Study on Comparison and Optimization of Power Factor Compensation Methods According to Operating Conditions of Induction Motors

Induction motors, as typical inductive loads, have the characteristic of lagging power factor because of the reactive power required to generate the rotating magnetic fields. Even when an induction motor is driven with a load close to the rated output, the power factor is mostly around 0.8 due to the influence of the inductive component. Recently, the importance of power factor has increased as power companies have increased the power factor from the existing 0.9 to 0.92. Common power factor compensation approaches include individual correction for each motor, group compensation for multiple motors, correction at the transformer’s secondary side, or a combination of these methods.<br/>This study simulated and analyzed the changes when power factor compensation capacitors were installed on the motor, transformer, and both sides under conditions where the load varied in the field and the size of the active power was different. As a result of the analysis, it was confirmed that it is desirable to install power factor correction devices of an appropriate size on both sides, and in particular, the size of the reactive power installed in the transformer needs to be calculated according to no-load operation.