SU1381643A1 - Method of detecting incomplete phase operation of three-phase network - Google Patents

Abstract

The invention relates to electrical engineering and is intended for use in electrical substations for monitoring the operation of bus breakers. The purpose of the invention is to provide reliable localization of a malfunction, which is the cause of an incomplete phase mode, in a controlled area of seA in a type that has comparable capacitive conductances relative to the ground on the input and output side. The signals from the sensors 4 and 5 of the zero-sequence voltage through the blocks 6 and 7 of the matching are fed to the inputs of the phase-compare; its block 8. In the event of a fault leading to an incomplete-phase mode occurring within the monitored section 1 between the zones of the sensors 4 and 5 , the indicated zero sequence voltages are in antiphase, the phase-equalizing unit 8 generates a malfunction signal that triggers the actuator 9. If the malfunction leading to the incomplete-phase mode lies outside the limits of the monitored section 1 of the network, the zero sequence voltages coincide in phase, block 8 and the executive authority 9 remain in the same state. 4 il. with (L

Description

uu

; - - (., + 1аСва.). (+ 1СоС 1),.

ju (Cft, + C9, + Sat2. + Cc, + Cc2)

de

r g A | Lv | C |

S m Svg S sg

50

total capacity

ground line wires connected to the buses of this substation, except for line 2;

wire capacitance of line 2;

U ;, Ug, U (. Are the phase voltages of the power sources.

As can be seen from expression (1), the voltage uU is due to the fact that when the phase breaks in the controlled section 1 of the network, the capacitances of the phases relative to the ground become different. In this case, the capacitances of phases B and C are greater

capacitance of phase A, therefore, the direction of the vector Li coincides with the direction of the vector of phase voltage of the source Id.

The voltage of the conductors relative to the earth from the input of the monitored section 1 of the network is as follows:

and up

+ whether

+ uU;

(2)

Up Uc + Di.

Zero-sequence voltage on the input side of the monitored section 1 of the network (FIG. 2)

zi (and, + Up

(Uo-t- Uf

Uc)

- and)

 3uU,

(3)

0,

Considering that U / + Ug + U, we have 3Uo Zdi.

The voltage of the wires relative to the earth on the output side of the monitored section 1 of the network is determined taking into account that the voltages of the wires of phases B and C are equal to the voltage of the wires on the side of the silently monitored section 1 of the network GG + uLI, Uc U + i, ll.

The wire A behind the monitored section 1 of the network relative to the ground acquires the potential of the neutral point of the consumer 3, which in this case is in the middle of the line connecting the vectors and a and b c (Fig. 3), therefore the voltage of the wire A at the output of the section 1 is in back phase with the voltage of the wire A at the inlet of the controded section, and the zero sequence voltage at the input of the controlled section 1 is out of phase with the zero sequence voltage at the output of this section. If there is no user 3 (idle of line 2), all the ratios are preserved except that there is no voltage U, and the zero sequence voltage at the output section 1 is also out of phase with the zero voltage at the input of the monitored section 1 of the network Although its absolute value is somewhat lower.

In case of incomplete phase mode, before and after the monitored section of network 1

the zero-sequence voltages at the input and output of co-op 1 section of network 1 are equal in amplitude and

with coincide in phase, since the input and output of the monitored section of network 1 are galvanically phase-connected.

According to the proposed method, the phase of the voltage of zero sequence of 10 at the input and output of the monitored section 1 of the network is compared in phase. If the controlled area 1 of the network voltage zero; the detector T1 at the input and output are in opposite to the phase, form a signal that

that the malfunction, which is the cause of the incomplete phase mode, is high on the monitored section of the network. The way can. carried out

20 a device that switches to the phase difference of the input signals.

The voltage U with for the sensor 4 voltage of zero sequence through the block 6

5 the first input of the phase switch 8, to the second input of which through the block 7 matched} P1, the voltage of zero succession comes from the sensor 5 of the voltage of the bullet dossier 30 (Fig .-). In the event of a fault in the monitored section 1 of the network, the zero-sequence voltage is out of phase, at the output of the phase-matching unit

-j, 8, a signal is formed, which leads to the actuation of the executive body 9.

In the event of faults occurring outside the monitored section of the network,

40 on sensors 4 and 5 of the voltage of the bullet sequence, the signals coincide in phase, there is no signal at the output of the phase-matching unit 8 and the actuator 9 does not operate.

Comparing the phase voltage of the zero sequence at the input and output of the monitored section of the network having comparable capacitive

5Q of conductivity relative to the ground from the input and output side, it is possible to reliably localize (detect) the fault, located within the limits of the monitored section,

Claims (1)

55 claims The method of detecting an incomplete-phase mode of a three-phase network, which consists in recording the occurrence of zero-sequence voltages at the input and output of the monitored section of the network, and after fixation, generates a signal on the network in an incomplete-phase mode, characterized in that ensuring reliable localization of the malfunction, which is the cause of the incomplete-phase mode, on the controlled  P Fig1 and( whether whether the network section having commensurate capacitive conductivities with respect to the ground from the input and output of this section, the indicated zero sequence voltages are compared in laser and form a signal about the presence of the indicated malfunction in the monitored network section if the compared voltages are counter-phased. (