SU1686580A1 - Power direction relay - Google Patents

Abstract

The invention relates to electrical engineering and can be used to determine the direction of power in line guards. The purpose of the invention is to expand the scope of the relay by using it in electrical installations without current transformers. During a short circuit under the action of the magnetic flux generated by the line current, the reed switch 5 triggers. The MEMORY 9 element stores the signal for 11 ms, so that, between the half-waves of the alternating current of the installation, the direct current continues to flow into the windings of 30-32 reed switches 1 , 2 and 4. The reed switch 4 is activated and, the closure contact 36, supplies alternating voltage to the windings 37 and 38 of the reed switches 3 and 6. The reed switches 2 and 6 activate and element 18 comes into action. As soon as the reed switch 2 disappears, at the output of the element AND 20 a signal appears, which through the element MEMORY 12 enters one input of the element AND 24, to the other input of which a signal arrives as soon as the reed switch 6 disappears. The TIME element 44 counts the boundary time and it is less than the coincidence time, then a signal appears at the output of the element OR 43 and at the output of the element MEMORY 16. Zil. Yo

Description

The invention relates to electrical engineering, namely to relay protection, and can be used to determine the direction of power in line protections.

The purpose of the invention is the expansion of the scope by use in electrical installations without current transformers.

In FIG. 1 shows a functional diagram of a power direction switch; in Figs. 2 and 3 are timing diagrams illustrating its operation during short circuit and in load conditions, respectively.

The device contains the first 1 and second reed switches with windings and contacts, the third reed switch with two windings and contact, the fourth 4 reed switch with winding and contact, the fifth 5 reed switch with contact, the sixth 6 reed switch with two windings and contact, rectifiers 7 and 8, the first 9 and second 10, third 11, fourth 12, fifth 13, sixth 14, seventh 15 and eighth 16 MEMORY elements, first 17 second 18, third 19, fourth 20, fifth 2! the sixth 22, seventh 23 and eighth 24 AND elements, with the direct input of the first 17 AND elements, as well as the inverse inputs of the second 18 and third 19 AND elements, connected via pin 25 of the first reed switch 1 to the positive pole 26 of the power source, which is also connected through contact 27 of the second reed switch is the direct input of the second 18 element And and the inverse ± moves of the first 17 and fourth 20 elements And the inverse input of the fifth 21 element And is connected through contact 28 of the third 3 reed switch to the positive pole 26 of the power source, to the negative pole 29 of which one leads of the windings 30-32 of the first 1, second 2, and fourth 4 reed switches are connected, respectively, the direct input of the fifth 21 element AND is connected to the output of the first 9 element of MEMORY, connected via an input via pin 33 of the fifth 5 reed switch to the positive pole 26 of the power source to which also through contact 34 of the sixth 6 reed switch, the inverse input of the sixth 22 element And, the output of the measuring transformer. 35 voltage through contact 36 of the fourth 4 reed switch is connected directly to the control windings 37 and 38 of the third and sixth 6 reed switches, and to the polar to the windings: 39 and 40 of the indicated reed switches - through rectifiers 7 and 8, the output of the first 17 element AND is connected through the first 41 element TIME and the second 10 element MEMORY in series to the direct input of the third 19 element AND, the second 42 element TIME, connected to the output to one input of OR element 43, to the other input of which the output of the third 44th TIME element is connected, the output of the second 18th AND element is connected through the fourth 45th TIME element to the input of the fifth 13th MEMORY element, the fifth 46th and sixth 47th elements of TIME.

The device operates as follows.

Reed switches 1 and 2 are installed in the magnetic field of the current of one of the phases of the power line. Reed switches 1-3 and 6 are polarized by applying direct current to the windings 30, 3! 39 and 40. The direct current is circulated with the help of reed switches 4 and 5 only when the current in the protected line increases to a value of 1, 3 1 load max. This is done in order not to keep the reed switches 1, 2, 3 and 6 all the time in the operating state, which adversely affects their properties and significantly reduces the service life.

