CN106093587A - A kind of large-scale grounding network grid grounding impedance measurement method - Google Patents

Abstract

The embodiment of the invention discloses a kind of large-scale grounding network grid grounding impedance measurement method, including: selected position, electric current pole, record current pole wire length；Position, recording voltage pole wire length is compensated according to described electric current pole position calculation voltage pole；Alien frequencies supply frequency is respectively set to (f Δ f) Hz and (f+ Δ f) Hz, synchronously tested (f Δ f) Hz and (voltage data that under f+ Δ f) Hz, voltage measurement point is corresponding with current measurement point and current data；Be filtered described voltage data and current data processing, obtain (voltage vector that f Δ f) Hz is corresponding and current vector, and (voltage corresponding for f+ Δ f) Hz to and current vector；(f Δ f) Hz and the (impedance ground under f+ Δ f) Hz is calculated respectively according to voltage pole wire length, current electrode lead length, voltage vector and current vector；The impedance ground under work frequency is calculated according to impedance ground.Described method considers current electrode lead, measures the parallel aerial circuit of earth neutral system and the electrical measurement coupling effect of voltage pole lead-in wire around loop, improves certainty of measurement.

Description

A kind of large-scale grounding network grid grounding impedance measurement method

This application claims and submitted Patent Office of the People's Republic of China, Application No. 201610124621.X, invention on 03 04th, 2016 The priority of the Chinese patent application of entitled " a kind of large-scale grounding network grid grounding impedance measurement method ", entire contents is by drawing With being incorporated in the present application.

Technical field

The present invention relates to grid grounding impedance measurement technical field, particularly relate to a kind of large-scale grounding network grid grounding impedance measurement side Method.

Background technology

The grounded screen of large-scale (such as transformer station) normally works at guarantee power equipment and rises in terms of Field Force's personal safety Important function.Impedance ground value is to weigh one of the most qualified important evidence of large-scale grounding network.As tied at construction of transformer substation Whether Shu Hou, reach to design requirement for checking substation ground network construction, need the earth resistance to substation ground network to carry out reality Measure.In addition it is also necessary to the earth resistance of transformer station is carried out periodic measurement, to ensure the size of substation ground network earth resistance Still its protection equipment and the function of personal safety can be met after running a period of time.Accurately measure the ground connection of substation ground network Resistance is significant to the reliability service of power system.

Fall-of-potential method is the basic skills of grounding resistance measurement, but in actual measurement work, to wiring landform The situation that condition is more severe, measurement will become extremely difficult, and the error of measurement result will become the biggest；Additionally, current potential Fall method needs repeated multiple times measurement, and workload is big, and the drafting of potential drop curve is the most relatively cumbersome, is unfavorable for execute-in-place.China The power department penalty method that typically uses fall-of-potential method to derive carry out the measurement of earth resistance, but penalty method is in theory Being all based on the premise of uniform soil, field actual measurement results is affected relatively big by soil inhomogeneities, often results in bigger measurement Error.

In terms of test power supply, the measurement of current grounding resistance of transformer substation grounding net mainly uses alien frequencies method.Alien frequencies method makes By variable-frequency power sources, test under the frequency of deviation power frequency, zero-sequence current interference in ground, extraneous Hz noise, High-frequency Interference, clutter The problems such as interference can be readily solved.But, existing measuring method cannot get rid of voltage pole lead-in wire and current electrode lead effectively The impact on measurement result of the alien frequencies electromagnetic coupled.It addition, when measuring the parallel shelf ceases to be busy that there is neutral ground around loop Lu Shi, the alien frequencies electromagnetic coupled measuring loop and parallel aerial circuit also brings along measurement error.

Summary of the invention

The embodiment of the present invention provides a kind of large-scale grounding network grid grounding impedance measurement method, of the prior art to solve Voltage pole lead-in wire and the alien frequencies electromagnetic coupled of current electrode lead and the alien frequencies electromagnetic coupled pair measuring loop and parallel aerial circuit The error problem that result causes.

In order to solve above-mentioned technical problem, the embodiment of the invention discloses following technical scheme:

Embodiments provide a kind of large-scale grounding network grid grounding impedance measurement method, including:

Selected position, electric current pole, record current pole wire length is L_in；

Compensating position according to described electric current pole position calculation voltage pole, recording voltage pole wire length is L_vn；

Alien frequencies supply frequency is respectively set to (f-Δ f) Hz and (f+ Δ f) Hz, synchronously tested described (f-Δ f) Hz and (voltage data that under f+ Δ f) Hz, voltage measurement point is corresponding with current measurement point and current data；

It is filtered described voltage data and current data processing, obtains described (the first voltage that f-Δ f) Hz is corresponding VectorWith the first current vectorAnd described (the second voltage vector that f+ Δ f) Hz is correspondingWith the second current vector

According to described voltage pole wire length L_vn, current electrode lead length L_in, the first voltage vectorSecond voltage to AmountAnd first current vectorSecond current vectorCalculate described (f-Δ f) Hz and (first under f+ Δ f) Hz respectively Impedance ground R_f-ΔfWith the second impedance ground R_f+Δf；

According to described first impedance ground R_f-Δf, the second impedance ground R_f+ΔfCalculate the 3rd impedance ground under work frequency R_f:

$R_f=\frac{1}{2}\[\mathrm{Re}\left(R_{f-\mathrm{\Δ}f}\right)+\mathrm{Re}\left(R_{f+\mathrm{\Δ}f}\right)\]+j\frac{1}{2}\[\mathrm{Im}\left(R_{f-\mathrm{\Δ}f}\right)\frac{50}{f-\mathrm{\Δ}f}+\mathrm{Im}\left(R_{f+\mathrm{\Δ}f}\right)\frac{50}{f+\mathrm{\Δ}f}\];$

Wherein, f is 50Hz work frequency, and Δ f is work frequency side-play amount, n=1,2,3.

