FR2803042A1 - FAULT LOCATION METHOD AND DEVICE FOR PARALLEL LINES - Google Patents

Abstract

The present invention relates to a method for locating a fault (F) in a section of parallel transmission lines, comprising the operations of measuring the currents and voltages of the two lines at a measurement location at one end (A ) of the section, determine the distance (d) to the fault, between the location of the measurement and the fault, as a solution to an equation comprising the distance from the fault as a variable and the resistance of the fault (RF). The invention is characterized in that the equation is: B1 d2 + B2 d + B3 + B4 RF = 0, where the parameters (B1, B2, B3, B4) depend on the symmetrical components of the currents and voltages measured locally, and in which the equation is solved respectively for the real parts and for the imaginary parts, to eliminate the resistance of the defect. The invention also relates to a device intended to implement the method.

Description

TECHNICAL FIELD The present invention relates to a method for locating a fault in a section of parallel transmission lines, comprising the operations which consist in measuring the intensities and voltages on two lines, at a point or location. measurement located at one end of the section, determine the fault distance between the measurement location and the fault as a solution to a second order equation having the distance to the fault as a variable. BACKGROUND OF THE INVENTION Power transmission lines are essential for continuously distributing electricity to end users, from a power plant, and are thus designed to ensure reliable distribution with the greatest possible continuity. Due to the increasing complexity of the electricity distribution system and the fact that transmission lines are exposed to the majority of short circuits that occur in the entire distribution system and are also the most difficult parts to maintain at inspect, efficient fault locating tools represent a huge advantage from an economic point of view. Current digital technology allows the implementation of sophisticated fault location algorithms. The article "An accurate locator with compensation for apparent reactance in the fault resistance resulting from remote-end infeed", IEEE Transactions on Power Apparatus and Systems, Vol. PAS-104, N 2, February 1 describes a fault location method. The method uses phase currents and voltages recorded at the near end. The main feature is that we consider the influence of incoming elements at the far end of the transmission line using full network model. A microprocessor filters the intensities and voltages of AC signals to extract the fundamental components of the signals. It then calculates the distance to the point of the fault, by compensating for the apparent reactance of the resistance of the fault resulting from the load current and the variations in the angles of impedance in the network. The method described in the above article and described in U S Patent No. 4,559,491 is mainly aimed at methods of locating faults in single lines. Accurate fault location in parallel lines requires compensation for two effects: the effect of incoming elements at the far end in the event of faults, through a fault resistor, and the effect of mutual coupling between lines for the zero sequence. Countermeasures of these effects are implemented, for example, in the asymmetric fault location device proposed in the above article. The method cited uses the local measurements (phase voltages, phase currents at the output of the faulty line, after and before the fault, and a zero sequence current at the output of the healthy line), as well as the impedance parameters for the line for equivalent distribution systems at both ends of the line. As the system impedance at the far end is not measurable with the asymmetric method, the fault location device according to the article uses the representative values of the impedances (for direct sequence (positive sequence)). This is possible, due to the relatively high robustness of this algorithm with respect to the mismatch between the real value and the representative value. However, in extreme cases of large mismatch, this is the additional source of error for the fault locator algorithm. In addition, the source impedances also undergo changes due to a fault. In addition, if there is an additional link between the points, the impedance of this equivalent link should be predicted in the fault location algorithm and, of course, the imprecision of this data affects the location of the fault as well. . BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to provide a method and a device for fault location which does not require knowing the impedances of the sources of the systems behind both the points and the device. impedance of the equivalent link between the points, and does not use the measurements before fault either. The object is obtained by the characterizing parts of claims and 5. The process according to the present invention has advantages over the processes mentioned above. Because of the use of the symmetrical components of the voltages and currents measured locally <B> i </B>, it is not necessary to obtain the source impedances, nor by measurement ri by calculation, to deduce the distance from the fault. The present method requires only the parameters of the impedances of the lines. This makes the method, and the algorithms used, more robust and more reliable with respect to the mismatch between the real value and the representative value, and independent of the inaccuracies of the data used. Furthermore, if an additional link is provided between the points, its impedance does not affect the present method.

