CN103777115B - Electric transmission line single-terminal positioning method based on fault transient state and steady-state signal wave velocity difference - Google Patents

Abstract

The invention discloses an electric transmission line single-terminal positioning method based on a fault transient state and a steady-state signal wave velocity difference. According to different fault types, different phases are selected as datum phases, phase-mode transformation is carried out on a transmission line fault current traveling wave signal and the fault current traveling wave mode signal for fault positioning is obtained; continuous wavelet transformation is carried out on the mode signal, the mode maximum value and the time corresponding to the mode maximum value of a wave tip wavelet transformation coefficient of a transient state initial traveling wave are extracted and the mode maximum value and the time corresponding to the mode maximum value of a wavelet transform coefficient on the scale corresponding to a steady-state signal are extracted. According to the propagation velocity difference of the mode signal and a transient state signal, the fault distance of an electric transmission line is comprehensively calculated. By means of the propagation velocity difference between the fault steady-state signal and the transient-state signal, the propagation velocity of the corresponding frequency is accurately determined according to the wavelet transform, and therefore the fault distance of the electric transmission line can be accurately calculated.

Description

Transmission line of electricity single end positioning method based on fault transient and steady-state signal velocity of wave difference

Technical field

The present invention relates to fault single end positioning method of power transmission line in power system.

Background technology

Traveling wave fault positioning method has Position location accuracy, reliability height, good stability and is affected by fault resstance Little the advantages of.At present, traveling wave fault positioning method has functional failure travelling wave positioning method based on Two-Terminal Electrical Quantities and is based on one-terminal data Functional failure travelling wave positioning method.Wherein, the functional failure travelling wave positioning method based on Two-Terminal Electrical Quantities is due to needing to utilize dual ended data, So that increase time synchronism apparatus, the Financial cost which not only adds fault location reduces alignment system simultaneously Reliability；And the functional failure travelling wave positioning method being currently based on one-terminal data needs the time of advent using initial traveling wave and echo true Determine fault concrete, therefore the precision of its positioning is affected by the detection of wavefront time of advent and traveling wave spread speed, In existing method, the identification of reflected traveling wave wave head is the principal element of restriction single-ended traveling wave localization method reliability simultaneously.If therefore Only fault distance can be determined using the relevant information of the initial wave head of traveling wave and avoid the identification of reflected traveling wave wave head will greatly Improve the reliability of single-ended traveling wave localization method.

Content of the invention

The invention provides a kind of transmission line of electricity single end positioning method based on fault transient and steady-state signal velocity of wave difference, should Method only need to measure initial traveling wave, is not required to measure fault echo, improves the quasi- reliability of positioning, simple to operate, feasibility is high.

The present invention is to solve its technical problem, and the technical scheme being adopted is: one kind is based on fault transient and steady-state signal The transmission line of electricity single end positioning method of velocity of wave difference, the steps include:

A, data acquisition and pretreatment

Fault wave recording device is from transmission line of electricity with sample rate f_sThe current signal i of collection a, b, c three-phase_a(t)、i_b(t)、i_c T () is sent to fault locator, wherein t represents sampling instant；Fault locator is by current signal i_a(t)、i_b(t)、i_c After (t) Filtering Processing, according to the fault type of tested transmission line of electricity, select, accordingly as benchmark phase, fault current to be believed Number carry out phase-model transformation using karenbauer (Ka Lunbaoer) matrix, obtain 1 of the transmission line of electricity electric current for fault location Mould signal x (t);

B, the extraction of framing signal

B1, the extraction of transient state travelling wave signal

The mid frequency choosing wavelet basiss is f_c, decomposition scale a₁=2f_c1 mould signal x (t) of transmission line of electricity electric current is carried out Continuous wavelet transform, obtains wavelet conversion coefficient c₁T (), in wavelet conversion coefficient c₁T () is upper to extract transient state travelling wave primary wave head mould Maximum corresponding moment t₁；Wavelet conversion coefficient c₁(t) corresponding frequency f₁=f_s/ 2 transient state travelling wave signals being positioning Frequency；

B2, the extraction of steady-state signal

The mid frequency choosing wavelet basiss is f_c, choose the decomposition scale a of wavelet transformation₂=f_s·f_c/ 50 pairs of transmission lines of electricity 1 mould signal x (t) of electric current carries out continuous wavelet transform, obtains wavelet conversion coefficient c₂(t)；In wavelet conversion coefficient c₂On (t) Extract steady-state signal modulus maximum corresponding moment t₂;Wavelet conversion coefficient c₂(t) corresponding frequency f₂=50hz as positions use Steady-state signal frequency；

