CN105116295A - Direct distribution overhead line fault range finding method based on traveling wave abrupt change distance calibration - Google Patents

Abstract

The invention relates to a direct distribution overhead line fault range finding method based on traveling wave abrupt change distance calibration, and belongs to the electric power system relay protection technology field. The method includes the steps: sampling the fault phase current of a faulty feed line and the initial end of the adjacent longest fine feed line at a sampling frequency 1MHZ once the single-phase earth fault of a direct distribution overhead line occurs, obtaining a voltage traveling wave of a bus end by means of a current traveling wave of the initial end of the adjacent longest fine feed line and also the impedance of the wave, calculating and constructing the current traveling wave by means of the current traveling wave of the initial end of the adjacent longest fine feed line and an obtained current traveling wave of a measuring end of the faulty feed line, applying the obtained voltage traveling wave and the current traveling wave to calculate voltage traveling wave distribution and current traveling wave distribution of the measuring end along the line, carrying out direction decomposition on the traveling wave distribution along the line, obtaining direction traveling waves along the line, extracting a forward traveling wave abrupt change and an opposite travelling wave abrupt change along the line, and multiplying the forward traveling wave abrupt change by the opposite travelling wave abrupt change in a traveling wave observation time window and conducting integration to establish a range finding function to achieve fault range finding. The theoretical analysis and a simulation result show that the method has a good effect.

Description

A kind of based on row ripple mutation distance demarcate directly join pole line fault distance-finding method

Technical field

The present invention be a kind of based on row ripple mutation distance demarcate directly join pole line fault distance-finding method, belong to Relay Protection Technology in Power System field.

Background technology

Under the Power Network Neutral determined, power network topology and bus outlet connection type; the time domain row wave-wave of protection installation place measuring point is to moment, wave head (sudden change) amplitude and polarity reflection row ripple attribute; containing fault location information; it and abort situation have corresponding relation; the time-domain transient initial row ripple of single-ended observation, trouble spot reflection wave or opposite end reflection wave-wave arrival time difference can be utilized to carry out Single Terminal Traveling Wave Fault Location; the capable ripple of fault initial row ripple that both-end can be utilized to observe reaches the difference in bilateral absolute moment, carries out both-end travelling wave ranging.In Single Terminal Traveling Wave Fault Location method, reflection wave identification in trouble spot is more complicated with examination, requires higher to row wave amplitude, steepness.Both-end travelling wave ranging does not need to carry out identification to trouble spot reflection wave, the machine being comparatively suitable for being formed travelling wave ranging realizes and robotization, but both-end travelling wave ranging requires that circuit two ends cycle accurate is synchronous, requires that the line length engineering participating in fault distance calculating exhales title value l close to its " true value ", unavoidably there is objective range error.In any case, current travelling wave ranging method is based on fault traveling wave temporal signatures mostly and observes row ripple on time shaft, to portray and wave head is demarcated, and the calculating of fault distance.Therefore, be badly in need of proposing a kind of new fault distance-finding method, be not subject to the effective identification of fault traveling wave wave head and range finding cycle accurate synchronously on the impact of localization of fault accuracy.

Summary of the invention

The object of the invention is to overcome the effective identification of conventional Time-domain travelling wave ranging requirement fault traveling wave and the synchronous limitation of range finding cycle accurate, propose a kind of demarcate based on row ripple mutation distance directly join pole line fault distance-finding method, in order to solve the problem.

Technical scheme of the present invention is: a kind of based on row ripple mutation distance demarcate directly join pole line fault distance-finding method, during direct distribution lines generation singlephase earth fault, under sampling rate 1MHz, fault feeder and the longest adjacent faulted phase current perfecting feeder line initiating terminal are sampled, obtain bus terminal voltage row ripple by the longest adjacent feeder line initiating terminal current traveling wave and the wave impedance thereof of perfecting, and utilize and adjacently the longlyest perfect current traveling wave that feeder line origin or beginning current traveling wave and fault feeder measuring end obtain to calculate structure current traveling wave.Apply voltage traveling wave that the voltage traveling wave that obtains and current traveling wave ask for measuring end to distribute along the line and current traveling wave distributes along the line, then to row ripple distribute along the line travel direction decompose, obtain the direction row ripple of distribution along the line, and extract the direct wave sudden change of distribution along the line and backward-travelling wave suddenlys change, finally the two is multiplied and when row ripple is observed, in window, carries out integration again realize fault localization to construct range function.