Accordingly, the present method does not require any pre-fault measurement to derive the distance from the fault. The benefits and advantages will emerge more precisely from the detailed description of the present invention and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description of the invention, reference will be made to the accompanying drawings, in which Fig. 1 is a schematic arrangement of parallel transmission lines of a fault location device; FIG. 2 shows an arrangement of a network in direct sequence of parallel transmission lines; FIG. 3 shows an arrangement of a network in reverse sequence (negative sequence) of parallel transmission lines; FIG. 4 shows an arrangement of a network in zero sequence sequence of parallel transmission lines; FIG. 5 shows an example of a fault appearing on transmission lines; FIG. 6 shows another example of a fault; FIG. 7 presents an example of the connection of a fault location device according to the invention to an existing line protection device * and FIG. 8 presents an example of a device and system implementing the method. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a schematic arrangement of a section of a three-phase supply line, comprising parallel transmission lines LA, LB placed between two points A and B. An equivalent link EL is also provided between dots. A FLAA fault locator is placed at point A and connected to the transmission lines. The fault location device is provided with means for measuring and processing information concerning the voltages and currents of the phases of the transmission lines. In Figure 1, a fault F is located somewhere on line LA. The voltages of the phases VA, the currents of the phases IAA from the defective line LA and the currents of the phases IAB from the healthy line LB are introduced into the fault location device FAA. Z o is the impedance for the zero sequence coupling between lines LA and LB. FIGS. 2, 3 and 4 respectively show the networks in direct sequence, in reverse sequence and in zero sequence. For the reverse sequence, it is assumed that the impedance of the ZLA transmission line, = Z ,,, 2. According to the present invention, it is proposed to express the direct sequence (V,) and the reverse sequence (VF2) of the voltage at a fault location F, taking into account the path of the defective line section (AF) - the equations (1a) and taking the path of the overall healthy line (LB) with the defective line section (BF) - the equations (1 b)

<I> YFI <SEP> i # Al <SEP> - <SEP> dZ, 41 <SEP> I <SEP> AAI </I>
<tb><I> E <SEP> F2 <SEP><B><U> V <SEP> A2 </U></B><SEP> - <SEP> d </I><SEP> ZL, 11 <SEP><I> I <SEP> AA2 <SEP> (1 <SEP> a) </I>

Le procédé selon l'invention se fonde sur l'utilisation du modèle de boucle de défaut général capable de couvrir différents types de défauts. C e modèle est exprimé en termes de composantes symétriques mesures locales et des données constantes, par la formule suivante

d est inconnue et est la distance du défaut recherchée (p.u.) comptée depuis le point A jusqu'à l'emplacement du défaut F, <U>VA,,</U> VA2, VAO sont les composantes symétriques des tensions mesurées au point local A, IAAi, IAA2, IAAO sont les composantes symétriques des intensités mesurées dans la ligne défectueuse, au point local A, IAB1, IAB2, IAW sont les composantes symétriques des intensités mesurées dans la ligne saine, au point local A, <B>!F1,</B> 1F2 sont les termes des séquences directe et inverse du courant l'emplacement de défaut, déterminés par les équations (2), Z A1, ZLB1 sont les impédances de séquence directe de la ligne défectueuse et de la ligne saine, ZLAO est l'impédance de séquence homopolaire de la ligne défectueuse, <I><U>Z ,O</U></I> est l'impédance pour le couplage en séquence homopolaire entre les lignes, RF est la résistance de défaut inconnue, a1, a2, aO, aF,, aF2, aFO sont les coefficients complexes dépendants type de défaut, consignés dans le Tableau 1 ci-après.

<I> -E <SEP> FI </I><SEP> = <SEP> (E41 <SEP><I> - <SEP> ZLBI <SEP> I <SEP> ABI) <SEP> - <SEP><B> (I- </B><SEP> d) ZLAI <SEP> I <SEP> Bal </I><SEP><B> (1 </B><SEP> b)
<tb><I> v <SEP> F2 <SEP> - <SEP> (v <SEP> A2 <SEP> ZLBI <SEP><B> I </B><SEP> AB2 <SEP>) <SEP> (1 <SEP> d) ZLAl <SEP> L <SEP> A2 </I> Taking into account that <I> i FI LAI + <U> I BAI </U></I> I <I><U>F2</U><B> LA </B>, + I </I> 8A, (1 c) and subtracting the equations <B> (l </B> a), (1 b) , one obtains, for the terms of direct sequence (IFl) and of reverse sequence (1F2) of the current in the defective path

The method according to the invention is based on the use of the general fault loop model capable of covering different types of faults. This model is expressed in terms of symmetrical components local measures and constant data, by the following formula

d is unknown and is the distance from the sought fault (pu) counted from point A to the location of the fault F, <U> VA ,, </U> VA2, VAO are the symmetrical components of the voltages measured at the point local A, IAAi, IAA2, IAAO are the symmetrical components of the currents measured in the defective line, at the local point A, IAB1, IAB2, IAW are the symmetrical components of the currents measured in the healthy line, at the local point A, <B> ! F1, </B> 1F2 are the terms of the forward and reverse sequence of current at the fault location, determined by equations (2), Z A1, ZLB1 are the forward sequence impedances of the faulty line and the line healthy, ZLAO is the zero sequence impedance of the faulty line, <I><U> Z, O </U></I> is the impedance for the zero sequence coupling between the lines, RF is the resistance of unknown fault, a1, a2, aO, aF ,, aF2, aFO are the complex coefficients depending on the type of fault, recorded in Table 1 below near.

