Do you understand the working principles of various synchronous generators

Generator voltage automatic regulator definition: A synchronous generator regulator that maintains the synchronous generator voltage at a predetermined value or changes the terminal voltage as planned. When the terminal voltage and reactive power of the synchronous motor change, the output current of the exciter is automatically controlled according to the corresponding feedback signal to achieve the purpose of automatically adjusting the terminal voltage or reactive power of the synchronous motor.

Automatic voltage regulators (AVR) for synchronous generators can be divided into three categories: thyristor automatic voltage regulation, TD1 type carbon resistance automatic voltage regulation, and phase compound excitation automatic voltage regulation. The following are the working principles of these three types of synchronous generator voltage automatic regulators.

1. SCR automatic voltage regulation

This voltage regulation method refers to using a thyristor connected in series or incorporated into the excitation circuit to control the excitation current, so that the output voltage of the generator can be automatically adjusted as the load changes. There are many ways to control the thyristor: one is to use an oscillation circuit composed of a single-junction transistor to generate a trigger pulse and change the charging voltage of the capacitor, thereby controlling the time when the trigger pulse is generated and changing the conduction angle of the thyristor; the other is to use The switching characteristics of the triode changes the charging voltage of the capacitor, controls the conduction time of the triode to generate a trigger pulse, and can also control the conduction angle of the thyristor.

2. TD1 type carbon resistance automatic voltage regulation

This voltage regulation method is used in the 6135ZD diesel generator set. Its working principle is: when the generator load is at the rated value, the voltage automatic regulator remains stable. At this time, the generator’s excitation current, voltage and main The excitation current is stable. As the load on the motor increases, causing the voltage to decrease, the voltage automatic regulator begins to adjust the carbon resistor to reduce its resistance, thereby increasing the excitation current of the generator and causing the output voltage of the generator to rise; conversely, the load decreases. hour, the voltage automatic regulator adjusts the resistance of the carbon chip resistor to increase, thereby reducing the excitation current and causing the voltage to drop.

3. Phase compound excitation automatic voltage regulation

For special equipment with large load changes during startup and operation, it is better to use the phase compound excitation automatic voltage regulation method. Therefore, in the power supply of special equipment, the generator control part mostly adopts the phase compound excitation automatic voltage regulation method. The basic principle of phase compound excitation automatic voltage regulation is: when the generator is no-load, the residual magnetization voltage of the armature tap winding is phase-shifted by 90° through the linear reactor. After being rectified by the three-phase bridge rectifier, the output DC current flows to the magnetic field. The winding is excited. When the residual magnet voltage is too low, direct current can be used for charging.

When the generator is loaded, its load current passes through the primary winding of the current transformer to produce a secondary current that is proportional to the primary winding current. This current can vary with the size of the required excitation current when the load changes with different power factors. Increase or decrease accordingly. With appropriate parameters, the excitation current required by the generator is supplied, so the voltage can be automatically adjusted to keep the voltage stable within a certain range. Because of its characteristics, it is widely used in engineering construction and special equipment.