Control Algorithms to Establish Hybrid AC/DC Distribution Systems Using Conventional Six-Switch Inverters

Many economic and technical advantages can be harnessed by establishing hybrid ac/dc distribution systems. However, the penetration of such systems is impeded by the need to modify existing network topologies and develop new interlinking converters. In this article, a control scheme is proposed to use conventional six-switch inverters (SS-INVs) and three-phase networks as hybrid dc/single-phase ac systems. The proposed control scheme can be included in an SS-INV along with traditional control schemes of three-phase systems. When the inverter is installed, the appropriate control function can be activated depending on whether it is integrated into a hybrid ac/dc system or to a three-phase ac network. In this way, inverters for hybrid ac/dc system can become ready in the market without a risk of failure in generating demand. The proposed controller addresses the coupling issue between the ac and dc sides of the system through an effective estimation of line impedances. Through simulation and experimental studies, the effectiveness of the proposed controller in interlinking ac and dc networks and eliminating the coupling between these two sides is demonstrated and verified.