Preferably, described described (the f-Δ f) Hz and (the first impedance ground R under f+ Δ f) Hz of calculating respectively_f-ΔfAnd second Impedance ground R_f+Δf, including:

According to described voltage pole wire length L_vn, current electrode lead length L_in, the first voltage vectorAnd first electric current to AmountCalculate described (the first impedance ground R under f-Δ f) Hz_f-Δf:

$\left(\begin{array}{c}{R}_{f-\mathrm{\Δ}f}\\ Z_m\\ Z_m^{\′}\end{array}\right)={\left(\begin{array}{ccc}{\stackrel{\·}{I}}_{11}& {\stackrel{\·}{I}}_{11}{L}_{v1}& {\stackrel{\·}{I}}_{11}{L}_{v1}{L}_{i1}\\ {\stackrel{\·}{I}}_{12}& {\stackrel{\·}{I}}_{12}{L}_{v2}& {\stackrel{\·}{I}}_{12}{L}_{v2}{L}_{i2}\\ {\stackrel{\·}{I}}_{13}& {\stackrel{\·}{I}}_{13}{L}_{v3}& {\stackrel{\·}{I}}_{13}{L}_{v3}{L}_{i3}\end{array}\right)}^{-1}\left(\begin{array}{c}{\stackrel{\·}{U}}_{11}\\ {\stackrel{\·}{U}}_{12}\\ {\stackrel{\·}{U}}_{13}\end{array}\right);$

According to described voltage pole wire length L_vn, current electrode lead length L_in, the second voltage vectorAnd second electric current VectorCalculate described (the second impedance ground R under f+ Δ f) Hz_f+Δf:

$\left(\begin{array}{c}{R}_{f+\mathrm{\Δ}f}\\ Z_m\\ Z_m^{\′}\end{array}\right)={\left(\begin{array}{ccc}{\stackrel{\·}{I}}_{21}& {\stackrel{\·}{I}}_{21}{L}_{v1}& {\stackrel{\·}{I}}_{21}{L}_{v1}{L}_{i1}\\ {\stackrel{\·}{I}}_{22}& {\stackrel{\·}{I}}_{22}{L}_{v2}& {\stackrel{\·}{I}}_{22}{L}_{v2}{L}_{i2}\\ {\stackrel{\·}{I}}_{23}& {\stackrel{\·}{I}}_{23}{L}_{v3}& {\stackrel{\·}{I}}_{23}{L}_{v3}{L}_{i3}\end{array}\right)}^{-1}\left(\begin{array}{c}{\stackrel{\·}{U}}_{21}\\ {\stackrel{\·}{U}}_{22}\\ {\stackrel{\·}{U}}_{23}\end{array}\right);$

Wherein, Z_mGo between for the voltage pole under unit length and the mutual impedance of current electrode lead, Z'_mFor with measure loop without The unit length coupled impedance closed.

Preferably, described according to described first impedance ground R_f-Δf, the second impedance ground R_f+ΔfCalculate under work frequency 3rd impedance ground R_f, including:

Obtain described first impedance ground R respectively_f-ΔfWith the second impedance ground R_f+ΔfReal part Re (R_f-Δf) and Re (R_f+Δf)；

Obtain described first impedance ground R respectively_f-ΔfWith the second impedance ground R_f+ΔfImaginary part Im (R_f-Δf) and Im (R_f+Δf)；

According to described Re (R_f+Δf)、Re(R_f-Δf) and Im (R_f+Δf)、Im(R_f-Δf), calculate described first impedance ground R_f-Δf With the second impedance ground R_f+ΔfArithmetic mean of instantaneous value, it is thus achieved that the 3rd impedance ground R under work frequency_f。

Preferably, described work frequency offset Δ f≤5Hz.

Preferably, described position, electric current pole and voltage pole compensation position meet the requirement of ground connection industry standard DL/T475.

The beneficial effect comprise that and eliminate measurement loop voltage pole lead-in wire and current electrode lead and measurement loop The electromagnetic coupled that the parallel aerial circuit of neutral ground around and voltage pole the go between impact on measurement result, substantially increases The certainty of measurement of impedance ground.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, for those of ordinary skill in the art Speech, on the premise of not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

A kind of wiring schematic diagram measured around loop without coupling shelf ceases to be busy that Fig. 1 provides for the embodiment of the present invention；

Fig. 2 for the embodiment of the present invention provide a kind of measure around loop exist one time coupling overhead transmission line wiring signal Figure；

Fig. 3 for the embodiment of the present invention provide a kind of measure around loop exist twice coupling overhead transmission lines wiring signal Figure；

Fig. 4 for the embodiment of the present invention provide a kind of measure exist around loop N return coupling overhead transmission line wiring signal Figure；

A kind of large-scale grounding network grid grounding impedance measurement method flow schematic diagram that Fig. 5 provides for the embodiment of the present invention.

Detailed description of the invention

For the technical scheme making those skilled in the art be more fully understood that in the present invention, real below in conjunction with the present invention Execute the accompanying drawing in example, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described enforcement Example is only a part of embodiment of the present invention rather than whole embodiments.Based on the embodiment in the present invention, this area is common The every other embodiment that technical staff is obtained under not making creative work premise, all should belong to present invention protection Scope.

In order to make those skilled in the art be more fully understood that the present invention program, below in conjunction with the accompanying drawings with embodiment to this Invention is described in further detail.

