CN105044551A - Fault positioning method for overhead line-high voltage cable mixing line - Google Patents

Abstract

The present invention provides a fault positioning method for an overhead line-high voltage cable mixing line, comprising the steps of: (1) respectively measuring three-phase voltage and current phasors of M and N end points at two sides of the line, respectively calculating negative sequence voltages, negative sequence currents, positive sequence voltages and positive sequence currents of the two sides through a symmetrical component method; (2) judging a fault type according to the negative sequence voltages; (3) if the fault type is asymmetric fault, respectively calculating a negative sequence voltage amplitude of each point along the line through the three-phase voltage and current phasors of two-terminal electrical quantities M and N sides, and determining that the points with the equal negative sequence voltage amplitude are fault points; (4) if the fault type is three-phase symmetrical fault, performing fault positioning through a method for comparing positive sequence voltage amplitude variations, and determining that the points with the equal positive sequence voltage amplitude variation are fault points. The fault positioning method of the present invention aims at parameter characteristics of the overhead line-high voltage cable mixing line, does not require synchronous two-terminal electrical quantities, does not need to perform fault section judgment in advance, does not have a pseudo root identification problem, and can adopt various quick search algorithms in the process of fault position search.

Description

A kind of pole line-high-tension cable mixed line fault localization method

Technical field

The present invention relates to a kind of method of field of relay protection in power, specifically relate to a kind of pole line-high-tension cable mixed line fault localization method.

Background technology

Along with the needs of China urban construction and development and environment, pole line-high-tension cable joint line is more and more extensive with its distinctive advantage application in power transmission and distribution project.When extra high voltage network breaks down, precise positioning fault excise fault as quickly as possible, reduces the loss that fault is brought to power equipment and system, and improve reliability and the security of Operation of Electric Systems, tool is of great significance.

For the research of UHV (ultra-high voltage) series-parallel connection line fault location, according to the difference of range measurement principle, traveling wave method and fault analytical method two class can be divided into.

Traveling wave method realizes the method for range finding according to traveling wave theory after line fault.Consider the feature that the different section velocity of wave of series-parallel connection circuit is different, the Algorithms of Travelling Wave Based Fault Location of application at present mainly contains the velocity of wave normalization method etc. of single-ended method, both-end method and different section, has speed fast, substantially not by advantages such as transition resistance affect.But when there is Multi sectional in joint line and multiple spot compensates, fault traveling wave is easily subject to the repeatedly catadioptric impact of the capable ripple of cable-aerial line joint, there is wave head and not easily catches, the shortcomings such as ranging success rate is lower.

Fault analytical method lists range equation according to the electric current and voltage of system relevant parameters and point distance measurement, carries out analytical calculation, obtain a kind of method of the distance between trouble spot to point distance measurement to it.The series-parallel connection line fault of current application is analyzed location algorithm and is mainly contained following several: (1) is based on the trouble spot searching algorithm etc. of fault point voltage amplitude, its algorithm principle is simple, but there is calculated amount large and pseudo-root identification problem when application circuit distribution parameter calculates.(2) range function based on fault point voltage current equation is set up, abort situation is solved, this method is for generic function more complicated joint line, and computational accuracy affects comparatively large by the accuracy of electric parameters collection, there is the problem that range measurement robustness is not high.

Summary of the invention

For overcoming above-mentioned the deficiencies in the prior art, the invention provides a kind of pole line-high-tension cable mixed line fault localization method.

Realizing the solution that above-mentioned purpose adopts is:

A kind of pole line-high-tension cable mixed line fault localization method, the method comprises following concrete steps:

Measurement obtains circuit both sides M, N end points three-phase voltage, electric current phasor, uses symmetrical component method to obtain negative sequence voltage, negative-sequence current, positive sequence voltage, the forward-order current of both sides respectively;

According to negative sequence voltage, failure judgement type is asymmetric fault or three-phase symmetrical fault;

For asymmetric fault, calculated each point negative sequence voltage amplitude along the line respectively then compared by the three-phase voltage of Two-Terminal Electrical Quantities M side and N side, electric current phasor, realize localization of fault;

For three-phase symmetrical fault, the method for positive sequence voltage variable quantity amplitude com parison is adopted to carry out localization of fault.

Measurement obtains circuit both sides M, N end points three-phase voltage, electric current phasor, uses that symmetrical component method obtains the negative sequence voltage of both sides respectively, negative-sequence current, positive sequence voltage, forward-order current comprise:

Line protective devices measure described circuit both sides M, N end points three-phase voltage, electric current phasor and

According to voltage phasor, the electric current phasor measured, symmetrical component method is used to obtain negative sequence voltage, negative-sequence current, positive sequence voltage, the forward-order current of both sides respectively: wherein the subscript 1 of each parameter represents positive order parameter, and subscript 2 represents negative phase-sequence parameter.

Whether be zero according to negative sequence voltage, failure judgement type is that asymmetric fault or three-phase symmetrical fault comprise:

then fault type is three-phase symmetrical fault;

$\begin{array}{c}{\stackrel{\·}{U}}_{m2}\≠0\\ {\stackrel{\·}{U}}_{n2}\≠0\end{array},$ Then fault type is asymmetric fault.

