Types of Generator Excitation Systems
The excitation system is divided into three main types based on the magnetic field current generation source
Direct current excitation systems
In this type of excitation system, direct current generators are used as a source of the current generation, which provides the current required for excitation through sweepers. The exciter may be rotated by an independent motor or generator axis, or it may be self-excitation or independent excitation. In the independent excitation mode, the excitation current of that excitation system is provided through an auxiliary excitation system that has a permanent magnetic field. Of course, these types of systems are old, and today alternating current and static systems are used. Some of these types of systems use an amplidyne voltage regulator
Alternating current excitation systems
In this type of excitation system, alternating current generators are used to generate the required excitation current in the rotor winding of the main generator. In this case, the exciter is usually placed on the main axis of the turbogenerator. Then the output current of the exciters is rectified and the direct current produced is transferred to the excitation coil of the main generator. The rectifier system can be stationary or rotating
Systems with static rectifier -
If the rectifier system is static, the direct current output produced by them must be transferred to the excitation coil of the main generator through brushes. In the case of using uncontrolled diode rectifiers, the alternating current is controlled by the exciter excitation regulator, which in turn is responsible for controlling the output voltage of the exciter
Systems with rotary rectifier -
In these types of systems, due to the rotating rectifiers, the need to use a brush or coal is eliminated and the direct current output of the exciter is directly applied to the main generator. The outline of this type of system is known as the brushless excitation system
Early systems of alternating current excitation used a combination of magnetic and rotary amplifiers as regulators, But most other systems use electronic amplifiers
Static current stimulation systems
In this method, the excitation current of the generator is supplied from an independent external source, which is usually a battery, and for proper use and increasing the life of the batteries, after starting the generator, this source is removed from the circuit and the power of the generator itself It is replaced by power electronics