SU52265A1 - Tire protection system - Google Patents

Description

3, the relay protection technique has a variety of schemes for protecting station and substation buses. The main difficulty in providing satisfactory protection for women with one oil switch on the branch is how to determine the damaged section (system) of women if the protection is chosen as fast-acting, based on differential principle.

The present invention aims to solve this problem. The proposed device for the protection of women has the choice of a damaged system of women, irrespective of whether the substations are operating with closed or open parallel oil switches.

To achieve this goal, the proposed device uses a special combination of differential protection of all branches of women with balanced protection.

The invention is illustrated in the drawing; in FIG. 1 which shows the circuit diagram of the device proposed in the first embodiment (with differential start and with current balance

and balance-voltmeter choice); FIG. 2-diagram of the device according to the second embodiment; FIG. 3-scheme according to the third variant (with differential current start and balancing-current choice); FIG. 4-circuit switching on balanced relays.

The differential circuit for each phase, except for the differential relay /, includes two balancing current relays 2 and a balanced relay 5.

Balance relay 5 is a balanced relay, on each arm of which there are two coils: a current coil and a voltage coil.

The protection enablement scheme is easy to remove from FIG. 1-2 drawings. Relay 2 is included in the common circuit of the differential circuit. Relay 5 is included in the shoulders of the first and second differential circuit bus systems. With this switch-on, with the parallel oil switch 6 closed, relays 2 and 5 generally operate in parallel, helping each other.

However, in some cases, relay 2 may refuse to select; in these cases, the relay 5 will work correctly, the operation of the current coils of the sleep relay 5

from drawing and special definition does not require. It should only be noted the purpose of the current transformers on the parallel oil switch 6, included in the overall differential circuit. The purpose of these current transformers is to compensate for the damage current flowing through the parallel oil switch, which creates a clear operation of the current part of the balanced relay 5 under these conditions.

The operation of relay 2 is also based on the principle of current comparison. From the diagram of FIG. 1 that the total fault current, flowing through the coil of the differential relay 7, also flows through both coils of both elements of the relay 2,

The difference of currents in different coils of the relay 2 is achieved by special connection of current transformers mounted on a parallel oil switch.

From the drawing it is easy to understand how to connect current transformers to the relay 2 coil.

If the damage occurs on one bus system, the current flowing from the healthy tire section through the parallel oil switch will also flow through the coils of relay 2, but for one relay 2 this current will be summed up with the full damage current in the working coil and deducted into the brake in the second relay, the combination of currents will be reversed, i.e., the currents will be summed in the brake coil and subtracted in the working coil.

Thus, only one relay 2 will work, which through intermediate relays 3, 4 will turn off the damaged bus system. If the damage occurs on the second system, the second relay 2 will work and will also select the damaged system.

The selection of the oil circuit breakers, which are associated with the damaged tire system, is made using the contacts on the disconnectors in the usual way. In the diagram of FIG. 1 these contacts are not shown, but they are located in lines 13, 4, 75 and 76 in those

places where these lines are conventionally shown broken.

In addition, in case of failure in the operation of both the balanced relay 2 and the balanced relay 5, it is proposed to apply a second pair of open contacts on each relay 2. In the presence of these open contacts, the latter are connected in series and close the circuit of intermediate relay 8. Thus, if relay 2 does not trip, tr will trigger relay 8 and turn off the parallel oil switch. When the parallel oil switch is open under the action of different voltages on the damaged and healthy sections of the women and under the action of the currents, the relay 5 will operate and turn off the damaged system of women. Voltage coils of the relay 5 are turned on in such a way that the voltage of a healthy system of women is applied to the shoulder of the damaged coil of the damaged system and vice versa. With such inclusion, the correct choice of the damaged system from the relay 5 is ensured.

However, relay 5 may give incorrect operation in case of a break in the fuse in the circuit of one of the voltage transformers. To eliminate the latter, the circuit provides for special automatic blocking of the voltage circuit by means of relays 9, 10, P, and 72.

It can be seen from the diagram that in case of a voltage imbalance, relay 9 will operate and close its contacts. Under these conditions, after a certain time delay, relay Yu will operate and turn on the relay / 2, which will open the voltage circuit to the relays of the relay 5.

The combination of relays 10, 7 / and 72 has the advantage that for a long time only one relay 72 is energized. Multi-contact relay 72 can be replaced by two standard ones.

Relay 72 provides two signaling contacts, one closing and one opening. If available, the staff will receive a signal in any condition where the normal position of the relay 72 is disturbed.

The advantage of the proposed scheme is that even when the voltage relay fails, the circuit does not lose selectivity either when the parallel oil switch is closed or open.

