What are the characteristics of synchronous generators and asynchronous generators?

Synchronous generators and asynchronous generators are two common types of generators, each with unique characteristics. The following is a detailed introduction:

Synchronous generator

The relationship between speed and frequency is fixed: the speed of a synchronous generator maintains a strict synchronous relationship with the frequency of the output current, that is, the speed (where is the speed, is the frequency, and is the number of pole pairs). This makes its output frequency stable and can provide stable power supply for devices with strict frequency requirements, such as grid power supply.

Convenient voltage regulation: By adjusting the excitation current, the output voltage can be conveniently regulated. In the power system, it is possible to flexibly adjust the voltage according to the needs of the grid and maintain the stability of the grid voltage.

Adjustable power factor: The power factor can be controlled by adjusting the excitation, which can generate both inductive and capacitive reactive power. This is beneficial for improving the power factor of the power grid, enhancing the quality of electrical energy, and improving the operational efficiency of the power grid.

Complex structure: Generally composed of a stator and a rotor, the rotor requires a DC excitation current to establish a magnetic field, usually requiring a specialized excitation system. The structure is relatively complex, the cost is high, and the maintenance workload is large.

Asynchronous generator

There is a slip between the speed and frequency of an asynchronous generator: there is a slip between the speed of the asynchronous generator and the synchronous speed, and the speed is not a fixed value that fluctuates with changes in the load. However, it can automatically adapt to load changes within a certain range without the need for complex speed control devices.

Simple structure and low cost: There is no DC excitation system, and the rotor structure is simple, usually squirrel cage or wound type. The manufacturing and maintenance costs are relatively low, and the reliability is high. It is suitable for some occasions that require high cost and reliability.

Simple grid connection: During grid connection, there is no need for strict synchronization conditions like synchronous generators. As long as the grid voltage and frequency are similar to those of the generator, it can be easily connected to the grid, and the operation is relatively simple.

Non adjustable power factor: Asynchronous generators need to absorb inductive reactive power from the grid to establish a magnetic field. Their power factor is usually lagging and cannot be directly adjusted, which may have a certain impact on the reactive power balance of the grid. In some situations where high power factor requirements are needed, additional reactive power compensation devices may be required.