For asymmetric fault, calculated each point negative sequence voltage amplitude along the line respectively then compared by the three-phase voltage of Two-Terminal Electrical Quantities M side and N side, electric current phasor, realize localization of fault and comprise:

With M end points for measurement point, by the negative sequence voltage of fault phase negative-sequence current the negative phase-sequence calculating M point moves ahead ripple row ripple anti-with negative phase-sequence amplitude and phase place;

The ripple that moves ahead is:

${\stackrel{\·}{F}}_{m2}={\stackrel{\·}{U}}_{m2}+Z_{C2}{\stackrel{\·}{I}}_{m2}$

Anti-row ripple is:

${\stackrel{\·}{B}}_{m2}={\stackrel{\·}{U}}_{m2}+Z_{C2}{\stackrel{\·}{I}}_{m2}$

Wherein, for parameter even overhead transmission line negative phase-sequence wave impedance; R ₂for the even overhead transmission line negative sequence resistance of parameter; L ₂for parameter even overhead transmission line negative phase-sequence inductance; G ₂for parameter even overhead transmission line negative phase-sequence conductance; C ₂for parameter even overhead transmission line negative phase-sequence electric capacity; ω=2 π f, f are ac frequency; I is imaginary part;

By setting step delta x, calculate the decay of negative phase-sequence row wave amplitude and the phase delay A of any point x in faulty line with fast search algorithm ₂(x);

$A_2\left(x\right)=e^{-{\mathrm{\γ}}_{2}x}=e^{-{\mathrm{\β}}_{2}x}\∠\left({-\mathrm{\α}}_{2}x\right)$

Wherein, ${\mathrm{\γ}}_2=\sqrt{(R_2+{\mathrm{i\ωL}}_2)(G_2+{\mathrm{i\ωC}}_2)}={\mathrm{\β}}_2+{\mathrm{i\α}}_2$ For negative phase-sequence attenuation constant; β ₂for the real part of negative phase-sequence attenuation constant; α ₂for the imaginary part of negative phase-sequence attenuation constant; A ₂x the phase delay of () is directly proportional to calculation level distance x, and amplitude attenuation part wherein and trouble spot distance are exponential relationship, being difficult to direct calculating, generally realizing by tabling look-up, can take larger storage space when Searching point is a lot of in actual device;

For reducing operand and saving storage space, amplitude attenuation part is adopted Taylor series expansion:

$\left|A_2\left(x\right)\right|=e^{-{\mathrm{\β}}_{2}x}=1-{\mathrm{\β}}_{2}x+0.5{\mathrm{\β}}_2{x}^2...$

Wherein, | A ₂(x) | be the amplitude of negative phase-sequence row wave amplitude decay;

Wherein β value is very little, is not that when growing especially, above formula adopts linear equivalence can reach very high precision at circuit;

$\left|A_2\left(x\right)\right|=e^{-{\mathrm{\β}}_{2}x}\≈1-{\mathrm{\β}}_{2}x$

Owing to not knowing the position of trouble spot when calculating, therefore the result of calculation before abort situation is real negative sequence voltage along the line in joint line, result of calculation after abort situation is false negative sequence voltage along the line, is decayed and phase delay, calculate negative sequence voltage along the line by negative phase-sequence row wave amplitude

${\stackrel{\·}{U}}_{\mathrm{xM}2}=\frac{1}{2}({\stackrel{\·}{F}}_{m2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{m2}/A_2\left(x\right))$

By negative sequence voltage along the line calculate the amplitude of negative sequence voltage along the line

$\left|{\stackrel{\·}{U}}_{\mathrm{xM}2}\right|=\left|\frac{1}{2}({\stackrel{\·}{F}}_{m2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{m2}/A_2\left(x\right))\right|$

When calculation level arrives cable area, because cable data is different from pole line parameter, therefore can not continue to adopt pole line head end voltage to calculate.The voltage at the pole line now calculated-cable connection point place is top voltage and adopts cable data to proceed the calculating of cable sections each point negative sequence voltage along the line amplitude;

With N end points for measurement point, in like manner negative sequence voltage along the line can be obtained amplitude

$\left|{\stackrel{\·}{U}}_{\mathrm{xN}2}\right|=\left|\frac{1}{2}({\stackrel{\·}{F}}_{n2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{n2}/A_2\left(x\right))\right|,$ negative phase-sequence for N point moves ahead ripple, for the anti-row ripple of N point negative phase-sequence;

With N end points for measurement point detailed measurements, computation process are as follows:

By the negative sequence voltage of fault phase negative-sequence current the negative phase-sequence calculating N point moves ahead ripple row ripple anti-with negative phase-sequence amplitude and phase place;

The ripple that moves ahead is:

${\stackrel{\·}{F}}_{n2}={\stackrel{\·}{U}}_{n2}+Z_{C2}{\stackrel{\·}{I}}_{n2}$

Anti-row ripple is:

