The core role of the excitation system in the generator

In simple terms: The excitation system is the 'power supply' that provides a DC magnetic field to the generator rotor, and it is the core control brain of the generator.

Main Functions

1. Establish a magnetic field and generate electricity
The generator stator generates electricity by cutting through the rotor's magnetic field. The excitation system supplies DC to the rotor to establish a stable rotor magnetic field, which is the fundamental prerequisite for the generator to produce voltage.

2. Regulate terminal voltage
By automatically adjusting the excitation current, it precisely controls the generator's output voltage, ensuring the stability of the grid voltage. This is a key method for grid voltage regulation.

3. Regulate reactive power
By changing the excitation level, the generator can increase or decrease the reactive power sent to or absorbed from the grid, reasonably distributing reactive load among units and improving the grid power factor.

4. Improve grid stability limit
When the system experiences disturbances or oscillations, the excitation system can quickly increase excitation, enhancing the generator's synchronizing torque and strengthening the static and transient stability of the power system.

5. Forced excitation and fault protection
During a grid short-circuit fault, forced excitation quickly increases rotor current, helping the system recover rapidly; during faults, it can also work with protection systems to quickly demagnetize, preventing generator overvoltage and damage.

6. Reasonable distribution of reactive load
For multiple generators running in parallel, excitation adjustment ensures a reasonable distribution of reactive power, avoiding unit overload.

In one sentence
Without excitation, a generator cannot produce electricity.