When transferring all lines to a single bus system, protection is automatically transferred to a hard differential circuit. The latter is accomplished by using auxiliary contacts on disconnectors. A possible scheme for using these auxiliary contacts is conventionally shown inside the dotted contour in the lower right corner of FIG. 1 drawing.

Protection may give incorrect operation if all lines are transferred to one of the strip systems, except for two lines allocated to the second bus system, for lifting from zero. However, the latter is easily eliminated by introducing into the scheme a special plug 17, which closes the staff when two lines are allocated for lifting from zero.

In case of failure in the operation of the main high-speed equipment, the scheme provides the usual backup protection, which will turn off the entire substation through the backup relays 23 and 24, operating with a certain time delay.

In the circuit of FIG. 2 there is no balanced relay .5, but balance voltmeter relays 18 and 19 are introduced.

Balanced-current relays 2 operating on the principle of comparison of currents in coils are included in the common wire of the differential circuit. The difference of currents in different coils is achieved by special connection of 2 current transformers installed on a parallel oil switch to a balanced current relay.

If the damage occurs on one of the bus systems with the parallel oil switch closed, the full fault current, flowing through the windings of the differential relay /, will flow through the windings of the balanced relays 2. Part of the current flowing through the parallel

The oil switch from the healthy section of the transformer will also flow through the coils of the balanced relays 2. At one of the balanced relays, this current is summed up with the total fault current in the working coil and subtracted into the brake coil. In the second balanced relay, the combination of currents will be reversed, i.e. the sum of the currents in the brake coil and the difference in the working coil. Thus, only one balanced relay will work and through the intermediate relay 4 or 3 will turn off the damaged section.

If the damage occurs on the second bus system, the second balanced relay will operate and will also shut down the damaged part of the installation. The selection of oil circuit breakers, which are associated with a damaged tire system, is made using the contacts on the disconnectors in the usual way (not shown in the diagram).

When using conventional current balancing relays, the protection could not be considered satisfactory, because in some conditions the latter would fail in operation.

These conditions include the cases when all lines are connected to one bus system, only one or two end lines or lines with low-power power sources are brought to the other system.

Under these conditions, if a fault occurs on the main bus system, the current through the parallel oil switch will be either zero or very small compared to the total fault current flowing through the differential relay /.

Under these conditions, balanced relays 2 will not work, and the protection will fail. To eliminate the latter, it is proposed to add a second pair of break contacts to the balanced relays 2.

With these contacts, this drawback is eliminated.

The opening contacts of both elements of the balanced relay 2 are connected in series and through them

the circuit is supplied to the intermediate relay 8. Therefore, if in the above conditions the balanced relays do not operate, then the relay 8 will operate and will turn off the parallel oil switch. After the parallel oil switch is turned off, the balanced section / 5 and J9 will select the damaged section.

From what has been said, it follows that in all conditions, when the parallel oil switch is closed, the protection will make the selection of a damaged tire system.

For the operating conditions of the bushes, when the parallel oil switch is open, it is provided to install two sets of JS and 79 balance-volt relays.

The author's research showed that if one of the tire systems is damaged under open oil conditions, the difference in damage between the damaged and healthy tire sections under all conditions will be quite sufficient for the correct operation of the balancing-volt relay / 5 and / 9. Therefore, in these conditions, the protection will also make the right choice of a damaged tire system.

In order to protect the false operation of the protection (balancing-volt-meter relays) in the event of a break in the fuse in the circuit of one of the voltage transformers, the circuit provides for automatic blocking using relays 9, 10, 11 and / 2. Under these conditions, balanced voltmeter relay 9 will operate; after a certain time delay set by the relay W, the intermediate relay 72 will work and stick, thereby breaking the DC circuit from both the balance-volt relay 18 and 19.

As in the scheme of FIG. 1, the combination of three relays 10, 11 and 72 is designed in such a way that only relay 72 is under continuous current. Relay 72 is provided with closing and opening alarm contacts that warn personnel of the disturbance of the normal position of the blocking relay 72 under any conditions.

The same combination of relays 9, W, 77 and 12 performs the role of automatically rebuilding the protection on a rigid differential circuit when switching all the lines to one bus system.

The main drawback of the circuit is that when the balance-volt-meter relays 18 and 19 are out of operation with the parallel oil switch closed, the protection loses selectivity, but in these conditions the entire protection substation will turn off the relay 23 and 24.

In the circuit of FIG. 3, both relays 5 and relays 18 and 19 are missing. The selection of the damaged part of the installation is carried out only by relay 2.

As in the first two variants, in the scheme in FIG. 3, the relay circuit 7 of the differential circuit includes two current-balance current relays 2 operating on the principle of comparing currents in coils. The difference of currents in different coils is achieved by means of special connection of the balance current relays 2 to current transformers installed on a parallel oil switch.