Concrete steps are:

(1) during direct distribution lines generation singlephase earth fault, under sampling rate 1MHz, the faulted phase current of fault feeder and the longest adjacent feeder line initiating terminal faulted phase current that perfects are sampled, obtain faulted phase current sampled value sequence respectively, be designated as: i (k), i ' (k), wherein k represents sampled point, k=1,2 ...

(2) the discrete series u of bus terminal voltage and structure current traveling wave is obtained respectively according to formula (1) and formula (2) _m(k) and i _m(k):

u _M(k)＝i′(k)×Z _c(1)

i _M(k)＝i(k)-i′(k)(2)

In formula, u _mk () is the terminal voltage of bus M, i _mthe structure current traveling wave of (k) fault feeder, Z _cfor feeder line wave impedance.

(3) calculating of distribution along the line: utilize formula (3) and formula (4) to calculate the voltage's distribiuting along the line of fault feeder and distribution of current along the line respectively.

$\begin{array}{c}{u}_{M,x}(x,k)=\frac{1}{2}{\left(\frac{Z_c+r_{s}x/4}{Z_c}\right)}^2\[u_M(k+\frac{w}{v_s})-i_M(k+\frac{x}{v_s})(Z_c+\frac{r_{s}x}{4})\]\\ +\frac{1}{2}{\left(\frac{Z_c-r_{s}x/4}{Z_c}\right)}^2\[u_M(k-\frac{x}{v_s})+i_M(k-\frac{x}{v_s})(Z_c-r_{s}x)\]\\ -{\left(\frac{r_{s}x/4}{Z_c}\right)}^2{u}_M\left(k\right)-\frac{r_{s}x}{4}\left(\frac{Z_c+r_{s}x/4}{Z_c}\right)\left(\frac{Z_c-r_{s}x/4}{Z_c}\right)i_M\left(k\right)\end{array}---\left(3\right)$

$\begin{array}{c}{i}_{M,x}(x,k)=\frac{1}{2Z_c}\left(\frac{Z_c+r_{s}x/4}{Z_c}\right)\[u_M(k+x/v_s)-i_M(k+x/v_s)\·(Z_c+r_{s}x/4)\]\\ -\frac{1}{2Z_c}\left(\frac{Z_c-r_{s}x/4}{Z_c}\right)\[u_M(k-x/v_s)+i_M(k-x/v_s)\·(Z_c-r_{s}x/4)\]\\ -\frac{1}{2Z_c}\·\frac{r_{s}x}{2Z_c}\[u_M\left(k\right)-i_M\left(k\right)(r_{s}x/4)\]\end{array}---\left(4\right)$

In formula, x is the distance of any point along the line to measuring end; V is the wave velocity of circuit; Z _cfor feeder line wave impedance; r _sfor circuit resistance per unit length; u _mk () is the terminal voltage of bus M; i _mk structure current traveling wave that () is fault feeder; u _m,x(x, k) is for the k moment is apart from the voltage at measuring end x place; i _m,x(x, k) is for the k moment is apart from the electric current at measuring end x place.

(4) direct wave and the backward-travelling wave of distribution along the line is calculated: calculate the capable ripple of forward voltage that fault feeder distributes, the capable ripple of reverse voltage distributed respectively along the line along the line according to formula (5) and formula (6), namely

u ⁺ _M,x＝(u _M,x+Z _ci _M,x)/2(5)

u ^- _M,x＝(u _M,x-Z _ci _M,x)/2(6)

(5) the direct wave gradient of distribution along the line and the calculating of backward-travelling wave gradient: the forward voltage gradient utilizing the difference structure distribution along the line of adjacent two sampled values of the capable ripple of forward voltage of distribution along the line, namely

c ⁺ _M,dif—u(k)＝u ⁺ _k,x(k)-u ⁺ _k,x(k-1)(7)

Utilize the reverse voltage gradient of the difference structure distribution along the line of adjacent two sampled values of the capable ripple of reverse voltage of distribution along the line, namely

c ^- _M,dif—u(k)＝u ^- _k,x(k)-u ^- _k,x(k-1)(8)

