Angela Card

How scattering parameters can benefit the development of all-electric ships

The power distribution system of future all-electric ships is expected to be different from typical terrestrial power distribution systems in a number of areas including grounding schemes and common-mode coupling to the ship hull. Simulation tools currently used to model terrestrial power systems do not take these differences into account. Scattering parameters are suggested to help validating existing models, support the development of specialized models for shipboard power systems, and ultimately facilitate the design of all-electric ships. This paper provides an overview of scattering parameter related activities within the Electric Ship Research and Development Consortium (ESRDC).

Tools and dielectric requirements for the design of marine cabling systems

This paper explores various power cable challenges for notional electric ship applications including future technology trends for shipboard power cables. To meet the demands of an “all electric ship,” the cabling requirements of the design are not a trivial issue which can result in significant error in estimating final size, weight, and cost at time of construction along with costly failures and early repairs that impact lifecycle cost. This paper provides information on the development of a design tool known as a “Generic Cable Calculator” to estimate parameters such as impedances, weights, and bending radii for ship power cabling. Analysis of actual experience in designing ship cabling suggests improvements in early design tools needed to capture additional requirements in terms of grounding, shielding, and satisfying current standards for cables used in the variable frequency drive train. Also addressed are results specific to future trends of cable insulation and future standards.

Time and frequency domain methods to evaluate grounding strategies for medium voltage DC shipboard power systems

Several key performance parameters of shipboard power systems are affected by the grounding scheme applied. The grounding scheme impacts the nature of voltage transients during switching events and faults, identifiability and locatability of ground faults, fault current levels, and power quality. Power system simulations play an important role in choosing an appropriate grounding scheme and optimizing its components. The tools typically used for power system analysis need to be carefully tested to determine if they are appropriate for modeling effects of different grounding schemes and in particular the high frequency transients. This paper sheds light on modeling and validation techniques specific to grounding models. Furthermore, insight is provided to present research into new types of power system modeling techniques based on scattering parameters for improved accuracy at higher frequencies of interest. A testbed designed to study the impact of different types of grounding schemes is also introduced and first characterization measurements in the frequency domain provided. The paper concludes with an outlook to future work, which will focus on rigorous validation of the models developed.

Using S3D to analyze ship system alternatives for a 100 MW 10,000 ton surface combatant

The Electric Ship Research and Development Consortium (ESRDC) conducted an extensive design exercise using the Smart Ship Systems Design (S3D) tool with the goal of exercising and improving the functionality of the S3D design environment currently under development by the ESRDC. S3D is a design environment that enables concurrent, multi-disciplinary collaboration and that introduces simulation capability in early-stage ship design [1]. This work examines the S3D design environments capabilities in a realistic design exercise. To this end, a baseline ship and several variants were designed with a 10,000 ton displacement and a 100 MW integrated power system to explore the effects of new technologies and to determine the capability of S3D in elucidating differences between design variants. Key features and performance effects of each design and an analysis of S3D capabilities are presented.

Early stage design tool for marine power interconnect systems

The requirements of a power interconnect system, which includes cables or busbars, are necessary to allow a realistic early stage design of an all electric ship. Characteristics such as the volume and weight for these components cannot be overlooked in a power dense all electric ship such as a naval surface combatant. A “Generic Cable Calculator” has been improved upon and implemented within the Smart Ship System Design (S3D) environment implemented by researchers in the Electric Ship Research and Development Consortium. The calculated cable information supports a space reservation algorithm realized by other ESRDC researchers to provide a more rational representation of the power interconnect system in the size range of 50 to 100 MW.

Co-simulation of electric ship power and control systems using high performance computing

In electric ship design the interaction of the physical plant with the power and energy control system is so complex that simulation for design or analysis is time consuming, especially when a range of time steps is required for dynamic simulation. This paper describes a unique solver that captures the power and control blocks of an electric ship power system described in Simulink and then creates simulations in C# ready for solution on a multicore computer. A comprehensive description of the workflow and results of verification testing are presented.