Analysis of the effect of using a variable speed drive on the power consumption of the ID fan drive motor

Cirebon Coal-Fired Power Plant Unit 1 uses an Induced Draft Fan (ID Fan) to regulate flue gas flow and maintain negative pressure inside the boiler. The current ID Fan control system still applies a blade pitch position mechanism with constant motor speed, resulting in high power consumption ranging from 2,547.9 kW to 4,311.2 kW. This condition is inefficient because the motor runs at constant speed regardless of changing load demands. This study aims to design a Variable Speed Drive (VSD) to control the ID Fan motor speed and analyze its impact on power consumption. The research was conducted using simulation with MATLAB/Simulink R2021a software. The VSD design consists of three main components: a three-phase rectifier, a buck converter-based DC link, and a three-phase PWM inverter, adjusted to meet the ID Fan operational pressure limit of 8.0 to 10.0 kPa. The simulation results show that with the implementation of VSD, the system pressure can be maintained within the safe range of 8.5 to 9.7 kPa, and the motor speed can be adjusted according to airflow demand. Power consumption decreased from 2,645.7 kW to 1,273.1 kW after implementing VSD, resulting in an energy saving of 62.1%. The application of VSD is proven to be effective in improving energy efficiency in the ID Fan system at the Cirebon Coal-Fired Power Plant Unit.