RU2177417C2 - Traction system fault detector - Google Patents

Abstract

FIELD: electrified transport. SUBSTANCE: invention can be used in power supply system for revealing short-circuits. Proposed fault detector for contact system has current and voltage sensors of first and second substations, feeder current sensor of damaged contact system, setters of signals defining distance to substation or sectioning position, and multifunctional converters. First multifunctional converter is made for forming output signal corresponding to distance from first substation to place of short circuit. Error caused by neglecting of current phase angles is determined. EFFECT: improved accuracy of short-circuit fault location in traction system. 2 cl, 3 dwg

Description

 The invention relates to electrified transport and can be used in traction power supply systems to determine the location of a short circuit.

 A device is known for fixing the short-circuit current of a damaged line [1]. The magnitude of the current is judged on the remoteness of the damage to the line. Other designs of fixing ammeters of a similar purpose are described in [2]. Their disadvantage is low accuracy, due to the fact that the magnitude of the short circuit current depends not only on the distance to the damage, but also on the voltage level on the substation tires and on the presence of an arc or transition resistance at the damage site [3].

A known method of two-sided measurement of currents in a traction network to determine the distance of a short circuit [4]. With this method, at the moment of a short circuit, the current I _{KA of} one substation and the current I _{KV of the} second (adjacent) substation are measured. Then calculate the ratio I _KA / (I _KA + I _KV ) or I _KV / (I _KA + I _KV ), the value of which is judged on the remoteness of the short circuit.

The dependence of this ratio is linear with respect to the distance l _to from the substation to the place of damage. The linear nature is distorted when the short circuit point is located near one of the substations [4], which introduces an error in the measurement of l _k . The largest error occurs when voltage levels at adjacent substations are different. According to [4], with a difference in voltage levels of adjacent substations of 10%, the error reaches 5%. With a distance of 25 km to the sectioning post, the error thus reaches 1.25 km.

 A device that implements this method and adopted as a prototype contains a current sensor at one substation, a current sensor at another substation, an adder, a divider, and a recording unit. A disadvantage of the known method and device based on it is low accuracy.

 The aim of the invention (technical result) is to increase the accuracy of determining the distance to the place of damage during two-sided measurement of currents of adjacent substations.

а второй многофункциональный преобразователь предназначен для формирования на выходе сигнала с, соответствующего поправочному коэффициенту, уменьшающему погрешность, обусловленную неучетом фазовых углов токов I'₁, I_A, I_B.The essence of the invention lies in the fact that in the device containing the current sensor I _{A of the} first substation, the current sensor I _{B of the} second substation, the first adder and the registration unit, the current sensor I ' _{1 of the} feeder of the damaged contact network at the first substation, a scale converter, and the second adder are additionally introduced , dial signal indicative of a distance l ₁ from the first substation to the position of the partition or (in the absence thereof) to the second substation, a multiplier, a first and a second multifunctional converters, the output of the sensor t ka I _A first substation is connected to a first input of the first adder, to the second input of which the current sensor is connected the output I _In the second substation, and to the first input of the second adder, the second input of which through scale converter coupled current sensor output I _'1 feeder damaged catenary at the first substation, the output of the second adder is connected to the first input of the first multifunction converter, the second input of which is connected to the output of the distance setter l ₁ , the third to the output of the multiplier, and the output of is single to the registration unit and the first input of the second multifunction converter, the second input of which is connected to the output of the signal generator characterizing the distance l ₁ , and the output is connected to the first input of the multiplier, the second input of which is connected to the output of the first adder, while the first multifunction converter receiving an output signal l _k characterizing the distance from the first substation to the place of a short circuit by implementing a computational algorithm in the form of mathematical whom expressions

and the second multifunction converter is designed to generate a signal c at the output that corresponds to a correction factor that reduces the error due to the neglect of phase angles of currents I ' ₁ , I _A , I _B.

In addition, the second multifunction converter is configured to generate a coefficient c at the output as the sum of two terms, one of which has the first constant value a, and the second is the product of the signal value at the output of the first multifunction converter by the ratio of the second constant value b to the signal value l ₁ , where a and b for a contact network consisting of one carrier cable and one contact wire are equal to a = 0.994, b = 0.006, respectively.

 The invention and its rationale are illustrated in FIG. 1, FIG. 2 and FIG. 3. In FIG. 1 shows a block diagram of a device. In FIG. 2 shows the power circuit of the traction network of a double-track section and its equivalent circuit. In Fig.3 shows graphs of the errors of the device.

The block diagram shown in FIG. 1 contains the following elements:
1 - current sensor I ' ₁ feeder damaged contact network;
2 - current sensor I _A at the first substation;
3 - current sensor I _B at the second substation;
4 - scale converter;
5 - second adder;
6 - the first adder;
7 - a signal adjuster characterizing the distance l ₁ from the first substation to the sectioning station or (if there is none) to the second substation;
8 - multiplier;
9 - the first multifunction converter;
10 - registration unit;
11 - the second multifunction converter.

