CN101183133A - Phase amount and zero sequence amount combined realization powerline both-end distance measuring method - Google Patents

Abstract

The present invention relates to the relay protection method in the field of a power system. The present invention discloses a method for realizing two-terminal fault location in the power system through two terminal synchronism sampling current and voltage according to the method of equal voltages at two ends of a fault point and using a phase current and a phase voltage without zero sequence current and zero sequence voltage. The method comprises main steps as follows: a line protection device samples to a line side current sensor secondary current and voltage sensor secondary voltage to obtain a corresponding instantaneous value of the current and the voltage. The Fourier form of a three phase current and a three phase voltage on the side is worked out using a Fourier algorithm. The phasor form of phase current and phase voltage obtained by filtering to compute of protecting synchronism sampling on the other side is received through optical fiber network of communication. The distance from the protection arranging place to the fault point is obtained using the situation that the phase voltages on two sides of the fault point is equal with each other. The method is not affected by the power supply impedance and the transition resistance in the line operation method. Theory and practice prove that the method greatly improves the accuracy of transmission line fault location.

Description

Phasor combines with the zero sequence amount and realizes the two ends of electric transmission line distance-finding method

Technical field

The present invention relates to field of power, relate more specifically to the method for electric power system fault range finding, is phase current and voltage and zero-sequence current and the residual voltage that utilizes the circuit two ends, and the distribution parameter of circuit itself is judged the method for transmission line malfunction position.

Background technology

Transmission line of electricity is the basic equipment of electric system generating, conveying electricity etc., occupies important status in electric system.During transmission line malfunction, if can carry out localization of fault fast and accurately, not only help in time to repair faulty line, the assurance electric system is reliably powered, and all very important to the safety and stability and the economical operation of electric system.

At present, the method for measuring distance of transmission line fault can be divided into single end distance measurement and two kinds of methods of both-end distance measuring.Utilize single-ended measurement not to be subjected to the restriction of line channel condition apart from method, but be subjected to the influence of too many factor and cause dysmetria true, just be difficult to eliminate such as the influence of transition resistance, and circuit model is to adopt lumped parameter model that location algorithm is difficult to reach pinpoint accuracy from principle to the former.

At present, the both-end distance measuring algorithm can be divided into based on the location algorithm of lumped parameter model with based on the location algorithm of distributed parameter model.Algorithm based on lumped parameter model can be divided into the consideration distributed capacitance again and not consider two kinds of distributed capacitance.On principle, it is more accurate than adopting lumped parameter model to adopt distributed parameter model, particularly for the high pressure long transmission line.The problem of bringing is the more complicated of finding the solution of equation, and calculated amount is big, for some iterative algorithm, also exists and finds the solution the problem of hyperbolic function, and result of calculation is very likely dispersed, thereby causes the range finding failure.Adopt in the middle of the algorithm of lumped parameter, consider that distributed capacitance is obviously accurate than not considering distributed capacitance, for short-term, can ignore the influence of distributed capacitance, but, not consider that distributed capacitance can bring bigger error for the middle or long line road.

Summary of the invention

For the extra-high voltage long transmission line, because the influence of line distribution capacitance electric current can not be ignored, therefore, traditional is foundation with the lumped parameter, and the algorithm that utilizes single-ended amount to carry out fault localization at the circuit head end can not satisfy the requirement of existing electric system to localization of fault, therefore, need a kind of new, simple Two-terminal Fault Location element is realized both-end distance measuring algorithm more accurately, to satisfy the demand of electric system under existence conditions.

Technical scheme of the present invention is as follows:

At first utilize existing synchronized algorithm that two ends electric current and voltage are adjusted to synchronously,

Line protective devices obtain the electric current and voltage instantaneous value to the voltage current waveform sampling of mutual inductor;

Obtain the phasor form of three-phase current and voltage by fourier algorithm;

Calculate both sides m by conversion by both sides three-phase current and voltmeter, the zero-sequence current I of n _M0, I _N0, residual voltage U _M0, U _N0The universal calculation equation of zero-sequence component is as follows:

I ₀＝(I _a+I _b+I _c)/3；

U ₀＝(U _a+U _b+U _c)/3；

In the formula: I ₀, U ₀Be gained zero-sequence current and residual voltage, I _a, I _b, I _c, U _a, U _b, U _c, be process Fu Shi filtering gained three-phase current and three-phase voltage;

Utilize phase current and voltage according to system failure situation again, get zero-sequence current during in conjunction with fault and residual voltage is found range;