Table <SEP> 1 <SEP> - <SEP> Coefficients <SEP> of <SEP> the equation <SEP> (3) <SEP> in <SEP> function <SEP> of the <SEP> type <SEP> of
<tb> default
<tb> Type <SEP> d <SEP> ai <SEP> a2 <SEP> ao <SEP> aF1 <SEP> aFZ <SEP> AFo
<tb> default
<tb> a- <SEP> 1 <SEP> 1 <SEP> 1 <SEP> 0 <SEP><U> 3 </U><SEP> 0
<tb> b- <SEP> a * a <SEP> a <SEP> 1 <SEP> 0 <SEP> 3 / <SEP> a * a <SEP><U> 0 </U>
<tb> c- <SEP> a <SEP> a * a <SEP> 1 <SEP> 0 <SEP> 31a <SEP> 0
<tb> ab <SEP> 1-a * a <SEP> 1-a <SEP> - <SEP><U> 0 </U><SEP> _ <B><U> 0 </U></B><SEP> - <SEP> 33 <SEP> 1, a * <SEP> - <SEP> 0
<tb> bc <SEP> a * aa <SEP> aa * a <SEP><U> 0 </U><SEP> - <SEP> 0 <SEP> a * <SEP> 0
<tb> ca <SEP> 1-a <SEP> 1-a * a <SEP> 0 <SEP> 0 <SEP> 1-a * a <SEP> 0
<tb> ab- <SEP> 1-a * a <SEP> 1-a <SEP> 0 <SEP> 1-a * a <SEP> 1-a * a <SEP> 0
<tb> bc- <SEP> a * aa <SEP> aa * a <SEP> 0 <SEP> a * aa <SEP> aa * a <SEP> 0
<tb> ca- <SEP> 1-a <SEP> 1-a * a <SEP> 0 <SEP> 1-a <SEP> 1-a * a <SEP> 0
<tb> abc
<tb> or <SEP> 1-a * a <SEP> 1-a <SEP> 3 / (1-a) <SEP> 0 <SEP> 0
<tb> abc where <SEP> a <SEP> = <SEP> expQ2p / 3) <SEP> and <SEP> a, <SEP> b <SEP> and <SEP> c <SEP> are <SEP> the <SEP> phases <SEP> and <SEP> g <SEP> is <SEP> the <SEP> earth. The aFo coefficients are set to zero to avoid the zero sequence component at the fault location F because this component is unreliable.

As an example of determining the coefficients of equation (3), we will describe below two types of defects (a-g and a-b-g).

The general fault loop equation (3) and equations (2) give a complex second order equation (4), which can be solved for the distance d sought for a fault d, and further for the unknown resistance RF at the level of this defect

(4)
<tb><I>BIdZ+B</I><B>y,</B><I>d+B</I><B>3</B><I> + BP, = 0 </ I><B> where </B>

II convient d'observer que les quantités et les coefficients utilisés dans B, - B4 sont définis dans l'équation (3) et dans le Tableau 1. L'équation complexe du second ordre (4) que l'on obtient peut être résolue en deux équations, respectivement une pour les parties réelles et une pour les parties imaginaires. Cela permet de calculer les deux inconnues la distance d du défaut et le résistance RF du défaut. On obtient pour les parties réelles et imaginaires

en éliminant la résistance RF inconnue, obtient

<I> B, f <SEP> = a, Im, ZL4, <SEP> + a, IA42 <SEP> Z <SEP> L4, <SEP> + aolA-VZL-V <SEP> + a "I, @ "Zmn, </I>
<tb><I> B3 <SEP> = <SEP> a, <SEP> TA, <SEP> a. <SEP> U ,, <SEP> + <SEP> ao <SEP> U # <SEP>></I>
<tb><I> By = _B3 <SEP> - </I>