See Fig. 1, Fig. 1 for the embodiment of the present invention provide a kind of measure around loop without coupling shelf ceases to be busy wiring illustrate Figure；L_i、L_vRepresenting current electrode lead and the length of voltage pole lead-in wire respectively, E is alien frequencies power supply.R, X represent under alien frequencies frequency respectively The resistive component of earth resistance and perceptual weight, remember R_g=R+jX.R_m、X_mRepresent unit length lead-in wire under alien frequencies frequency respectively Mutual resistance and mutual reactance, remember Z_m=R_m+jX_m。

Shown in the voltage that voltage measurement point records such as formula (1).

$\stackrel{\·}{U}=\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v={\stackrel{\·}{U}}_g+{\stackrel{\·}{U}}_m---\left(1\right)$

Wherein, It is respectively voltage data and current data that synchronized sampling obtains Alien frequencies voltage phasor after processing after filtering and non-power-frequency current phasor.

Being known by formula (1), the voltage that voltage measurement point records is made up of two parts.Part I is that non-power-frequency current connects at alien frequencies Voltage drop on earth resistance；Part II is the induced voltage that the non-power-frequency current in current electrode lead goes between at voltage pole, i.e. electricity Interference voltage on the lead-in wire of pressure pole, as shown in formula (2).

${\stackrel{\·}{U}}_m=\stackrel{\·}{I}{Z}_m{L}_v=\stackrel{\·}{I}\left(R_m+{\mathrm{jX}}_m\right)L_v---\left(2\right)$

Being known by formula (2), the interference voltage that voltage pole is gone between by current electrode lead is made up of two parts, and a part is by mutual resistance R_mL_vProducing, a part is by mutual reactance jX_mL_vProduce.

When measuring ground network ground resistance, if a low-voltage circuit of stopping transport is as measuring loop, low-voltage circuit electric parameter The accounting of middle resistance is relatively big, if the mutual resistance not considered between current electrode lead and voltage pole lead-in wire, may be to the survey of earth resistance Amount brings bigger error.

A coupling overhead transmission line is there is in a kind of measurement that seeing Fig. 2, Fig. 2 provides for the embodiment of the present invention around loop Wiring schematic diagram；In Fig. 2, Z_m1Represent the mutual resistance between electric current pole under alien frequencies frequency f, voltage pole lead-in wire and the every phase conductor of overhead transmission line Anti-, Z_mRepresent the unit length mutual impedance between current electrode lead and voltage pole lead-in wire.

Note Z_sRepresent the self-impedance of the every phase conductor of overhead transmission line, Z under alien frequencies frequency f_mmRepresent overhead transmission line under alien frequencies frequency f Mutual impedance between any two phase conductors, in overhead transmission line three-phase shown in the non-power-frequency current relation such as formula (3) of sensing.

$\left\{\begin{array}{c}{\stackrel{\·}{I}}_{1a}{Z}_{s}L+{\stackrel{\·}{I}}_{1b}{Z}_{mm}L+{\stackrel{\·}{I}}_{1c}{Z}_{mm}L+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\\ {\stackrel{\·}{I}}_{1a}{Z}_{mm}L+{\stackrel{\·}{I}}_{1b}{Z}_{s}L+{\stackrel{\·}{I}}_{1c}{Z}_{mm}L+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\\ {\stackrel{\·}{I}}_{1a}{Z}_{mm}L+{\stackrel{\·}{I}}_{1b}{Z}_{mm}L+{\stackrel{\·}{I}}_{1c}{Z}_{s}L+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\end{array}\right.---\left(3\right)$

In Fig. 2, shown in the voltage that voltage measurement point records such as formula (4).

$\stackrel{\·}{U}=\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v+{\stackrel{\·}{I}}_{1a}{Z}_{m1}{L}_v+{\stackrel{\·}{I}}_{1b}{Z}_{m1}{L}_v+{\stackrel{\·}{I}}_{1c}{Z}_{m1}{L}_v---\left(4\right)$

Can be obtained by formula (3) and formula (4),

$\begin{array}{c}\stackrel{\·}{U}=\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v-\stackrel{\·}{I}\frac{3Z_{m1}^2{L}_i{L}_v}{\left(Z_s+2Z_{mm}\right)L}\\ =\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v-\stackrel{\·}{I}{L}_i{L}_v\frac{3Z_{m1}^2}{Z_{0}L}\\ ={\stackrel{\·}{U}}_g+{\stackrel{\·}{U}}_m\end{array}---\left(5\right)$

Wherein,Z₀Zero sequence impedance for overhead transmission line.

In formula (3)～(5),The same formula of implication (1),Represent in overhead transmission line A, B, C three-phase respectively and feel The non-power-frequency current answered, L represents overhead transmission line length.

From formula (5), measuring in the case of there is single time parallel aerial circuit around loop, voltage measurement point records Voltage is made up of three parts.Part I is non-power-frequency current voltage drop on alien frequencies earth resistance；Part II is electric current pole The non-power-frequency current in lead-in wire induced voltage on voltage pole goes between；Part III is that the non-power-frequency current in overhead transmission line is at voltage Induced voltage on the lead-in wire of pole.Part II and Part III have collectively constituted the interference voltage on voltage pole lead-in wire.

For some large-scale substations, using stoppage in transit overhead transmission line as when measuring loop, measuring loop may Overhead transmission line with twice or more than twice produces alien frequencies coupling effect, as it is shown on figure 3, what Fig. 3 provided for the embodiment of the present invention The wiring schematic diagram coupling overhead transmission lines is there is twice in a kind of measurement around loop.

If the self-impedance of twice overhead transmission lines is respectively Z_s1、Z_s2, the mutual impedance that every time overhead transmission line three is alternate is respectively Z_mm1、Z_mm2, the mutual impedance between twice overhead transmission lines is Z_m12, the length of twice overhead transmission lines is respectively L₁、L₂, twice overhead transmission lines The a length of L being mutually coupled₁₂, then the relational expression of overhead transmission line each phase non-power-frequency current is as shown in (6).

