SU45347A1 - Device to protect electrical installation from generators falling out of sync - Google Patents

Description

It is known that when the normal operating generators drop out of synchronous operation, the flux density of the active power changes when the equalizing eye flows in the network, which can be caught by the energy direction relay, connected in appropriate way.

The action of the proposed device to protect the electrical installation against the loss of generators from synchronism is based on the use of these phenomena. For this purpose, it uses a bi-directional energy relay, in which: 1) a voltage winding is connected in series with normally open contacts of an intermediate relay controlled by starting relays, and acting on the swings in the installation of a special self-blocking relay, 2) contacts are on in the circuit of the windings of the other two self-blocking intermediate relays, the contacts of which are connected in series to the switching circuit; By this, the goal is achieved that the energy direction relay comes into effect only when oscillations and can cause the closing circuit to close only in the case of a rov if during the operation of this relay the direction of the active power in the installation changes.

-.-- L -; -. - -. - -. . The drawing shows a diagram of the electrical connections of the devices constituting the proposed device.

A protected installation is attached to tires A, B, C. Current transformers / feed the windings of the maximum starting relays 2 and the current winding of the relay 6 for the direction of energy. The protection circuit comprises an intermediate relay 5, self-blocking intermediate relays 4, 5, 7 and 8, time relays P and 70; The blenders 77 are included in the electric circuit. The voltage winding of the relay for the direction of energy receives current from the buses a, b, c, o fed by a voltage transformer. Switching off the installation is performed by the proposed device in the event that, if the relay of the energy direction, connected to the linear current and phase voltage, at the level of the surge current greater than the rated current, switches its contacts. In the event of a short circuit, starting relays 2 are active, which switch on the intermediate relay. and time relay 10.

Relay 3 switches on relay 4, which remains in its current position until the moment when relay 9 opens the contacts.

After the short circuit is turned off, there can be four cases: the first case — when there are no subsequent swings, the second — when there are swings that do not cause a drop, the synchro settings, and a third — when the installation drops out of syncro after disconnection of short circuits is not directly, but after accumulation of the oscillation of the oscillations, the fourth, when the loss of the setting: out of synchronism, comes immediately after sending a short circuit.

If, after switching off the short circuit, no oscillations occur, the current relays 2 return to their original position immediately after the short circuit is turned off, and the whole device after the action of relay 9.

If, after a short trip, the coils occur, current relays 2, after the contacts open, close them again, then open them again, and so on. After the short-circuit trip of the relay 2 opens, the relay 5 will turn on; if the contacts of relay 2 are closed again, then the voltage winding circuit of relay 6 is closed and thus relay B will turn on .I

If repeated tripping and contact closure follow, relay 6 will alternately turn on or off.

When the system drops out of synchronism after a cumulative swell buildup, relay b, being switched on using relays 2, 5, - and 5, will first close one contact, turning on, for example, relay 7, and then, when the active power flow changes sign, turns on relay 8 (or vice versa).

Relays 7 and (5 after switching on remain in the on position until the relay 2 contacts are closed. After both 7 7 relays have acted, the protected installation is switched off.

When the loss of the installation of synchronism occurs immediately after switching off the short circuit, dey; The relay of the direction of energy will occur after the second asynchronous swing cycle, i.e. after

the angle between the emf vectors, having decreased to 0 °, will begin to increase again to 180-360, i.e., in the event that the generators are not drawn into synCrONISM. : -:

The relay b is most appropriate to perform responsive to power W I,. and .sin (-a), where / is the current in the relay, f /, is the voltage at the relay terminals, and is the angle between the current and voltage at the relay, to is the impedance installation angle, since such a turnip will switch KOHTaKtOB after the angle between the emf vectors will exceed 180. At an angle between the vectors of emf at 180 ° the relay will be in neutral.

The proposed device must be installed in the protection installation in such a way that it is provided sufficient for the relay to act on the magnitude of the input voltage at the divergence angles of the emf vectors. between 120 and 240 °.

The subject matter of the invention.

A device for protecting an electrical installation against generators falling out of sync, in which the starting relays serve to close the winding circuit of the intermediate relay, characterized by the use of a double-acting energy direction relay, in which, firstly, the voltage winding is connected in series with the normally open contacts an intermediate relay and operating when oscillations in the installation of a self-blocking relay 5, secondly, the contacts are included in the winding circuits of two self-blocking intermediate relays 7 vi 8, the contacts of which are connected in series to the switching circuit in order that the relay b would come into effect only when it swings and could cause the switching circuit to close only if the direction of the active power in the installation changes.

G.

E copyright testimony A. B. Barzam

No. 45347