SU575754A1 - Device for limiting minimum excitation current of synchronous generator - Google Patents

Description

The invention relates to a technique for the automatic regulation of synchronous generators and can be used to limit their minimum excitation current.

A device is known for limiting the minimum excitation current of a synchronous generator, comprising a phase discriminator whose inputs serve to connect to the voltage and currents of the generator; a comparison circuit whose input serves to connect to the same voltage as the input of the phase discriminator, and the outputs of the comparison circuit and phase discriminator are made on a direct current and are connected in series 1.

A disadvantage of the known limiter of the minimum excitation current is the limitation on an approximately linear relationship between active and reactive power, although this relationship must be non-linear in order to use the generating power of the generator.

The purpose of the invention is to more fully use the generator in the mode of reactive power consumption.

The goal is achieved in the proposed device due to the fact that it is equipped with a total current limiting circuit containing a rectifier at the input that is connected

on the generator current. The rectifier output is connected to a load resistance, which is connected in series with the outputs of the phase discriminator and the comparison circuit.

In order to provide tuning, the total current limits are consistent with the load resistance, additionally introduced stabilizers and a variable resistor are included.

FIG. 1 is a schematic diagram of the proposed device for limiting the minimum excitation current of a synchronous generator; in fig. The 2 curves characterizing the operation of the device (on the axes of the ordinates; | 1, the values of the active and reactive components of the current are plotted).

The device for limiting the minimum excitation current of the generator comprises an intermediate voltage transformer 1; intermediate current transformers 2, 3 and 4; phase discriminator 5, consisting of rectifiers 6, 7, resistor 8 and filter 9; comparison circuit 10, consisting of a rectifier 11, a stabilizer (Zener diode) 12, and a filter 13; total current limiting circuit 14 consisting of rectifier 15, stabilizer (zener diode) 16, resistors 17, 18, and filter

nineteen; output circuit 20 consisting of diode 21 and resistor 22.

The device works as follows.

The input of the phase discriminator 5 is the voltage between phases B and C from the secondary windings of the intermediate voltage transformer 1 and the voltage proportional to the current of phase A or phases A and C simultaneously from the secondary terminals of the intermediate current transformers 2 and 3. These voltages are are summed electrically and fed to the rectifiers 6 and 7. The voltage from the rectifier output b and 7 is fed to the filter 9.

The rectifier II of the comparison circuit 10 is supplied with voltage from the intermediate voltage transformer 1, the rectified voltage is fed in series to the Zener diode 12 and the filter 13. To the input of the rectifier 15 of the total current limiting circuit 14 is proportional to the current of the phase A, from the intermediate current transformer 4. From the output of the rectifier 15, the voltage goes through the Zener diode 16 to the resistors 17, 18 and the filter 19. The voltage from the output of the filter 9 of the phase discriminator 5 is summed with the signal from the output of the filter 19 but to the total current, and the total signal is compared with the voltage decreasing from the output ((iltra 13 of the comparison circuit 10. The resultant signal through the output chain 20 is fed to the actuator in the excitation control system.

If the device does not have a total current limiting circuit 14, the limitation is performed in accordance with the characteristic Q shown in FIG. 2

When using the total current limiting circuit 14, the current transformer 4 is supplied with a phase A current. At a certain setpoint value, which is determined by the number of zener diodes 16, the output of the circuit 14 is the voltage added to the output

the voltage of the phase discriminator 5 and the characteristic nonlinear limiting characteristic} (curve b, fig. 2). The degree of non-linearity of the limiting characteristic is adjusted by the variable resistor 17, and the approximation of the limiting characteristic to the limit (curve in, Fig. 2) is determined by adjusting the resistor 8 of the phase discriminator 5.

Claims (2)

1. A device for limiting the minimum excitation current of a synchronous generator, containing a phase discriminator, the inputs of which serve to connect to the voltage and currents of the generator, a comparison circuit whose code serves to connect to the same voltage as the phase discriminator input, and the outputs of the comparison circuit and the phase discriminator are made on a direct current and connected in series, characterized in that, in order to use the generator more fully in the mode of reactive power consumption, it is equipped with minutes limitation on the total current, the input of which serves for connection to a current generator and comprising a rectifier at the input, the output of which is connected to soprotivlenie.m load, which is included in series with vyhoda.mi phase discriminator and a comparison circuit. 2. The device according to claim 1, characterized in that, in order to provide adjustment of the full current limiting circuit, additionally introduced zener diodes and an alternating resistor are included in series with the resistance of the load. Sources of information. Acquisition. Into iuniMenie during examination: . Proceedings of VEI, wob. 73, pp. 14-17. G5 Or- , about