A current is generated in the windings 30 and 31, creating a magnetic flux By (Fig. 2)

By = Vi a ’Cotes + CzBv; - = HF. (1) Osr where Kots and Kz are the detuning and safety factors, Kots is selected taking into account the sensitivity and selectivity of the directional current protection of a particular object and ranges from 1.1 to 1.5;

_K - return ratio reed switch;

Ver ⁼ K) 1 sr1,

Ext.a “Kg Cn.a, Κι and Kg - proportionality coefficients;

Vn.a, Ver and Vv - induction of magnetic fluxes along the reed switch plates created by Icp currents. 1 response (the current at which the reed switch is activated) in the winding, the amplitude value of the nominal current _of 1 _N .a electrical load phase, near which it is located, and a current return at which it returns to its original position. When (1) a reed switch 1 is open (closed after actuation by the impact Icpt constant current) under fault contacts ti time with increasing current amplitude _1N .a connection to I / ³ (Fig. 2 it corresponds Bi * ³⁾ and for the time xg with an increase in current to 1 ^{g KZ} (Vg ^KZ ). In all cases, it disappears at Bi, and in the latter case twice (points 48 and 49).

Thus, the reed switch 1 falls into the negative half-wave of the alternating current of the protected installation, and the reed switch 2 falls into the positive one, however, the falling-off time of the reed switch cannot be used to compare the specified areas of coincidence or mismatch of the current phases in the line and the phase-to-phase voltage, since the time tom, during which the reed switches remain in a fallen state, (ti. t2) depends on the value of the short-circuit current.

Therefore, the elements MEMORY 11 and 12 store the signal for a time tA = 0.01 s, which corresponds to φκ = π. In this case,? D (rv) is the specified region of the phase change of currents 10 (voltages) B and A for relays with a comparison of phases, the response characteristics of which correspond to the following conditions:

- (fv ~ fc> + dd - <5β) <φ <φb - φνρ + <5d - <5c. (2) where <5a and dv are the angles between the transition point through about the corresponding curve and the beginning of the 2θ regions of phi and fv. In our case (dd - dv) it depends on the ratios of the amplitudes of the compared quantities in the short circuit. So, if for both compared quantities

V / ³ > 2.5 V ".a,

Ap = 1.5: _K = 0.4-0.7.

then (dd - <3c) = 15-20 °. If for one of the values 2 Ext.a <B ι ^Κ3 <3 Ext.a, and for the other 30 B / ³ > (45-50) Ext.a, then (dd - dv) = 50-60 °.

Assuming that in (2) the expression in brackets and π on the right-hand side are equal, having set fk = i and having determined (<5d-dv) we find 35 fgr = 2 ⁺ - <3c; фв = π + (For - dv, (3) time trp = is set on the elements TIME 42 and 44, tB - on the elements MEMORY 14 and 15.

Due to the fact that a direct current can be supplied to the reed switch windings by a reed switch 5 both in the negative and positive half-waves, for example, at time t3 (Fig. 2), when the reed switch 1 trips (point 50) and falls off at point 49. and not at point 48, from which the tA counting should start, in order to correctly fix the negative polarity with 50 reed switch 1, the counting should begin after the reed switch has been triggered when the reed switch 2 is not working (magnetic fluxes acting on the reed switch 2, shown at the bottom of Fig. 2). This 55 is carried out using elements AND 17-20 with an inverse input, elements TIME41 and 45 and MEMORY and 13. Elements .41, 45 and 46, 47 have time delays t4 = 1 ms and t5 = 2 ms, t4 takes into account the possibility of simultaneous operation and falling away of reed switches, ts is the delay in the operation of reed switches 6 and 4 relative to reed switches 1 and 2 5 when direct current is applied. The MEMORY elements 10 and 13 memorize the signals for t6 = 15 ms, providing, together with the And 19 and 20 elements, the fixation of the negative and positive half-waves regardless of the amplitude In ^KZ (i.e., at points 48 and 51, etc.).

In order for the reed switches 3 and 6 to fix the negative and positive polarity of the voltage supplied from the transformer 35, it is necessary that

1p2 = (15-30) 1 _C p2, 1s = (1, 3-2) 1p2. (4) where 1p2 is the direct current supplied to the windings 39 and 40 through rectifiers 7 and 8:

1 ₃ - the current supplied to the windings 37 and 38; icp2 - trip current of reed switches 3 and 6.

In FIG. Figure 3 shows the magnetic fluxes Vu2 proportional to the current 1 _P 2 acting on the reed switch 3 in normal mode at rated voltage.

