Reactive Power Compensation of Induction Motors Supplied with Unbalanced Voltage

Induction motors degrade power factor by drawing current that lags the supplied voltage, which is typically rectified by adding shunt capacitor banks. Unfortunately, traditional methods used for calculating the size of capacitors do not properly account for voltage unbalance, and no guidelines exist for correcting degraded power factor under such conditions. In this paper, improvement capacitors found with various methods are implemented in the Electromagnetic Transients Program for reactive compensation of a 6-pole, 10 HP, 230 V, squirrel-cage IM supplied with unbalanced voltage. The Currents' Physical Components power theory is utilized to decompose the line current into orthogonal components and analyze the limitations of the different compensation methods.