SU1309155A1 - Device for distance protection of electric power line with branching - Google Patents

Abstract

This invention relates to electrical engineering and can be used in relay protection devices. The purpose of the invention is to improve the reliability of the setting from the closures of the transformers of the wiring OC J / JB Jc. From the output of shaper 1, signals proportional to the difference in the currents of the negative sequence of the two phases are fed to the inputs of the converter 2 sinusoidal voltages into square pulses, as well as to the inputs of phase shifting elements 3 and 4. At the output of the selector 6 a special phase, to the inputs of which phase currents, in the case of a two-phase short circuit, a continuous signal appears at the inputs of the block 5 for shifting the front and rear edges of the pulses. Comparison of pulse signals with shifted edges allows a continuous signal at the output of the converter to indicate that the monitored parameters of the line are out of acceptable limits. 3 il. i SB GO about CD 01 SP

Description

The invention relates to electrical engineering and is intended for use in devices for remote protection of power lines with branches from inter-short circuits and phase-to-phase short circuits to earth.

The purpose of the invention is to improve the reliability of the detuning from the circuit for the transformers of the branch.

FIG. 1 shows a functional diagram of the proposed device; in fig. 2 shows a characteristic of a known device in the complex plane of resistance of a short-circuit loop for two-phase short circuits to earth; in fig. 3 shows the characteristics of devices in the same plane with two-phase short circuits between phases.

The device contains a shaper 1 compensated line voltage, a voltage proportional to the difference of currents of the negative sequence of any two phases and voltages proportional to the difference of phase TOKOEJ, eight outputs of which are connected to the corresponding inputs of the converter 2 sinusoidal voltages into rectangular pulses directly, and two others through phase-shifting elements 3 and 4, and the outputs N A, B, C of converter 2 are connected through the block 5 of the shift of the front and rear edges of the pulses to the logic el And 7, and the outputs K, D, E, F, R, G of converter 2 are connected to block 8 of the shift of the front and rear edges of the pulses, the output of which is connected to the fifth input of the logic element And 7, and the corresponding outputs of the selector 6 of the special phase are connected to the inputs of blocks 5 and 8 shift the front and rear edges of the pulses, and the output of the logic element And 7 is connected to the transducer 9 pulse signals into a continuous signal, the output of which is the output of the device.

The device works as follows.

The inputs of the former 1 of the compared values are received, the voltage Od., U ;, OS and the currents i, Ig, ic of the corresponding phases A, B, C. At its outputs, voltages are formed proportional to the difference of the currents of the reverse sequence of two phases, and C:

and n (r, - 1 ,,),

where n is the coefficient. proportionality of voltages Ui, Uf, Of, proportional to the difference of currents of two phases:

(iB-ie);

(); (1s - 1l);

where K is the coefficient of proportionality and

compensated line voltage:

about; 0 ,, -ZA (U- ic);

Dis od -Zy (i, -.- ij; p «- Zy (U-i,); 50 0" e HXTi. (IE-ic);

about 0лв нхтр (ЫЛ

Od psl -jXrpdc-u);

where zy is the setpoint resistance;

Хт | 1 - inductive resistance of the transformer of the answer - 0. . . occurrences;

UBC - SA is the corresponding line voltage. . Voltage formation is possible.

02based on the currents of other phases, in this case - it is necessary to change the compensated linear voltages accordingly, 1,

Tensions Ove, Ui, UBC, U ;; , Og,, Of, Of, Of arrive at the inputs of the converter 2 sinusoidal voltages at 0 rectangular pulses, the sign of which coincides with the sign of the instantaneous values of the corresponding voltages.

Voltage 0 and OC are supplied respectively to the phase-shifting elements.

3 and 4, performing, transformation: O; but. 0, in;

about ;, a-. ABOUT, .

where the phase operators a e - ° and on.

Further, these voltages are fed to the corresponding inputs of the transducer 2 sinusoidal voltages into rectangular pulses.

