CN103777115A - 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

Based on fault transient and the poor transmission line of electricity single end positioning method of steady-state signal velocity of wave

Technical field

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

Background technology

Traveling wave fault positioning method has that accurate positioning, reliability are high, good stability and be subject to the advantages such as the impact of fault resstance is little.At present, traveling wave fault positioning method has the functional failure travelling wave positioning method based on Two-Terminal Electrical Quantities and the functional failure travelling wave positioning method based on single-ended amount.Wherein, the functional failure travelling wave positioning method based on Two-Terminal Electrical Quantities is because needs utilize both-end data, thereby need to increase time synchronism apparatus, and the financial cost that has so not only increased localization of fault has reduced the reliability of positioning system simultaneously; And at present the functional failure travelling wave positioning method based on single-ended amount need to utilize and determines that fault is concrete the time of arrival of initial row ripple and reflection wave, therefore the precision of its location is subject to the detection of wavefront time of arrival and the impact of row velocity of wave propagation, and 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 can only utilize the relevant information of the initial wave head of row ripple determines fault distance and avoids the identification of reflected traveling wave wave head to improve widely the reliability of single-ended traveling wave localization method.

Summary of the invention

The invention provides that a kind of the method only need be measured initial row ripple, does not need to measure fault reflection wave based on fault transient and the poor transmission line of electricity single end positioning method of steady-state signal velocity of wave, improved the accurate reliability in location, simple to operate, feasibility is high.

The present invention is for solving its technical matters, and the technical scheme adopting is: a kind of based on fault transient and the poor transmission line of electricity single end positioning method of steady-state signal velocity of wave, the steps include:

A, data acquisition and pre-service

Fault wave recording device from transmission line of electricity with sampling rate F _sgather the current signal i of A, B, C three-phase _a(t), i _b(t), i _c(t) be sent to fault locator, wherein t represents sampling instant; Fault locator is by current signal i _a(t), i _b(t), i _c(t) after filtering is processed; according to the fault type of tested transmission line of electricity; select corresponding as benchmark phase; utilize Karenbauer (Ka Lunbaoer) matrix to carry out phase-model transformation to fault current signal, obtain the 1 mould signal x (t) for the transmission line of electricity electric current of localization of fault;

The extraction of B, positioning signal

The extraction of B1, transient state travelling wave signal

The centre frequency of choosing wavelet basis is f _c, decomposition scale a ₁=2f _cthe 1 mould signal x (t) to transmission line of electricity electric current carries out continuous wavelet transform, obtains wavelet conversion coefficient C ₁(t), at wavelet conversion coefficient C ₁(t) upper moment t corresponding to transient state travelling wave primary wave head mould maximum value that extract ₁; Wavelet conversion coefficient C ₁(t) corresponding frequency F ₁=F _s/ 2 are the frequency of the transient state travelling wave signal of location use;

The extraction of B2, steady-state signal

The centre frequency of choosing wavelet basis is f _c, choose the decomposition scale a of wavelet transformation ₂=F _sf _c1 mould signal x (t) of/50 pairs of transmission line of electricity electric currents carries out continuous wavelet transform, obtains wavelet conversion coefficient C ₂(t); At wavelet conversion coefficient C ₂(t) upper moment t corresponding to steady-state signal modulus maximum that extract ₂; Wavelet conversion coefficient C ₂(t) corresponding frequency F ₂=50Hz is the frequency of the steady-state signal of location use;

C, one-end fault location

C1, calculate respectively the mould wave velocity matrix V of transient state travelling wave signal of location use according to the model of transmission line of electricity ₁the mould wave velocity matrix V of steady-state signal with location use ₂:

$V_1=2\mathrm{\π}{F}_1/\mathrm{im}\left(\sqrt{Z_1{Y}_1}\right)$

$V_2=2\mathrm{\π}{F}_2/\mathrm{im}\left(\sqrt{Z_2{Y}_2}\right)$

Wherein, Z ₁, Y ₁being respectively frequency is F ₁mould impedance and the mould admittance matrix of transmission line corresponding to transient state travelling wave signal, Z ₂, Y ₂being respectively frequency is F ₂mould impedance and the mould admittance matrix of transmission line corresponding to the steady-state signal of=50Hz, Z ₁, Y ₁, Z ₂, Y ₂be the matrix of 3*3, im represents the imaginary part of asking plural;

In mould wave velocity matrix V ₁in get the element of the second row secondary series as the mould ripple v of transient state travelling wave signal ₁, in mould wave velocity matrix V ₂in get the element of the second row secondary series as the mould ripple v of transient state travelling wave signal ₂;

