SU1577068A1 - Device for automatic regulation of synchronous generator excitation with exciter - Google Patents

Abstract

The device relates to electrical engineering. The purpose of the invention is to increase the stock of dynamic stability of parallel operation of synchronous generators. A device for automatically controlling the excitation of a synchronous generator is a series-connected voltage measuring unit connected from its input to the generator leads via a voltage transformer, an amplifier covered by a nonlinear flexible negative feedback containing the differentiator and limiters of the maximum values of the input voltage an output current, and a driver connected from the side of its output to the excitation winding of the synchronous generator. A new device is the installation at the output of a differentiator of a flexible coupling circuit of a nonlinear element with a functional dependence of its resistance on the magnitude of the voltage. The installation of a nonlinear element in a nonlinear flexible negative feedback link circuit reduces the duration of the maximum output current of this link due to an earlier onset of the moment of discharge of the capacitor, which is part of the differentiator, and a decrease in the maximum value to which it increases during charging. a capacitor occurring in the process of forcing an excitation caused by a decrease in the voltage on the generator leads when a short circuit occurs. Reducing the duration of the maximum output current of a flexible negative feedback link reduces its retarding effect on the process of increasing the control signal passing through the main feedback channel of the automatic excitation control system and directed at a short circuit to an increase in the voltage of the synchronous generator winding. As a result, the growth rate of the braking torque on its shaft increases, the movement of the rotor in the direction of increasing the magnitude of its angle of departure slows down and eventually the likelihood of disturbance of the dynamic stability caused by a short circuit decreases. At the same time, with the right choice of limiting levels, the effectiveness of flexible feedback from the point of view of damping low-frequency self-recoil is almost not reduced. 2 Il.

Description

3

The invention relates to electrical engineering and can be used in excitation systems for general industrial synchronous generators.

The purpose of the invention is to increase the limit of the dynamic stability of a synchronous generator with aperiodic disturbances in the network having a discontinuous nature.

FIG. 1 shows a diagram of the operation of the device; in fig. 2 is a block diagram of a device for automatically controlling excitation of a synchronous generator with an exciter.

The device for automatic regulation of the excitation of the synchronous generator 1 consists of

connected to the sensor 2 for 20

solid lines, dashed lines are shown to compare the course of processes in the case of the use of the known device.

In the initial stationary mode, the generator voltage Ur / 0 and the exciter UB {O. equal to the nominal values, the input voltage on the flexible feedback link is some non-zero value UBJf,., currents in the IAM $ differentiator circuit and in the feedback output circuit i

are zero. At time t.

you

f5 a short circuit occurs, accompanied by a decrease in the generator voltage by 5% (curve 14, fig. 2). Under the influence of an automatic excitation controller

synchronous generator, automatic excitation controller 3 and driver 4, which is a set of a rectifying transformer connected to the outputs of a synchronous generator, and a thyristor converter, the power input of which is connected to the output of the rectifying transformer, the control input is connected to the output of the automatic excitation controller, and the output is connected to the excitation winding of the synchronous generator. The automatic regulator consists of a voltage measuring unit 5 connected in series, a first amplifier 6 connected to the measuring unit through its first control input, an output low-pass filter 7, and also includes a non-linear node 8 of a flexible negative feedback encompassing the amplifier 6 and connected from the input side to the output terminals of this amplifier, and from the output side to its second control input. The non-linear node 8 of the flexible negative feedback includes serially connected low-pass input filter 9, differentiator 10, non-linear element 11, whose resistance decreases with increasing voltage, a second amplifier 12 and a limiter 13 of the maximum current output level of the link flexible negative feedback.

The operation of the device is illustrated by the diagrams shown in FIG. one

in this case, a rapid increase in voltage occurs at the output of amplifier 6 (curves 15, Fig. 2). The current Ddlf in the differentiator circuit (curves 16, fig. 2) increases with some delay in relation to the voltage at the input of the flexible negative feedback link. Accordingly, with the increase of this current, the output current i ВЬ. | X of this link increases (curves 17, fig. 2). At time t, it increases to the setpoint of limiter 13, i.e. - up to its maximum value and continues to remain at this level for some time ut. At time t, the voltage at the output of the differentiator reaches a value corresponding to the fracture of the current-voltage characteristic of the nonlinear element 11, its resistance sharply decreases, as a result of which it also slows down after a short period of time. it begins to subside. At time t

(t)

this current becomes equal to the value corresponding to such an amplifier output current, at which the limiter in the amplifier output circuit goes to the inactive zone, after which the amplifier's output current begins to fall. The duration of the maximum current flow of the output of a flexible feedback link when a nonlinear resistor is found in the output circuit of the differentiator (иt,) is significantly less than in its absence (Јta), as a result of which

In this case, the rate of increase of the excitation voltage increases markedly (curves 18, fig. 2), the increment of the braking torque on the shaft of the synchronous generator increases, as a result of which the dynamic instability is prevented (fig. 1). The shaded area in the lower graph of FIG. 1 is a quantitative measure of the positive effect that the device provides from the point of view of dynamic stability.

To the extent that the increase in the dynamic stability of the synchronous generator is achieved, the quality of the power supply to consumers is also improved: the more significant integral increment of the excitation voltage in the postemergency mode that it provides leads to a more rapid recovery of the voltage on the outputs of the generator and in the adjacent power area.

Claims (1)

Invention Formula Device for automatic regulation of excitation sync77068 generator with a pathogen containing a measuring unit connected from the input side to the outputs of the sensors of the operating parameters a synchronous generator, the first amplifier, the output of which is intended to be connected to the control input of the exciter, and the first summing Q input of the control of the first amplifier is connected to the output of the measuring element, a flexible negative node. feedback, made in the form of a differentiator low-pass filter between the jc, the second amplifier and the maximum current limiter whose output is connected to the second summing control input of the first amplifier, non-linear element, characterized in that, in order to increase the dynamic stability of the synchronous generator with aperiodic disturbances in the network, the nonlinear element has a resistance inversely proportional to the applied voltage, and is connected between the differentiator a second amplifier. 20 25 15 Fig f FIG. 2