characterized in that, described meter is calculated A1, B1, C1, A2, B2, the self-impedance of C2 phase conductor, the method for self-admittance is:

Described phase self-admittance measurement comprises the following steps:

The first step: by tested phase head end and terminal open circuit, all the other not tested phase head end and end shorted to earths;

Second step: add alternating voltage at tested phase head end, first and last end synchro measure obtains tested phase head end voltage, head end electric current, terminal voltage, end current, wherein end current is measured as zero, and the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: obtain phase self-admittance by following formula:

$\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1\\ {\stackrel{\&CenterDot;}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\&lambda;l}& Z_c\sinh \mathrm{\&lambda;l}\\ \frac{\sin \mathrm{\&lambda;l}}{Z_c}& \cosh \mathrm{\&lambda;l}\end{array}\right]\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_2\\ {\stackrel{\&CenterDot;}{I}}_2\end{array}\right]$

In formula

represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\&lambda;}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor phase wave impedance, λ is phase circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length phase self-capacitance, phase self-resistance, from reactance, phase self-conductance with from susceptance, z is phase self-impedance, y is phase self-admittance;

The measurement of described phase self-impedance comprises the following steps:

The first step: by tested phase head end open circuit, tested phase end shorted to earth, all the other not tested phase head end and terminal open circuits;

Second step: add alternating voltage at tested phase head end, first and last end synchro measure obtains tested phase head end voltage, head end electric current, terminal voltage, end current, wherein terminal voltage is zero, the time error of described first and last end synchro measure is less than 1 microsecond;

The 3rd step: obtain phase self-impedance by following formula:

$\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_1\\ {\stackrel{\&CenterDot;}{I}}_1\end{array}\right]=\left[\begin{array}{cc}\cosh \mathrm{\&lambda;l}& Z_c\sinh \mathrm{\&lambda;l}\\ \frac{\sin \mathrm{\&lambda;l}}{Z_c}& \cosh \mathrm{\&lambda;l}\end{array}\right]\left[\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_2\\ {\stackrel{\&CenterDot;}{I}}_2\end{array}\right]$

In formula

represent respectively phase head end voltage, electric current and terminal voltage, the electric current surveyed, l is line length, $Z_C=\sqrt{z/y}=\sqrt{(r_0+{\mathrm{jx}}_0)/(g_0+{\mathrm{jb}}_0)},$ $\mathrm{\&lambda;}=\sqrt{\mathrm{zy}}=\sqrt{(r_0+{\mathrm{jx}}_0)(g_0+{\mathrm{jb}}_0)},$ B ₀=ω c ₀, ω is power supply angular frequency, Z _cfor phase wave impedance, λ is phase circuit propagation constant, z=r ₀+ jx ₀, y=g ₀+ jb ₀, c ₀, r ₀, x ₀, g ₀, b ₀be respectively phase conductor unit length phase self-capacitance, phase self-resistance, from reactance, phase self-conductance with from susceptance, z is phase self-impedance, y is phase self-admittance.

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