Wherein B _C p2 proportional to the current 1 _C p2 actuation reed 3: _n .a - current in the winding 37 at the nominal voltage; V1n ^ks - at the voltage during a short circuit in a particular point of the line. The selected relationships (4) are due to a decrease in voltage during short circuit. The first allows you to maintain polarization during short-circuit near the substation tires, the second - with errors in the voltage transformer and rectifier.

In the load mode of the protected line, direct current is not supplied to the reed switch windings 1 and 2, as well as an alternating voltage to the reed switch windings 3 and 6, since the reed switch 5 does not come into operation at the outputs of the elements And 17, 18,21 and 22 with an inverse input no signals.

In case of short circuit on the line under the influence of the magnetic flux generated by the line current, the reed switch 5 is activated, the MEMORY element 9 remembers the signal for 11 ms, so that while the reed switch 5 falls off between the installation half-waves, the direct current continues to be supplied to the relay circuit.

The windings of 30-32 reed switches 1,2 and 4 are streamlined with direct current. 4 and reed switch triggered by closing contact 36 feeds the variable voltage to the windings 37 and 38 of the reed 3 and 6. reed switches 1 and 2 are two magnetic flux B and _Y 1. e.g. Βι ^κ3 . If a fault occurred at time t3, then reed switch 1 remains in an unworked position, since it is affected by the flow Β _Δ = Byi - Bi «В _С p1. Reed switch 2 at this moment is triggered, since it is exposed to the flow of Vu1 + Bi ^K3 > Bcpi, reed switch 6 is also triggered, element And 18 comes into effect. Through and the element 13 stores the signal for the time te, and as soon as the reed switch 2 disappears (point 52), a signal appears at the output of the And 20 element, which through the MEMORY 12 element is supplied to the first input of the And 24 element. A signal after falling off will be received at its second input reed switch 6 (point 53). Element 44 counts the time trp, at the time tcoen of the coincidence of signals tcoen> trp, a signal appears at the output of the OR element 43 and at the output of the MEMORY element 16.

Since a comparison of the coincidence time occurs every half-wave of an alternating Current, the response time of the device will not exceed 0.021 s even when an electromechanical relay, for example, of a polarized type, is installed at the output.

Claims (1)

Claim A power direction switch containing the first and second reed switches with windings and contacts and two rectifiers, characterized in that, in order to expand the scope by using electrical installations without current transformers, a third reed switch with two windings and a contact, a fourth reed switch with a marking and contact, fifth reed switch with contact, sixth reed switch with two windings and contact, first, second, third, fourth, fifth, sixth, seventh and eighth elements MEMORY, first, second, third, fourth, fifth, sixth, the eighth and eighth elements AND, the first, second, third, fourth, fifth and sixth elements TIME and the OR element, while the first and second reed switches are designed for installation in the magnetic field of the current phase of the protected object, the direct input of the first element And, as well as inverse inputs the second and third elements And are connected through the contact of the first reed switch to the positive pole of the power source, to which are also connected via the contact of the second reed switch the direct input of the second element And the inverse inputs of the first and fourth elements And, inverse input the fifth element And is connected through the contact of the third reed switch to the positive pole of the power source, to the negative pole of which one leads of the windings of the first, second and fourth reed switches are connected, the direct input of the fifth element And is connected to other terminals of the windings of the reed switches, as well as to the output of the first element MEMORY, connected by the input through the fifth reed contact to the positive pole of the power source, to which is also connected via the sixth reed contact the inverse input of the sixth AND element, whose direct input connected to the output of the first MEMORY element, the output of the voltage measuring transformer through the contact of the fourth reed switch is directly connected to the control windings of the third and sixth reed switches directly, and to the polarizing windings of the indicated reed switches through rectifiers, the output of the first AND element is connected through the first TIME and the second MEMORY element connected in series to direct input of the third element I. the output of which through the third element MEMORY is connected to one direct input of the seventh element And connected to the output through the second TIME element to one input of the OR element, to the other input of which is connected through the third TIME element the output of the eighth AND element, one direct input of which is connected through the fourth MEMORY element to the output of the fourth AND element, whose direct input is connected through the fifth MEMORY element connected in series and the fourth TIME element to the output of the second AND element, the output of the fifth AND element is connected through the fifth TIME element and the sixth MEMORY element connected in series to another direct input of the seventh AND element , the output of the sixth AND element is connected through the sixth TIME element and the seventh MEMORY element connected in series to another direct input of the eighth AND element, and the output of the OR element is connected to the input of the eighth MEMORY element.