A Bidirectional Transformerless Direct AC-AC Dynamic Voltage Restorer with Extended Compensation Range and Up/Down Capability

The primary focus of this article is on enhancing the performance of direct AC/AC converters for their application in Dynamic Voltage Restorer (DVR) through modifications in the configuration of the AC/AC converter interconnection. In the proposed configuration, contrary to conventional setups, the converter's input power is supplied from the load side and applied in series to the grid. This arrangement allows for a substantial increase in the compensating range of the DVR without the need for alterations in the circuit topology of the AC/AC converter. Following the introduction of the converter circuit topology, the proposed configuration is presented. The theoretical analysis is then elaborated, and finally, the presented theory is validated through simulating the converter's performance in condition of 30% voltage sag and 30% voltage swell for DVR application under a 2KW load.