SU613473A1 - Synchronous generator excitation limiting device - Google Patents

Description

one

This invention relates to the field of voltage regulation in electrical networks.

Devices are known for limiting the upper excitation limit of synchronous generators, in which it is necessary to convert the rotor current into alternating current, which enters the measuring unit of the upper excitation limit limiter.

Devices are known for limiting the lower excitation limit.

The closest to the invention is the limiter, which contains a generator voltage meter, a generator current meter, an adder, the inputs of which are connected to a voltage meter and generator current converter, an amplifier, whose input is connected to the output of the adder. generator excitation torus, and a reference element connected to the second input of the adder.

A disadvantage of the known excitation limiter is that the characteristic of the available reactive power of the generators as a function of its active power is approximated by a linear characteristic or by means of a piecewise linear approximation containing a large methodical error, and for

piecewise linear and linear approximation, it is necessary to reveal the reactive n active components of generator currents, convert them to scalar values and

perform with them algebraic operations. For this purpose, slider measuring organs containing phase discriminators are used.

In addition, this device may limit only the lower and defined excitation.

The purpose of the invention is to simplify the device and distribute the range of use of the limiter.

For this purpose, an active current line has been used in the quality of the generator-to-voltage converter.

A non-linear approximation of the available reactive current of the generator from its active current and voltage was carried out in the device, which almost eliminated the methodological error of tuning the limit of the lower excitation level. This device can be used to limit the upper excitation limit without additional control of the rotor current of the generator, since the dependence of the available reactive current of the generator on its active current and voltage at the nominal rotor current is a circle whose center is offset relative to the origin by generator.

The total current sensor used in the proposed limiter is simple, since it is the active resistance flowing around the current.

The block diagram of the inclusion of the proposed device is shown in the drawing.

It contains the voltage meter 1 of the generator of the limiter of the upper or lower excitation limits; generator 2 current meter; generator 3 current to voltage converter; adder 4 voltage; reference element 5 connected to the second input of the adder; the amplifier 6, the installation device 7 of the excitation controller 8 for the synchronous generator; synchronous generator 9.

If the device is used as the upper excitation limiter, then in the adder the limiter voltage proportional to the generated reactive current coincides in phase with the voltage of the generator coming from the meter 1.

If the device is used as a limiter for the lower excitation limit, then in the adder the limiter voltage proportional to the reactive current consumed coincides in phase with the voltage supplied by the meter.

The operation of the limiter is carried out as follows.

If the reactive current of the generator does not exceed the permissible maximum limits in the mode of transport and under-excitation, the setpoint of the limiters in the adder 4 is not reached and they do not work. If the generator's reactive current approaches the permissible limit in the over-excitation or pedal excitation mode, the limitation of the corresponding limit is triggered, and at its output there appears a signal acting through the amplifier 6 on the amplifier of the excitation controller 8 or on the installation device 7 of the controller 8 and

translates generator 9 into the region of permissible modes.

If the active current of the generator changes, the corresponding voltage from the output of the functional converter 3 is fed to an adder with an angle of 90 ° relative to the voltage of the generator and changes the setpoint of the allowable value of the generator's reactive current in accordance with its available

power.

The described excitation limiter provides a more complete use of the available reactive power of the generator and, consequently, increases the efficiency of the electrical network mode, and also significantly simplifies the design of the limiters compared to the existing ones and allows using the apparatus to limit the lower and upper excitation limits.

same construction.

When using a relay that distinguishes the over-excitation mode from the under-excitation mode, it is possible to carry out the adjustment of the limiter settings, which can be used simultaneously to limit the upper and lower excitation limits.

Claims (1)

Invention Formula A device for limiting the excitation of a synchronous generator, containing a generator voltage meter, a generator current meter connected to the input of the generator current-voltage converter, an adder, the inputs of which are connected to the generator voltage meter and generator current-voltage converter, amplifier whose input is on to the output of the adder, and the output serves to connect to a generator excitation regulator, and a reference element connected to the second input of the adder, characterized in that, in order to simplify and extend the field of use, a resistance is used as a converter of the current to the voltage in the voltage.