(6) direct wave of calculating distribution along the line suddenlys change and backward-travelling wave sudden change: the capable ripple sudden change of forward voltage distributed along the line according to formula (9) extraction faulty line, namely

${S^{+}}_{M,2u}(x,k)=\underset{n=k-R+1}{\overset{k}{\Σ}}{\[{c^{+}}_{M,dif\_u}\left(k\right)\]}^3---\left(9\right)$

According to the capable ripple sudden change of reverse voltage that formula (10) extraction faulty line distributes along the line, namely

${S^{-}}_{M,2u}(x,k)=\underset{n=k-R+1}{\overset{k}{\Σ}}{\[{c^{-}}_{M,dif\_u}\left(k\right)\]}^3---\left(10\right)$

In formula, R is taken as 3.

(7) structure of range function: adopt formula (11) and formula (12), window [k when direct wave step (6) obtained sudden change is multiplied with backward-travelling wave sudden change and observes respectively at row ripple ₀, k ₀+ l/ (2v)] and [k ₀+ l/ (2v), k ₀+ l/v] in carry out integration, obtain range function f _uI(x) and f _uIIthe row ripple sudden change along the line of (x).

$\begin{array}{cc}{f}_{uI}\left(x\right)={\∫}_{k_0}^{k_0+l/2v}{S}_{M,2u}^{+}(x,k)\×S_{M,2u}^{-}(x,k)dk& x\∈\[0,l/2\]\end{array}---\left(11\right)$

$\begin{array}{cc}{f}_{uII}\left(x\right)={\∫}_{k_0+l/2v}^{k_0+l/v}{S}_{M,2u}^{+}(x,k)\×S_{M,2u}^{-}(x,k)dk& x\∈\[l/2,l\]\end{array}---\left(12\right)$

In formula, k ₀represent the fault initial row ripple due in that measuring end M detects; L is fault feeder line length.

(8) structure of localization of fault criterion: calculate [k according to step (7) ₀, k ₀+ l/ (2v)] and [k ₀+ l/ (2v), k ₀+ l/v] two in succession time window in, range function f _uI(x) and f _uIIx the distribution catastrophe point along the line of (), its respective distances is designated as [x respectively _i1, x _i2... ] and [x _iI1, x _iI2... ].If [x _i1, x _i2... ] in mutation distance x ^* _i[x _iI1, x _iI2... ] in mutation distance x ^* _iImeet the line length constraint condition shown in formula (13), and x ^* _icatastrophe point polarity be negative, x ^* _iIcatastrophe point polarity be negative, x ^* _icatastrophe point amplitude be less than x ^* _iIcatastrophe point amplitude, then fault is positioned within half line length, and the distance of trouble spot distance measuring end is x ^* _i; If [x _i1, x _i2... ] in mutation distance x ^* _i[x _iI1, x _iI2... ] in mutation distance x ^* _iImeet the line length constraint condition shown in formula (13), and x ^* _icatastrophe point polarity be negative, x ^* _iIcatastrophe point polarity be negative, x ^* _icatastrophe point amplitude be greater than x ^* _iIcatastrophe point amplitude, then fault is positioned at outside half line length, and the distance of trouble spot distance measuring end is x ^* _iI.

x ^* _I+x ^* _II＝l(13)。

The invention has the beneficial effects as follows:

The present invention is directed to and directly join overhead transmission line and carry out localization of fault, its principle is simple, does not need to demarcate fault traveling wave wave-wave head, and not by the impact of the factor such as fault instantaneity, fault resistance change, range measurement accurately and reliably.

Accompanying drawing explanation

Fig. 1 is embodiment 1, embodiment 2 directly join overhead system structural drawing;

Fig. 2 is within half line length under fault, [k ₀, k ₀+ L ₁/ (2v)] time window in range function f _uthe sudden change distribution results of (x);

Fig. 3 is within half line length under fault, [k ₀+ L ₁/ (2v), k ₀+ L ₁/ v] time window in range function f _u(x) sudden change distribution results;

Fig. 4 is outside half line length under fault, [k ₀, k ₀+ L ₁/ (2v)] time window in range function f _uthe sudden change distribution results of (x);

Fig. 5 is outside half line length under fault, [k ₀+ L ₁/ (2v), k ₀+ L ₁/ v] time window in range function f _u(x) sudden change distribution results.