C, one-end fault positioning

C1, be calculated respectively according to the model of transmission line of electricity positioning transient state travelling wave signal mould wave velocity matrix v₁ Mould wave velocity matrix v with the steady-state signal of positioning₂:

$v_1=2\mathrm{\π}{f}_1/\mathrm{im}\left(\sqrt{z_1{y}_1}\right)$

$v_2=2\mathrm{\π}{f}_2/\mathrm{im}\left(\sqrt{z_2{y}_2}\right)$

Wherein, z₁、y₁Being respectively frequency is f₁The mould impedance of the corresponding transmission line of transient state travelling wave signal and mould admittance square Battle array, z₂、y₂Being respectively frequency is f₂The mould impedance of the corresponding transmission line of steady-state signal of=50hz and mould admittance matrix, z₁、y₁、 z₂、y₂It is the matrix of 3*3, im represents the imaginary part seeking plural number；

In mould wave velocity matrix v₁In take the mould ripple v as transient state travelling wave signal for the element of the second row secondary series₁, in mould ripple Rate matrices v₂In take the mould ripple v as transient state travelling wave signal for the element of the second row secondary series₂；

This is because when according to the fault type of tested transmission line of electricity, select suitable as benchmark phase when, 1 mould obtaining Component will not be mixed in into other modulus compositions, and in wave velocity matrix v₁Or v₂In second row the second column element be 1 mold component Spread speed, be to avoid it therefore when selecting the wave velocity as corresponding signal for second row the second column element to carry out calculating The impact of its mold component speed, thus ensure the accuracy of location Calculation.

C2, calculating fault distance:

Fault distance d calculates according to following formula:

$d=\frac{v_1\·v_2}{v_1-v_2}(t_2-t_1)$

This is because it is assumed that the moment that fault occurs is t when fault occurs₀, and trouble point transient state letter at positioner Number identical with steady-state signal propagation distance d, so that

$\left\{\begin{array}{c}d=v_1(t_1-t_0)\\ d=v_2(t_2-t_0)\end{array}\right.$

Wherein, v₁For transient signal frequency f₁Spread speed, v₂For transient signal frequency f₂Spread speed.Thus can Push away trouble point apart from d is:

$d=\frac{v_1\·v_2}{v_1-v_2}(t_2-t_1)$

Compared with prior art, the invention has the beneficial effects as follows:

(1) amount of calculation is little.By fault temporarily, steady-state signal propagation speed differential determine fault distance, it is only necessary to determine transient state Initial wavefront in component and the spread speed of steady-state component, you can fault distance is precisely calculated, need not be to fault The reflection wave head of traveling wave carries out any process, thus amount of calculation is little, and feasibility is high.

(2) Position location accuracy is high.Frequently with the propagation time difference of zero mould and line mould in existing traveling wave fault positioning method To carry out fault location, and zero line ripple detection speed is affected by frequency and decay, between time difference and fault distance no longer It is linear relationship, and zero line wave component amplitude attenuation is serious compared with line mould, the measurement accuracy of therefore zero line wave velocity is no Method is protected, and is not required to calculate zero line ripple detection speed in the present invention, only need to calculate the speed of the corresponding frequencies of 1 mould signal, Accurately and reliably, Position location accuracy is high for computational methods, to timely lookup and process circuit fault it is ensured that the safe operation of electrical network, carries High stability of power system simultaneously reduces operating cost, has important society and economic worth.

Fault type according to tested transmission line of electricity in above-mentioned step a, selects concrete as benchmark phase accordingly Way is:

If fault type is three phase short circuit fault, select a phase as the benchmark phase of phase-model transformation, after choosing phase-model transformation 1 mould signal is as fault current traveling wave mould signal x (t)；

This is because in three-phase line, the reflection coefficient matrix p of transient current travelling waves trouble point_fFor:

$p_f={[2z_m^{-1}+t^{-1}{y}_{f}t]}^{-1}{t}^{-1}{y}_{f}t---\left(1\right)$

In formula, z_mModulus characteristic impedance matrix for circuit:

$z_m=\left[\begin{array}{ccc}{z}_0& 0& 0\\ 0& z_1& 0\\ 0& 0& z_2\end{array}\right]---\left(2\right)$

T is karenbauer (Ka Lunbaoer) phase-model transformation matrix:

$t=\left[\begin{array}{ccc}1& 1& 1\\ 1& -2& 1\\ 1& 1& -2\end{array}\right]---\left(3\right)$

y_fFor fault admittance matrix, it is the inverse of fault impedance matrix:

$y_f=r_f^{-1}={\left[\begin{array}{ccc}{r}_g+r_a& r_g& r_g\\ r_g& r_g+r_b& r_g\\ r_g& r_g& r_g+r_c\end{array}\right]}^{-1}---\left(4\right)$

Wherein r_gFor fault ground resistance, and r_a, r_b, r_cTransition resistance for each phase.t^-1y_fT is referred to as the equivalent of trouble point Admittance matrix.