$X=\frac{1}{{2\mathrm{\&gamma;}}_1}\ln \frac{((I_{\mathrm{n\&phi;}}-I_{n0}){\mathrm{<figure-callout\; id="1"\; label="Z\; c"\; filenames="S2007101783579E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}_c+(U_{\mathrm{n\&phi;}}-U_{n0}))+((I_{\mathrm{n\&phi;}}-I_{m0})Z_{c1}-(U_{\mathrm{m\&phi;}}-U_{m0}))e^{r_{1}l}}{((I_{\mathrm{n\&phi;}}-I_{n0})Z_{c1}-(U_{\mathrm{n\&phi;}}-U_{n0}))+((I_{\mathrm{m\&phi;}}-I_{m0})Z_{c1}+(U_{\mathrm{m\&phi;}}-U_{m0}))e^{-r_{1}l}}---\left(1\right)$

In the formula: subscript increase φ represents separate, φ=a, and b, c, n, m represent the circuit both sides;

Z _C1Be circuit positive sequence wave impedance;

γ ₁Propagation constant for circuit;

I _{N φ}, I _{M φ}, U _{N φ}, U _{M φ}The phase voltage of representing phase current, n side and the m side of n side and m side respectively;

L represents the protection domain Route Length, need be given in advance, and unit is km;

X is the distance that circuit n end is arrived in the trouble spot, and unit is km;

Formula (1) has been owing to removed zero-sequence current and residual voltage, therefore, and for the establishment of drawing a conclusion;

1) for single-phase earthing with wait fault mutually indirectly because the influence of having removed zero-sequence component, therefore, principle for each mutually the fault distance of surveying all be correct fault distance;

2) for phase-to phase fault, principle is separately all set up for relevant with fault; For with irrelevant mutually separate of fault owing to all equate by the both end voltage of two ends protection installation place conversion to this point at every bit, therefore,

Formula does not have to be separated;

3) for three-phase fault because each mutually all has fault relevant, therefore for each mutually fault distance that this principle is surveyed all be accurately the trouble spot to the distance of protecting the installation place.

4) owing to removed zero-sequence component in the principle, therefore, for the range finding accuracy during through arcing ground improves a lot through high resistance earthing fault and trouble spot.

5) as seen from the above analysis, this principle all can be suitable for for any fault;

Description of drawings

Fig. 1 has shown route protection and variable position synoptic diagram.

Specific embodiments

As shown in Figure 1, line protective devices installation site and calculating expression amount have been shown.

Wherein: X is the distance that the n end is arrived in the trouble spot, and unit is km, and arbitrary phase current at circuit n, m two ends and phase voltage and zero-sequence current and residual voltage are respectively I _{N φ}, I _{M φ}, U _{N φ}, U _{M φ}, I _N0, I _M0, U _N0, U _M0, φ represents separate, φ=a, and b, c, l represent the protection domain Route Length, are unit with km.

At first utilize ripe sampling markers to adjust synchronized algorithm with the two ends data sync, such as utilize the sampling label relatively known at present with footwork realize the both sides protective device synchronously;

Obtain the Fu Shi form of this side three-phase current and three-phase voltage by fourier algorithm, and the phasor form that receives offside protection synchronized sampling and the electric current that calculates through filtering, voltage by the optical-fibre communications net;

Utilize strain sequence arithmetic to calculate the residual voltage and the zero-sequence current U at circuit two ends _N0, U _M0, I _N0, I _M0, circuit just (is being born) preface wave impedance Z _C1Just (bearing) preface propagation constant γ 1 can calculate by following formula according to prior given parameter in advance,

${\mathrm{<figure-callout\; id="1"\; label="Z\; c"\; filenames="S2007101783579E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}_c=\sqrt{({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="S2007101783579E00011.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+\mathrm{j\&omega;}{L}_1)/({\mathrm{<figure-callout\; id="1"\; label="g"\; filenames="S2007101783579E00011.png"\; state="\{\{state\}\}">g</figure-callout>}}_1+\mathrm{j\&omega;}{C}_1)},$ ${\mathrm{\&gamma;}}_1=\sqrt{({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="S2007101783579E00011.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+\mathrm{j\&omega;}{L}_1)*({\mathrm{<figure-callout\; id="1"\; label="g"\; filenames="S2007101783579E00011.png"\; state="\{\{state\}\}">g</figure-callout>}}_1+\mathrm{j\&omega;}{C}_1)}$ In the formula: r ₁Be circuit resistance per unit length, L ₁Be circuit unit length induction reactance, g ₁For the electricity of lead unit length is over the ground led (generally smaller, as can to ignore), C ₁Be the circuit capacitance per unit length; Because of the positive sequence and the negative phase-sequence element of circuit are equal, therefore, in negative phase-sequence range finding computing formula, available positive sequence wave impedance Z _C1With positive sequence propagation constant γ ₁

Utilize phasor calculation abort situation formula as follows:

