SU1019375A1 - Meter of distance to short-circuit locations - Google Patents

Abstract

MEASURING THE DISTANCE TO THE SHORT CIRCUITS, containing the current and voltage measurement units, the outputs of which are connected to the corresponding damaged phase selection units, the control unit, the memory elements and the indication element, which are The aim is neither accuracy nor accuracy. Measuring the distance of 00 short-circuit places, the separation section for the reactive component of the current, two current difference separation units, the division unit are introduced, and the outputs of the damaged phase selectors are connected to EVE blocks. and the release of the reactive component of the current, the output of which is connected to the first input of the first current difference separation unit, the output of which is connected to the first, input of the depreciation block, the output of which is connected to the output terminal and the first phase, is connected to the first input of the memory element This voltage, the second input of which is connected to the first output of the corrugation unit, the second output of which is connected to the second inputs of the unit in selecting the difference of currents, the output of the second block for selecting the damaged phase is connected MAHB control inputs and isolating vto0o- goblrka current difference, whose output is connected to a second input of the dividing -product, a third input coupled to an output of memory element voltage.

Description

110

The invention relates to a burdock technique and an emergency emergency automation of transmission lines.

A device is known for measuring the distance to a short circuit by the impedance of a short circuit PetPi containing current and voltage transducers, dividing units, current and voltage memory elements, a multiplier-division unit and a pulse counter l.

The drawback of the device is low ACCURACY of measurement due to the neglect of transient resistance at the site of damage, as well as the inconvenience of recalculating the readings for lines with wires of different cross sections.

Closest to the invention is a device measuring the distance to a short circuit by the inductive resistance of a short circuit loop containing current and voltage measuring organs, two damaged phase selection units, whose inputs are connected to the current and voltage measuring outputs, bpok separation of the reactive voltage component, the division unit, the control unit and the display element.

A disadvantage of the known device is the low measurement accuracy of the inductive impedance of the short circuit loop and, consequently, the distance to the fault, as well as the possibility of false readings, since the reactive component of the voltage is determined not relative to the short circuit current, but relative to the total short circuit Therefore, the device allows a sufficient degree; Accuracy is rebuilt from the active resistances of the "1 line and the transition resistance in

short circuit location and introduces significant errors especially when

high load currents, with short circuits with an arc, as well as in rural electrical networks, in which power lines have a significant specific active resistance.

The circuit of the invention is to increase the reliability and accuracy of measuring the distance to short circuits by reducing the measurement error of the inductive resistance of the short circuit loop.

The goal is achieved by

 that the measuring circuit contains current and voltage measuring blocks, the outputs of which are connected to the corresponding blocks of the selection of damaged phases, the control unit, the memory elements, and the element

3752

display unit, a reactive component D5 allocation unit, two current difference separation units, a multiplication division unit, the outputs of the selection units

5 damaged phases are connected to the inputs of the reactive component isolation unit, the output of which is connected to the first input of the first current difference separation unit, the output of which is connected to the first input of the multiplication division unit, the output of which is connected to the display element, the output of the first selection unit damaged (} The device is connected to the first input of the memory element.

5, the second input of which is connected to the first output of the control unit, the second output of which is connected to the second inputs of the allocation units: the difference of the currents, the output of the second block of the selected unit

The 2Q phase is connected to the inputs of the control unit and the second difference difference unit. currents, the output of which is connected to the second input of the division-multiplication unit, the third input of which is connected to the output of the voltage storage element.

FIG. 1 shows a block diagram of a meter; in fig. 2 is a block diagram of a current difference extraction unit; in fig. 3 is a block diagram of a dividing-multiply unit.

The device contains blocks 1 and 2 for measuring voltage and current, blocks 3 and 4 for selecting damaged phases, control block 5, voltage memory element 6, block 7 for extracting the reactive component of the current, blocks 8 and 9 for separating the difference

35 currents, unit 10-multiplication and elevieHT 11 indications.

The current difference selection unit may be executed according to the block diagram of FIG. 2, 40, and it includes elements 12vi 13 of the current memory.