$\left\{\begin{array}{c}{\stackrel{\·}{I}}_{1a}{Z}_{s1}{L}_1+{\stackrel{\·}{I}}_{1b}{Z}_{mm1}{L}_1+{\stackrel{\·}{I}}_{1c}{Z}_{mm1}{L}_1+\left({\stackrel{\·}{I}}_{2a}+{\stackrel{\·}{I}}_{2b}+{\stackrel{\·}{I}}_{2c}\right)Z_{m12}{L}_{12}+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\\ {\stackrel{\·}{I}}_{1a}{Z}_{mm1}{L}_1+{\stackrel{\·}{I}}_{1b}{Z}_{s1}{L}_1+{\stackrel{\·}{I}}_{1c}{Z}_{mm1}{L}_1+\left({\stackrel{\·}{I}}_{2a}+{\stackrel{\·}{I}}_{2b}+{\stackrel{\·}{I}}_{2c}\right)Z_{m12}{L}_{12}+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\\ {\stackrel{\·}{I}}_{1a}{Z}_{mm1}{L}_1+{\stackrel{\·}{I}}_{1b}{Z}_{s1}{L}_1+{\stackrel{\·}{I}}_{1c}{Z}_{s1}{L}_1+\left({\stackrel{\·}{I}}_{2a}+{\stackrel{\·}{I}}_{2b}+{\stackrel{\·}{I}}_{2c}\right)Z_{m12}{L}_{12}+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\\ \left({\stackrel{\·}{I}}_{1a}+{\stackrel{\·}{I}}_{1b}+{\stackrel{\·}{I}}_{1c}\right)Z_{m12}{L}_{12}+{\stackrel{\·}{I}}_{2a}{Z}_{s2}{L}_2+{\stackrel{\·}{I}}_{2b}{Z}_{mm2}{L}_2+{\stackrel{\·}{I}}_{2c}{Z}_{mm2}{L}_2+\stackrel{\·}{I}{Z}_{m2}{L}_i=0\\ \left({\stackrel{\·}{I}}_{1a}+{\stackrel{\·}{I}}_{1b}+{\stackrel{\·}{I}}_{1c}\right)Z_{m12}{L}_{12}+{\stackrel{\·}{I}}_{2a}{Z}_{mm2}{L}_2+{\stackrel{\·}{I}}_{2b}{Z}_{s2}{L}_2+{\stackrel{\·}{I}}_{2c}{Z}_{mm2}{L}_2+\stackrel{\·}{I}{Z}_{m2}{L}_i=0\\ \left({\stackrel{\·}{I}}_{1a}+{\stackrel{\·}{I}}_{1b}+{\stackrel{\·}{I}}_{1c}\right)Z_{m12}{L}_{12}+{\stackrel{\·}{I}}_{2a}{Z}_{mm2}{L}_2+{\stackrel{\·}{I}}_{2b}{Z}_{mm2}{L}_2+{\stackrel{\·}{I}}_{2c}{Z}_{s2}{L}_2+\stackrel{\·}{I}{Z}_{m2}{L}_i=0\end{array}\right.---\left(6\right)$

Due toWhereinIt is respectively in twice overhead transmission lines Alien frequencies zero-sequence current, formula (6) can abbreviation be

$\left\{\begin{array}{c}{\stackrel{\·}{I}}_{10}{Z}_{10}{L}_1+3{\stackrel{\·}{I}}_{20}{Z}_{m12}{L}_{12}+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\\ {\stackrel{\·}{I}}_{20}{Z}_{20}{L}_{12}+3{\stackrel{\·}{I}}_{10}{Z}_{m12}{L}_{12}+\stackrel{\·}{I}{Z}_{m2}{L}_i=0\end{array}\right.---\left(7\right)$

Solve formula (6) and formula (7) obtains

$\left\{\begin{array}{c}{\stackrel{\·}{I}}_{1a}={\stackrel{\·}{I}}_{1b}={\stackrel{\·}{I}}_{1c}={\stackrel{\·}{I}}_{10}=-\frac{Z_{20}{Z}_{m1}{L}_2-3Z_{m2}{Z}_{m12}{L}_{12}}{9Z_{m12}^2{L}_{12}^2-L_1{L}_2{Z}_{10}{Z}_{20}}\stackrel{\·}{I}{L}_i=-{\mathrm{\ϵ}}_1\stackrel{\·}{I}{L}_i\\ {\stackrel{\·}{I}}_{2a}={\stackrel{\·}{I}}_{2b}={\stackrel{\·}{I}}_{2c}={\stackrel{\·}{I}}_{20}=-\frac{Z_{10}{Z}_{m2}{L}_1-3Z_{m1}{Z}_{m12}{L}_{12}}{9Z_{m12}^2{L}_{12}^2-L_1{L}_2{Z}_{10}{Z}_{20}}\stackrel{\·}{I}{L}_i=-{\mathrm{\ϵ}}_2\stackrel{\·}{I}{L}_i\end{array}\right.---\left(8\right)$

It can be seen that in formula (8)

And ε₁、ε₂Only relevant with the relative position between the parameter of overhead transmission line and measurement loop and overhead transmission line, if surveyed Use an overhead transmission line of stopping transport as measuring loop during amount earth resistance, then can ensure that and changing voltage pole and position, electric current pole When putting, properly functioning overhead transmission line invariant position relative with between the overhead transmission line of stoppage in transit, i.e. it is believed that ε₁、ε₂For certain value.This Time, shown in the voltage that in Fig. 3, voltage measurement point records such as formula (9).

