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Introduction to the composition and requirements of diesel generator excitation system

June 17, 2022
The excitation system is an important part of synchronous generator. The performance and reliability of the excitation system directly affect the quality of power supply and the reliability and stability of synchronous generator operation. This article introduces the composition and requirements of diesel generator excitation system.
Composition of excitation system
When a synchronous generator is running, the excitation winding needs DC current from DC power supply to establish a constant magnetic field. To maintain a constant output voltage during operation, the excitation current must be adjusted in time with the change of load. These are the basic tasks that the excitation system of a synchronous generator should perform, therefore, excitation consists of two parts.
excitation power source (unit) - supplying DC excitation current to the excitation winding of the synchronous generator.
Excitation regulator - manually or automatically adjusts the magnitude of the excitation current output from the excitation power unit to meet the requirements of the generator operation, according to the operating status of the generator set.
The excitation control system, which consists of the synchronous generator and the excitation system together, exerts control over the excitation power source of the excitation system according to the changes of the voltage, current or other parameters of the synchronous generator.
Requirements of the excitation system
Synchronous generators and their excitation systems are closely linked to the development of electronic technology. In order to meet the standards and requirements put forward by users for synchronous generators, the excitation system should have the following properties.
1、Have enough excitation power to provide the required excitation current when the generator is no-load and full-load.
2, has good response characteristics, the excitation system should ensure that the synchronous generator system at rest has high steady-state voltage accuracy, the output characteristics of the excitation system and the generator itself should strive to be consistent with the regulation characteristics, in the generator load changes can occur when the short circuit, can timely adjust the excitation current to maintain the generator output voltage basically unchanged, and make the protection device reliable action.
3, with a certain degree of strong excitation capacity, for some reason caused by a serious drop in the generator output voltage or start similar capacity of asynchronous motor, can quickly provide a large enough excitation current in a short period of time, so that the voltage quickly back to a given value.
4, the excitation device should be reliable, small in size, light in weight, easy to use and maintain.