What Is the Excitation System for Generator

by Starlight Generator dieselgeneratortech

1. Excitation control system

Excitation system is an important part of AC synchronous generator, which controls the voltage and reactive power of the synchronous generator. In addition, the speed control system controls the speed (frequency) and active power of the prime mover and generator. Both are the main control systems for the generator set. The excitation control system is a feedback control system composed of synchronous generator and its excitation system.

The main role of the excitation system

1) Adjust the excitation current according to the change of generator load to maintain the terminal voltage as a given value;

2) Control the parallel operation of reactive power distribution between generators;

3) Improve the static stability of the parallel operation of the generator;

4) Improve the transient stability of the parallel operation of the generator;

5) When there is a fault inside the generator, de-excitation is performed to reduce the degree of fault loss

6) Maximum excitation limit and minimum excitation limit are applied to the generator according to the operation requirements.

Generator excitation system is a general term for the power supply and its accessory equipment that supply the excitation current of synchronous generator. It is generally composed of excitation power unit and excitation regulator.

Usually, generator excitation system includes DC exciter, brushless exciter, and AC exciter, etc.

The excitation regulator is the main part of the excitation control system. It generally senses the change of the generator voltage and then exerts a control effect on the excitation power unit. The excitation power unit does not change the excitation voltage of its output until the excitation regulator has changed the given control command.

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.