CN102508112A - Method for fault location of transmission line - Google Patents

Abstract

The invention discloses a method for fault location of a transmission line, which is characterized in that: a voltage sensor is used for sampling a three-phase voltage signal of a bus voltage to obtain a three-phase voltage signal; a current sensor is used for sampling a three-phase current signal of a bus current to obtain a three-phase current signal; a signal conditioning circuit is used for modulating the three-phase voltage signal and the three-phase current signal, and the conditioned three-phase voltage signal and the conditioned three-phase current signal are obtained; a microprocessor is used for performing the analog-digital conversion on the conditioned three-phase voltage signal and the conditioned three-phase current signal and for collecting data, the collected data are analyzed and processed to obtain an expected value of a fault distance, and the expected value of the fault distance is displayed through a display module; and a fault line can be determined by a user according to the expected value of the fault distance so as to repair the fault line. Due to the adoption of the method, the repairing efficiency of the fault line can be improved, the precision on finding the fault line is approved by a test to be improved, and a good effect can be realized.

Description

A kind of method that is used for measuring distance of transmission line fault

Technical field

The present invention relates to power system transmission line fault localization field, particularly a kind of method that is used for measuring distance of transmission line fault.

Background technology

Isolated neutral or be called non-direct ground system or small current neutral grounding system through the electrical network of grounding through arc.This method of operation has obtained using widely in the 35kv of China and following electric system.When non-direct ground system generation singlephase earth fault, though under the not too big situation of earth point fault current, the permission system continues operation 1-2 hour, if fault current is bigger, will light electric arc in the trouble spot,

Cause arc overvoltage, the insulation breakdown that this possibly cause non-fault phase enlarges fault.Therefore, the non-direct ground system singlephase earth fault is studied very necessity.

The inventor finds to have following shortcoming and defect in the prior art at least in actual applications: in the circuit of reality; Because the fault signature during small current system generation single-phase earthing is not obvious and fault current is little; Signal to noise ratio is less, so be difficult to get access to the trouble point; And Zero sequence parameter can change along with the change of environment, weather, can cause range accuracy to reduce like this.

Summary of the invention

The invention provides a kind of method that is used for measuring distance of transmission line fault, this method can get access to faulty line accurately, and has solved the problem that distance accuracy that the change because of environment, weather causes reduces, and has improved maintenance efficiency, sees hereinafter for details and describes:

A kind of method that is used for measuring distance of transmission line fault said method comprising the steps of:

(1) voltage sensor is sampled to the three-phase voltage signal of busbar voltage, obtains three-phase voltage signal;

(2) current sensor is sampled to the three-phase current signal of bus current, obtains three-phase current signal;

(3) said voltage sensor is input to signal conditioning circuit with said three-phase voltage signal, and said current sensor is input to said signal conditioning circuit with said three-phase current signal;

(4) said signal conditioning circuit is nursed one's health said three-phase voltage signal and said three-phase current signal; Obtain conditioning back three-phase voltage signal and conditioning back three-phase current signal, and three-phase current signal after said conditioning back three-phase voltage signal and the said conditioning is transferred to microprocessor;

(5) said microprocessor to said conditioning back three-phase voltage signal and said conditioning after three-phase current signal carry out analog to digital conversion and image data; Said data to collecting are carried out analyzing and processing; Obtain the expectation value of fault distance, and the expectation value of said fault distance is shown through display module;

(6) user confirms faulty line according to the expectation value of said fault distance, and said faulty line is keeped in repair.

Said in the step (5) carries out analyzing and processing to the said data that collect, and the expectation value of obtaining fault distance is specially:

1) with zero sequence impedance Z ₀As random quantity, said microprocessor obtains zero sequence impedance Z ₀Scope;

$Z_0=(r_1+3r_g)+j(0.1885\ln \frac{D_g}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

In the formula, r ₁Be aerial condutor resistance (Ω/km), r _g=π ²F * 10 ^-4Ω/km, D _mBe circuit geometric mean distance (m) that r is the radius (m) of aerial condutor, zero sequence impedance Z ₀Unit be Ω/km;

According to D _gRange computation obtain Z ₀Scope:

