SU379012A1 - DEVICE FOR PROTECTION OF SYNCHRONOUS GENERATOR - Google Patents

Description

one

The invention relates to the field of power engineering and is intended to protect synchronous generators.

Known devices for protection of a synchronous generator, containing a minimum voltage relay connected to a voltage circuit, and a measuring current organ connected to the secondary winding of a current transformer, whose outputs are connected to an actuator, cannot be used in self-excited synchronous generator protection circuits.

In order to protect a self-excited synchronous generator in the described device, a minimum current relay, for example, based on a nonlinear bridge consisting of resistors and zener diodes, is used as a measuring current organ.

The drawing shows a diagram of the proposed device.

The device contains a minimum current organ consisting of an intermediate current transformer 1, a rectifying bridge with diodes 2-5, a coupling capacitor 6, a non-linear bridge with resistances 7, 8 and zener diodes 9, 10 with a blocking diode //; a minimum voltage body consisting of a rectifying bridge on diodes 12-15, ballast 16,

a smoothing capacitor 17, a nonlinear bridge with resistances 18, 19, and zener diodes 20, 21; An argao executive consisting of a transistor 22, a relay 23 and a limiting diode 24, 25.

The primary winding of the transformer / is included in the circuit of current transformers, and the rectifying bridge with diodes 12-15 in the circuit of voltage transformers of the protected generator.

The current of transformer 1, after rectifying and smoothing by capacitor 6, flows through the resistances 7, 8 w. zener diodes 9, 10 nonlinear bridge. CRE large levels

The current voltage across the resistances 7, 8 is greater than the voltage across the zener diodes H0, and the reverse voltage (with a plus on the collector of the transistor) limited by an open diode is applied to the transistor 22 and the relay 23. When the current decreases to a certain level, the voltage across the resistances 7, 8 becomes less than the voltage of the zener diodes 9, 10, and the transistor 22 to the circuit - the relay 23 is applied

supply voltage of normal sign, the value of which depends on the current generator. Diode 11 in this mode is locked by reverse voltage. By the same principle, the minimum voltage organ at a normal voltage level of the generator supplies to the control gap of the base-emitter of the transistor 22 a blocking voltage. When the voltage drops to a certain level, the voltage across the gap is reversed and the transistor 22 opens. Resistance 16 serves to limit the current through the non-linear bridge.

If only the current is reduced, then the supply voltage of the transistor 22 — relay 23 may have a sign and a value sufficient to operate the relay, however, the transistor is locked with a minimum voltage organ. If only the voltage is lowered, an opening voltage is created at the control gap of the transistor, however, due to the absence of the power circuit voltage, the relay does not operate.

Thus, a necessary condition for the operation of the relay 23 is the simultaneous decrease in the current and voltage of the generator.

In the case when the current or voltage of the generator disappears completely, the relay does not operate due to the absence of the supply voltage or control voltage of the transistor. This prevents the device from operating in the event of an abnormal current or voltage in the normal generator mode, so the device does not require special interlocking circuits that are required by conventional undercurrent relays or voltages.

Subject invention

A device for protection of a synchronous generator, containing a minimum voltage relay connected to a voltage circuit,

and measuring current organ connected to the secondary winding of the current transformer, the outputs of which are connected to the executive body, characterized in that, in order to protect the synchronous generator with

self-excitation, as a measuring current body, a minimum current relay was used, made, for example, on the basis of a nonlinear bridge consisting of resistors and zener diodes.