It should be observed that the quantities and the coefficients used in B, - B4 are defined in equation (3) and in Table 1. The second order complex equation (4) that we obtain can be solved in two equations, respectively one for the real parts and one for the imaginary parts. This makes it possible to calculate the two unknowns, the distance d from the fault and the RF resistance from the fault. We obtain for the real and imaginary parts

by eliminating the unknown RF resistance, obtains

<I>B; d '+ B6id + B; <SEP> = 0 </I>

où . <I> B <B> B1 </B><SEP> ReB41m </I>
<tb><I> B5 <SEP> - <SEP> Bfaï <SEP> B1 </I><SEP> IMB4 <SEP> Re
<tb><B><I> B6 <SEP> a. </I></B><I><SEP> - <SEP> BtjeBglm </I>
<tb><I> Bd. <SEP> = <SEP> BCcL- </I><SEP> BQ
<tb><I> BT4. <SEP> = <SEP> 83 </I><B> j </B><I> @ </I> 134 <SEP><I> 1m </I>
<tb> B7 <SEP> = <SEP> 81a.- <SEP> B3lmBRf, The desired value of the distance to a fault is obtained by solving the quadratic equation (6)

or .

La résistance de défaut inconnue RF peut être estimée par.

z delt <I≥ B6 - B <B> 7 </B></I>

The unknown fault resistance RF can be estimated by.

<I>'<SEP> B <SEP> R <SEP> B @% B <SEP> `t1 <SEP> n, </I> as an example, we will describe below the recovery of the coefficients for two types of faults that may occur. <U> Fault </U> aa This type of fault is shown schematically in figure 5. The fault loop equation is obtained by taking the defective phase voltage of phase a and the defective phase current of the phase also, but compensated with respect to the zero sequence component of the defective line LA and also with respect to the mutual coupling in zero sequence of the healthy line LB, namely <U> Voltage of < / U> default <U> loop: </U> vFL-vau <I≥ </I> a @ L-Âj + az @, 2 + aoL <I≥ </I> t @j + L, @ z + @ The voltage drop across the defective section of line in the vicinity of local point A is expressed by

ce qui établit que les composantes de séquences ont relation suivante : IFi = IF2 = IFO, finalement, IF = IFa = 3 IF2, d'où aF1 = aFo = +, aF2 = 3. <B><U>Défaut</U></B> a-b-4 Ce type de défaut est présenté de manière schématique la figure Dans ce cas, on obtient l'équation de boucle de défaut en prenant signal de tension comme la différence des tensions des phases défectueuses à partir des phases a et b, et le signal de courant comme la différence des intensités à partir des phases défectueuses, là encore des phases a b <U>Tension de boucle de défaut</U>

chute de tension à travers les deux phases défectueuses tronçon de ligne défectueux (au voisinage du point local A)

Finalement, on obtient =1 -a2; =1 a; =0; Pour la détermination des coefficients aF,, aF2, aFO, il a été observé que

Finally, <SEP> on <SEP> gets
<tb> ai <B≥ </B> 1 <SEP>;
<tb> a2 <SEP> = 1
<tb> = 1;
<tb> For <SEP> determine <SEP> the <SEP> coefficients <SEP> aF1, <SEP> aF2, <SEP> aFO, <SEP> on <SEP> a <SEP> observed
<tb> = <SEP><B> IFb </B><SEP> = <SEP> IF1 <SEP> + <SEP><B> IF2 </B><SEP> + <SEP><B> IFO < / B>
<tb> hence <SEP> aF1 <SEP> = <SEP> aF2 <SEP> = <SEP> aF0 <SEP> = <SEP><B> 1 </B>
<tb> If <SEP> one <SEP> takes <SEP> account <SEP> of <SEP> does <SEP> that, <SEP> in <SEP> the <SEP> phases <SEP> healthy <SEP> : <SEP> = <SEP> IFS <SEP> = <SEP> 0,
<tb> on <SEP> form <SEP> the following <SEP> equations <SEP>

which establishes that the components of sequences have the following relation: IFi = IF2 = IFO, finally, IF = IFa = 3 IF2, hence aF1 = aFo = +, aF2 = 3. <B><U> Default </ U ></B> ab-4 This type of fault is presented schematically in the figure In this case, we obtain the fault loop equation by taking voltage signal as the difference of the voltages of the defective phases from the phases a and b, and the current signal as the difference in currents from faulty phases, again from phases ab <U> Fault loop voltage </U>

voltage drop across the two defective phases defective line section (in the vicinity of local point A)