${\stackrel{\·}{B}}_{n2}={\stackrel{\·}{U}}_{n2}+Z_{C2}{\stackrel{\·}{I}}_{n2}$

Wherein, $Z_{C2}=\sqrt{(R_2+i{\mathrm{\ωL}}_2)/(G_2+{\mathrm{i\ωC}}_2)}$ For parameter even overhead transmission line negative phase-sequence wave impedance; R ₂for the even overhead transmission line negative sequence resistance of parameter; L ₂for parameter even overhead transmission line negative phase-sequence inductance; G ₂for parameter even overhead transmission line negative phase-sequence conductance; C ₂for parameter even overhead transmission line negative phase-sequence electric capacity; ω=2 π f, f are ac frequency; I is imaginary part;

Owing to not knowing the position of trouble spot when calculating, therefore the result of calculation before abort situation is real negative sequence voltage along the line in joint line, result of calculation after abort situation is false negative sequence voltage along the line, is decayed and phase delay, calculate negative sequence voltage along the line by negative phase-sequence row wave amplitude

${\stackrel{\·}{U}}_{\mathrm{xN}2}=\frac{1}{2}({\stackrel{\·}{F}}_{n2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{n2}/A_2\left(x\right))$

By negative sequence voltage along the line calculate the amplitude of negative sequence voltage along the line

$\left|{\stackrel{\·}{U}}_{\mathrm{xN}2}\right|=\left|\frac{1}{2}({\stackrel{\·}{F}}_{n2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{n2}/A_2\left(x\right))\right|$

After there is the unbalanced fault of the alternate or two phase ground of single-phase earthing, two-phase in joint line, circuit can produce negative sequence voltage.Because fault frontal line negative sequence voltage is 0, therefore after fault, negative sequence voltage amplitude variable quantity is current negative sequence voltage amplitude;

Relatively amplitude if equal, then x is fault distance, if unequal, change x by setting step delta x, continue to calculate negative sequence voltage along the line, calculate to the equal termination of amplitude, now x is fault distance.

For three-phase symmetrical fault, adopt the method for positive sequence voltage variable quantity amplitude com parison to carry out localization of fault and comprise:

With M end points for measurement point, by the positive sequence voltage of fault phase forward-order current the positive sequence calculating M point moves ahead ripple row ripple anti-with positive sequence amplitude and phase place;

The ripple that moves ahead is:

${\stackrel{\·}{F}}_{m1}={\stackrel{\·}{U}}_{m1}+Z_{C1}{\stackrel{\·}{I}}_{m1}$

Anti-row ripple is:

${\stackrel{\·}{B}}_{m1}={\stackrel{\·}{U}}_{m1}+Z_{C2}{\stackrel{\·}{I}}_{m1}$

Wherein, $Z_{C1}=\sqrt{(R_1+i{\mathrm{\ωL}}_1)/(G_1+{\mathrm{i\ωC}}_1)}$ For parameter even overhead transmission line positive sequence wave impedance; R ₁for the even overhead transmission line positive sequence resistance of parameter; L ₁for parameter even overhead transmission line positive sequence inductance; G ₁for parameter even overhead transmission line positive sequence conductance; C ₁for parameter even overhead transmission line positive sequence electric capacity; ω=2 π f, f are ac frequency; I is imaginary part;

By setting step delta x, calculate the decay of positive sequence row wave amplitude and the phase delay A of any point x in faulty line with fast search algorithm ₁(x);

$A_1\left(x\right)=e^{-{\mathrm{\γ}}_{1}x}=e^{-{\mathrm{\β}}_{1}x}\∠\left({-\mathrm{\α}}_{1}x\right)$

Wherein, ${\mathrm{\γ}}_1=\sqrt{(R_1+{\mathrm{i\ωL}}_1)(G_1+{\mathrm{i\ωC}}_1)}={\mathrm{\β}}_1+{\mathrm{i\α}}_1$ For positive sequence attenuation constant; β ₁for the real part of positive sequence attenuation constant; α ₁for the imaginary part of positive sequence attenuation constant; A ₁x the phase delay of () is directly proportional to calculation level distance x, and amplitude attenuation part wherein and trouble spot distance are exponential relationship, being difficult to direct calculating, generally realizing by tabling look-up, can take larger storage space when Searching point is a lot of in actual device;

For reducing operand and saving storage space, amplitude attenuation part is adopted Taylor series expansion:

$\left|A_1\left(x\right)\right|=e^{-{\mathrm{\β}}_{1}x}=1-{\mathrm{\β}}_{1}x+0.5{\mathrm{\β}}_1{x}^2...$

Wherein, | A ₁(x) | be the amplitude of positive sequence row wave amplitude decay;

Wherein β value is very little, is not that when growing especially, above formula adopts linear equivalence at circuit;

$\left|A_1\left(x\right)\right|=e^{-{\mathrm{\β}}_{1}x}\≈1-{\mathrm{\β}}_{1}x$

Decayed and phase delay by positive sequence row wave amplitude, calculate positive sequence voltage along the line

${\stackrel{\·}{U}}_{\mathrm{xM}1}=\frac{1}{2}({\stackrel{\·}{F}}_{m1}{A}_1\left(x\right)+{\stackrel{\·}{B}}_{m1}/A_1\left(x\right))$

Positive sequence voltage variable quantity before adopting measurement point voltage phasor after fault to deduct fault, the method for voltage phasor obtains, the multiple of phasor time delay difference complete cycle ripple after fault and before fault;