$\begin{array}{c}\stackrel{\·}{U}=\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v+\left({\stackrel{\·}{I}}_{1a}+{\stackrel{\·}{I}}_{1b}+{\stackrel{\·}{I}}_{1c}\right)Z_{m1}{L}_v+\left({\stackrel{\·}{I}}_{2a}+{\stackrel{\·}{I}}_{2b}+{\stackrel{\·}{I}}_{2c}\right)Z_{m2}{L}_v\\ =\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v+3{\stackrel{\·}{I}}_{10}{Z}_{m1}{L}_v+3{\stackrel{\·}{I}}_{20}{Z}_{m2}{L}_v\end{array}---\left(9\right)$

Formula (8) is substituted into formula (9), and abbreviation can obtain

$\begin{array}{c}\stackrel{\·}{U}=\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v-3{\mathrm{\ϵ}}_1\stackrel{\·}{I}{L}_i{Z}_{m1}{L}_v-3{\mathrm{\ϵ}}_2\stackrel{\·}{I}{L}_i{Z}_{m2}{L}_v\\ =\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v-\stackrel{\·}{I}{L}_i{L}_v\left(3{\mathrm{\ϵ}}_1\stackrel{\·}{I}{Z}_{m1}+3{\mathrm{\ϵ}}_2{Z}_{m2}\right)\\ ={\stackrel{\·}{U}}_g+{\stackrel{\·}{U}}_m\end{array}---\left(10\right)$

Wherein,When overhead transmission line and survey When measuring the relative invariant position between loop, Z'_mFor certain value.Comparison expression (5), formula (10) understand, in the case of two kinds, and voltage measurement Point records the expression formula of voltage and has identical form.

N is there is and returns coupling overhead transmission line in a kind of measurement that seeing Fig. 4, Fig. 4 provides for the embodiment of the present invention around loop Wiring schematic diagram.Knowable to double back overhead transmission line calculates with the derivation measured when loop couples completely, measure and exist around loop During parallel aerial circuit, overhead transmission line and measurement circuitry constitute an alien frequencies electromagnetic coupled system, and equipment of measuring injects ground connection Non-power-frequency current in electrode is the excitation of this system, every by overhead transmission line of the non-power-frequency current flow through in current electrode lead Inducing alien frequencies zero-sequence current mutually, the non-power-frequency current induced in i.e. every time overhead transmission line is equal.When exist N return overhead transmission line with When measuring loop coupling completely, in overhead transmission line shown in the relation of zero-sequence current such as formula (11).

$\left\{\begin{array}{c}{\stackrel{\·}{I}}_{10}{Z}_{10}{L}_1+...+3{\stackrel{\·}{I}}_{k0}{Z}_{m1k}{L}_{1k}+...+3{\stackrel{\·}{I}}_{n0}{Z}_{m1n}{L}_{1n}+\stackrel{\·}{I}{Z}_{m1}{L}_i=0\\ \begin{array}{c}.\\ .\\ .\end{array}\\ 3{\stackrel{\·}{I}}_{10}{Z}_{mk1}{L}_{k1}+...+{\stackrel{\·}{I}}_{k0}{Z}_{k0}{L}_k+...+3{\stackrel{\·}{I}}_{n0}{Z}_{mkn}{L}_{kn}+\stackrel{\·}{I}{Z}_{mk}{L}_i=0\\ \begin{array}{c}.\\ .\\ .\end{array}\\ 3{\stackrel{\·}{I}}_{10}{Z}_{mn1}{L}_{n1}+...+3{\stackrel{\·}{I}}_{k0}{Z}_{mnk}{L}_{nk}+...+{\stackrel{\·}{I}}_{n0}{Z}_{n0}{L}_n+\stackrel{\·}{I}{Z}_{mn}{L}_i=0\end{array}\right.---\left(11\right)$

In formula, Z_k0Represent that kth returns the unit length zero sequence impedance of overhead transmission line, L_kRepresent that kth returns the length of overhead transmission line, L_tkShow that t returns overhead transmission line and kth and returns the coupling length of overhead transmission line, Z_mtkRepresent that t returns overhead transmission line and returns aerial line with kth The unit length mutual impedance on road, Z_mkRepresent that kth is returned overhead transmission line and measures the unit length mutual impedance in loop,Represent that kth is returned The zero-sequence current of overhead transmission line,Represent measure time be injected in ground electrode non-power-frequency current (k, t=1,2 ..., n).

Formula (11) is converted into matrix expression, has

Solve this matrix equation, obtain kth and return the zero-sequence current flow through in overhead transmission lineAs shown in formula (13).

${\stackrel{\·}{I}}_{k0}=-{\mathrm{\ϵ}}_k\stackrel{\·}{I}{L}_i---\left(13\right)$

It can be seen that affect ε_kValue because have: N returns the impedance of overhead transmission line, N returns the length of overhead transmission line and N returns Overhead transmission line and the mutual impedance measured between loop.Wherein, it is relevant that the first two amount only returns overhead transmission line with N, is two definite values；Work as survey After amount loop is selected, N returns overhead transmission line and the mutual impedance measured between loop is also a definite value.So, ε_kBe one fixing Value.

