# Solid-State Transformer-Based DC Power Distribution Network for Shipboard Applications
###### Abstract  
Due to simplicity, efficiency, and the ability to accommodate energy storage devices, DC distribution networks have been seen as an optimal alternative to AC distribution networks, especially aboard future electric ships. The emerging distribution DC system entails new control and management techniques. Therefore, an integrated DC power distribution network aboard an electric ship is selected as the case study in this paper. To meet the requirements of such a large-scale mobile power system, a multiport solid-state transformer (SST) based on silicon carbide (SiC) switches/MOSFETs is proposed. Thus, the system embodiment can significantly be reduced. Moreover, at the DC distribution level, a high penetration of renewable generation with energy storage is allowed and a six-phase asymmetrical induction machine (IM) can directly be integrated. Simulations have been conducted based on a 2 MW shipboard distribution network. The effects of the propulsion system dynamics on the SST are highlighted as well. Finally, a 2 kW lab-scale prototype has been implemented to validate the theoretical findings. [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON], [PERSON]. efficient integration of renewables and energy storage systems, which include stability problems that seem to appear. Consequently, future shipboard distribution power systems will preferably be based on DC grids. When compared to shipboard AC distribution networks, DC networks are more advantageous in many ways, such as operation resiliency, efficiency, system size, and fault current limitation [8]. An extensive overview of DC shipboard microgrids presenting various system configurations and power converters is given in Ref. [9]. The system configurations are categorized into bipolar and unipolar bus architectures [10,11]. Amongst the two bus architectures, the bipolar one is the most utilized. Moreover, the arrangement of power components is based on radial [12], zonal [13], or ring [14] structures. The integrated shipboard DC networks typically comprise power generation modules, propulsion systems, and service loads. With the rapid development in the employed power converters, not only conventional generators and fuel cells but also renewable energy sources and energy storage systems can be integrated into the power generation system. In that case, both the propulsion system and ship service loads can be fed from the integrated power system aboard a ship instead of being supplied from separate systems [3]. Table 1 summarizes several aspects of both the conventional and proposed shipboard power distribution systems. One of the most effective components in the electric distribution networks of the shipboard system is the power transformer. The traditional distribution systems commonly experience operational problems associated with conventional power transformers that include the possibility of load harmonic injections into the local grid, which affects the nearby loads [15]. Therefore, the solid-state transformer (SST) has emerged as a promising alternative in the emerging DC power distribution network aboard ships [16,17]. SSTs have been used in several practical areas, such as marine, power distribution, and traction applications [16]. Concerning the power distribution applications, SSTs play a vital role in the integration of the renewable energy sources into the distribution systems, which improves the performance and power quality issues of the system using components with reduced size, cost, and complexity [18]. In Ref. [19], an SST has been used in the integration of the solar energy to the grid. Moreover, SSTs share in the operation of microgrids and the smart grids to facilitate reactive power support, harmonic mitigation, and energy distribution balance in the grid [20,21]. This resulted in a new concept for the SST that is called an energy router, which manages the energy flow and other functions [22]. SSTs are  
Figure 1: Conventional shipboard power system [7].