$\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xM}1}={\stackrel{\·}{U}}_{\mathrm{xM}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xM}1}(t-\mathrm{RT})$

Wherein, t is for measuring the moment; T is the time of a cycle; R is the multiple of difference cycle;

By positive sequence voltage variable quantity calculate the amplitude of positive sequence voltage variable quantity along the line

$\left|\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xM}1}\right|=|{\stackrel{\·}{U}}_{\mathrm{xM}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xM}1}(t-\mathrm{RT})|$

When calculation level arrives cable area, because cable data is different from pole line parameter, therefore can not continue to adopt pole line head end voltage to calculate.The voltage at the pole line now calculated-cable connection point place is top voltage and adopts cable data to proceed the calculating of cable sections each point positive sequence voltage along the line amplitude variable quantity;

With N end points for measurement point, positive sequence voltage variable quantity amplitude along the line in like manner can be obtained

$\left|\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xN}1}\right|=|{\stackrel{\·}{U}}_{\mathrm{xN}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xN}1}(t-\mathrm{RT})|,$ for the positive sequence voltage along the line being measurement point with N end points;

With N end points for measurement point detailed measurements, computation process are as follows:

By the positive sequence voltage of fault phase forward-order current the positive sequence calculating N point moves ahead ripple row ripple anti-with positive sequence amplitude and phase place;

The ripple that moves ahead is:

${\stackrel{\·}{F}}_{n1}={\stackrel{\·}{U}}_{n1}+Z_{C1}{\stackrel{\·}{I}}_{n1}$

Anti-row ripple is:

${\stackrel{\·}{B}}_{n1}={\stackrel{\·}{U}}_{n1}+Z_{C1}{\stackrel{\·}{I}}_{n1}$

Wherein, $Z_{C1}=\sqrt{(R_1+i{\mathrm{\ωL}}_1)/(G_1+{\mathrm{i\ωC}}_1)}$ For parameter even overhead transmission line positive sequence wave impedance; R ₁for the even overhead transmission line positive sequence resistance of parameter; L ₁for parameter even overhead transmission line positive sequence inductance; G ₁for parameter even overhead transmission line positive sequence conductance; C ₁for parameter even overhead transmission line positive sequence electric capacity; ω=2 π f, f are ac frequency; I is imaginary part;

Decayed and phase delay by positive sequence row wave amplitude, calculate positive sequence voltage along the line

${\stackrel{\·}{U}}_{\mathrm{xN}1}=\frac{1}{2}({\stackrel{\·}{F}}_{n1}{A}_1\left(x\right)+{\stackrel{\·}{B}}_{n1}/A_1\left(x\right))$

Positive sequence voltage variable quantity before adopting measurement point voltage phasor after fault to deduct fault, the method for voltage phasor obtains, the multiple of phasor time delay difference complete cycle ripple after fault and before fault;

$\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xN}1}={\stackrel{\·}{U}}_{\mathrm{xN}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xN}1}(t-\mathrm{RT})$

Wherein, t is for measuring the moment; T is the time of a cycle; R is the multiple of difference cycle;

By positive sequence voltage variable quantity calculate the amplitude of positive sequence voltage variable quantity along the line

$\left|\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xN}1}\right|=|{\stackrel{\·}{U}}_{\mathrm{xN}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xN}1}(t-\mathrm{RT})|$

Relatively positive sequence voltage variable quantity amplitude if equal, then x is fault distance, if unequal, change x by setting step delta x, continue to calculate positive sequence voltage variable quantity along the line, calculate to the equal termination of variable quantity amplitude, now x is fault distance.

Compared with prior art, the present invention has following beneficial effect:

The present invention is directed to the parameter characteristic of pole line-cable series-parallel connection circuit, frequency domain parameter is adopted to calculate, propose the novel mixed line fault location algorithm based on voltage sequence amount change amount comparing analysis along the line, based on the Two-Terminal Electrical Quantities of joint line, do not require that Two-Terminal Electrical Quantities is synchronous, do not need first to carry out fault section judgement, there is not pseudo-root identification problem, various fast search algorithm can be adopted in abort situation search procedure, do not affect by transition resistance, do not need to table look-up in voltage along the line calculates, computing velocity is fast.

Accompanying drawing explanation

Fig. 1 is typical two section joint line schematic diagram in the present invention;

Fig. 2 is transmission line of electricity negative sequence network schematic diagram in the present invention;

Fig. 3 is electric transmission line positive sequence network diagram in the present invention;

Fig. 4 is electric transmission line positive sequence voltage variety network diagram in the present invention;

Fig. 5 is mixed line fault location algorithm process flow diagram in the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.

The invention provides the pole line-high-tension cable mixed line fault localization method based on voltage sequence amount change amount comparing analysis along the line.For asymmetric fault, calculate each point negative sequence voltage amplitude along the line respectively by Two-Terminal Electrical Quantities and then compare, namely the point that negative sequence voltage amplitude is equal is trouble spot; For three-phase symmetrical fault, adopt the method for positive sequence voltage variable quantity amplitude com parison to carry out localization of fault, namely the point that positive sequence voltage amplitude variable quantity is equal is trouble spot.

