Abstract: A controller (130) for compensating reactive power and selected current load harmonics in an unbalanced multi-phase power distribution system. Control current is injected from a multi-phase voltage source inverter (118) into the multi-phase power distribution system as a function of the voltage and current provided by the source inverter 118. The injected current is operative to balance the load seen by the power distribution system including non-linear/distorted and unbalanced loads in each phase. The controller includes an inner loop control processor (216), an outer loop control processor, and an adaptation processor. The adaptation processor (238) is operative to estimate a selected set of predetermined harmonic components in the periodic disturbance which is a function of the unknown system parameters, the source current, the source voltage, and their time derivatives in stationary coordinates.

Abstract: A controller (236) for an uninterruptible power supply (UPS) compensates for harmonic distortion in the output current (224,26,228). The controller also provides a control vector (230) also with input from the adaptation processor (234).