This is because when according to the fault type of tested transmission line of electricity, and it is suitable to benchmark phase time to select, 1 mold component can not be mixed in into other modulus compositions, and in wave velocity matrix V ₁or V ₂in the second row secondary series element be the velocity of propagation of 1 mold component, be therefore the impact that can avoid other mold component speed when selecting the second row secondary series element to calculate as the wave velocity of corresponding signal, thus the accuracy of assurance 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 be because fault occur time, assumed fault occur moment be t ₀, and trouble spot is identical with steady-state signal propagation distance d to locating device place transient signal, therefore has:

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

Wherein, v ₁for transient signal frequency F ₁velocity of propagation, v ₂for transient signal frequency F ₂velocity of propagation.Thereby can be derived from trouble spot and apart from d be:

$d=\frac{v_1\·v_2}{v_1-v_2}(t_2-t_1)$

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

(1) calculated amount is little., steady-state signal propagation speed differential temporary by fault determined fault distance, only need to determine initial wavefront in transient state component and the velocity of propagation of steady-state component, can accurately calculate fault distance, carry out any processing without the reflection wave head to fault traveling wave, thereby calculated amount is little, feasibility is high.

(2) accurate positioning is high.In existing traveling wave fault positioning method, the normal propagation time difference that adopts zero mould and line mould carries out localization of fault, and zero line ripple detection speed is subject to the impact of frequency and decay, it between mistiming and fault distance, is no longer linear relationship, and zero line wave component amplitude attenuation serious compared with line mould, therefore the measurement accuracy of zero line wave velocity cannot be protected, in the present invention, do not need to calculate zero line ripple detection speed, only need the speed of the corresponding frequencies of calculating 1 mould signal, computing method accurately and reliably, accurate positioning is high, to searching in time and processing circuitry fault, guarantee the safe operation of electrical network, improve stability of power system and reduce operating cost, there is important society and economic worth.

In above-mentioned steps A, according to the fault type of tested transmission line of electricity, select as the specific practice of benchmark phase to be accordingly:

If fault type is three phase short circuit fault, select A as the benchmark phase of phase-model transformation, choose 1 mould signal after phase-model transformation as the capable mode signal of fault current x (t);

This is because in three-phase line, the reflection coefficient matrix P of transient current travelling waves trouble spot _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 _cfor the transition resistance of each phase.T ^-1y _ft is called the Equivalent Admittance Matrix of trouble spot.

In the time that fault type is three-phase ground fault, because three phase short circuit fault is symmetrical fault, therefore can establish R for formula (4) _a=R _b=R _c=R, Rg is tending towards infinitely great simultaneously, and therefore, when the benchmark phase time of selecting A as phase-model transformation, the Equivalent Admittance Matrix of short dot 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, transient current travelling waves can be expressed as respectively at reflection coefficient matrix and the refraction coefficient matrix of trouble spot:

$P_{\mathrm{ABC}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{Z_1}{Z_1+2R}& 0\\ 0& 0& \frac{Z_2}{Z_2+2R}\end{array}\right]---\left(6\right)$

From formula (6), when take A mutually as benchmark can be full decoupled by system, between each mould signal, all do not exist mould to mix phenomenon, while there is three phase short circuit fault, the energy of 1 mould signal is the highest simultaneously, be conducive to the extraction of Wavelet Modulus Maxima, therefore select the benchmark phase of A as phase-model transformation in the present invention, choose 1 mould signal after phase-model transformation as the capable mode signal of fault current 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, select the benchmark phase of B as phase-model transformation;

This is because in the time that BC two-phase short-circuit fault occurs system, can establish R for formula (4) _b=R _c=R, simultaneously Rg and R _abe tending towards infinitely great, if therefore take A mutually as the benchmark phase time of 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 can be expressed as at the reflection coefficient matrix of trouble spot:

$P_{\mathrm{BC}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{Z_1({3Z}_2+4R)}{{3Z}_1{Z}_2+4R(Z_1+Z_2)+4R^2}& \frac{{2Z}_{1}R}{{3Z}_1{Z}_2+4R(Z_1+Z_2)+{4R}^2}\\ 0& \frac{{2Z}_{2}R}{{3Z}_1{Z}_2+4R(Z_1+Z_2)+4R^2}& \frac{4R(Z_1+R)}{{3Z}_1{Z}_2+4R(Z_1+Z_2)+4R^2}\end{array}\right]---\left(8\right)$

As can be seen here, between 1 mold component and 2 mold components, having produced and mixed phenomenon, therefore no matter now selected 1 mold component or 2 mold components as analytic target, all there is certain error in its velocity of propagation, thereby positioning error is increased.

