Current control of unbalanced electrical systems

The vector modeling approach is employed to describe the behavior of unbala nced three-phase (three-wire), unbalanced two-phase and single-phase system s. In the case of single-phase systems, a fictitious circuit is introduced in order to create the vector model. Continuous-time and discrete-time curr ent controllers based on the vector approach are presented. The current con trol scheme is based on two controllers, one for the positive sequence and another for the negative sequence. The controllers are implemented in the s ynchronous reference frame and in the stationary reference frame. In the st ationary reference frame, the use of the same integral gains for both contr ollers simplifies the equations of the control law, especially for single-p hase systems. Simulation and experimental results obtained with a pulsewidt h modulation voltage-source inverter supplying unbalanced systems are prese nted.