Design and Control of Solid State Transformer for DC Micro Grid Applications

Abstract

Abstract newlineNowadays, the concept of a DC micro-grid has gained special attention due to the newlineproliferation of power electronic-controlled loads and the integration of renewable newlineenergy sources (RESs). In DC micro-grid, there is no requirements of synchronization newlineas in the AC network, no conflicts with the frequency and harmonics, and no concerns newlineabout reactive power management. Further, the DC microgrid is used to supply electric newlinepower with RES in off-grid locations without producing greenhouse gases. Moreover, newlinethe use of an energy storage system (ESS) in the DC micro-grid improves the newlinereliability of the system as well. Primarily, the DC micro-grid is operated in two newlinedifferent modes: i.e. islanded mode and grid-connected mode. These modes of newlineoperation mainly depend on the integration of RESs to reduce the carbon footprint in newlinethe environment. Hence, multi-stage power electronic converters (MPECs) are newlinerequired to have a smooth transition between these two modes. The various structure newlineof MPECs are employed at different locations in the DC micro-grid network depending newlineon the use and ease of implementation. Further, it requires a reliable control system to newlinemodulate the power flow between various components in the DC micro-grid network. newlineThus, in view of the structural and control aspects required for the MPECs, and newlineinterlinks with the various components of the DC micro-grid network, this thesis newlinepresents the proposed MPECs, termed as Solid-State-Transformer (SST) for the DC newlinemicro-grid applications. Basically, the SST is the multistage power electronic newlineconverters, which links with the high frequency transformer. It can provide various newlineessential structural and control features required in the DC micro-grid applications. newlineHence, in the recent years, an enormous research efforts have made in the design and newlinedevelopment of SST to make it as a centralized element in the DC micro-grid network. newlineHowever, literature study in the area of SST reveals that the structure of topologies newlineemployed at either stage of the SST is having signi