Abstract: This paper introduces the analysis and solutions to some problems in the selection, control, and commissioning of frequency converters through the practical application of high-voltage frequency converters in the energy-saving retrofit of fans in thermal power plants. Keywords : High-voltage frequency converter; Fan energy saving; Retrofit 0 Introduction The No. 8 boiler of Juhua Group's thermal power plant is a 280t/h boiler, using a dual induced draft fan type, with fan model Y4-6o-11N. 22.5D, equipped with a three-phase AC asynchronous motor with a rated power of 630kW and a voltage of 6kV. The damper adopts baffle adjustment, and the normal operating opening is generally only about 50%, forming a pressure difference on both sides of the baffle, causing throttling losses; at the same time, the fan baffle actuator is a high-torque electric actuator, which has a high failure rate and a low automatic operation rate of the fan. Therefore, we have modified the induced draft volume adjustment method, using frequency conversion speed regulation technology to control and adjust the air volume to achieve energy saving, consumption reduction, and improve the level of automation of regulation. 1. Selection of Variable Frequency Drive (VFD) Capacity Generally, the VFD capacity is selected in the same way as the motor capacity to allow for speed adjustments within the rated output range. However, in actual production, the appropriate VFD capacity is usually selected based on the actual operating conditions. This satisfies production needs while saving on VFD investment and reducing the need for auxiliary facilities. Based on the configuration and normal operating conditions of the #8 boiler's induced draft fan at this plant, it was learned that the designers considered the presence of a desulfurization device in the duct and the good adjustment characteristics of the damper opening at around 70%, thus configuring a 6300kW motor. Simultaneously, the induced draft fan power under rated conditions was analyzed, and it was found that the fan power would not exceed 350kW under various operating conditions. If VFD speed control is used, with the damper fully open, the throttling loss will be significantly reduced, and the fan power will still not exceed 350kW. Therefore, a 4000kW VFD should be selected to meet the above requirements for fan speed adjustment under various operating conditions. 2. Performance and Benefit Prediction After Adopting Variable Frequency Speed ​​Control The main characteristic of adopting variable frequency speed control is the elimination or reduction of throttling losses by the damper. The energy-saving effect is related to the fan's performance, operating conditions, and the damper opening degree. [b][align=center]For details, please click: Application of High-Voltage Variable Frequency Drives in Fan Energy-Saving Retrofit[/align][/b]