Fig. 1 is typical two section joint line schematic diagram of the present invention, and joint line is made up of two parts, and MJ section is pole line, and length is l _m, JN section is high voltage power cable, and length is l _n, J is blend tie point.Line protective devices survey sheet 1 circuit both sides M, N end points three-phase voltage, electric current phasor and f is line failure point, may in MJ section, may in JN section, also may at J point.

According to voltage phasor, the electric current phasor measured, symmetrical component method is used to obtain negative sequence voltage, negative-sequence current, positive sequence voltage, the forward-order current of both sides respectively:

According to negative sequence voltage then fault type is asymmetric fault; $\begin{array}{c}{\stackrel{\·}{U}}_{m2}\≠0\\ {\stackrel{\·}{U}}_{n2}\≠0\end{array},$ Then fault type is three-phase symmetrical fault.

For asymmetric fault, calculated each point negative sequence voltage amplitude along the line respectively then compared by the three-phase voltage of Two-Terminal Electrical Quantities M side and N side, electric current phasor, realize localization of fault.

Fig. 2 transmission line of electricity negative sequence network schematic diagram, with M end points for measurement point, by the negative sequence voltage of fault phase negative-sequence current the negative phase-sequence calculating M point moves ahead ripple row ripple anti-with negative phase-sequence amplitude and phase place:

The ripple that moves ahead is:

${\stackrel{\·}{F}}_{m2}={\stackrel{\·}{U}}_{m2}+Z_{C2}{\stackrel{\·}{I}}_{m2}$

Anti-row ripple is:

${\stackrel{\·}{B}}_{m2}={\stackrel{\·}{U}}_{m2}+Z_{C2}{\stackrel{\·}{I}}_{m2}$

Wherein, $Z_{C1}=\sqrt{(R_2+i{\mathrm{\ωL}}_2)/(G_2+{\mathrm{i\ωC}}_2)}$ For parameter even overhead transmission line negative phase-sequence wave impedance; R ₂for the even overhead transmission line negative sequence resistance of parameter; L ₂for parameter even overhead transmission line negative phase-sequence inductance; G ₂for parameter even overhead transmission line negative phase-sequence conductance; C ₂for parameter even overhead transmission line negative phase-sequence electric capacity.

By setting step delta x, calculate the decay of negative phase-sequence row wave amplitude and the phase delay A of any point x in faulty line with point by point search algorithm ₂(x):

$A_2\left(x\right)=e^{-{\mathrm{\γ}}_{2}x}=e^{-{\mathrm{\β}}_{2}x}\∠\left({-\mathrm{\α}}_{2}x\right)$

Wherein, ${\mathrm{\γ}}_2=\sqrt{(R_2+{\mathrm{i\ωL}}_2)(G_2+{\mathrm{i\ωC}}_2)}={\mathrm{\β}}_2+{\mathrm{i\α}}_2$ For negative phase-sequence attenuation constant; β ₂for the real part of negative phase-sequence attenuation constant; α ₂for the imaginary part of negative phase-sequence attenuation constant; A ₂x the phase delay of () is directly proportional to calculation level distance x, and amplitude attenuation part wherein and trouble spot distance are exponential relationship, being difficult to direct calculating, generally realizing by tabling look-up, can take larger storage space when Searching point is a lot of in actual device.

For reducing operand and saving storage space, amplitude attenuation part is adopted Taylor series expansion:

$\left|A_2\left(x\right)\right|=e^{-{\mathrm{\β}}_{2}x}=1-{\mathrm{\β}}_{2}x+0.5{\mathrm{\β}}_2{x}^2...$

Wherein, | A ₂(x) | be the amplitude of negative phase-sequence row wave amplitude decay;

Wherein β value is very little, is not that when growing especially, above formula adopts linear equivalence at circuit;

$\left|A_2\left(x\right)\right|=e^{-{\mathrm{\β}}_{2}x}\≈1-{\mathrm{\β}}_{2}x$

Owing to not knowing the position of trouble spot when calculating, the result of calculation therefore before abort situation is real negative sequence voltage along the line in joint line, the result of calculation after abort situation is false negative sequence voltage along the line.Decayed and phase delay by negative phase-sequence row wave amplitude, calculate negative sequence voltage along the line

${\stackrel{\·}{U}}_{\mathrm{xM}2}=\frac{1}{2}({\stackrel{\·}{F}}_{m2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{m2}/A_2\left(x\right))$

By negative sequence voltage along the line calculate the amplitude of negative sequence voltage along the line

$\left|{\stackrel{\·}{U}}_{\mathrm{xM}2}\right|=\left|\frac{1}{2}({\stackrel{\·}{F}}_{m2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{m2}/A_2\left(x\right))\right|$

When calculation level arrives cable area, because cable data is different from pole line parameter, therefore can not continue to adopt pole line head end voltage to calculate.The voltage at the pole line now calculated-cable connection point J place is top voltage and adopts cable data to proceed the calculating of cable sections each point negative sequence voltage along the line amplitude.

With N end points for measurement point, in like manner negative sequence voltage along the line can be obtained amplitude

After there is the unbalanced fault of the alternate or two phase ground of single-phase earthing, two-phase in joint line, circuit can produce negative sequence voltage.Because fault frontal line negative sequence voltage is 0, therefore after fault, negative sequence voltage variable quantity is current negative sequence voltage.

