Synchronous Generator and Reactive Power

Synchronous generators are widely used in electrical power systems to convert mechanical energy into electrical energy. One of the important characteristics of a synchronous generator is its ability to generate and absorb reactive power. Reactive power is a component of electrical power that is responsible for creating and sustaining magnetic fields in inductive loads such as motors and transformers.

1. Definition of Reactive Power:
Reactive power is the power that oscillates between the generator and the load due to the presence of inductive or capacitive elements in the circuit. It is measured in volt-amperes reactive (VAR) and is denoted by the symbol Q. Reactive power does not perform any useful work but is essential for maintaining voltage levels and ensuring the stability of the power system.

2. Generation of Reactive Power:
Synchronous generators can generate reactive power when they are connected to an electrical grid. The generator, when operated with a leading power factor (lagging reactive power), supplies reactive power to the grid. This is achieved by adjusting the excitation current or field voltage of the generator. By increasing the excitation, the generator produces a leading current that leads the voltage waveform. This leading current supplies reactive power to the grid.

3. Absorption of Reactive Power:
Synchronous generators can also absorb reactive power from the grid when they are operated with a lagging power factor (leading reactive power). In this mode, the generator acts as a load and consumes reactive power from the grid. By decreasing the excitation, the generator produces a lagging current that lags behind the voltage waveform. This lagging current absorbs reactive power from the grid.

4. Importance of Reactive Power Control:
The ability of synchronous generators to generate and absorb reactive power is crucial for maintaining voltage stability and regulating the power flow in electrical power systems. By controlling the excitation levels, the generator can adjust the amount of reactive power it supplies or absorbs. This control helps to maintain system voltages within acceptable limits and prevents voltage collapse or instability.

In conclusion, synchronous generators have the capability to both generate and absorb reactive power. This ability is essential for maintaining voltage stability and regulating power flow in electrical power systems. By adjusting the excitation levels, the generator can control the amount of reactive power it supplies or absorbs, ensuring the proper functioning of the power system.