Second, the characteristics of the generator and excitation current
1, voltage regulation
The automatic adjustment of the excitation system can be seen as a negative feedback control system that is regulated by voltage. The reactive load current is the main cause of the voltage drop at the generator terminal. When the excitation current is constant, the terminal voltage of the generator will decrease as the reactive current increases. However, in order to meet the user's requirements for power quality, the terminal voltage of the generator should remain basically unchanged. The way to achieve this requirement is to adjust the excitation current of the generator as the reactive current changes.
2. Adjustment of reactive power:
When the generator and the system are operated in parallel, it can be considered to operate with the busbar of the infinitely large capacity power supply. The excitation current of the generator must be changed, and the induced potential and the stator current also change. At this time, the reactive current of the generator also changes. When the generator is operated in parallel with an infinite capacity system, in order to change the reactive power of the generator, the excitation current of the generator must be adjusted. The generator excitation current that is changed at this time is not so-called "regulation", but merely changes the reactive power that is sent to the system.
3. Distribution of reactive load:
The parallel-moving generators distribute the reactive current proportionally according to their respective rated capacities. Large-capacity generators should bear more reactive load, while smaller ones provide less reactive load. In order to realize the automatic distribution of reactive load, the excitation current of the automatic high-voltage regulation can be used to change the excitation current of the generator to maintain the terminal voltage constant, and the inclination of the voltage regulation characteristic of the generator can be adjusted to realize the parallel operation of the generator. Reasonable distribution of reactive load.