If mutually as the benchmark phase of phase-model transformation, the Equivalent Admittance Matrix of short dot can be written as take B:

$Y_{\mathrm{BC}}=\frac{1}{R}\left(\begin{array}{ccc}1& 0& -1\\ 0& 1& -1\\ -1& -1& 2\end{array}\right)---\left(9\right)$

Now, transient current travelling waves can be expressed as at the reflection coefficient matrix of trouble spot:

$P_{\mathrm{BC}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{Z_1}{Z_1+2R}& 0\\ 0& -\frac{{2Z}_{2}R}{(Z_1+2R)({3Z}_2+2R)}& \frac{{3Z}_2}{{3Z}_2+2R}\end{array}\right]---\left(10\right)$

As can be seen here, can not mix into 2 mold components, and in 2 mold components, can mix part 1 mold component at 1 mold component, therefore now select 1 mold component as analytic target, can there is not error in its velocity of propagation, thereby can obtain positioning result accurately.

If mutually as the benchmark phase of phase-model transformation, the Equivalent Admittance Matrix of short dot can be written as take C:

$Y_{\mathrm{BC}}=\frac{1}{R}\left(\begin{array}{ccc}1& -1& 0\\ -1& 2& -1\\ 0& -1& 1\end{array}\right)---\left(11\right)$

Now, transient current travelling waves can be expressed as at the reflection coefficient matrix of trouble spot:

$P_{\mathrm{BC}}=\left[\begin{array}{ccc}0& 0& 0\\ 0& \frac{{3Z}_1}{{3Z}_1+2R}& -\frac{{2Z}_{1}R}{(Z_2+2R)({3Z}_1+2R)}\\ 0& 0& \frac{Z_2}{Z_2+2R}\end{array}\right]---\left(12\right)$

As can be seen here, can not mix into 1 mold component, and in 1 mold component, can mix part 2 mold components at 2 mold components, therefore now select 2 mold components as analytic target, can there is not error in its velocity of propagation, thereby can obtain positioning result accurately.

Due in the transmission line of electricity of complete transposition, 1 mold component is identical with 2 mold components, therefore for the versatility of ensuring method, in patent of the present invention, select the benchmark phase of B as phase-model transformation, choose 1 mould signal after phase-model transformation as current traveling wave mould signal x (t).

In like manner, to BC two-phase short circuit and ground fault or A phase earth fault, select B can guarantee mutually the accuracy of location as the benchmark of phase-model transformation.

In like manner, in the time that fault type is BC two-phase short-circuit fault or BC two-phase short circuit and ground fault or A phase earth fault, select the benchmark phase of B as phase-model transformation; In the time that fault type is CA two-phase short-circuit fault or CA two-phase short circuit and ground fault or B phase earth fault, selecting C is all the accuracy in order to guarantee Fault Locating Method as the benchmark of phase-model transformation mutually.

Below in conjunction with embodiment, the present invention is described in further detail.

Embodiment

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

A, data acquisition and pre-service

Fault wave recording device gathers the current signal i of A, B, C three-phase with sampling rate Fs from transmission line of electricity _a(t), i _b(t), i _c(t) be sent to fault locator, wherein t represents sampling instant; Fault locator is by current signal i _a(t), i _b(t), i _c(t) after filtering is processed, according to the fault type of tested transmission line of electricity, select corresponding as benchmark phase, utilize Karenbauer (Ka Lunbaoer) matrix to carry out phase-model transformation to fault current signal, obtain the 1 mould signal x (t) for the transmission line of electricity electric current of localization of fault.Sample frequency is generally selected 5-20kHz.

The extraction of B, positioning signal

The extraction of B1, transient state travelling wave signal

The centre frequency of choosing wavelet basis is f _c, decomposition scale a ₁=2f _cthe 1 mould signal x (t) to transmission line of electricity electric current carries out continuous wavelet transform, obtains wavelet conversion coefficient C ₁(t), at wavelet conversion coefficient C ₁(t) upper moment t corresponding to transient state travelling wave primary wave head mould maximum value that extract ₁; Wavelet conversion coefficient C ₁(t) corresponding frequency F ₁=F _s/ 2 are the frequency of the transient state travelling wave signal of location use;

The extraction of B2, steady-state signal

The centre frequency of choosing wavelet basis is f _c, choose the decomposition scale a of wavelet transformation ₂=F _sf _c/ 50,1 mould signal x (t) of transmission line of electricity electric current is carried out to continuous wavelet transform, obtain wavelet conversion coefficient C ₂(t); At wavelet conversion coefficient C ₂(t) upper moment t corresponding to steady-state signal modulus maximum that extract ₂; Wavelet conversion coefficient C ₂(t) corresponding frequency F ₂=50Hz is the frequency of the steady-state signal of location use;

C, one-end fault location

C1, calculate respectively the mould wave velocity matrix V of transient state travelling wave signal of location use according to the model of transmission line of electricity ₁the mould wave velocity matrix V of steady-state signal with location use ₂:

