Synchronous and asynchronous generators are both devices used to convert mechanical energy into electrical energy. However, they operate differently and have distinct characteristics. Here are the main differences between the two:
Synchronous Generator: A synchronous generator rotates at a constant speed that is synchronized with the grid frequency. It generates electricity at a fixed frequency (e.g., 50 Hz or 60 Hz) regardless of the load connected to it. The rotor of a synchronous generator turns at the same speed as the rotating magnetic field produced by the stator, which ensures synchronization with the grid.
Asynchronous Generator (also known as Induction Generator): An asynchronous generator does not have a fixed rotational speed and is not inherently synchronized with the grid frequency. Instead, it operates at a speed slightly lower than synchronous speed. It relies on the concept of induction to induce electrical current in its windings when it is connected to a grid. The speed of an induction generator is influenced by the load it is driving.
Synchronous Generator: Synchronous generators require an external force to initially bring them to synchronous speed before they can start generating electrical power. This is typically achieved by connecting the generator to an already synchronized power source and then gradually increasing its mechanical input to match the grid frequency.
Asynchronous Generator: Asynchronous generators are inherently easier to start since they do not need to match the grid frequency precisely. They can self-start when connected to a power source, such as a grid, due to their asynchronous nature.
Synchronous Generator: The speed of a synchronous generator is rigidly fixed and cannot be easily adjusted, making it less flexible in certain applications. However, in power plants, synchronous generators are commonly used because their fixed speed helps maintain grid stability.
Asynchronous Generator: Asynchronous generators have variable speed and can adjust their rotational speed according to the load. This feature makes them suitable for certain applications like wind and hydroelectric power generation, where the available mechanical input may fluctuate.
Synchronous Generator: Synchronous generators are commonly used in large power plants, where their constant speed and grid synchronization are essential for maintaining the stability of the electrical grid.
Asynchronous Generator: Asynchronous generators find applications in variable speed applications like wind turbines, small-scale hydropower plants, and certain industrial applications where a constant grid synchronization is not required.
In summary, the main differences between synchronous and asynchronous generators lie in their synchronization with the grid, starting mechanisms, speed control, and the specific applications they are most suited for.