부산대학교 도서관

The unified power quality conditioner (UPQC) integrated with the battery energy storage system not only mitigates the power quality problems on the grid side and load side but also supplies active power to the load or the grid. The wide voltage variation of the battery and the high efficiency of the whole system can be achieved with the hybrid connected configuration, i.e., the battery is connected simultaneously to the series and shunt converters of the UPQC directly and indirectly through the dc–dc converter. However, the control and modulation strategies are the major challenges for this configuration. This study proposes a control scheme based on asymmetrical sinusoidal pulse width modulation (SPWM) to realize high-efficiency active power delivery, thereby addressing the issue above. The mechanism of the modulation scheme to regulate active power is revealed, and the voltage variation of the battery is considered. The modified SPWM strategy features easy implementation and a low computation burden. The effectiveness of the system with the proposed control and modulation schemes is verified by both simulation and experimental results.