Embodiment

Below in conjunction with the drawings and specific embodiments, the invention will be further described.

During direct distribution lines generation singlephase earth fault, under sampling rate 1MHz, fault feeder and the longest adjacent faulted phase current perfecting feeder line initiating terminal are sampled, obtain bus terminal voltage row ripple by the longest adjacent feeder line initiating terminal current traveling wave and the wave impedance thereof of perfecting, and utilize and adjacently the longlyest perfect current traveling wave that feeder line origin or beginning current traveling wave and fault feeder measuring end obtain to calculate structure current traveling wave.Apply voltage traveling wave that the voltage traveling wave that obtains and current traveling wave ask for measuring end to distribute along the line and current traveling wave distributes along the line, then to row ripple distribute along the line travel direction decompose, obtain the direction row ripple of distribution along the line, and extract the direct wave sudden change of distribution along the line and backward-travelling wave suddenlys change, finally the two is multiplied and when row ripple is observed, in window, carries out integration again realize fault localization to construct range function.

Embodiment 1:

Adopt 35kV as shown in Figure 1 to feed out circuit more and directly join overhead system, fault feeder L ₁=20km, and its, two ends were the connection type of " I-III " class bus combination at whole story, measuring end is arranged at top M.Perfect feeder line L ₂=5km, L ₃=15km, and to perfect line end be III class bus connection type.Suppose feeder line L ₁within half line length, distance M holds 8km place that A phase earth fault occurs, and the initial phase angle of fault is 90 °, and transition resistance is set to 0.01 Ω, sampling rate is 1MHz, adopt voltage traveling wave and structure current traveling wave, material calculation along the line gets 0.1km, chooses window [k when two row ripples are in succession observed respectively ₀, k ₀+ L ₁/ (2v)] and [k ₀+ L ₁/ (2v), k ₀+ L ₁/ v] expert's wave datum, can be calculated range function f _uI(x) and f _uIIx () distributes as shown in Figures 2 and 3 along row ripple long completely sudden change.As shown in Figure 2, [k ₀, k ₀+ l/ (2v)] time window in, f _uIcatastrophe point A (the x)=8km of (x), and polarity is negative; As shown in Figure 3, [k ₀+ l/ (2v), k ₀+ l/v] time window in, f _uIIcatastrophe point B (the x)=12km of (x), and polarity is negative.Because A (x)+B (x)=8+12=20km, meet the line length constraint condition shown in formula (13), and the amplitude of A (x) is less than the amplitude of B (x), so fault is positioned within half line length, the distance of trouble spot distance measuring end M is 8km.

Embodiment 2:

Adopt 35kV as shown in Figure 1 to feed out circuit more and directly join overhead system, fault feeder L ₁=20km, and its, two ends were the connection type of " I-III " class bus combination at whole story, measuring end is arranged at top M.Perfect feeder line L ₂=5km, L ₃=15km, and to perfect line end be III class bus connection type.Suppose feeder line L ₁outside half line length, distance M holds 14km place that A phase earth fault occurs, and the initial phase angle of fault is 90 °, and transition resistance is set to 0.01 Ω, sampling rate is 1MHz, adopt voltage traveling wave and structure current traveling wave, material calculation along the line gets 0.1km, chooses window [k when two row ripples are in succession observed respectively ₀, k ₀+ L ₁/ (2v)] and [k ₀+ L ₁/ (2v), k ₀+ L ₁/ v] expert's wave datum, can be calculated range function f _uI(x) and f _uIIx () distributes as shown in Figure 4 and Figure 5 along row ripple long completely sudden change.As shown in Figure 4, [k ₀, k ₀+ l/ (2v)] time window in, f _uIcatastrophe point B (the x)=6km of (x), and polarity is negative; As shown in Figure 5, [k ₀+ l/ (2v), k ₀+ l/v] time window in, f _uIIcatastrophe point A (the x)=14km of (x), and polarity is negative.Because A (x)+B (x)=14+6=20km, meet the line length constraint condition shown in formula (13), and the amplitude of B (x) is greater than the amplitude of A (x), so fault is positioned at outside half line length, the distance of trouble spot distance measuring end M is 14km.