If damage occurs on one of the bus systems with the parallel oil switch closed, the full fault current flowing through the windings of the differential relay 7 will flow through the windings of both balanced relays 2, but part of the current flowing to the damage site from a healthy tire system through the parallel the oil switch will flow through the coils of the balanced relays as well.

For one of the balanced relays, this current will be summed with the total fault current in the working coil and subtracted in the brake coil with the full current of the differential relay. In the second balanced relay, the combination of current will be the opposite, i.e. the sum of the currents in the brake coil and the difference in the working coil. Thus, only one balanced relay will work and will turn off through (conditionally shown) intermediate relay 3 of the damaged bus system.

If damage happens on | the second bus system, then the second balanced relay 2 will operate and similarly will turn off the second (damaged) section through the relay 4.I

The selection of oil switches that are associated with a damaged tire system is made using the contacts on the disconnectors (not shown) .I

Using conventional current balancing relays 2, the protection could not be considered satisfactory, because under some conditions I would have refused to work. This happens when all the lines are connected to one bus system i, to the other: only one or two end lines (without power at the opposite end) or lines with a weak power source are brought to the system. Under these conditions, if there is a fault on the busbar system to which all lines are led, the current of the second busbar section through the parallel oil switch will be either zero or very small compared to the total fault current flowing through the differential relay 7. In these The conditions of the balanced relays 2 are not affected and the protection would fail in operation.

To avoid such a case, the balanced relays 2 are supplied with a second pair of j contacts (in the diagram in Fig. 4 these contacts are not shown j).

The opening contacts of both relays 2 are connected in series and an intermediate relay 8 is passed through them. Thus, if the balanced relays do not operate under the specified conditions, j relay 8 will work and through relay 3 4 will turn off the entire substation.

Relay 8 has the purpose of backup protection, usually taken in case of failure in the operation of the main relays.

The advantage of the scheme is that the protection is fast-acting.

The drawback of the scheme is that the latter can only be applied at substations that operate on both systems.

tires with closed parallel oil switches. When the parallel oil switch is open and simultaneous operation on both bus systems, the protection has no selectivity.

The subject matter of the invention.

Claims (7)

1. A device for protecting a busbar system containing an inter-area circuit breaker and equipped with differential protection; oh, covering all branches of a women, characterized in that two balance current relays 2, the windings of which are fed by current from the secondary windings, are connected to the relay / differential circuit. current transformers installed on the inter-circuit breaker, so that in the balance-current relay 2 of the damaged busbar section, the current flowing through the inter-area circuit breaker is summed up with the current The damage in the working winding was subtracted in the brake winding from the total current of the differential relay, in order to ensure the selective operation of one element of relay 2 and disconnect the damaged busbar system. 2. In the device according to claim 1, application in relay 2 of the second pair of contacts mounted on the rocker arm of relay 2, operating in opening and connected with an operating current circuit with differential relays and with intermediate relay 3, in order to prevent failures in the operation of balance current relays 2 when powered from one bus system of all branches and from another system of one or two dead-end lines or lines with a weak power source. 3. The form of the device according to claim 1, characterized in that the differential protection arms, in addition to the differential / and current-balance 2 relays, include balanced relays 5, one arm of which has a current winding of the first system and a voltage winding of the second system tires, and vice versa, with the goal that by turning on the windings of the relay 5 to ensure both the current selection of the damaged bus system and the voltage selection. 4. In the device according to claim 3, in order to prevent false actions of protection in case of blown fuses or phase failure in the circuit of one of the voltage transformers, the use of a relay 9 serving to block the voltage circuit and connected to the secondary winding of the voltage transformer and the relay / (- 72 included in the operational chain. 5. In the device according to claim 3, the use of relay 72, which is permanently under operating voltage and serves as for opening the voltage coil circuit of relay 3 from both voltage transformers under any condition of voltage imbalance through time relay / O and to close the signal circuit in order to control the operation of the device. 6. The form of the device Item 1, characterized in that each bus system has a set of balancing-volt-meter relays 75, 79 connected by an operating current circuit through the contacts of differential relays /, balancing-volt-meter relays 75, 79 and the winding of the switching-off relays 3, 4. 7. In the device according to claim 6, in order to prevent false actions of protection in case of blown fuses and phase failure in the circuit of one of the voltage transformers and when transferring the power of all lines from one bus system, using voltage-balanced relays 9 that serve to block the voltage circuit and included in the secondary circuit of voltage transformers, and time relays 10 and two intermediate relays 77, 72, included in the operational circuit to implement automatic transfer of protection to the differential circuit. Fig, - --O ..- J (O-1 | l: (i 1 S Y about i i i   J .. : rl r.w j, - -L V i - -e-- -, : SOUTH: -. .01 4.4.J-: 4PO