$X=\frac{1}{2{\mathrm{\&gamma;}}_1}\ln \frac{((I_{\mathrm{n\&phi;}}-I_{n0}){\mathrm{<figure-callout\; id="1"\; label="Z\; c"\; filenames="S2007101783579E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}_c+(U_{\mathrm{n\&phi;}}-U_{n0}))+((I_{\mathrm{m\&phi;}}-I_{m0})Z_{c1}-(U_{\mathrm{m\&phi;}}-U_{m0}))e^{r_{1}l}}{((I_{\mathrm{n\&phi;}}-I_{n0})Z_{c1}-(U_{\mathrm{n\&phi;}}-U_{n0}))+((I_{\mathrm{m\&phi;}}-I_{m0})Z_{c1}+(U_{\mathrm{m\&phi;}}-U_{m0}))e^{-r_{1}l}}---\left(1\right)$

In the following formula: subscript increase φ represents separate, φ=a, and b, c, n, m represent the circuit both sides;

Z _C1Be circuit positive sequence wave impedance;

γ ₁Propagation constant for circuit;

I _{N φ}, I _{M φ}, U _{N φ}, U _{M φ}The phase voltage of representing phase current, n side and the m side of n side and m side respectively;

L represents the protection domain Route Length, need be given in advance, and unit is km;

X is the distance that circuit n end is arrived in the trouble spot, and unit is km;

For singlephase earth fault, because the influence of having removed zero-sequence component, therefore, formula is all set up mutually for each, for alternate or alternate earth fault, all sets up for the phase relevant with fault, and for three-phase fault, each is all set up mutually.Owing to removed the influence of zero-sequence current and residual voltage mutually for each in the principle, therefore, improve a lot, therefore applicable to the range finding element of any fault for the range finding accuracy when high resistance earthing fault and earth point are bad.

Compare with present used location algorithm, this algorithm is not subjected to line mutual-inductance, not affected by trouble point transition resistance etc., And be not subjected to the impact of system power supply impedance and load current, and because zero-sequence component is the phasor phase of simple three phases Add, therefore, calculate simply, no matter the method is to symmetric fault, and asymmetric fault can both be suitable for. And And because used data or be known, perhaps be can long-standing amount after the fault, therefore, need only the fault existence, This formula is namely applicable.

Compare with present used both-end distance measuring algorithm and since formula in used be standard natural Exponents and logarithm, therefore, from On the existing Calculating Foundation, existing standard operation. Theory and practice shows that this algorithm improves a lot to range accuracy.

Claims (1)

1. One kind in electric system by two ends electric current and voltage and the method for utilizing Transmission Line Distributed Parameter that fault is found range, this method comprises the steps:

   Utilize synchronized algorithm that two ends electric current and voltage are adjusted to synchronously;

   Line protective devices obtain the electric current and voltage instantaneous value to the voltage current waveform sampling of mutual inductor;

   Obtain the phasor form of three-phase current and three-phase voltage by fourier algorithm, subscript a, b, c represent the phase in the three-phase respectively;

   Calculate both sides m by conversion by both sides three-phase current and voltmeter, the zero-sequence current I of n _M0, I _N0, residual voltage U _M0, U _N0The universal calculation equation of zero-sequence component is as follows:

   I ₀＝(I _a+I _b+I _c)/3；

   U ₀＝(U _a+U _b+U _c)/3；

   In the formula: I ₀, U ₀Be gained zero-sequence current and residual voltage, I _a, I _b, I _c, U _a, U _b, U _c, be process Fu Shi filtering gained three-phase current and three-phase voltage;

   By phase current, phase voltage and the zero-sequence current of two ends homophase, that residual voltage gets fault localization is as follows:

   $X=\frac{1}{2{\mathrm{\&gamma;}}_1}\ln \frac{((I_{\mathrm{n\&phi;}}-I_{n0})Z_{c1}+(U_{\mathrm{n\&phi;}}-U_{n0}))+((I_{\mathrm{m\&phi;}}-I_{m0})Z_{c1}-(U_{\mathrm{m\&phi;}}-U_{m0}))e^{r_{1}l}}{((I_{\mathrm{n\&phi;}}-I_{n0})Z_{c1}-(U_{\mathrm{n\&phi;}}-U_{n0}))+((I_{\mathrm{m\&phi;}}-I_{m0})Z_{c1}+(U_{\mathrm{m\&phi;}}-U_{m0}))e^{-r_{1}l}}$

   Wherein: X is the distance that the n end is arrived in the trouble spot, and unit is km, and arbitrary phase current at circuit n, m two ends and phase voltage and zero-sequence current and residual voltage are respectively I _{N φ}, I _{M φ}, U _{N φ}, U _{M φ}, I _N0, I _M0, U _N0, U _M0, subscript increase φ represents separate, φ=a, and b, c, two ends must be the phasors of homophase; Z _C1Be circuit positive sequence wave impedance, γ ₁Be circuit positive sequence propagation constant, l represents the protection domain Route Length, is unit with km.

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