Power inverter apparatus using a transformer with its primary winding connected the source end and a secondary winding connected to the load end of an AC power line to insert series compensation

摘要

Series voltage compensation is provided in an ac power line by connecting the inverter unit of a dynamic voltage restorer (DVR) in series with the primary winding of a load transformer, which may already be present, thereby eliminating the need for injection transformers. For three-phase ac power lines the three primary phase windings can be either wye or delta connected. If they are wye connected, a three-phase inverter with a common dc source is preferred. For delta connected primary phase windings, separate single-phase inverters each with its own floating dc source can be directly connected in series with each primary phase winding. Preferably however, the poles of a two-phase inverter are direct connected in series between two of the primary phase windings and a common source phase, and share a common dc source referenced to the common source phase. While a single-phase inverter with its isolated dc source can be used for the third delta connected primary phase winding, it is further preferred that this single-phase inverter share the common dc source used by the two-phase inverter. In that case, one injection transformer is needed to isolate the compensation voltage inserted by this single-phase inverter in series with the third delta connected primary winding. Similar DVR arrangements can be used to provide series voltage compensation on the load side of a transformer with a delta connected secondary winding.