SU1250995A1 - Method and apparatus for determining location of one-phase ground leakage in electricity supply network - Google Patents

Description

The description provides a mathematical expression for determining the distance to the damage site. The device implementing the method contains current and voltage sensors 1 and 2, current filters 3 and 4, and a single harmonic component, current and voltage filters 5 and .6 Another harmonic component and an inverter. The invention relates to electrical engineering, in particular, to methods and devices for determining the distance to the place of damage in electrical power networks by parameters. emergency mode.

The purpose of the invention is to increase accuracy by eliminating the influence of the transient resistance at the point of closure and conduction of the conductors of the line phase and reducing the time to determine the location of the damage as a result of applying current and load filters and automating the results.

The earth fault current in aerial networks of 6-10 kV contains, in addition to the main frequency current, a number of odd harmonic components determined by non-linearity of magnetic transformer systems. By filtering two harmonic components from the current of the damaged phase and from the voltage of the damaged phase, one can determine the distance to the closure distance from the inductance of the damaged section.

A mathematical expression for determining the distance to the closure point is derived from the conditions

H.

I, / (uJn, L ,, - l) 2+ (R,. I + R)

Uj 1, / (., 1) 2 +

a „e-G + R“)

and, and, - the components of the voltage

from the flow of the harmonically 35 components of the current of the first and second frequencies, respectively, from the measuring point to the point of damage; 40

unit 7. The goal is achieved by eliminating the effect of transient resistance at the point of closure and conduction of the conductors of the line phase. In addition, the time to determine the location of damage is reduced by using current and voltage filters and automating computations. 2 s, p. f-ly, 1 ill.

p5

R

uJ ,, n

the components of the current flowing through the damaged phase are the first and second frequencies, respectively;

specific inductance of the wires of the line phase; specific resistance of the conductors of the phase line;

angular frequency of the main harmonic of the network; the numbers of the corresponding harmonics of the first and second frequencies, and

P

 P.

1 2 9

K „- transition resistance

in place of closure. By transforming (1), a distance determination method is obtained:

T

1 uJL ,,

(and / 1,) -. (

cJ P2 - P (2)

The drawing shows a device for implementing the method.

The device contains sensors 1 and 2 of current and voltage, filters 3 and 4 of current and voltage of one harmonic component, filters 5 and 6 of current and voltage of another harmonic component and computational, unit 7. The output of current sensor 1 is connected to the inputs of two filters 3 and 5 harmonic components of the current. The output of voltage sensor 2 is connected to the inputs of two filters 4 and 6 of the harmonic voltage components. . The outputs of the harmonic components of the current and voltage connections3125

yen with the inputs of the computing unit 7..

Open-core induction coils or current transformers can be used as current sensors, and capacitive dividers, antennas, and voltage transformers can be used as voltage sensors.

The device works as follows.

When earth current sensors 1 and 2 are closed and the voltage of the damaged phase at any point in the network, the corresponding filters 3-6 of both harmonic components simultaneously send signals of two harmonic components to the computing unit 7 (n and n) current and voltage. With a predetermined specific inductance of the line, this is enough to calculate the distance t to the closure point using formula (2).

The selection of harmonic components is determined by the specific conditions of the networks. In most cases, it is advisable to use the 5th and 11th or 7th and 13th harmonics.

The proposed method and device is most appropriately applied in electrical networks with a voltage of 6-10 kV with any type of support, overhead lines that are not passed in areas with permafrost soils.

Claims (2)

1. A method for determining the location of a single-phase earth fault in an electrical network, consisting in that - select the harmonic of the network and measure the corresponding component of the current flowing through the damaged wire, which also differs from - in order to increase accuracy and reduce time Editor L. Pchelinska Compiled by Yu.Kareev Tehred V. Kadar Proofreader E. Sirohman Order 4406/42 Circulation 728. Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 . Production and printing company, Uzhgorod, st. Project, 4 The determinations, the component of the voltage drop of the frequency, are measured, the harmonics of the network is determined, and the corresponding components of the current and voltage are measured, and the distance to the closing point is determined from the calculation formula: -i1 / 2 where T is the distance to the closure point;  - specific inductance of the wires of the lineJ - - the angular frequency of the main harmonic of the network; p and p - numbers corresponding harmonics; I and I are the higher harmonic components of the current corresponding to the numbered numbers, and, and, and., Are the components of the voltage drop. 2. A device for determining the location of a single-phase earth fault in an electrical network containing current and voltage sensors, the output of each of which is connected to the input of the corresponding first current filter and voltage of one harmonic component, characterized in that, in order to increase the accuracy and reduce the time to determine the location of a single-phase closure, the second current and voltage filters of another harmonic component and the computing unit are introduced into the device, and the inputs of the second current filters and voltages of another ha The harmonic component is connected respectively to the outputs of the current and voltage sensors, and the outputs of all current and voltage filters of one and the other harmonic components are connected to the corresponding inputs of the computing unit.