$V_1=2\mathrm{\π}{F}_1/\mathrm{im}\left(\sqrt{Z_1{Y}_1}\right)$

$V_2=2\mathrm{\π}{F}_2/\mathrm{im}\left(\sqrt{Z_2{Y}_2}\right)$

Wherein, Z ₁, Y ₁being respectively frequency is F ₁mould impedance and the mould admittance matrix of transmission line corresponding to transient state travelling wave signal, Z ₂, Y ₂being respectively frequency is F ₂mould impedance and the mould admittance matrix of transmission line corresponding to the steady-state signal of=50Hz, Z ₁, Y ₁, Z ₂, Y ₂be the matrix of 3*3, im represents the imaginary part of asking plural;

In mould wave velocity matrix V ₁in get the element of the second row secondary series as the mould ripple v of transient state travelling wave signal ₁, in mould wave velocity matrix V ₂in get the element of the second row secondary series as the mould ripple v of transient state travelling wave signal ₂;

C2, calculating fault distance:

Fault distance d calculates according to following formula:

$d=\frac{v_1\·v_2}{v_1-v_2}(t_2-t_1)$

In this routine steps A, according to the fault type of tested transmission line of electricity, select as the specific practice of benchmark phase to be accordingly:

If fault type is three phase short circuit fault, select the benchmark phase of A as 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 the benchmark phase of A as 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, select the benchmark phase of B as 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, select the benchmark phase of C as phase-model transformation.

Claims (2)

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

A, data acquisition and pre-service

Fault wave recording device from transmission line of electricity with sampling rate F _sgather the current signal i of A, B, C three-phase _a(t), i _b(t), i _c(t) be sent to fault locator, wherein t represents sampling instant; Fault locator is by current signal i _a(t), i _b(t), i _c(t) after filtering is processed; according to the fault type of tested transmission line of electricity; select corresponding as benchmark phase; utilize Karenbauer (Ka Lunbaoer) matrix to carry out phase-model transformation to fault current signal, obtain the 1 mould signal x (t) for the transmission line of electricity electric current of localization of fault;

The extraction of B, positioning signal

The extraction of B1, transient state travelling wave signal

The centre frequency of choosing wavelet basis is f _c, decomposition scale a ₁=2f _cthe 1 mould signal x (t) to transmission line of electricity electric current carries out continuous wavelet transform, obtains wavelet conversion coefficient C ₁(t), at wavelet conversion coefficient C ₁(t) upper moment t corresponding to transient state travelling wave primary wave head mould maximum value that extract ₁; Wavelet conversion coefficient C ₁(t) corresponding frequency F ₁=F _s/ 2 are the frequency of the transient state travelling wave signal of location use;

The extraction of B2, steady-state signal

The centre frequency of choosing wavelet basis is f _c, choose the decomposition scale a of wavelet transformation ₂=F _sf _c1 mould signal x (t) of/50 pairs of transmission line of electricity electric currents carries out continuous wavelet transform, obtains wavelet conversion coefficient C ₂(t); At wavelet conversion coefficient C ₂(t) upper moment t corresponding to steady-state signal modulus maximum that extract ₂; Wavelet conversion coefficient C ₂(t) corresponding frequency F ₂=50Hz is the frequency of the steady-state signal of location use;

C, one-end fault location

C1, calculate respectively the mould wave velocity matrix V of transient state travelling wave signal of location use according to the model of transmission line of electricity ₁the mould wave velocity matrix V of steady-state signal with location use ₂:

$V_1=2\mathrm{\π}{F}_1/\mathrm{im}\left(\sqrt{Z_1{Y}_1}\right)$

$V_2=2\mathrm{\π}{F}_2/\mathrm{im}\left(\sqrt{Z_2{Y}_2}\right)$

Wherein, Z ₁, Y ₁being respectively frequency is F ₁mould impedance and the mould admittance matrix of transmission line corresponding to transient state travelling wave signal, Z ₂, Y ₂being respectively frequency is F ₂mould impedance and the mould admittance matrix of transmission line corresponding to the steady-state signal of=50Hz, Z ₁, Y ₁, Z ₂, Y ₂be the matrix of 3*3, im represents the imaginary part of asking plural;

In mould wave velocity matrix V ₁in get the element of the second row secondary series as the mould ripple v of transient state travelling wave signal ₁, in mould wave velocity matrix V ₂in get the element of the second row secondary series as the mould ripple v of transient state travelling wave signal ₂;

C2, calculating fault distance:

Fault distance d calculates according to following formula:

$d=\frac{v_1\·v_2}{v_1-v_2}(t_2-t_1)$

As described in right 1 based on fault transient and the poor transmission line of electricity single end positioning method of steady-state signal velocity of wave, it is characterized in that: in described steps A, according to the fault type of tested transmission line of electricity, select as the specific practice of benchmark phase to be accordingly:

If fault type is three phase short circuit fault, select the benchmark phase of A as 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 the benchmark phase of A as 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, select the benchmark phase of B as 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, select the benchmark phase of C as phase-model transformation.