Generator excitation method and working principle
Generator excitation
The generator excitation system is a general term for the power supply and its accessory equipment that supply the synchronous generator excitation current. It generally consists of two main parts: the excitation power unit and the excitation regulator.
The generator excitation system includes a DC exciter, a non-excitation machine, an AC exciter, and the like. In the past ten years, due to the emergence and use of new technologies, new processes and new devices, the excitation mode of generators has been continuously developed and improved. In the aspect of automatic adjustment of the excitation device, many new types of adjustment devices have been continuously developed and promoted.
System composition
The excitation power unit supplies an excitation current to the synchronous generator rotor; and the excitation regulator controls the output of the excitation power unit based on the input signal and a given adjustment criterion. The automatic excitation regulator of the excitation system plays a considerable role in improving the stability of the parallel unit of the power system. In particular, the development of modern power systems has led to a trend of lowering the stability limit of the unit, and has also led to the continuous development of excitation technology. The excitation system of the synchronous generator is mainly composed of two parts: a power unit and a regulator (device). as the picture shows:
The excitation power unit is a portion of the excitation power source that supplies a DC excitation current to the rotor winding of the synchronous generator, and the excitation regulator controls the output of the excitation power unit according to an input signal required by the control and a given adjustment criterion. The entire system consisting of the excitation regulator, the excitation power unit and the generator itself is called the excitation system control system. The excitation system is an important part of the generator, which has a great impact on the safe and stable operation of the power system and the generator itself.
main role
The main functions of the excitation system are:
1) Adjust the excitation current according to the change of the 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 a fault occurs inside the generator, de-excitation is performed to reduce the degree of fault loss;
6) The maximum excitation limit and minimum excitation limit are applied to the generator according to the operation requirements.