 Elements 2, 3, 6, 11 are known, used in the prototype. The remaining elements are new, as are the connections between them.

 The output of the current sensor 1 through a scale converter 4 is connected to the second input of the second adder 5. The output of the current sensor 2 is connected to the first input of the second adder 5 and the first input of the first adder 6, to the second input of which the output of the current sensor 3 is connected. The output of the second adder 5 is connected to the first input of the first multifunction converter 9, to the second input of which the output of the distance adjuster 7 is connected, and the output of the multiplier 8 is connected to the third input. The output of the first multifunction converter 9 is connected to the unit EGISTRATION 10 to first and second multifunctional input transducer 11, the second input of which is connected to the output setpoint distance 7, and an output connected to the second input of the multiplier 8.

The current sensors 1, 2, 3 are made in a known manner, for example, based on measuring current transformers. The current sensor I generates a signal I ' ₁ at the output, the current sensor 2 generates a signal I _A at the output, the current sensor 3 generates an I _B signal at the output.

Scale Converter 4 can be performed, for example, in the form of an analog operational amplifier with a constant gain. At the output of element 4, a signal 2I ' _{1 is formed} .

Adders 5 and 6 do not have features in comparison with the known ones and can be performed, for example, on the basis of operational amplifiers. The signal at the output of adder 5 is 2I ' ₁ -I _A. The signal at the output of adder 6 is I _A + I _B.

The distance adjuster 7 generates a constant signal l ₁ at the output. It can be made in the form of a potentiometer or a source of stable voltage.

The multiplier 8 has no features and is a typical element of analog technology. The output signal of the multiplier 8 is equal to (I _A + I _B ).

где с - поправочный коэффициент.The multifunction converter 9 is configured to receive an output signal l _k , characterizing the distance from the first substation to the place of a short circuit, by implementing a computational algorithm of mathematical expression:

where c is the correction factor.

 The multifunction converter 9 performs the operations of summation, subtraction, multiplication and division, that is, typical operations of the analogue technique, therefore it has no execution features.

The multifunction converter 11 is designed to generate an output signal corresponding to a correction factor c, which reduces the error due to the neglect of phase angles of currents I ' ₁ , I _A , I _B. The dependence of the output signal c from l _to and l ₁ may be different. In the application, as a dependent item, a dependence of the form is proposed
c = a + bl _c / l ₁ , (2)
where a, b are constants.

 Recommended for a contact network consisting of a support cable and a contact wire, a = 0.994, b = 0.006.

 This dependence can be implemented using known elements of analog technology, such as operational amplifiers.

 The multifunction converter 11 is included in the feedback circuit of the multiplier 8.

When a short circuit occurs in the contact network, the current sensors 1, 2 and 3 record the current values I ' ₁ , I _A , I _B , on the basis of which the functional converter 9 determines the distance l _to the fault location, fixed in the registration unit 10.

 The rationale for the principle of operation and accuracy is illustrated in FIG. 2 and FIG. 3.

In FIG. 2a shows a typical equivalent circuit of the traction network, fully consistent with the known [5]. In this diagram:
U _{A, xx} , U _{B, xx} open-circuit voltage of substations A and B;
Z _pA , Z _pB - resistance of substations A and B;
Z _pA , Z _pB - resistance of the rail circuit from point K, respectively, to substations A and B;
R _d - arc resistance at the site of damage;
Z ' _{sun, 1} , Z'' _{sun, 1} - resistance, taking into account the mutual inductive effect of contact networks of adjacent paths on the plot l ₁ ;
Z ' ₁ , Z'' ₁ - resistance of the contact network of the damaged path, respectively, on the section l _to and l ₁ - l _to ;
Z _1q - resistance of the contact network intact (adjacent) paths on the plot l ₁ ;
Z ₂ - the resistance of the contact network of two paths on the plot l ₂ ;
I ' ₁ , I'' ₁ - currents in the contact network of the damaged path, respectively, on the section l _to and l ₁ - l _to ;
I _1q - current undamaged path in the area l ₁ .

В соответствии с [5] известно, что

где Z_к1 - погонное сопротивление 1 км контактной сети;
Z_вс - погонное сопротивление, учитывающее взаимное индуктивное влияние контактных сетей на длине 1 км.Based on the 1st and 2nd Kirchhoff laws for the equivalent circuit shown in FIG. 2, we have

In accordance with [5], it is known that

where Z _k1 - linear resistance 1 km of the contact network;
Z _sun - linear resistance, taking into account the mutual inductive effect of contact networks over a length of 1 km.