Claims (2)

1. one kind based on row ripple mutation distance demarcate directly join pole line fault distance-finding method, it is characterized in that: during direct distribution lines generation singlephase earth fault, under sampling rate 1MHz, fault feeder and the longest adjacent faulted phase current perfecting feeder line initiating terminal are sampled, obtain bus terminal voltage row ripple by the longest adjacent feeder line initiating terminal current traveling wave and the wave impedance thereof of perfecting, utilize and adjacently the longlyest perfect current traveling wave that feeder line origin or beginning current traveling wave and fault feeder measuring end obtain to calculate structure current traveling wave; Apply voltage traveling wave that the voltage traveling wave that obtains and current traveling wave ask for measuring end to distribute along the line and current traveling wave distributes along the line, then to row ripple distribute along the line travel direction decompose, obtain the direction row ripple of distribution along the line, and extract the direct wave sudden change of distribution along the line and backward-travelling wave suddenlys change, finally the two is multiplied and when row ripple is observed, in window, carries out integration again realize fault localization to construct range function.

2. according to claim 1 based on row ripple mutation distance demarcate directly join pole line fault distance-finding method, it is characterized in that concrete steps are as follows:

(1) during direct distribution lines generation singlephase earth fault, under sampling rate 1MHz, the faulted phase current of fault feeder and the longest adjacent feeder line initiating terminal faulted phase current that perfects are sampled, obtain faulted phase current sampled value sequence respectively, be designated as: i (k), i ' (k), wherein k represents sampled point, k=1,2,

(2) the discrete series u of bus terminal voltage and structure current traveling wave is obtained respectively according to formula (1) and formula (2) _m(k) and i _m(k):

u _M(k)＝i′(k)×Z _c(1)

i _M(k)＝i(k)-i′(k)(2)

In formula, u _mk () is the terminal voltage of bus M, i _mthe structure current traveling wave of (k) fault feeder, Z _cfor feeder line wave impedance;

(3) calculating of distribution along the line: utilize formula (3) and formula (4) to calculate the voltage's distribiuting along the line of fault feeder and distribution of current along the line respectively:

$\begin{array}{c}{u}_{M,x}\left(x,k\right)=\frac{1}{2}{\left(\frac{Z_c+r_{s}x/4}{Z_c}\right)}^2\[u_M\left(k+\frac{x}{v_s}\right)-i_M\left(k+\frac{x}{v_s}\right)\left(Z_c+\frac{r_{s}x}{4}\right)\]\\ =\frac{1}{2}{\left(\frac{Z_c-r_{s}x/4}{Z_c}\right)}^2\[u_M\left(k-\frac{x}{v_s}\right)+i_M\left(k-\frac{x}{v_s}\right)\left(Z_c-r_{s}x\right)\]\\ -{\left(\frac{r_{s}x/4}{Z_c}\right)}^2{u}_M\left(k\right)-\frac{r_{s}x}{4}\left(\frac{Z_c+r_{s}x/4}{Z_c}\right)\left(\frac{Z_c-r_{s}x/4}{Z_c}\right)i_M\left(k\right)\end{array}---\left(3\right)$

$\begin{array}{c}{i}_{M,x}\left(x,k\right)=\frac{1}{2Z_c}\left(\frac{Z_c+r_{s}x/4}{Z_c}\right)\[u_M\left(k+x/v_s\right)-i_M\left(k+x/v_s\right)\·\left(Z_c+r_{s}x/4\right)\]\\ -\frac{1}{2Z_c}\left(\frac{Z_c-r_{s}x/4}{Z_c}\right)\[u_M\left(k-x/v_s\right)+i_M\left(k-x/v_s\right)\·\left(Z_c-r_{s}x/4\right)\]\\ -\frac{1}{2Z_c}\·\frac{r_{s}x}{2Z_c}\[u_M\left(k\right)-i_M\left(k\right)\left(r_{s}x/4\right)\]\end{array}---\left(4\right)$

In formula, x is the distance of any point along the line to measuring end; V is the wave velocity of circuit; Z _cfor feeder line wave impedance; r _sfor circuit resistance per unit length; u _mk () is the terminal voltage of bus M; i _mk structure current traveling wave that () is fault feeder; u _m,x(x, k) is for the k moment is apart from the voltage at measuring end x place; i _m,x(x, k) is for the k moment is apart from the electric current at measuring end x place;