N returns overhead transmission line with when measuring loop and couple completely, and the voltage that voltage measurement point records such as formula (14) is shown,

$\begin{array}{c}\stackrel{\·}{U}=\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v+3{\stackrel{\·}{I}}_{10}{Z}_{m1}{L}_v+...+3{\stackrel{\·}{I}}_{k0}{Z}_{mk}{L}_v+...+3{\stackrel{\·}{I}}_{n0}{Z}_{mn}{L}_v\\ =\stackrel{\·}{I}{R}_g+\stackrel{\·}{I}{Z}_m{L}_v-\stackrel{\·}{I}{L}_i{L}_v\left(3{\mathrm{\ϵ}}_1{Z}_{m1}+...+3{\mathrm{\ϵ}}_k{Z}_{mk}+...+3{\mathrm{\ϵ}}_n{Z}_{mn}\right)\\ ={\stackrel{\·}{U}}_g+{\stackrel{\·}{U}}_m\end{array}---\left(14\right)$

Wherein,Z'_m=-3 (ε₁Z_m1+…+ε_kZ_mk+…+ε_nZ_mn), when built on stilts When circuit is with the relative invariant position measured between loop, Z'_mFor certain value.Comparison expression (5), (10), (14) are it can be seen that no matter Measuring the overhead transmission line that there are how many times couplings completely around loop, voltage measurement point records the expression formula of voltage and is respectively provided with identical Form.

Analyze for above, return the flat of earth neutral system when measuring the N (N >=1) that there is coupling completely around loop During row overhead transmission line, embodiments provide a kind of large-scale grounding network grid grounding impedance measurement method, such as Fig. 5, specifically include:

Step S101: selected position, electric current pole, record current pole wire length is L_in。

Step S102: compensating position according to described electric current pole position calculation voltage pole, recording voltage pole wire length is L_vn。

Described position, electric current pole and voltage pole compensate position and meet the requirement of ground connection industry standard DL/T475.

Step S103: alien frequencies supply frequency is respectively set to (f-Δ f) Hz and (f+ Δ f) Hz, synchronously tested (f-Δ f) Hz and (voltage data that under f+ Δ f) Hz, voltage measurement point is corresponding with current measurement point and current data.

Concrete, in embodiments of the present invention, large-scale grounding network grounding resistance measurement is used for alien frequencies power supply, i.e. exist Testing under the frequency of deviation power frequency, the power frequency supply f used in embodiment is 50Hz, and Δ f is work frequency side-play amount, in this reality Execute in example, Δ f≤5Hz.

Step S104: be filtered described voltage data and current data processing, obtains (the first electricity under f-Δ f) Hz The amount of pressing toWith the first current vector(the second voltage vector under f+ Δ f) HzWith the second current vector

Concrete, when alien frequencies supply frequency be (during f-Δ f), current electrode lead length L of first record_i1, and according to electricity Stream position, pole, determines that voltage pole compensates position, and recording voltage pole wire length is L_v1, from voltage measurement point V and current measurement point A Synchronously tested voltage data and current data, after filtered process, obtain the first voltage vectorWith the first current vectorUnder First group of voltage phasor and current vector, be respectively

Alien frequencies supply frequency keeps constant, changes position, electric current pole, and record current pole wire length is L_i2, recalculate electricity Pressure compensation position, pole, voltage pole wire length is L_v2.From the synchronously tested voltage data of voltage measurement point V and current measurement point A and Current data, after filtered process, obtains the first voltage vectorWith the first current vectorUnder second group of voltage phasor and Current vector, be respectively

Alien frequencies supply frequency keeps constant, changes position, electric current pole, and record current pole wire length is L_i3, recalculate electricity Pressure compensation position, pole, voltage pole wire length is L_v3.From the synchronously tested voltage data of voltage measurement point V and current measurement point A and Current data, after filtered process, obtains the first voltage vectorWith the first current vectorUnder the 3rd group of voltage phasor and Current vector, is respectively

When alien frequencies supply frequency be (during f+ Δ f), current electrode lead length L of first record_i1And voltage pole wire length For L_v1, from the synchronously tested voltage data of voltage measurement point V and current measurement point A and current data, after Filtering Processing, obtain second Voltage vectorWith the second current vectorUnder first group of voltage phasor and current vector, be respectively

Alien frequencies supply frequency keeps constant, changes position, electric current pole, and record current pole wire length is L_i2, recalculate electricity Pressure compensation position, pole, voltage pole wire length is L_v2.From the synchronously tested voltage data of voltage measurement point V and current measurement point A and Current data, after filtered process, obtains the second voltage vectorWith the second current vectorUnder second group of voltage phasor and Current vector, is respectively

Alien frequencies supply frequency keeps constant, changes position, electric current pole, and record current pole wire length is L_i3, recalculate electricity Pressure compensation position, pole, voltage pole wire length is L_v3.From the synchronously tested voltage data of voltage measurement point V and current measurement point A and Current data, after filtered process, obtains the second voltage vectorWith the second current vectorUnder the 3rd group of voltage phasor and Current vector, be respectivelyWith

Step S105: according to voltage pole wire length L_vn, current electrode lead length L_in, the first voltage vectorSecond electricity The amount of pressing toAnd first current vectorSecond current vectorCalculate (f-Δ f) Hz and (first under f+ Δ f) Hz respectively Impedance ground R_f-ΔfWith the second impedance ground R_f+Δf。

Concrete, according to voltage pole wire length L_vn, current electrode lead length L_in, the first voltage vectorAnd first electricity Flow vector(the first impedance ground R under f-Δ f) Hz is calculated by formula (15)_f-Δf；

$\left(\begin{array}{c}{R}_{f-\mathrm{\Δ}f}\\ Z_m\\ Z_m^{\′}\end{array}\right)={\left(\begin{array}{ccc}{\stackrel{\·}{I}}_{11}& {\stackrel{\·}{I}}_{11}{L}_{v1}& {\stackrel{\·}{I}}_{11}{L}_{v1}{L}_{i1}\\ {\stackrel{\·}{I}}_{12}& {\stackrel{\·}{I}}_{12}{L}_{v2}& {\stackrel{\·}{I}}_{12}{L}_{v2}{L}_{i2}\\ {\stackrel{\·}{I}}_{13}& {\stackrel{\·}{I}}_{13}{L}_{v3}& {\stackrel{\·}{I}}_{13}{L}_{v3}{L}_{i3}\end{array}\right)}^{-1}\left(\begin{array}{c}{\stackrel{\·}{U}}_{11}\\ {\stackrel{\·}{U}}_{12}\\ {\stackrel{\·}{U}}_{13}\end{array}\right)---\left(15\right)$

