The Voltage Source Converter (VSC) of Distribution Static Compensator (DSTATCOM) can compensate for the source voltage sag and swell. However, it cannot compensate for the voltage interruption. On the other hand, the VSC of the Uninterruptible Power Supply (UPS) can compensate for the source voltage interruption. However, it cannot compensate for the voltage sag and swell. A combined operation of the DSTATCOM and UPS is needed to

overcome these limitations. Conventionally, an energy storage system and two VSCs are required to combine the operation of DSTATCOM and UPS.

A control algorithm that uses a single VSC and a battery-supercapacitor energy storage system to function as DSTATCOM and UPS is proposed in this talk. The VSC and the battery-supercapacitor energy storage system mitigates the sag, swell, and interruption of the source voltages. Under the normal source voltages, this system mitigates the load current harmonics, unbalance, and reactive power. The proposed control algorithm uses a State of Charge (SoC) based scheme to control the battery-supercapacitor energy storage system. This control scheme protects the battery and supercapacitor from overcharging. Also, it eliminates the ripples in the load angle during voltage sag and swells. The efficacy of the proposed control scheme has been verified through the simulation and experimental studies of the VSC with the battery-supercapacitor energy storage system.