$Z_{0\max }=(r_1+3r_g)+j(0.1885\ln \frac{D_{g\max }}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

$Z_{0\min }=(r_1+3r_g)+j(0.1885\ln \frac{D_{g\min }}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

In the formula, Z _0maxBe maximum zero sequence impedance, Z _0minBe minimum zero sequence impedance;

Wherein, $D_{g\mathrm{Max}}=\frac{660}{\sqrt{{\mathrm{F\γ}}_{\mathrm{Min}}}}=2950m,$ $D_{g\mathrm{Min}}=\frac{660}{\sqrt{{\mathrm{F\γ}}_{\mathrm{Max}}}}=933m$

In the formula, f is the frequency (Hz) of conditioning back three-phase current, γ _MinBe minimum conductivity; γ _MaxBe maximum conductivity;

2) said microprocessor is according to said zero sequence impedance Z ₀Scope obtain the number percent D of fault distance _FiWith fault distance L _Fi

Z _0i＝Z _0min+(Z _0max-Z _0min)α

In the formula, α is equally distributed random number, is produced by computer simulation, and span is between (0,1);

$D_{\mathrm{fi}}=\frac{R_e\left(U_a\right)I_m\left(I_{\mathrm{af}}\right)-I_m\left(U_a\right)R_e\left(I_{\mathrm{af}}\right)}{I_m\left(I_{\mathrm{af}}\right)R_e[{\mathrm{ZI}}_a+(Z_{0i}-Z)I_{a0}]-R_e\left(I_{\mathrm{af}}\right)I_m[{\mathrm{ZI}}_a+(Z_{0i}-Z)I_{a0}]}$

In the formula, U _aBe line voltage distribution, I _aBe line current, I _AfBe line fault electric current, I _A0Be circuit zero-sequence current, R _e(), R _e[], I _m() and I _m[] represented respectively measuring real part and imaginary part mutually in the bracket;

L _fi＝L×D _fi

In the formula, L is a total track length, and unit is km;

3) said microprocessor is to said fault distance L _FiAsk expectation value;

$E\left(L_f\right)=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{L}_{\mathrm{fi}}$

In the formula, E (L _f) be the expectation value of fault distance, unit is km.

Said method also comprises:

Said microprocessor is sent in PC or the internet through the expectation value of serial ports with said fault distance.

A kind of method that is used for measuring distance of transmission line fault provided by the invention, this method has following advantage:

The present invention confirms faulty line through the scope that gets access to faulty line, faulty line is keeped in repair again, and has improved the maintenance efficiency of faulty line, and through verification experimental verification, this method has improved the precision of searching faulty line, has good effect.

Description of drawings

Fig. 1 is the structural representation of non-direct ground system provided by the invention;

Fig. 2 is a kind of process flow diagram that is used for the method for measuring distance of transmission line fault provided by the invention.

Embodiment

For making the object of the invention, technical scheme and advantage clearer, embodiment of the present invention is done to describe in detail further below in conjunction with accompanying drawing.

Referring to Fig. 1 and Fig. 2, a kind of method that is used for measuring distance of transmission line fault may further comprise the steps:

101: voltage sensor is to the three-phase voltage signal (U of busbar voltage _a, U _bAnd U _c) sample, obtain three-phase voltage signal;

102: current sensor is to the three-phase current signal (I of bus current _a, I _bAnd I _c) sample, obtain three-phase current signal;

103: voltage sensor is input to signal conditioning circuit with three-phase voltage signal, and current sensor is input to signal conditioning circuit with three-phase current signal;

104: signal conditioning circuit is nursed one's health three-phase voltage signal and three-phase current signal, obtain conditioning back three-phase voltage signal and nurse one's health the back three-phase current signal, and three-phase current signal transfers to microprocessor after will nursing one's health the back three-phase voltage signal and nursing one's health;

Through signal conditioning circuit three-phase voltage signal and three-phase current signal have been carried out filtering.