According to voltage pole wire length L_vn, current electrode lead length L_in, the second voltage vectorAnd second current vector(the second impedance ground R under f+ Δ f) Hz is calculated by formula (16)_f+Δf；

$\left(\begin{array}{c}{R}_{f+\mathrm{\Δ}f}\\ Z_m\\ Z_m^{\′}\end{array}\right)={\left(\begin{array}{ccc}{\stackrel{\·}{I}}_{21}& {\stackrel{\·}{I}}_{21}{L}_{v1}& {\stackrel{\·}{I}}_{21}{L}_{v1}{L}_{i1}\\ {\stackrel{\·}{I}}_{22}& {\stackrel{\·}{I}}_{22}{L}_{v2}& {\stackrel{\·}{I}}_{22}{L}_{v2}{L}_{i2}\\ {\stackrel{\·}{I}}_{23}& {\stackrel{\·}{I}}_{23}{L}_{v3}& {\stackrel{\·}{I}}_{23}{L}_{v3}{L}_{i3}\end{array}\right)}^{-1}\left(\begin{array}{c}{\stackrel{\·}{U}}_{21}\\ {\stackrel{\·}{U}}_{22}\\ {\stackrel{\·}{U}}_{23}\end{array}\right)---\left(16\right)$

Wherein, Z_mGo between for the voltage pole under unit length and the mutual impedance of current electrode lead, Z'_mFor with measure loop without The unit length coupled impedance closed.

Step S106: according to the first impedance ground R_f-ΔfWith the second impedance ground R_f+ΔfThe 3rd calculated under work frequency connects Ground impedance R_f。

Concrete, first obtain the first impedance ground R_f-ΔfWith the second impedance ground R_f+ΔfReal part Re (R_f-Δf) and Re (R_f+Δf)；Obtain the first impedance ground R again_f-ΔfWith the second impedance ground R_f+ΔfImaginary part Im (R_f-Δf) and Im (R_f+Δf)；Finally According to described Re (R_f+Δf)、Re(R_f-Δf) and Im (R_f+Δf)、Im(R_f-Δf), calculate the first impedance ground R_f-ΔfWith the second ground connection resistance Anti-R_f+ΔfArithmetic mean of instantaneous value, obtain the 3rd impedance ground R under work frequency according to formula (17)_f:

$R_f=\frac{1}{2}\[\mathrm{Re}\left(R_{f-\mathrm{\Δ}f}\right)+\mathrm{Re}\left(R_{f+\mathrm{\Δ}f}\right)\]+j\frac{1}{2}\[\mathrm{Im}\left(R_{f-\mathrm{\Δ}f}\right)\frac{50}{f-\mathrm{\Δ}f}+\mathrm{Im}\left(R_{f+\mathrm{\Δ}f}\right)\frac{50}{f+\mathrm{\Δ}f}\]---\left(17\right)$

The present embodiment has also built model in PSCAD, and the measuring method proposing the present invention carries out simulating, verifying.Its In, the setting value of impedance ground is R_Set=0.2+j0.1 (Ω), set Δ f=3Hz, then alien frequencies frequency select respectively 47Hz and 53Hz.Under 47Hz and 53Hz alien frequencies frequency, calculate the 3rd impedance ground, and compare with setting value.

Measure to exist around loop one time to couple completely and around overhead transmission line and measurement loop, there are twice coupling shelfs completely Simulation result during ceases to be busy road is respectively such as Tables 1 and 2.

Table 1: measure and there is a coupling overhead transmission line simulation result completely around loop

Table 2: measure and there are twice coupling overhead transmission line simulation results completely around loop

During by above simulation result it can be seen that there is an all fronts coupling overhead transmission line around measurement loop, Power-frequency earthing decision value, the i.e. the 3rd impedance ground is 0.2011+j0.1013, there are two go back tos all fronts when measuring around loop During coupling overhead transmission line, power-frequency earthing decision value, the i.e. the 3rd impedance ground is 0.1996+j0.0995, is all sufficiently close to connect The setting value of ground impedance, it was demonstrated that grid grounding impedance measurement method proposed by the invention can eliminate Mutual Inductance Coupling between lead-in wire effectively And measurement loop couples the impact on measurement result with overhead transmission line, it is possible to obtain impedance ground value accurately.

It should be noted that in this article, such as the relational terms of " first " and " second " or the like is used merely to one Individual entity or operation separate with another entity or operating space, and not necessarily require or imply these entities or operate it Between exist any this reality relation or order.And, term " includes ", " comprising " or its any other variant are intended to Contain comprising of nonexcludability, so that include that the process of a series of key element, method, article or equipment not only include those Key element, but also include other key elements being not expressly set out, or also include for this process, method, article or set Standby intrinsic key element.In the case of there is no more restriction, statement " including ... " key element limited, it is not excluded that Other identical element is there is also in including the process of described key element, method, article or equipment.

The above is only the detailed description of the invention of the present invention, makes to skilled artisans appreciate that or realize this Bright.Multiple amendment to these embodiments will be apparent to one skilled in the art, as defined herein General Principle can realize without departing from the spirit or scope of the present invention in other embodiments.Therefore, the present invention It is not intended to be limited to the embodiments shown herein, and is to fit to and principles disclosed herein and features of novelty phase one The widest scope caused.