The division block-multiplication can be performed according to the block diagram of FIG. 3, while in eix) the composition includes a multiplying-decimal element 14 and a dividing element 15.

The device works as follows.

In pre-crash mode with exits

 The blocks i VI 2 are voltage removed, proportional to the current values of the voltage U and the current 3, respectively, which are passed to the outputs: blocks 3 and 4, the voltage from the output of block 7 is removed,

55 is proportional to the reactive component of the current Dp, equal to the output of the current 33 to the sine of the phase shift between this current and the voltage U. All the memory elements work in the special mode.

During a short circuit, the blocks 3 and 4 are connected to the damaged phases and on their slots there appear voltages proportional to the voltage respectively and it and the current 3x in the short circuit mode. At the same time, the control unit 5 is activated and instantly switches the elements 12 into blocks 8 and 9 into memory mode, the outputs of the element 12 are fixed with a voltage {1NE, proportional to the current (in block 8) and the reactive component of the current (in block 9) in the pre-crash mode. From this point on, the memory elements 13 in the allocation points of the difference of currents begin to track the difference between the voltages supplied respectively from blocks 7 and 4 and the voltages stored on the elements 12.

. After a time delay O, 1-O, 2 s, necessary for the detuning of an electric transient, the control unit 5 switches the memory memory element 6 into the memory mode, a. also elements 13 of blocks 8 and 9. At the input of element 6, the voltage is proportional to the voltage UK in the short circuit mode, the output of the block 8 is voltage, proportional to the difference A Etz short circuit current and the pre-emergency mode, at the output of the battery 9 is voltage is proportional to the difference between the reactive components of these currents. From this point on, unit 1O of division of multiplication enters, KOTOR11Y multiplies the incoming voltages U ((. And & ER) and double division by voltage (or division by the square aanpsi of marriage) iLc, coming from block 8,

In accordance with the flowchart of FIG. 3. This operation is carried out in 2 stages:

first, a multiplication-division operation is performed by element 14 as a result of which a voltage proportional to the value, is fixed at the output of the latter. UK.OP

LEK

and then item 15 divides this value into. the value, after which the result from the output of block 10 is fed to the ill element of the display, the reading of which is proportional to the inductive resistance of the short-circuit petPe, and, consequently, to the distance to the place of damage.

The transmission coefficient of the device as a whole can easily be adjusted by changing the transmission ratios of blocks 7-1O and element b, which achieves, directly calculating the distance in units.

As shown by the calculations, the proposed device provides a significant increase in the accuracy of determining the distance to short-circuit sites and makes it possible to detach from short-circuit tens and hundreds ohms from active resistances in the loop, which is not achievable in the known device.

I

; The device can be used; Dp determining the places of short circuits | Ny for a group of lines of any configuration of buses departing from one section and, moreover, can be used to determine the distance to the places of short circuits in the networks with insulated neutral during short-term switching of the circuit On the ground in the double circuit to earth, the circuit on the buses of the substation of one of the healthy phases, as in this case the active resistance of the short circuit loop can be 1 very large.

 L

Claims (1)

SHORT-CIRCUIT DISTANCE METER, containing current and voltage measuring units, the outputs of which are connected to the corresponding fault phase selection units, a control unit, 'memory elements and an indication element, characterized in that, with a chain for increasing the reliability and accuracy of measuring short distances short circuits, a block for isolating the reactive component of the current, two blocks for isolating the current difference, a division-multiplication block, the outputs of the blocks for selecting the damaged phases are connected to the methods of the block reactive component of the current, the output of which is connected to the first input of the first block of the current difference difference, the output of which is connected to the first, the input of the division-multiplication unit, the output of which is connected to the display element, the output of the first damaged phase selection block is connected to the first input of the voltage memory element, the second input of which is connected to the first output of the control unit, the second output of which is connected to the second inputs of the blocks for distinguishing the current difference, the output of the second block for selecting the damaged phase is connected to the inputs of the unit and the control and allocation vtorogobloka difference currents, the output of which is connected to the second input depeniya-multiplier, a third input coupled to an output element pamya- minute voltage. ma? M □ 1