When fault type is for three-phase ground fault, because three phase short circuit fault is symmetrical fault, therefore can for formula (4) If r_a=r_b=r_c=r, simultaneously rg tend to infinitely great, therefore, when select a phase as phase-model transformation benchmark phase when, short dot etc. Effect admittance matrix can be written as:

$y_{\mathrm{abc}}=\frac{1}{3r}\left(\begin{array}{ccc}2& -1& -1\\ -1& 2& -1\\ -1& -1& 2\end{array}\right)---\left(5\right)$

Therefore, the reflection coefficient matrix in trouble point for the transient current travelling waves and coefficient of refraction matrix can be expressed as respectively:

$p_{\mathrm{abc}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{z_1}{z_1+2r}& 0\\ 0& 0& \frac{z_2}{z_2+2r}\end{array}\right]---\left(6\right)$

From formula (6), when can be full decoupled by system on the basis of a phase, between each mould signal, all there is not mould Mix phenomenon, the energy highest of 1 mould signal during three phase short circuit fault occurs simultaneously, is conducive to the extraction of Wavelet Modulus Maxima, therefore Select a phase as the benchmark phase of phase-model transformation in the present invention, choose 1 mould signal after phase-model transformation as fault current traveling wave mould Signal x (t)；

If fault type is bc two-phase short-circuit fault or bc two-phase short circuit and ground fault or a phase earth fault, b phase is selected to make Benchmark phase for phase-model transformation；

This is because when system occurs bc two-phase short-circuit fault, r can be set for formula (4)_b=r_c=r, rg and r simultaneously_aTend to Infinity, if during benchmark phase therefore with a phase as phase-model transformation, the Equivalent Admittance Matrix of short dot can be written as:

$y_{\mathrm{bc}}=\frac{1}{r}\left(\begin{array}{ccc}2& -1& -1\\ -1& 1& 0\\ -1& 0& 1\end{array}\right)---\left(7\right)$

Now, transient current travelling waves are represented by the reflection coefficient matrix of trouble point:

$p_{\mathrm{bc}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{z_1({3z}_2+4r)}{{3z}_1{z}_2+4r(z_1+z_2)+4r^2}& \frac{{2z}_{1}r}{{3z}_1{z}_2+4r(z_1+z_2)+{4r}^2}\\ 0& \frac{{2z}_{2}r}{{3z}_1{z}_2+4r(z_1+z_2)+4r^2}& \frac{4r(z_1+r)}{{3z}_1{z}_2+4r(z_1+z_2)+4r^2}\end{array}\right]---\left(8\right)$

As can be seen here, create between 1 mold component and 2 mold components and mix phenomenon, therefore no matter now select 1 mold component or All there is certain error as analysis object, its spread speed in 2 mold components, so that position error increases.

If the benchmark phase with b phase as phase-model transformation, the Equivalent Admittance Matrix of short dot can be written as:

$y_{\mathrm{bc}}=\frac{1}{r}\left(\begin{array}{ccc}1& 0& -1\\ 0& 1& -1\\ -1& -1& 2\end{array}\right)---\left(9\right)$

Now, transient current travelling waves are represented by the reflection coefficient matrix of trouble point:

$p_{\mathrm{bc}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{z_1}{z_1+2r}& 0\\ 0& -\frac{{2z}_{2}r}{(z_1+2r)({3z}_2+2r)}& \frac{{3z}_2}{{3z}_2+2r}\end{array}\right]---\left(10\right)$

As can be seen here, will not mix into 2 mold components in 1 mold component, and part 1 mold component in 2 mold components, can be mixed, therefore Now select 1 mold component as analysis object, its spread speed all without there is error, so as to obtain accurate positioning result.