(4) direct wave and the backward-travelling wave of distribution along the line is calculated: calculate the capable ripple of forward voltage that fault feeder distributes, the capable ripple of reverse voltage distributed respectively along the line along the line according to formula (5) and formula (6), that is:

u ⁺ _M,x＝(u _M,x+Z _ci _M,x)/2(5)

u ^- _M,x＝(u _M,x-Z _ci _M,x)/2(6)

(5) the direct wave gradient of distribution along the line and the calculating of backward-travelling wave gradient: the forward voltage gradient utilizing the difference structure distribution along the line of adjacent two sampled values of the capable ripple of forward voltage of distribution along the line, that is:

c ⁺ _M,dif—u(k)＝u ⁺ _k,x(k)-u ⁺ _k,x(k-1)(7)

Utilize the reverse voltage gradient of the difference structure distribution along the line of adjacent two sampled values of the capable ripple of reverse voltage of distribution along the line, that is:

c ^- _M,dif—u(k)＝u ^- _k,x(k)-u ^- _k,x(k-1)(8)

(6) direct wave of calculating distribution along the line suddenlys change and backward-travelling wave sudden change: the capable ripple sudden change of forward voltage distributed along the line according to formula (9) extraction faulty line, that is:

${S^{+}}_{M,2u}(x,k)=\underset{n=k-R+1}{\overset{k}{\Σ}}{\[{c^{+}}_{M,dif\_u}\left(k\right)\]}^3---\left(9\right)$

According to the capable ripple sudden change of reverse voltage that formula (10) extraction faulty line distributes along the line, that is:

${S^{-}}_{M,2u}(x,k)=\underset{n=k-R+1}{\overset{k}{\Σ}}{\[{c^{-}}_{M,dif\_u}\left(k\right)\]}^3---\left(10\right)$

In formula, R is taken as 3;

(7) structure of range function: adopt formula (11) and formula (12), window [k when direct wave step (6) obtained sudden change is multiplied with backward-travelling wave sudden change and observes respectively at row ripple ₀, k ₀+ l/ (2v)] and [k ₀+ l/ (2v), k ₀+ l/v] in carry out integration, obtain range function f _uI(x) and f _uIIthe row ripple sudden change along the line of (x);

$f_{uI}\left(x\right)={\∫}_{k_0}^{k_0+l/2v}{S}_{M,2u}^{+}(x,k)\×S_{M,2u}^{-}(x,k)dk,x\∈\[0,l/2\]---\left(11\right)$

$f_{uII}\left(x\right)={\∫}_{k_0+l/2v}^{k_0+l/v}{S}_{M,2u}^{+}(x,k)\×S_{M,2u}^{-}(x,k)dk,x\∈\[l/2,l\]---\left(12\right)$

In formula, k ₀represent the fault initial row ripple due in that measuring end M detects; L is fault feeder line length;

(8) structure of localization of fault criterion: calculate [k according to step (7) ₀, k ₀+ l/ (2v)] and [k ₀+ l/ (2v), k ₀+ l/v] two in succession time window in, range function f _uI(x) and f _uIIx the distribution catastrophe point along the line of (), its respective distances is designated as [x respectively _i1, x _i2,] and [x _iI1, x _iI2,]; If [x _i1, x _i2,] in mutation distance x ^* _i[x _iI1, x _iI2,] in mutation distance x ^* _iImeet the line length constraint condition shown in formula (13), and x ^* _icatastrophe point polarity be negative, x ^* _iIcatastrophe point polarity be negative, x ^* _icatastrophe point amplitude be less than x ^* _iIcatastrophe point amplitude, then fault is positioned within half line length, and the distance of trouble spot distance measuring end is x ^* _i; If [x _i1, x _i2,] in mutation distance x ^* _i[x _iI1, x _iI2,] in mutation distance x ^* _iImeet the line length constraint condition shown in formula (13), and x ^* _icatastrophe point polarity be negative, x ^* _iIcatastrophe point polarity be negative, x ^* _icatastrophe point amplitude be greater than x ^* _iIcatastrophe point amplitude, then fault is positioned at outside half line length, and the distance of trouble spot distance measuring end is x ^* _iI;

x ^* _I+x ^* _II＝l(13)。