The pulses from the outputs N, A, B, C of the converter 2 sinusoidal voltages to np are the coal impulses corresponding to the 0-2, Ovs, UBC, OCA tendencies, go to the front and rear edges of the pulses, where the fronts are shifted pulses. For example, the leading edge of the pulse of the corresponding voltage Ua is shifted towards the narrowing to

0 for as long as there is a short pulse at the moment the onset of the appearance of a rectangular one, i.e., at the moment of the transition of the voltage Oa from negative to positive values. At the same time, the pulses corresponding to the voltages O AC,,

Osl can shift, for example, the leading front in the direction of expansion by a certain angle (3. Moreover, the presence of voter 6 makes it possible for a special phase to short-circuit to earth with / move the fronts of one of the

Q pulses corresponding to the voltage OBC Odv or Oc, depending on the name of the closed phases.

So, at a de-phase phase short circuit of A and B on the ground, at one output a selector 6 of a special phase, at the inputs of which phase currents are applied, a continuous signal appears, which is then fed to the corresponding inputs of the unit of the front and rear edges of the pulses .

In this case, in block 5, the shift of the front and rear edges of the pulses expands by an angle P only, the pulse corresponding to the voltage OBS, and the other two remain unchanged.

Similarly, when the phases C and A are short-circuited to earth, when a signal appears at another output of the selector 6 of a special phase, also connected to the 5-front and-falling pulses shift unit, the angle expands (3 only the pulse corresponding to the voltage UAB etc. Modified pulses from the outputs of block 5 shift the front and rear edges of the pulses are fed to the inputs of the logical element I 7.

The pulses from the outputs K, D, E, F, R, G of the transducer 2 sinusoidal voltages are delivered to the rectangular pulses at the corresponding 1 inputs of the 8-shift unit of the leading and trailing edges of the pulses. The rising edges of the pulses corresponding to Of, Of, Of, shift towards the constriction until there is only a short pulse at the moment the onset of the appearance of a rectangular impulse, i.e. at the moment of the transition of the voltages Of, Of and Of from negative values to positive. At the same time, for pulses corresponding to voltages 0, Od,, the leading fronts are shifted by an angle φ in the direction of extension, and the rear ones are also shifted by an angle φ in the direction of contraction. Thus, the pulses with voltages of 0, 0,,, are shifted by an angle (f relative to their initial position.

Moreover, it should be noted that the presence of a special phase selector 6 allows, at the output of the shift block 8, of the front and rear edges of pulses, a signal is obtained that corresponds to the realization of only that level, which includes a coherent linear voltage of the damaged phases. In a two-phase short circuit between phases B and C, at the output. a block of 9 shifts of the leading and trailing edges of the pulses, a signal appears corresponding to the implementation of the equation, which includes 0. In the case of a two-phase short circuit between phases A and B, at the output of block 9 of the shift of the front and rear edges of the pulses, there appears only a signal corresponding to the implementation of the equation, which also includes td.

The modified and pulses from the output of the 8-shift block of the front and rear edges of the pulses are fed to the input of the logic element 7, the output of which is a pulse signal, then fed to the input of the converter 9 of the pulse signals into a continuous signal that converts the short pulse signal into continuous continuous signal.

A signal at the output of the specified device appears when the following three conditions are fulfilled simultaneously:

- (iLi argpK / O. 180 °; (t)

5-pL2 argO e / O. 180 °; (2.)

-pL3 argO «/ O, i 180 ° (3)

where p - adjustable in block 5 of the shift of the front and rear edges of the pulses angle;

About LI, La, LS - logical variables, accepting values equal to "when there} 1I signal correspond (pno on the first, second and third, voter 6 special, n equal to" O in the absence of

specified signals and one of the following three conditions:

- (/ 01 ps | - |: (}

- ((g)

0- l argl; /0.l-f ,,; (b)

where φ „is the angle of the ggg line.