Relatively amplitude if equal, then x is fault distance, if unequal, change x by setting step delta x, continue to calculate negative sequence voltage along the line, calculate to the equal termination of amplitude, now x is fault distance.

For three-phase symmetrical fault, the method for positive sequence voltage variable quantity amplitude com parison is adopted to carry out localization of fault.Fig. 3 electric transmission line positive sequence network diagram, with M end points for measurement point, by the positive sequence voltage of fault phase forward-order current the positive sequence calculating M point moves ahead ripple row ripple anti-with positive sequence amplitude and phase place:

The ripple that moves ahead is:

${\stackrel{\·}{F}}_{m1}={\stackrel{\·}{U}}_{m1}+Z_{C1}{\stackrel{\·}{I}}_{m1}$

Anti-row ripple is:

${\stackrel{\·}{B}}_{m1}={\stackrel{\·}{U}}_{m1}+Z_{C1}{\stackrel{\·}{I}}_{m1}$

Wherein, $Z_{C1}=\sqrt{(R_1+i{\mathrm{\ωL}}_1)/(G_1+{\mathrm{i\ωC}}_1)}$ For parameter even overhead transmission line positive sequence wave impedance; R ₁for the even overhead transmission line positive sequence resistance of parameter; L ₁for parameter even overhead transmission line positive sequence inductance; G ₁for parameter even overhead transmission line positive sequence conductance; C ₁for parameter even overhead transmission line positive sequence electric capacity.

By setting step delta x, calculate the decay of positive sequence row wave amplitude and the phase delay A of any point x in faulty line with point by point search algorithm ₁(x):

$A_1\left(x\right)=e^{-{\mathrm{\γ}}_{1}x}=e^{-{\mathrm{\β}}_{1}x}\∠\left({-\mathrm{\α}}_{1}x\right)$

Wherein, ${\mathrm{\γ}}_1=\sqrt{(R_1+{\mathrm{i\ωL}}_1)(G_1+{\mathrm{i\ωC}}_1)}={\mathrm{\β}}_1+{\mathrm{i\α}}_1$ For positive sequence attenuation constant; β ₁for the real part of positive sequence attenuation constant; α ₁for the imaginary part of positive sequence attenuation constant; A ₁x the phase delay of () is directly proportional to calculation level distance x, and amplitude attenuation part wherein and trouble spot distance are exponential relationship, being difficult to direct calculating, generally realizing by tabling look-up, can take larger storage space when Searching point is a lot of in actual device.

For reducing operand and saving storage space, amplitude attenuation part is adopted Taylor series expansion:

$\left|A_1\left(x\right)\right|=e^{-{\mathrm{\β}}_{1}x}=1-{\mathrm{\β}}_{1}x+0.5{\mathrm{\β}}_1{x}^2...$

Wherein, | A ₁(x) | be the amplitude of positive sequence row wave amplitude decay;

Wherein β value is very little, is not that when growing especially, above formula adopts linear equivalence at circuit.

$\left|A_1\left(x\right)\right|=e^{-{\mathrm{\β}}_{1}x}\≈1-{\mathrm{\β}}_{1}x$

Owing to not knowing the position of trouble spot when calculating, the result of calculation therefore before abort situation is real positive sequence voltage along the line in joint line, the result of calculation after abort situation is false positive sequence voltage along the line.Decayed and phase delay by positive sequence row wave amplitude, calculate positive sequence voltage along the line

${\stackrel{\·}{U}}_{\mathrm{xM}1}=\frac{1}{2}({\stackrel{\·}{F}}_{m1}{A}_1\left(x\right)+{\stackrel{\·}{B}}_{m1}/A_1\left(x\right))$

When calculation level arrives cable area, because cable data is different from pole line parameter, therefore can not continue to adopt pole line head end voltage to calculate.The voltage at the pole line now calculated-cable connection point J place is top voltage and adopts cable data to proceed the calculating of cable sections each point positive sequence voltage along the line amplitude.

Fig. 4 is electric transmission line positive sequence voltage variety network diagram, positive sequence voltage variable quantity before adopting measurement point voltage phasor after fault to deduct fault, the method for voltage phasor obtains, the multiple of phasor time delay difference complete cycle ripple after fault and before fault:

$\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xM}1}={\stackrel{\·}{U}}_{\mathrm{xM}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xM}1}(t-\mathrm{NT})$

Wherein, t is for measuring the moment; T is the time of a cycle; N is the multiple of difference cycle;

By positive sequence voltage variable quantity calculate the amplitude of positive sequence voltage variable quantity along the line

With N end points for measurement point, positive sequence voltage variable quantity along the line in like manner can be obtained

Relatively positive sequence voltage variable quantity amplitude if equal, then x is fault distance, if unequal, change x by setting step delta x, continue to calculate positive sequence voltage variable quantity along the line, calculate to the equal termination of variable quantity amplitude, now x is fault distance.

Finally should be noted that: above embodiment is only for illustration of the technical scheme of the application but not the restriction to its protection domain; although with reference to above-described embodiment to present application has been detailed description; those of ordinary skill in the field are to be understood that: those skilled in the art still can carry out all changes, amendment or equivalent replacement to the embodiment of application after reading the application; but these change, revise or be equal to replacement, all applying within the claims awaited the reply.