If the benchmark phase with c phase as phase-model transformation, the Equivalent Admittance Matrix of short dot can be written as:

$y_{\mathrm{bc}}=\frac{1}{r}\left(\begin{array}{ccc}1& -1& 0\\ -1& 2& -1\\ 0& -1& 1\end{array}\right)---\left(11\right)$

Now, transient current travelling waves are represented by the reflection coefficient matrix of trouble point:

$p_{\mathrm{bc}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{{3z}_1}{{3z}_1+2r}& -\frac{{2z}_{1}r}{(z_2+2r)({3z}_1+2r)}\\ 0& 0& \frac{z_2}{z_2+2r}\end{array}\right]---\left(12\right)$

As can be seen here, will not mix into 1 mold component in 2 mold components, and part 2 mold component in 1 mold component, can be mixed, therefore Now select 2 mold components as analysis object, its spread speed all without there is error, so as to obtain accurate positioning result.

Because, in the transmission line of electricity of complete transposition, 1 mold component and 2 mold components are identicals, therefore for ensuring method Versatility, in patent of the present invention select b phase as phase-model transformation benchmark phase, choose phase-model transformation after 1 mould signal make For current traveling wave mould signal x (t).

In the same manner, to bc two-phase short circuit and ground fault or a phase earth fault, selection b phase can as the benchmark phase of phase-model transformation To guarantee the accuracy positioning.

In the same manner, when fault type is for bc two-phase short-circuit fault or bc two-phase short circuit and ground fault or a phase earth fault, choosing Select b phase as the benchmark phase of phase-model transformation；When fault type is ca two-phase short-circuit fault or ca two-phase short circuit and ground fault or b phase During earth fault, c phase is selected to be provided to ensure the accuracy of Fault Locating Method as the benchmark phase of phase-model transformation.

With reference to specific embodiment, the present invention is described in further detail.

Specific embodiment

A kind of specific embodiment of the present invention is, a kind of transmission line of electricity based on fault transient and steady-state signal velocity of wave difference Single end positioning method, the steps include:

A, data acquisition and pretreatment

Fault wave recording device gathers the current signal i of a, b, c three-phase from transmission line of electricity with sample rate f s_a(t)、i_b(t)、i_c T () is sent to fault locator, wherein t represents sampling instant；Fault locator is by current signal i_a(t)、i_b(t)、i_c After (t) Filtering Processing, according to the fault type of tested transmission line of electricity, select, accordingly as benchmark phase, fault current to be believed Number carry out phase-model transformation using karenbauer (Ka Lunbaoer) matrix, obtain 1 of the transmission line of electricity electric current for fault location Mould signal x (t).Sample frequency typically selects 5-20khz.

B, the extraction of framing signal

B1, the extraction of transient state travelling wave signal

The mid frequency choosing wavelet basiss is f_c, decomposition scale a₁=2f_c1 mould signal x (t) of transmission line of electricity electric current is carried out Continuous wavelet transform, obtains wavelet conversion coefficient c₁T (), in wavelet conversion coefficient c₁T () is upper to extract transient state travelling wave primary wave head mould Maximum corresponding moment t₁；Wavelet conversion coefficient c₁(t) corresponding frequency f₁=f_s/ 2 transient state travelling wave signals being positioning Frequency；

B2, the extraction of steady-state signal

The mid frequency choosing wavelet basiss is f_c, choose the decomposition scale a of wavelet transformation₂=f_s·f_c/ 50, to transmission line of electricity 1 mould signal x (t) of electric current carries out continuous wavelet transform, obtains wavelet conversion coefficient c₂(t)；In wavelet conversion coefficient c₂On (t) Extract steady-state signal modulus maximum corresponding moment t₂;Wavelet conversion coefficient c₂(t) corresponding frequency f₂=50hz as positions use Steady-state signal frequency；

C, one-end fault positioning

C1, be calculated respectively according to the model of transmission line of electricity positioning transient state travelling wave signal mould wave velocity matrix v₁ Mould wave velocity matrix v with the steady-state signal of positioning₂:

$v_1=2\mathrm{\π}{f}_1/\mathrm{im}\left(\sqrt{z_1{y}_1}\right)$

$v_2=2\mathrm{\π}{f}_2/\mathrm{im}\left(\sqrt{z_2{y}_2}\right)$

Wherein, z₁、y₁Being respectively frequency is f₁The mould impedance of the corresponding transmission line of transient state travelling wave signal and mould admittance square Battle array, z₂、y₂Being respectively frequency is f₂The mould impedance of the corresponding transmission line of steady-state signal of=50hz and mould admittance matrix, z₁、y₁、 z₂、y₂It is the matrix of 3*3, im represents the imaginary part seeking plural number；

In mould wave velocity matrix v₁In take the mould ripple v as transient state travelling wave signal for the element of the second row secondary series₁, in mould ripple Rate matrices v₂In take the mould ripple v as transient state travelling wave signal for the element of the second row secondary series₂；

