In thermal power plants, fans and pumps are the main energy-consuming devices. Usually, 15 to 20% of the input energy is consumed by motors and fans or the pump itself, and about 35 to 50% of the input energy is controlled by dampers or valves. The use of throttling is consumed, so there is great potential for energy-saving retrofitting of turbines and pumps in power plants. If a motor speeder is used to replace the original damper, damper, and valve to regulate the flow, a significant energy saving effect will be achieved.

The frequency conversion speed regulation uses the variable frequency power source to change the frequency of the motor stator winding, thus changes the synchronous speed to realize the speed regulation. The frequency conversion system first rectifies the alternating current in the power grid into direct current, and then inverts the inverter into an alternating current with adjustable frequency, and supplies the alternating current motor to change the rotational speed of the motor. This method has high efficiency, wide range and high precision speed control performance. The complete series of specifications can meet various needs. Therefore, it is widely used and is the most ideal speed regulation method for future development. In particular, current source high-voltage frequency converters have obvious advantages in places where dynamic accuracy is required, and are suitable for applications in rolling mills and lifting equipment. The three-level high-voltage frequency conversion device, due to its fewer devices and relatively simple structure, is more suitable for 3.3kv or 4.16kv motor applications. The high-voltage frequency converter with multi-level structure of the power unit is suitable for fans and pumps, but it is not suitable for use in places with high dynamic requirements.

The frequency conversion regulation technology is a relatively advanced and ideal adjustment technology. Its power-saving effect is obvious, and its investment recovery cycle is short. Therefore, its comprehensive economic efficiency is still relatively high. From the viewpoint of energy conservation, the use of frequency converter technology is an ideal choice.