Claims (5)

1. a large-scale grounding network grid grounding impedance measurement method, it is characterised in that including:

Selected position, electric current pole, record current pole wire length is L_in；

Compensating position according to described electric current pole position calculation voltage pole, recording voltage pole wire length is L_vn；

Alien frequencies supply frequency is respectively set to (f-△ f) Hz and (f+ △ f) Hz, synchronously tested described (f-△ f) Hz and (f+ △ F) under Hz, voltage measurement point is corresponding with current measurement point voltage data and current data；

It is filtered described voltage data and current data processing, obtains the first voltage vector that described (f-△ f) is corresponding for HzWith the first current vectorAnd the second voltage vector that described (f+ △ f) is corresponding for HzWith the second current vector

According to described voltage pole wire length L_vn, current electrode lead length L_in, the first voltage vectorSecond voltage vector And first current vectorSecond current vectorCalculate the first ground connection under described (f-△ f) Hz and (f+ △ f) Hz respectively Impedance R_f-△fWith the second impedance ground R_f+△f；

According to described first impedance ground R_f-△f, the second impedance ground R_f+△fCalculate the 3rd impedance ground R under work frequency_f:

$R_f=\frac{1}{2}\[\mathrm{Re}\left(R_{f-\mathrm{\Δ}f}\right)+\mathrm{Re}\left(R_{f+\mathrm{\Δ}f}\right)\]+j\frac{1}{2}\[\mathrm{Im}\left(R_{f-\mathrm{\Δ}f}\right)\frac{50}{f-\mathrm{\Δ}f}+\mathrm{Im}\left(R_{f+\mathrm{\Δ}f}\right)\frac{50}{f+\mathrm{\Δ}f}\];$

Wherein, f is 50Hz work frequency, and △ f is work frequency side-play amount, n=1,2,3.

Large-scale grounding network grid grounding impedance measurement method the most according to claim 1, it is characterised in that described calculate institute respectively State the first impedance ground R under (f-△ f) Hz and (f+ △ f) Hz_f-△fAnd the second impedance ground R_f+△f, including:

According to described voltage pole wire length L_vn, current electrode lead length L_in, the first voltage vectorAnd first current vectorCalculate the first impedance ground R under described (f-△ f) Hz_f-△f:

$\left(\begin{array}{c}{R}_{f-\mathrm{\Δ}f}\\ Z_m\\ Z_m^{\′}\end{array}\right)={\left(\begin{array}{ccc}{\stackrel{\·}{I}}_{11}& {\stackrel{\·}{I}}_{11}{L}_{v1}& {\stackrel{\·}{I}}_{11}{L}_{v1}{L}_{i1}\\ {\stackrel{\·}{I}}_{12}& {\stackrel{\·}{I}}_{12}{L}_{v2}& {\stackrel{\·}{I}}_{12}{L}_{v2}{L}_{i2}\\ {\stackrel{\·}{I}}_{13}& {\stackrel{\·}{I}}_{13}{L}_{v3}& {\stackrel{\·}{I}}_{13}{L}_{v3}{L}_{i3}\end{array}\right)}^{-1}\left(\begin{array}{c}{\stackrel{\·}{U}}_{11}\\ {\stackrel{\·}{U}}_{12}\\ {\stackrel{\·}{U}}_{13}\end{array}\right);$

According to described voltage pole wire length L_vn, current electrode lead length L_in, the second voltage vectorAnd second current vectorCalculate the second impedance ground R under described (f+ △ f) Hz_f+△f:

$\left(\begin{array}{c}{R}_{f+\mathrm{\Δ}f}\\ Z_m\\ Z_m^{\′}\end{array}\right)={\left(\begin{array}{ccc}{\stackrel{\·}{I}}_{21}& {\stackrel{\·}{I}}_{21}{L}_{v1}& {\stackrel{\·}{I}}_{21}{L}_{v1}{L}_{i1}\\ {\stackrel{\·}{I}}_{22}& {\stackrel{\·}{I}}_{22}{L}_{v2}& {\stackrel{\·}{I}}_{22}{L}_{v2}{L}_{i2}\\ {\stackrel{\·}{I}}_{23}& {\stackrel{\·}{I}}_{23}{L}_{v3}& {\stackrel{\·}{I}}_{23}{L}_{v3}{L}_{i3}\end{array}\right)}^{-1}\left(\begin{array}{c}{\stackrel{\·}{U}}_{21}\\ {\stackrel{\·}{U}}_{22}\\ {\stackrel{\·}{U}}_{23}\end{array}\right);$

Wherein, Z_mGo between for the voltage pole under unit length and the mutual impedance of current electrode lead, Z'_mFor unrelated with measuring loop Unit length coupled impedance.

Large-scale grounding network grid grounding impedance measurement method the most according to claim 1, it is characterised in that described according to described One impedance ground R_f-△f, the second impedance ground R_f+△fCalculate the 3rd impedance ground R under work frequency_f, including:

Obtain described first impedance ground R respectively_f-△fWith the second impedance ground R_f+△fReal part Re (R_f-Δf) and Re (R_f+Δf)；

Obtain described first impedance ground R respectively_f-△fWith the second impedance ground R_f+△fImaginary part Im (R_f-Δf) and Im (R_f+Δf)；

According to described Re (R_f+Δf)、Re(R_f-Δf) and Im (R_f+Δf)、Im(R_f-Δf), calculate described first impedance ground R_f-△fWith Two impedance ground R_f+△fArithmetic mean of instantaneous value, it is thus achieved that the 3rd impedance ground R under work frequency_f。

Large-scale grounding network grid grounding impedance measurement method the most according to claim 1, it is characterised in that described work frequency is inclined Shifting amount △ f≤5Hz.

Large-scale grounding network grid grounding impedance measurement method the most according to claim 1, it is characterised in that position, described electric current pole Compensate position with voltage pole and meet the requirement of ground connection industry standard DL/T475.