1. Composition
of the excitation regulator
Generator semiconductor
excitation regulator is mainly composed of three basic units: measurement
comparison, comprehensive amplification and phase shift trigger. Each unit is
composed of several links.
1) The measurement
comparison unit consists of voltage measurement, comparison setting and
adjustment. The voltage measurement section includes measuring rectification
and filtering circuit, and some have positive sequence voltage filters. The
measurement comparison unit is configured to measure the converted DC voltage
proportional to the generator terminal voltage and compare it with a reference
voltage corresponding to the rated voltage of the generator to obtain a
deviation of the generator terminal voltage from its given value. The voltage
deviation signal is input to the integrated amplifier unit, and the positive
sequence voltage filter can improve the accuracy of the regulator when the
generator is running asymmetrically, and can improve the excitation capability
when asymmetric short circuit occurs. The function of the adjustment link is to
change the adjustment coefficient of the regulator to ensure stable and
reasonable distribution of reactive power between the gensets in parallel
operation.
2) The comprehensive
amplification unit synthesizes and amplifies the measurement signal, in order
to obtain the good static and dynamic characteristics of the adjustment system
and meet the operation requirements, in addition to the voltage deviation signal
from the basic device, sometimes it is necessary to synthesize other signals
such as stable signals, limit signals, and compensation signals from auxiliary
device according to requirements. The integrated amplified control signal is
input to the phase shifting trigger unit.
3) The phase shifting
trigger unit includes synchronization, phase shifting, pulse formation, and
pulse amplification. According to the change of the input control signal, the
phase shifting trigger unit changes the phase of the trigger pulse output to
the thyristor, that is, changes the control angle (or phase shift angle), so as
to control the output voltage of the thyristor rectifier circuit to adjust the
excitation current of the generator. In order to trigger the pulse to touch off
the thyristor reliably, it is often necessary to use the pulse amplification
link for power amplification.
The synchronization
signal is taken from the main loop of the thyristor rectifier, ensuring that
the trigger pulse is emitted when the thyristor anode voltage is in the
positive half cycle, so that the trigger pulse is synchronized with the main
loop.
There is usually a
manual part in the excitation system. When the automatic part of the excitation
regulator fails, it can be switched to the manual mode.
2.
Requirements for the excitation regulator
1) High reliability and
stable operation. Corresponding measures should be taken in circuit design,
component selection and assembly process.
2) Good steady state and
dynamic characteristics.
3) The time constant of
the excitation regulator should be as small as possible.
4) The structure is
simple, the maintenance and repair is convenient, and gradually achieves
systemization, standardization and generalization.
The above related
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