105: microprocessor carries out analog to digital conversion and image data to nursing one's health the back three-phase voltage signal with conditioning back three-phase current signal; Data to collecting are carried out analyzing and processing; Obtain the expectation value of fault distance, and the expectation value of fault distance is shown through display module;

Wherein, the data that collect are carried out analyzing and processing, the expectation value of obtaining fault distance is specially:

(1) with zero sequence impedance Z ₀As random quantity, microprocessor obtains zero sequence impedance Z ₀Scope;

Wherein, ground conductivity becomes with environment, weather, has corresponding relation between ground conductivity and the Zero sequence parameter, and the zero sequence impedance of selecting system is as random quantity.

Calculate D by ground conductivity _g:

$D_g=\frac{660}{\sqrt{\mathrm{f\γ}}}---\left(1\right)$

In the formula, f is the frequency (Hz) of conditioning back three-phase current, and γ is ground conductivity (S/m), D _gThe equivalent degree of depth (m) for imaginary lead.

When f=50Hz, the ground conductivity γ of dry earth _Min=10 ^-3S/m (γ _MinBe minimum conductivity), the ground conductivity γ of moist earth _Max=10 ^-2S/m (γ _MaxBe maximum conductivity).

Range computation according to ground conductivity γ obtains D _gScope:

$D_{g\max }=\frac{660}{\sqrt{{\mathrm{f\γ}}_{\min }}}=2950m,$ $D_{g\min }=\frac{660}{\sqrt{{\mathrm{f\γ}}_{\max }}}=933m---\left(2\right)$

In the formula, D _GmaxBe the maximum equivalent degree of depth of imaginary lead, D _GminThe minimum equivalent degree of depth for imaginary lead.During f=50Hz, by D _gCalculate zero sequence impedance Z ₀:

$Z_0=(r_1+3r_g)+j(0.1885\ln \frac{D_g}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)---\left(3\right)$

In the formula, r ₁Be aerial condutor resistance (Ω/km), r _gBe ground resistance (Ω/km), r _g=π ²F * 10 ^-4Ω/km, D _mBe circuit geometric mean distance (m) that r is the radius (m) of aerial condutor, zero sequence impedance Z ₀Unit be Ω/km.

According to D _gRange computation obtain Z ₀Scope:

$Z_{0\max }=(r_1+3r_g)+j(0.1885\ln \frac{D_{g\max }}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

(4)

$Z_{0\min }=(r_1+3r_g)+j(0.1885\ln \frac{D_{g\min }}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

In the formula, Z _0maxBe maximum zero sequence impedance, Z _0minBe minimum zero sequence impedance.

(2) microprocessor is according to zero sequence impedance Z ₀Scope obtain the number percent D of fault distance _FiWith fault distance L _Fi

Wherein, at general regional zero sequence impedance Z ₀Obey evenly distribution, in certain scope, get a series of zero sequence impedance Z ₀, calculate zero sequence impedance Z at random by formula (5) _0i, (i=1,2,3 ... N):

Z _0i＝Z _0min+(Z _0max-Z _0min)α (5)

In the formula, α is equally distributed random number, is produced by computer simulation, and span is between (0,1).

Calculate the number percent D of a series of fault distance by formula (6) _Fi, (i=1,2,3...n):

$D_{\mathrm{fi}}=\frac{R_e\left(U_a\right)I_m\left(I_{\mathrm{af}}\right)-I_m\left(U_a\right)R_e\left(I_{\mathrm{af}}\right)}{I_m\left(I_{\mathrm{af}}\right)R_e[{\mathrm{ZI}}_a+(Z_{0i}-Z)I_{a0}]-R_e\left(I_{\mathrm{af}}\right)I_m[{\mathrm{ZI}}_a+(Z_{0i}-Z)I_{a0}]}---\left(6\right)$

In the formula, U _aBe line voltage distribution, I _aBe line current, I _AfBe line fault electric current, I _A0Be circuit zero-sequence current, Z=Z ₁=Z ₂(Z ₁, Z ₂Be respectively positive sequence, the negative phase-sequence line impedance of circuit), R _e(), R _e[], I _m() and I _m[] represented respectively measuring real part and imaginary part mutually in the bracket.

Calculate a series of fault distance L by formula (7) _Fi, (i=1,2,3...n):

L _fi＝L×D _fi (7)

In the formula, L is a total track length, and unit is km.