Claims (5)

1. pole line-high-tension cable mixed line fault localization method, it is characterized in that, described method comprises:

(1) three-phase voltage, the electric current phasor of difference measuring circuit both sides M, N end points; Symmetrical component method is used to calculate negative sequence voltage, negative-sequence current, positive sequence voltage, the forward-order current of both sides respectively;

(2) according to described negative sequence voltage, failure judgement type;

(3) if asymmetric fault, calculated each point negative sequence voltage amplitude along the line respectively then compared by the three-phase voltage of Two-Terminal Electrical Quantities M side and N side, electric current phasor, namely the point that negative sequence voltage amplitude is equal is trouble spot;

(4) if three-phase symmetrical fault, adopt the method for positive sequence voltage variable quantity amplitude com parison to carry out localization of fault, namely the point that positive sequence voltage amplitude variable quantity is equal is trouble spot.

2. Fault Locating Method according to claim 1, is characterized in that, in described step (1):

The three-phase voltage of described circuit both sides M, N end points measured by line protective devices and electric current phasor

Described calculating comprises the negative sequence voltage of circuit both sides negative-sequence current positive sequence voltage forward-order current wherein the subscript 1 of each parameter represents positive order parameter, and subscript 2 represents negative phase-sequence parameter.

3. Fault Locating Method according to claim 2, it is characterized in that, in described step (2), described judgement comprises:

If described negative sequence voltage is zero then described fault type is three-phase symmetrical fault;

If described negative sequence voltage is non-vanishing then described fault type is asymmetric fault.

4. Fault Locating Method according to claim 2, it is characterized in that, in described step (3), described asymmetric fault, calculates each point negative sequence voltage amplitude along the line respectively by Two-Terminal Electrical Quantities and then compares, comprising:

With described M end points for measurement point, by the negative sequence voltage of fault phase negative-sequence current the negative phase-sequence calculating M point moves ahead ripple row ripple anti-with negative phase-sequence amplitude and phase place;

The described ripple that moves ahead is:

${\stackrel{\·}{F}}_{m2}={\stackrel{\·}{U}}_{m2}+Z_{C2}{\stackrel{\·}{I}}_{m2}$

Described anti-row ripple is:

${\stackrel{\·}{B}}_{m2}={\stackrel{\·}{U}}_{m2}-Z_{C2}{\stackrel{\·}{I}}_{m2}$

Wherein, $Z_{C2}=\sqrt{(R_2+\mathrm{i\ω}{L}_2)/(G_2+\mathrm{i\ω}{C}_2)}$ For parameter even overhead transmission line negative phase-sequence wave impedance; R ₂for the even overhead transmission line negative sequence resistance of parameter; L ₂for parameter even overhead transmission line negative phase-sequence inductance; G ₂for parameter even overhead transmission line negative phase-sequence conductance; C ₂for parameter even overhead transmission line negative phase-sequence electric capacity; ω=2 π f, f are ac frequency; I is imaginary part;

By setting step delta x, calculate the decay of negative phase-sequence row wave amplitude and the phase delay A of any point x in faulty line with fast search algorithm ₂(x);

$A_2\left(x\right)=e^{-{\mathrm{\γ}}_{2}x}=e^{-{\mathrm{\β}}_{2}x}\∠(-{\mathrm{\α}}_{2}x)$

Wherein, ${\mathrm{\γ}}_2=\sqrt{(R_2+\mathrm{i\ω}{L}_2)(G_2+\mathrm{i\ω}{C}_2)}={\mathrm{\β}}_2+i{\mathrm{\α}}_2$ For negative phase-sequence attenuation constant; β ₂for the real part of negative phase-sequence attenuation constant; α ₂for the imaginary part of negative phase-sequence attenuation constant; A ₂x the phase delay of () is directly proportional to calculation level distance x, and amplitude attenuation part wherein and trouble spot distance are exponential relationship;

Amplitude attenuation part is adopted Taylor series expansion:

$\left|A_2\left(x\right)\right|=e^{-{\mathrm{\β}}_{2}x}=1-{\mathrm{\β}}_{2}x+0.5{\mathrm{\β}}_2{x}^2...$

Wherein, | A ₂(x) | be the amplitude of negative phase-sequence row wave amplitude decay;

Wherein β value is very little, is not that when growing especially, above formula adopts linear equivalence at circuit;

$\left|A_2\left(x\right)\right|=e^{-{\mathrm{\β}}_{2}x}\≈1-{\mathrm{\β}}_{2}x$

Decayed and phase delay by negative phase-sequence row wave amplitude, calculate negative sequence voltage along the line

${\stackrel{\·}{U}}_{\mathrm{xM}2}=\frac{1}{2}({\stackrel{\·}{F}}_{m2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{m2}/A_2\left(x\right))$

By negative sequence voltage along the line calculate the amplitude of negative sequence voltage along the line

$\left|{\stackrel{\·}{U}}_{\mathrm{xM}2}\right|=\left|\frac{1}{2}({\stackrel{\·}{F}}_{m2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{m2}/A_2\left(x\right))\right|$

With described N end points for measurement point, in like manner negative sequence voltage along the line can be obtained amplitude

$\left|{\stackrel{\·}{U}}_{\mathrm{xN}2}\right|=\left|\frac{1}{2}({\stackrel{\·}{F}}_{n2}{A}_2\left(x\right)+{\stackrel{\·}{B}}_{n2}/A_2\left(x\right))\right|,$ negative phase-sequence for N point moves ahead ripple, for the anti-row ripple of N point negative phase-sequence;

Relatively amplitude if equal, then x is fault distance, if unequal, change x by setting step delta x, continue to calculate negative sequence voltage along the line, calculate to the equal termination of amplitude, now x is fault distance.