C2, calculating fault distance:

Fault distance d calculates according to following formula:

$d=\frac{v_1\·v_2}{v_1-v_2}(t_2-t_1)$

Fault type according to tested transmission line of electricity in step a of this example, selects concrete as benchmark phase accordingly Way is:

If fault type is three phase short circuit fault, select a phase as the benchmark phase of phase-model transformation；

If fault type is ab two-phase short-circuit fault, ab two-phase short circuit and ground fault or c phase earth fault, a phase is selected to make Benchmark phase for phase-model transformation；

If fault type is bc two-phase short-circuit fault, bc two-phase short circuit and ground fault or a phase earth fault, b phase is selected to make Benchmark phase for phase-model transformation；

If fault type is ca two-phase short-circuit fault, ca two-phase short circuit and ground fault or b phase earth fault, c phase is selected to make Benchmark phase for phase-model transformation.

Claims (2)

1. a kind of transmission line of electricity single end positioning method based on fault transient and steady-state signal velocity of wave difference, the steps include:

A, data acquisition and pretreatment

Fault wave recording device is from transmission line of electricity with sample rate f_sThe current signal i of collection a, b, c three-phase_a(t)、i_b(t)、i_cT () passes Deliver to fault locator, wherein t represents sampling instant；Fault locator is by current signal i_a(t)、i_b(t)、i_cT () filters After process, according to the fault type of tested transmission line of electricity, select, accordingly as benchmark phase, fault-current signal to be utilized Karenbauer (Ka Lunbaoer) matrix carries out phase-model transformation, obtains 1 mould signal x of the transmission line of electricity electric current for fault location (t)；

B, the extraction of framing signal

B1, the extraction of transient state travelling wave signal

The mid frequency choosing wavelet basiss is f_c, decomposition scale a₁=2f_c1 mould signal x (t) of transmission line of electricity electric current is carried out even Continuous wavelet transformation, obtains wavelet conversion coefficient c₁T (), in wavelet conversion coefficient c₁T () is upper to extract transient state travelling wave primary wave head mould pole It is worth greatly corresponding moment t₁；Wavelet conversion coefficient c₁(t) corresponding frequency f₁=f_s/ 2 transient state travelling wave signals being positioning Frequency；

B2, the extraction of steady-state signal

The mid frequency choosing wavelet basiss is f_C,Choose the decomposition scale a of wavelet transformation₂=f_s·f_c/ 50 pairs of transmission line of electricity electric currents 1 mould signal x (t) carry out continuous wavelet transform, obtain wavelet conversion coefficient c₂(t)；In wavelet conversion coefficient c₂T () is upper to extract Steady-state signal modulus maximum corresponding moment t₂；Wavelet conversion coefficient c₂(t) corresponding frequency f₂=50hz is the steady of positioning The frequency of state signal；

C, one-end fault positioning

C1, be calculated respectively according to the model of transmission line of electricity positioning transient state travelling wave signal mould wave velocity matrix v₁With fixed The mould wave velocity matrix v of the steady-state signal of position₂:

Wherein, z₁、y₁Being respectively frequency is f₁The mould impedance of the corresponding transmission line of transient state travelling wave signal and mould admittance matrix, z₂、y₂Being respectively frequency is f₂The mould impedance of the corresponding transmission line of steady-state signal of=50hz and mould admittance matrix, z₁、y₁、z₂、 y₂It is the matrix of 3*3, im represents the imaginary part seeking plural number；

In mould wave velocity matrix v₁In take the mould ripple v as transient state travelling wave signal for the element of the second row secondary series₁, in mould wave velocity Matrix v₂In take the mould ripple v as steady-state signal for the element of the second row secondary series₂；

C2, calculating fault distance:

Fault distance d calculates according to following formula:

.

2. the transmission line of electricity single end positioning method based on fault transient and steady-state signal velocity of wave difference as claimed in claim 1, its It is characterised by: the fault type according to tested transmission line of electricity in described step a, select concrete as benchmark phase accordingly Way is:

If fault type is three phase short circuit fault, select a phase as the benchmark phase of phase-model transformation；

If fault type is ab two-phase short-circuit fault, ab two-phase short circuit and ground fault or c phase earth fault, select a phase as phase The benchmark phase of modular transformation；

If fault type is bc two-phase short-circuit fault, bc two-phase short circuit and ground fault or a phase earth fault, select b phase as phase The benchmark phase of modular transformation；

If fault type is ca two-phase short-circuit fault, ca two-phase short circuit and ground fault or b phase earth fault, select c phase as phase The benchmark phase of modular transformation.