RU27753U1 - DEVICE FOR PROTECTION AGAINST VOLTAGE IN THE WINDING OF EXCITATION OF A SYNCHRONOUS MACHINE WITH A BRUSHLESS AC PURCHASER WITH A ROTATING SEMICONDUCTOR RECTIFIER - Google Patents

Description

DEVICE FOR PROTECTION AGAINST VOLTAGE IN THE WINDING

EXCITATIONS OF SYNCHRONOUS MA1PINB1 WITH BRUSHLESS

AC DRIVER, ROTATING

SEMICONDUCTORS B1M VB1 RECTIFIER

The utility model relates to electrical engineering and is used to protect the excitation winding of synchronous machines from overvoltages that occur; they occur during startup and asynchronous operation modes, transients in the network, etc.

Known devices are protected against overvoltages on the excitation winding of synchronous machines, where a circuit with a nonlinear characteristic is connected in parallel with the excitation winding, for example, a thyristor with a zener diode connected between the control electrode and the anode (Glebov I.A. and Loginov S.I. “Systems excitation and regulation of synchronous motors, Leningrad, "Energy". To increase the reliability of the device, between the control electrode and the cathode of the thyristor, include a capacitor (AS USSR No. 788259, HO2H 7/08, 1979) or a relay contact connected to the exciter armature through an additional rectifier (AS USSR No. 534010, HO2H 7/08, 1974)

The disadvantage of the devices is that when they are triggered in synchronous operation of the machine (when the excitation is applied), to turn off the thyristor, it is necessary to turn off the excitation current and, as a rule, due to the significant residual magnetization of the exciter, the machine must also be stopped. In addition, in a device with a relay, protection of the excitation circuits of an electric machine from overvoltage in synchronous operation is practically absent.

It is also known a device containing two serially connected thyristors connected in parallel to the excitation winding of a synchronous machine, and the common point of the thyristors is connected to one of the phases of the pathogen armature (US No. 3098959, class 318-181).

Such a connection provides locking of the thyristors without turning off the excitation, however, while the current flow through the thyristors can reach three half-cycles of the exciter frequency and requires the use of thyristors with large values of I t and, accordingly, with large dimensions and mass, which causes certain difficulties in their placement anchored pathogen.

IPC НО2Н 7/08, 7/00

A rotating semiconductor rectifier contains two threshold elements (a zener diode, a varistor), two RL units and two thyristors connected to a semiconductor rectifier and a synchronous machine excitation winding, with one of the thyristors connected in parallel to the rectifier diode of the anode group and the other in opposite to parallel to the diode cathode group of any other rectifier arm.

The drawing shows a schematic diagram of a device.

The scheme of the device includes: the excitation winding of the synchronous machine 1, brushless AC exciter with a semiconductor rectifier 2, threshold elements 3, 4, blocks RL 5 and 6, thyristors 7 and 8.

The excitation winding of a synchronous machine is protected by shunting it in one direction by the diodes of a rotating rectifier, and in the other direction by a protective circuit consisting of thyristors 7 and 8, connected in series with the armature windings of the exciter 2.

When the voltage on the excitation winding 1 reaches the breakdown value of the threshold elements 3.4, thyristors 7 and 8 open and the voltage on the excitation winding 1 decreases. RL 5 and 6 blocks are used to increase the noise immunity of the protective circuit.

The turn-off time of thyristors 7 and 8 with a given excitation does not exceed one half-period of the pathogen frequency. Thus, the average value of the current flowing through the thyristors, compared with the device according to US patent No. 3098959, less than three times. This significantly increases the reliability of the synchronous machine and the pathogen, reduces its size and weight, improves operating conditions.

The device according to the claimed utility model is used in brushless exciters of generators.

Sources of information:

1.I.A. Glebov and S.I.Loginov Excitation and regulation systems for synchronous machines, Leningrad, Energy.

2.A.s. USSR No. 788259, Н02Н 7/08, 1979

3.A.S. USSR No. 534010, HO2H 7/08, 1974

4.US Patent No. 3098959, CL.318-181.1961.

Author: /IllL-N.A. Lazarkov

Applicant:

Claims (1)

Device for overvoltage protection on the excitation winding of a synchronous machine with a brushless AC exciter with a rotating semiconductor rectifier, containing two threshold elements, two RL units and two thyristors connected to a semiconductor rectifier and an excitation winding of a synchronous machine, characterized in that one of the thyristors is turned on in the opposite direction - parallel to the anode diode, and the other parallel to the diode of the cathode group of any other arm of a semiconductor rectifier.