(3) microprocessor is to fault distance L _FiAsk expectation value.

Wherein, solution procedure is repeated (n generally gets 10～50) n time, calculating mean value obtains the expectation value of fault distance:

$E\left(L_f\right)=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{L}_{\mathrm{fi}}---\left(8\right)$

In the formula, E (L _f) be the expectation value of fault distance, unit is km.

106: the user confirms faulty line according to the expectation value of fault distance, and faulty line is keeped in repair.

Wherein, this step is specially the scope of in the scope of distance fault equipment expectation value, confirming faulty line, in the scope of faulty line, searches faulty line, and faulty line is keeped in repair.When non-direct ground system generation singlephase earth fault; Under the not too big situation of earth point fault current, allow to continue operation 1-2 hour, but do not allow long-time running; Can be used for getting rid of the fault of circuit during this period of time, through trying to achieve the expectation value E (L of fault distance _f), a bit of scope that can find fault to take place fast and has accurately been confirmed faulty line, faulty line is keeped in repair again, and has improved maintenance efficiency.

Further, for the expanding application scope, microprocessor can also be sent in PC or the internet through the expectation value of serial ports with fault distance.

Verify the feasibility of the embodiment of the invention below with two concrete experiments, see hereinafter for details and describe:

Microprocessor in the embodiment of the invention is that the S3C2410 chip of kernel is that example describes with the ARM920T of Samsung; Voltage sensor and current sensor be the collection busbar voltage and the bus current of timing respectively, adopts 100kHz or above data sampling frequency.Under the situation of power frequency 50Hz, in one-period 0.02s, need to gather 2000 data.

Experiment one

Utilize ATP software and MATLAB software to carry out emulation; Referring to Fig. 3; Be 10.5kv at first with an electric pressure; The electric system of neutral by arc extinction coil grounding is an example, the total length L=10km of circuit, and A earth fault mutually takes place at 3km, 5km and the 7km place of circuit in the small current neutral grounding system of being simulated.Circuit unit length zero sequence impedance Z ₀, 14.6＜| Z ₀|＜17.0,75.8＜arg (Z ₀)＜77.8.Suppose that actual zero sequence impedance is every km Z ₀=0.36+j1.42k Ω; The fault transition resistance is 10 Ω; Calculate zero sequence impedance Z0i at random, utilize formula (6)～(7) to calculate a series of fault distance then, the expectation value of utilizing formula (8) to calculate fault distance at last is respectively 2.9650km, 4.9424km, 6.9204km.Confirm the scope of faulty line according to the expectation value of fault distance, the faulty line that finds faulty line and simulation in advance is very approaching, has proved the accuracy of searching faulty line.

Experiment two

Utilizing ATP software and MATLAB software to carry out emulation, is 10.5kv with an electric pressure at first, and line length is the single-phase earthing system of 10km.A phase nonmetal character earth fault, stake resistance R take place in this single-phase earthing system at circuit 4.945km place _F=50 Ω calculate the expectation value of fault distance.Repeat emulation experiment and obtain 500 data; The trouble spot distribution situation is as shown in table 1; The fault distance that wherein calculates has 90.4% in 4.942km～4.947km scope; These data provide the condition that on a section that lacks on the transmission line, finds the trouble spot, have proved the accuracy of searching faulty line, and have improved maintenance efficiency.

Table 1

In sum; The embodiment of the invention provides a kind of method that is used for measuring distance of transmission line fault; This method is confirmed faulty line through the scope that gets access to faulty line, faulty line is keeped in repair again, and has improved the maintenance efficiency of faulty line; Through verification experimental verification, this method has improved the precision of searching faulty line.

It will be appreciated by those skilled in the art that accompanying drawing is the synoptic diagram of a preferred embodiment, the invention described above embodiment sequence number is not represented the quality of embodiment just to description.