5. Fault Locating Method according to claim 2, is characterized in that, in described step (4), described three-phase symmetrical fault, adopts the method for positive sequence voltage variable quantity amplitude com parison to carry out localization of fault, comprising:

With described M end points for measurement point, by the positive sequence voltage of fault phase forward-order current the positive sequence calculating M point moves ahead ripple row ripple anti-with positive sequence amplitude and phase place;

The described ripple that moves ahead is:

${\stackrel{\·}{F}}_{m1}={\stackrel{\·}{U}}_{m1}+Z_{C1}{\stackrel{\·}{I}}_{m1}$

Described anti-row ripple is:

${\stackrel{\·}{B}}_{m1}={\stackrel{\·}{U}}_{m1}-Z_{C1}{\stackrel{\·}{I}}_{m1}$

Wherein, $Z_{C1}=\sqrt{(R_1+\mathrm{i\ω}{L}_1)/(G_1+\mathrm{i\ω}{C}_1)}$ For parameter even overhead transmission line positive sequence wave impedance; R ₁for the even overhead transmission line positive sequence resistance of parameter; L ₁for parameter even overhead transmission line positive sequence inductance; G ₁for parameter even overhead transmission line positive sequence conductance; C ₁for parameter even overhead transmission line positive sequence electric capacity; ω=2 π f, f are ac frequency; I is imaginary part;

By setting step delta x, calculate the decay of positive sequence row wave amplitude and the phase delay A of any point x in faulty line with fast search algorithm ₁(x);

$A_1\left(x\right)=e^{-{\mathrm{\γ}}_{1}x}=e^{-{\mathrm{\β}}_{1}x}\∠(-{\mathrm{\α}}_{1}x)$

Wherein, ${\mathrm{\γ}}_1=\sqrt{(R_1+\mathrm{i\ω}{L}_1)(G_1+\mathrm{i\ω}{C}_1)}={\mathrm{\β}}_1+i{\mathrm{\α}}_1$ For positive sequence attenuation constant; β ₁for the real part of positive sequence attenuation constant; α ₁for the imaginary part of positive sequence attenuation constant; A ₁x the phase delay of () is directly proportional to calculation level distance x, and amplitude attenuation part wherein and trouble spot distance are exponential relationship;

Amplitude attenuation part is adopted Taylor series expansion:

$\left|A_1\left(x\right)\right|=e^{-{\mathrm{\β}}_{1}x}=1-{\mathrm{\β}}_{1}x+0.5{\mathrm{\β}}_1{x}^2...$

Wherein β value is very little, is not that when growing especially, above formula adopts linear equivalence at circuit;

$\left|A_1\left(x\right)\right|=e^{-{\mathrm{\β}}_{1}x\≈}1-{\mathrm{\β}}_{1}x$

Wherein, | A1 (x) | be the amplitude of positive sequence row wave amplitude decay;

Decayed and phase delay by positive sequence row wave amplitude, calculate positive sequence voltage along the line

${\stackrel{\·}{U}}_{\mathrm{xM}1}=\frac{1}{2}({\stackrel{\·}{F}}_{m1}{A}_1\left(x\right)+{\stackrel{\·}{B}}_{m1}/A_1\left(x\right))$

Positive sequence voltage variable quantity before adopting measurement point voltage phasor after fault to deduct fault, the method for voltage phasor obtains, the multiple of phasor time delay difference complete cycle ripple after fault and before fault;

$\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xM}1}={\stackrel{\·}{U}}_{\mathrm{xM}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xM}1}(t-\mathrm{RT})$

Wherein, t is for measuring the moment; T is the time of a cycle; R is the multiple of difference cycle;

By positive sequence voltage variable quantity calculate the amplitude of positive sequence voltage variable quantity along the line

$\left|\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xM}1}\right|={|\stackrel{\·}{U}}_{\mathrm{xM}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xM}1}(t-\mathrm{RT})|$

With described N end points for measurement point, positive sequence voltage variable quantity along the line in like manner can be obtained

$\left|\mathrm{\Δ}{\stackrel{\·}{U}}_{\mathrm{xN}1}\right|={|\stackrel{\·}{U}}_{\mathrm{xN}1}\left(t\right)-{\stackrel{\·}{U}}_{\mathrm{xN}1}(t-\mathrm{RT})|,$ for the positive sequence voltage along the line being measurement point with N end points;

Relatively positive sequence voltage variable quantity amplitude if equal, then x is fault distance, if unequal, change x by setting step delta x, continue to calculate positive sequence voltage variable quantity along the line, calculate to the equal termination of variable quantity amplitude, now x is fault distance.