Introduction of excitation system

The excitation system is the power system and its ancillary equipment supplied to excitation current for synchronous generator. Excitation Systems includes excitation power and excitation device. 

The main body of excitation power is exciter or excitation transformer. 

The excitation device is an electrical control device that controls and adjusts excitation current besides excitation power in excitation systems of synchronous generator. According to different specification, type and operating requirement, it consists of regulating panel, control panel, de-excitation screen and rectifier separately. 

Excitation system is the important part of generator and is a must-have equipment for power stations. It also has significant influence and effect on the safe and stable operation of the power system and the generator itself. 

The main function of the excitation system
1. Maintain voltage for a given value of machine side according to the generator load changes to adjust the excitation current corresponding.

2. Control reactive power allocation between parallel operation of the generator.

3. Improve static stability of the generator parallel operation.

4. Improve transient stability of the generator parallel operation.

5. Deexcitation to reduce loss fault when internal generator failure.

6. According to operational requirements to limit the maximum excitation and the minimum excitation of generator.

Classification of the excitation
As per the excitation mode of DC generator, it can be divided into separate excitation, shunt excitation, cascade excitation, and compound excitation, etc.
According to the way of rectifying:
1. Rotating type excitation 
Rotating type excitation includes DC & AC and brushless excitation.
2. Static type excitation 
Static type excitation consists of potential source static exciter and composite power static exciter.