Finally, we get = 1 -a2; = 1 a; = 0; For the determination of the coefficients aF ,, aF2, aFO, it was observed that

<I> -1-a2Y <SEP> aF2 = 1-a, <SEP> aFp = 0 </I> A fault location device according to the present invention can be connected directly to the section of line as shown in the figure 1, or through a line protection device LS, as seen in figure 7. The measured values of the currents of the two lines, IAA, IAB, and the voltages VA are sent to the device and to the fault location device via voltage and current transformers (not shown). In the event that a fault appears on the LA line, the LS line protection device sends an S signal to the fault location device. On the one hand, this signal triggers the start of the fault distance calculation by the fault location device, and on the other hand, the signal S contains information about the type of fault, defined in Table 1, which has occurred. When necessary, the line protection device can also send a signal which trips a circuit breaker (not shown). If the fault location device is connected directly, it can be provided with its own triggering means.

DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 8 shows an embodiment of a clamping device to determine the distance from a point, at one end of a transmission line, until a fault appears. on the transmission line, according to the method described, comprising certain measuring devices, converters of measured values, processing units for the calculation algorithms of the method, means for indicating the distance to the fault calculated and a printer for printing the calculated fault.

In the presented embodiment, measuring devices 1 to 3 for continuously measuring all phase currents both from faulty line LA and from healthy line LB and phase voltages are placed at point A In the measurement converters at 6, a certain number of these values measured consecutively, which, in the presence of a fault, are sent to a calculation unit 7, are filtered and stored. The calculation unit is equipped with the described calculation algorithms, programmed for the operations necessary for the calculation of the distance to the fault and the resistance of the fault. The computing unit also receives known values, such as line impedances. In relation to the appearance of a fault, information concerning the type of fault can be sent to the calculation unit to choose the right coefficients. When the calculation unit has determined the distance to the fault, it is displayed on the device and / or sent to display means located remotely. A printout of the results can also be made. In addition to signaling the distance to the fault, the device can produce reports in which are recorded measured values of the intensities of the two lines, the voltages, the type of fault or other values associated with a given fault located at a certain point. distance.

The computing unit may include filters to filter the signals, A / D converters to convert and sample the signals, and a microprocessor. The microprocessor comprises a central processing unit CPU performing the following functions: retrieving the measured values, processing the measured values, calculating the distance to the fault, and sending the results of the calculations. The microprocessor further includes a data memory and a program memory.

A computer program serving to implement a method according to the present invention is stored in the program memory.

It will be appreciated that the computer program may also be executed on a general purpose computer, rather than on a specially designed computer.

The software includes elements of computer program code or portions of software code which enable the computer to perform said method using the equations, algorithms, data and calculations described above. Part of the program can be stored in a processor, as above, but also in a RAM chip, ROM, PROM or EPROM or the like. The program may be stored, in part or in whole, on or other medium that can be read by the computer, such as a magnetic disk, CD-ROM or DVD, hard disk, memory storage means magneto-optics, in volatile memory, in flash memory, in the form of firmware, or stored on a data server.

The invention also relates to the method for the implementation by a computer program of the method as described above, characterized in that it comprises the implementation of the following steps receiving values of currents and voltages from the two lines, at a measurement location placed at one end (A) of the section, calculate a distance (d) to the fault, between the measurement location and the fault, as a solution of an equation comprising as variable the distance (d ) to the fault and the fault resistance (RF), as well as parameters depending on the symmetrical components of the currents and voltages measured locally, in which the equation is solved respectively for the real parts and for the imaginary parts, to eliminate the resistance of the fault (RF), and give the distance (d) to the fault.

According to a variant, said method is characterized in that said steps are put in a form which can be read by a computer.

According to one variant, said method implements a computer program. It will be understood that the embodiments described above and shown in the drawings are to be considered as non-limiting examples of the present invention, and that the latter is defined by the appended claims.

Claims (6)

<U> Claims </U> 1. A method of locating a fault (F) in a section of parallel transmission lines, comprising the operations which consist of measuring the currents and voltages of the two lines at a measuring point located at one end (A) of the section, determining the distance (d) to the fault, between the point of measurement and the fault, as a solution to an equation comprising the distance from the fault (d) as a variable and the resistance of the fault (RF), characterized in that the equation is

<I> B, <SEP> d <SEP> `<SEP> + <SEP> B2 <SEP> d <SEP> + <SEP> B <SEP> j <SEP> + <SEP> B + KF <SEP> = <SEP> 0 </I> where the parameters (B1, B2, B3, B4) depend on the symmetrical components of the intensities and voltages measured locally, and in which the equation is solved respectively for the real parts and for the imaginary parts , to eliminate the resistance of the fault. 2. Method according to claim 1, characterized in that the parameters (B1, B2, B3, B4) are expressed by