Расчеты показывают, что в выражении (6) вместо комплексных величин

можно использовать их абсолютные значения I'₁, I_A, I_B. В этом случае вместо (6) получаем:

Ошибка (погрешность), которая возникает при определении расстояния l_к до места повреждения, равна

На фиг. 3 приведены графики зависимости погрешности Δ l от отношения l_к/l₁. Кривые 1, 2 и 3 соответствуют расстоянию l до поста ПС 20, 25 и 30 км и сопротивлению R_д дуги 0 и 5 Ом. Погрешность определения удаленности повреждения Δ l при этом не превышает 240 м, т. е. в 5 раз меньше, чем у прототипа.Substituting expressions (5) in (4) and using (3), we obtain:

Calculations show that in expression (6) instead of complex quantities

their absolute values I ' ₁ , I _A , I _B can be used. In this case, instead of (6) we get:

The error (error) that occurs when determining the distance l _to the place of damage is

In FIG. 3 shows graphs of the dependence of the error Δ l on the ratio l _to / l ₁ . Curves 1, 2 and 3 correspond to the distance l to the position of the SS 20, 25 and 30 km, and the arc resistance R _d 0 and 5 ohms. The error in determining the distance of damage Δ l in this case does not exceed 240 m, i.e., 5 times less than that of the prototype.

 To further reduce the error Δ l, the invention proposes to determine the distance to the place of damage not by formula (7), but by formula (1).

The correction factor c, formed by the element 11 of the structural diagram (Fig. 1), included in the feedback circuit, is determined by the mathematical dependence (2). Graphs 4, 5, 6 of the error Δl = l '' _k - l ' _k are shown in FIG. 3 for a = 0.994 and b = 0.006.

 Curves 4, 5, and 6 correspond to the same extreme conditions as curves 1, 2, and 3. The maximum error in this case does not exceed 60 m, which is 20 times less than that of the prototype.

 The voltage level at adjacent substations does not affect the accuracy of the principle of action.

 The above rationale confirms the feasibility of the invention and the achievement of the technical result, which consists in increasing accuracy.

Sources of information
1. AS USSR 230081. Device for fixing current or voltage values / B.E. Kazan, V.V. Kuznetsov (USSR). Publ. BI N 35, 1969.

 2. Borukhman A.A., Kudryavtsev A.A., Kuznetsov A.P. Devices for determining the location of damage on overhead power lines. Ed. 2nd, rev. and add. - M .: Energy, 1980.

 3. Shalyt G.M. Determination of places of damage in electrical networks. - M .: Energoizdat, 1982.

 4. Bochev A.S., Kuznetsov V.V., Tupchenko M.Yu. Methods for automatically determining the location of a short circuit with a 2x25 kV power system. In: Relay protection and automation of railway power supply devices. Interuniversity. Sat scientific tr Proceedings of the RIIZHT, vol. 144. -Rostov n / A, 1978.P. 71-75.

 5. Figurnov EP Resistance of electric traction network of single-phase alternating current. Electricity, 1997, N 5. S. 23-29.

Claims (2)

1. A locator for damage to the traction network, comprising a current sensor I _{A of the} first substation, a current sensor I _{B of the} second substation, a first adder and a registration unit, characterized in that a current sensor I ′ _{1 of the} feeder of the damaged contact network at the first substation is additionally introduced therein, a scale converter, a second adder setpoint distance l ₁ from the first substation to the position of the partition or (in the absence thereof) to the second substation, a multiplier, a first and a second multifunctional converters, the output current I _A sensor ne howl substation connected to the first input of the first adder, to the second input of which the current sensor is connected the output I _B of the second substation, and to the first input of the second adder, the second input of which through scale converter coupled current sensor output I _'1 feeder damaged catenary the first substation , the output of the second adder is connected to the first input of the first multifunction converter, the second input of which is connected to the output of the distance adjuster l ₁ , the third to the output of the multiplier, and the output is connected to the registration unit and the first input of the second multifunction converter, the second input of which is connected to the output of the distance adjuster l ₁ , and the output is connected to the first input of the multiplier, the second input of which is connected to the output of the first adder, while the first multifunction converter is configured to receive the signal l _k , corresponding to the distance from the first substation to the short circuit, by implementing a computational algorithm in the form of a mathematical expression

and the second multifunction converter is designed to generate a signal c at the output that corresponds to a correction factor that reduces the error due to the neglect of phase angles of currents I ' ₁ , I _A , I _B. 2. The device according to claim 1, in which the second multifunction converter is configured to form coefficient c as a sum of two members, one of which has a first constant value a, and the second is a product of the signal value at the output of the first multifunction converter by the ratio of the second constant value b to the signal value l ₁ , where a and b, for the contact network, consisting of one carrier cable and one contact wire, are 0.994 and 0.006, respectively.

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