In pormalnom |) hedgehog. Of operation of the protected transmission line there is no negative sequence current. Wherein

there is no voltage jl, logical interlaces LI, Li, Lj are equal to "O, and the bunch of voltage vectors 0, 0, OCA cannot be covered with an angle of 180. At that, conditions (1) - (6) are not fulfilled and the device does not work .

0 Lree two-phase short circuits to earth, for example, when the phases B and C are earth to ground, the response conditions (1) (4) are primed

35

-Xarg-y, z

O Xarg-U

: i80

OTCVTa triggers conditions (5) and (6).

Pa figs. Figure 2 shows the response characteristic of the device in the complex plane P1I resistance of a short-circuit loop in the absence of a fault current. With other combinations of closed phases characteristic. similar. The location of the special points of the PAB and RSD characteristics is determined by the parameters of the grid system. Moreover, by setting a parameter (5, the shape of the device characteristic can be adjusted, this ensures high sensitivity of the device during two-phase short circuits in the protected zone and high selectivity for all types of short circuits, and for this device the phase-to-phase short circuit of the branch transformer will be outside.

In sec. In two-phase short circuits between phases, for example, between phases B and C, conditions (4) take the form

triggers (1) -

0 ° arg- j - 180 °; Ui

() K 180 °; Ug

0 ° arg- | 4,180 °;

and

and --f „agg- - 180 ° f„.

FIG. ; For this case, the characteristic of slapping the device in the complex plane of the loop resistance of a short gr: myc in the absence of an emergency current is shown. In this case, the device also provides good sensitivity at two-phase short circuits between the phases in the protection zone and high selectivity, with all types of external short circuits and short circuits behind the tap changer.

Thus, the proposed remote sensing body has high sensitivity in the case of two-phase short circuits between phases and two-phase short circuits to ground while maintaining high selectivity for all types of external short circuits and short circuits behind the branch transformer while maintaining the length of the drive zone.

Claims (1)

Invention Formula A device for remote protection of power lines with branches against phase-to-phase short circuits and phase-to-phase short circuits on the ground, containing a unit for generating comparable values, to the inputs of which current and voltage of the dead-line phases are applied. J two outputs of which are connected to the corresponding inputs of the sinusoidal voltage transducer directly into rectangular pulses, and the other two via phase-shifting blocks, and the transducer outputs are electrically connected through the front and rear edges of the pulses with the consecutively connected logic element And and the converter of pulse signals into a continuous the signal whose output is the output of the device, this contains a selector of a special phase, the inputs of which are connected to currents power transmission, and the outputs are connected to the corresponding inputs of the shift unit of the front and rear edges of pulses, characterized in that, in order to increase the reliability of the detuning from the circuits behind the tapping transformer, an additional shift unit of the front and rear edges of the pulses is introduced, 0 the block formation of compared values is made in the form of a unit for the formation of compensated linear voltages, a voltage proportional to the difference of currents of the reverse sequence of two phases, and voltages proportional to the difference of currents 5 any two phases, eight outputs of which are connected to the converter of sinusoidal values into square impulses directly, and two - via phase-shifting blocks, with four outputs of the converter connected via a front and rear shifting unit of the F0101g pulses And gate, the other six outputs of the converter are connected to the second block of the shift of the leading and trailing edges of the pulses, the output of which is connected to the fifth input of the logic element I, while the corresponding outputs of the selector of the special phase are connected enes inputs to shift the front and rear edges of pulses of blocks, and the output of the AND gate is connected to the transducer pulse signals :: continuous signal. I 0 five 0 Jx fuz.2 Editor G. Volkova Order 1443/48 Compiled by V. Belov Tehre I. VeresKorrektor N. King Circulation 619 Subscription VNIIPI State Committee of the USSR on the case of inventions and discoveries 113035, Moscow, Zh-35, Raushsk iab., 4/5 Proizodizhodstvenno-noligraphicheskoe enterprise, Uzhgorod, ul. Project, 4 fuz. 3