<I≥ <SEP> a <SEP> r <SEP> <B> I </B> <SEP> .1s11 <SEP> Z <SEP> LV <SEP>% <SEP> a <SEP> 1 <SEP> I </I> <SEP>.-T12 <SEP> <I> Z <SEP> C.-Il <SEP> + <SEP> an <SEP> I <SEP> @ LY @ <SEP> Z <SEP> Lp <SEP> + <SEP> a, <SEP> I </I> <SEP>.-18!) <SEP> <I> Zm0 </I>

, <tb> B3 <SEP> <B><I≥</I></B> <I> a <B>, <SEP> + </B> a, <SEP> <B> P '</ B > </I>, # L <SEP> <B> 2 <SEP> <I>+</I></B> <I> a </I> <SEP> "<SEP> T @ <SEP> <B> IV </B>

B9 <SEP> = <SEP> <I> -B3 <SEP> <B>-</B> </I> <SEP> B> <SEP>>

3. Method according to claim 1, characterized in that eliminates the resistance of the defect from the real and imaginary parts, allowing

get <SEP> quadratic <SEP> equation <SEP>: <SEP> <I> Bsd <SEP> <B> l '</B> <SEP> + <SEP> B6 @ <SEP> B @ <SEP> - <SEP> D </I> and we obtain the desired value of the distance to a fault, as the solution of the quadratic equation

where z delt <I≥ B6 - 4B5 B7 </I>

4. Method according to claim 1, characterized in that the measured values are applied to a general fault loop expressed by

the complex coefficients serving for the recovery of the parameters (B ,, B2, B3, B4), and in which the a; are types of defects. 5. Method according to claim 4, characterized in that the terms of direct sequence (IF,) and reverse sequence (1F2) of the current of the defective section are obtained from the formulas.

where ZLA1 and ZLB1 are the direct sequence impedances of the two lines. 6. Device for locating a fault (F) in a section of parallel transmission lines, comprising calculation members provided for calculating, on the basis of the values of currents and voltages measured in the vicinity of one end of said section and the known impedance of the lines, the distance between the measuring location and the fault, characterized in that the calculating members are provided to determine, on the basis of the information concerning the type of fault in question and the complex quantities measured values, and using a network model, the default distance as the solution of an equation

<I> Bl <SEP> d <SEP> Z <SEP> + <SEP> BËd <SEP> + <SEP> B3 </I> <SEP> + <SEP> <I> B4- <B> R, - </B> </I> <SEP> = <SEP> 0 having as variable the distance (d) to the fault and the fault resistance, 'the parameters (B1, B2, B3, B4) depend on the symmetrical components of the currents and voltages measured locally, and in which the equation is solved respectively for the real parts and for imaginary parts, to eliminate the resistance of the fault. Use of a device according to claim 6 for determining distance to fault in a parallel transmission line. 8. Use of a device according to claim 6 for recording signal currents and voltages associated with a fault, located at a distance (d) from a measurement point (A). 9. A computer program comprising computer code means and / or parts of software codes to enable a computer or a processor to perform the steps of receiving values of currents and voltages from the two lines, in one. measurement location placed at one end (A) of the section, calculate a distance (d) to the fault, between the measurement location and the fault, as a solution of an equation comprising as variable the distance (d) to the fault and the fault resistance (RF), as well as parameters which depend on the symmetrical components currents and voltages measured locally, in which the equation is solved respectively for the real parts and for the imaginary parts, to eliminate fault resistance (RF), and give the distance (d) to the fault. A computer program according to claim 9, contained on or in a medium which can be read by a computer. 1. Method for the implementation by a computer program of the method according to any one of claims 1 to 5, characterized in that it comprises the implementation of the following steps to receive values of currents and voltages from the two lines, at a measurement location placed at one end (A) of the section, calculate a distance (d) to the fault, between the measurement location and the fault, as a solution of an equation comprising as variable the distance (d) to the fault and fault resistance (RF), as well as parameters which depend on the symmetrical components of the currents and voltages measured locally, in which the equation is solved respectively for the real parts and for the imaginary parts, to eliminate fault resistance ( RF), and give the distance (d) to the fault. A method according to claim 11, characterized in that said steps are put in a form which can be read by a computer. 13. The method of claim 1 or 12, characterized in that it implements a computer program.