The transition to the electric ship requires evolving from passive power regulation to active state anticipation with data linkage and controls between machinery and mission systems to become an agile power and energy system. Toward this, the Navy sponsored research initiatives are currently developing a new Power Electronic Power Distribution System (PEPDS) paradigm. A key enabler for a successful PEPDS R&D program is a well-developed and documented functional system architecture as the basis for collaborate research and subsequent future performance studies. The technical approach is to employ Model-Based Systems Engineering (MBSE), to capture stakeholder needs, behaviors, structures, and measures for PEPDS in a system model. This work has recently baselined a functional architecture, which is a solution-independent description of what a system does, defining the trade space for design. The present paper provides an overview of the process, product, and prospects of that functional architecture.
Pulse power loads encompass various demanding applications, in which a certain electrical apparatus absorbs a large amount of power for a very short duration. The impact of this type of loads on the shipboard power system performance is of great interest for both new building and ships retrofitting. The goal of this work is, firstly, to investigate the theoretical definition and classification of the pulse power load, considering the relevant references today available. A survey on the typical applications is then conducted, considering also the type of technology adopted at the point of delivery. Time and frequency domain analysis techniques are then investigated, emphasizing the recommended performance requirements. Finally, a set of simulations is proposed considering a benchmark power profile. Results show that the tools identified represent an effective mean to investigate the expected performance of a shipboard power system in the presence of pulse power loads, toward the adoption of the model based design approach.
State estimation is critical to maintaining system stability and reliability as it enables real-time monitoring of the power system operation and facilitates fault detection, minimizing the risk of power outages and improving overall system performance. This paper presents a state estimation method based on graph neural networks, aiming to improve time efficiency and extended observability. Graph neural networks can aggregate information and dependencies from voltage and power measurement at the critical buses, making them more effective for state estimation on non-grid structured data. The IEEE 123-bus system is used as a case study to evaluate comprehensively the state estimation performance. The proposed model provides a better performance for mapping measurement data with states compared to other neural networks.
The emerging Small Modular Reactor (SMR) technology can potentially provide a reliable source of energy for All-Electric Ships (AES) with reduced greenhouse gas emissions. The successful drive of the electric propulsion systems in SMR-based AES needs high maneuverability in the supply of power, which is however constrained by the physical and safety limits of the SMR. SMR may not be able to precisely match the supply/demand on its own, especially during rapid load changes such as pulse loads. An effective solution is to leverage a battery energy storage system (BESS) as the primary source of frequency control to compensate for the remaining mismatches between the demand and supply. In order to increase the reliability of SMR-based AES, in this paper, a reliable operational scheme based on the dynamic modeling of the SMR-BESS-AES is proposed. Simulation results show that the SMR-BESS-AES system is capable of providing flexible operations in the presence of highly variable loads under different scenarios, such as ship acceleration, deceleration, and under pulse loads or severe weather conditions.
The main purpose of Navy amphibious ships is to transport Marines, their weapons, equipment, and supplies toward distant operating areas to enable the conduction of expeditionary operations ashore. Although amphibious ships can be used to support Marines' landings against opposing military forces, they are also employed for operations in peace. This kind of vessel has large storage capability, which enables them to operate helicopters and landing crafts for the transfer of personnel and supplies from ship to shore without the need for port facilities. Thanks to their versatility, amphibious ships are in force in all major Navies. The main purpose of this paper is to carry out a study about the power and propulsion system of the next-generation Landing Platform Dock. This study proposes an innovative Integrated Electrical and Electronic Power System with a DC zonal power distribution system and full electric pod propulsion. The DC zonal power distribution will allow the installation onboard of innovative components and weapons (e.g., Laser Gun and modular fixed-face radar), while pod propulsion will improve the dynamic positioning capability, a key feature for this type of ship.