The above is merely preferred embodiment of the present invention, and is in order to restriction the present invention, not all within spirit of the present invention and principle, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. a method that is used for measuring distance of transmission line fault is characterized in that, said method comprising the steps of:

(1) voltage sensor is sampled to the three-phase voltage signal of busbar voltage, obtains three-phase voltage signal;

(2) current sensor is sampled to the three-phase current signal of bus current, obtains three-phase current signal;

(3) said voltage sensor is input to signal conditioning circuit with said three-phase voltage signal, and said current sensor is input to said signal conditioning circuit with said three-phase current signal;

(4) said signal conditioning circuit is nursed one's health said three-phase voltage signal and said three-phase current signal; Obtain conditioning back three-phase voltage signal and conditioning back three-phase current signal, and three-phase current signal after said conditioning back three-phase voltage signal and the said conditioning is transferred to microprocessor;

(5) said microprocessor to said conditioning back three-phase voltage signal and said conditioning after three-phase current signal carry out analog to digital conversion and image data; Said data to collecting are carried out analyzing and processing; Obtain the expectation value of fault distance, and the expectation value of said fault distance is shown through display module;

(6) user confirms faulty line according to the expectation value of said fault distance, and said faulty line is keeped in repair.

2. a kind of method that is used for measuring distance of transmission line fault according to claim 1 is characterized in that, said in the step (5) carries out analyzing and processing to the said data that collect, and the expectation value of obtaining fault distance is specially:

1) with zero sequence impedance Z ₀As random quantity, said microprocessor obtains zero sequence impedance Z ₀Scope;

$Z_0=(r_1+3r_g)+j(0.1885\ln \frac{D_g}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

In the formula, r ₁Be aerial condutor resistance (Ω/km), r _g=π ²F * 10 ^-4Ω/km, D _mBe circuit geometric mean distance (m) that r is the radius (m) of aerial condutor, zero sequence impedance Z ₀Unit be Ω/km;

According to D _gRange computation obtain Z ₀Scope:

$Z_{0\max }=(r_1+3r_g)+j(0.1885\ln \frac{D_{g\max }}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

$Z_{0\min }=(r_1+3r_g)+j(0.1885\ln \frac{D_{g\min }}{\sqrt[3]{{{\mathrm{rD}}_m}^2}}+0.0157)$

In the formula, Z _0maxBe maximum zero sequence impedance, Z _0minBe minimum zero sequence impedance;

Wherein, $D_{g\mathrm{Max}}=\frac{660}{\sqrt{{\mathrm{F\γ}}_{\mathrm{Min}}}}=2950m,$ $D_{g\mathrm{Min}}=\frac{660}{\sqrt{{\mathrm{F\γ}}_{\mathrm{Max}}}}=933m$

In the formula, f is the frequency (Hz) of conditioning back three-phase current, γ _MinBe minimum conductivity; γ _MaxBe maximum conductivity;

2) said microprocessor is according to said zero sequence impedance Z ₀Scope obtain the number percent D of fault distance _FiWith fault distance L _Fi

Z _0i＝Z _0min+(Z _0max-Z _0min)α

In the formula, α is equally distributed random number, is produced by computer simulation, and span is between (0,1);

$D_{\mathrm{fi}}=\frac{R_e\left(U_a\right)I_m\left(I_{\mathrm{af}}\right)-I_m\left(U_a\right)R_e\left(I_{\mathrm{af}}\right)}{I_m\left(I_{\mathrm{af}}\right)R_e[{\mathrm{ZI}}_a+(Z_{0i}-Z)I_{a0}]-R_e\left(I_{\mathrm{af}}\right)I_m[{\mathrm{ZI}}_a+(Z_{0i}-Z)I_{a0}]}$

In the formula, U _aBe line voltage distribution, I _aBe line current, I _AfBe line fault electric current, I _A0Be circuit zero-sequence current, R _e(), R _e[], I _m() and I _m[] represented respectively measuring real part and imaginary part mutually in the bracket;

L _fi＝L×D _fi

In the formula, L is a total track length, and unit is km;

3) said microprocessor is to said fault distance L _FiAsk expectation value;

$E\left(L_f\right)=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{L}_{\mathrm{fi}}$

In the formula, E (L _f) be the expectation value of fault distance, unit is km.

3. a kind of method that is used for measuring distance of transmission line fault according to claim 1 is characterized in that said method also comprises:

Said microprocessor is sent in PC or the internet through the expectation value of serial ports with said fault distance.

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