Impedance Matching-Based Power Flow Analysis for UPQC in Three-Phase Four-Wire Systems

Different from the extant power flow analysis methods, this paper discusses flows for unified quality conditioner (UPQC) in three-phase four-wire systems point of view impedance matching. To end, combined with designed control strategies, establishing method UPQC model is presented, and on basis, system can be equivalent to an adjustable model. After that, a concept matching introduced into study operation principle system, i.e., how changes its states under grid voltage variations through discussing relationships among node impedances. In way, nodes series parallel converter are matched two sets impedances opposite directions, which mean that one operates rectifier state draw energy other inverter transmit energy. Consequently, no matter what voltages change, dynamically ensure output always equal load impedances, so as realize balances system. Finally, correctness matching-based validated by experimental results.