All-Electric Ship Design: From Electrical Propulsion to Integrated Electrical and Electronic Power Systems

Electrical propulsion is not a novel concept in marine systems. However, the availability of power electronic converters has proved to be the Key Enabling Technology for electrification of large ships. This paper starts with a summary of EP drives, which led to the birth of all-electric ships. Electric power generation and control systems are then presented, which make it possible to exploit the integrated electrical power system. To ease comprehension of the issues in designing such a system, its conventional design process is given. Then, the reasons that are pushing ahead the research in the shipboard power systems sector are discussed. The need for research in the design methods area is demonstrated through an overview of the latest results of technological research. Finally, a summary of the most significant results on the design tools research is given, including early stage design, dependable-oriented design, and the improvements achievable through software simulators and hardware-in-the-loop are discussed. The goal of this paper is to demonstrate why research on design methods is as important as a technological one, on the basis of the needs concerning the design, integration, and management of future 'integrated electrical and electronic power systems' (power systems with power conversion quota approaching 100%)

Voltage Stability in Large Marine-Integrated Electrical and Electronic Power Systems

Offshore oil and gas vessels operating in deep and ultra-deep waters demand larger and more sophisticated power and control systems. This tendency brings new challenges in integrated power system's design, especially for platforms/vessels requiring both dynamic positioning and high levels of redundancy. Voltage stability is essential in such systems, being in islanded operation (with related limited power generation) and with continuously changing load demands. In particular, voltage stability issues can arise due to the increasing amount of power electronic converters installed onboard, used to feed variable frequency drives and other electronic loads. Indeed, most of these have a controlled front-end, whose control can affect network voltage with a destabilizing effect named constant power loads (CPLs) instability. Such a behavior deserves special attention in islanded power systems, mostly if the quota of power electronics loads on the total installed power reaches very high values (up to the 85% for new large all electric ships). This paper initially focuses on the CPL voltage instability. Two different models to assess voltage stability in marine systems with high penetration of electronic power conversion are given, focusing on a design-stage assessment. Using the conditions obtained by such models, a practical stability analysis methodology is proposed, to help assessing voltage stability already at design stage, to avoid equipment retrofits during vessel building or commissioning. Finally, some practical case studies are discussed, and solutions to overcome the CPL instability are suggested

Inland waterway gas-fueled vessels: CASM-based electrification of a pushboat for the European network

The peculiarities of the European inland waterway transport are analyzed, and a novel design of a pushboat for barges convoys is proposed and optimized for the Rhine-Danube corridor. To this aim, a hybrid parallel electric propulsion system is adopted with the perspective to define an eco\u2013friendly vessel. The present work is to be intended as the early-stage in the proof-of-concept (POC) for commercial technologies useful for the electrification of pushboats employed in inland waterway navigation. Specifically, the optimal design solution is highlighted by evaluating of proper attribute weights, which determine the degree of closeness among possible solution and the design target. In particular, CASM methodology to minimize CAPEX and OPEX of a pushboat is adopted

Medium voltage DC power systems on ships: An offline parameter estimation for tuning the controllers' linearizing function

Future shipboard power systems using Medium Voltage Direct (MVDC) technology will be based on a widespread use of power converters for interfacing generating systems and loads with the main DC bus. Such a heavy exploitation makes the voltage control challenging in the presence of tightly controlled converters. By modeling the latter as constant power loads (CPLs), one possibility to ensure the bus voltage stability is offered by the linearizing via state feedback technique, whose aim is to regulate the generating DC-DC power converters to compensate for the destabilizing effect of the CPLs. Although this method has been shown to be effective when system parameters are perfectly known, only a partial linearization can be ensured in case of parameter mismatch, thus, jeopardizing the system stability. In order to improve the linearization, therefore, guaranteeing the voltage stability, an estimation method is proposed in this paper. To this aim, offline tests are performed to provide the input data for the estimation of model parameters. Such estimated values are subsequently used for correctly tuning the linearizing function of the DC-DC converters. Simulation results for bus voltage transients show that in this way converters become sources of stabilizing power

The Role of Voltage Controls in Modern All-Electric Ships: Toward the all electric ship

Ships have witnessed an astounding evolution in the last 200 years. The introduction of the combustion engine has started an ever-faster change, both in the performance and functionality given by the ships. From the steam-powered ships of the early 1800s to the modern diesel-electric ships, the improvements were significant and increasingly rapid. In particular, in the last 30 years, the design of ships has made a huge leap ahead, both in terms of efficiency of the entire vessel and new functions given to the owners. This is due to the progressive electrification that has occurred

Adaptive Neural Network-Based Control of a Hybrid AC/DC Microgrid

In this paper, the behavior of a grid-connected hybrid ac/dc microgrid has been investigated. Different renewable energy sources - photovoltaics modules and a wind turbine generator - have been considered together with a solid oxide fuel cell and a battery energy storage system. The main contribution of this paper is the design and the validation of an innovative online-trained artificial neural network-based control system for a hybrid microgrid. Adaptive neural networks are used to track the maximum power point of renewable energy generators and to control the power exchanged between the front-end converter and the electrical grid. Moreover, a fuzzy logic-based power management system is proposed in order to minimize the energy purchased from the electrical grid. The operation of the hybrid microgrid has been tested in the MATLAB/Simulink environment under different operating conditions. The obtained results demonstrate the effectiveness, the high robustness and the self-adaptation ability of the proposed control system

Shore-to-Ship Power

This contribution starts with a review of the state of the art of existing high-voltage shore connection (HVSC) systems in terms of principles, rules, publications, technologies, and relevant installations. Then, tutorial sections present the main technical aspects of HVSC systems as ship-to-shore interface, shore equipment (transformers, converters, etc.), onboard devices (cubicles, shore switchboard, etc.), operating sequences, and feasibility aspects, for both commercial and military applications. Finally, some technical challenges are presented, concerning intentional/unintentional bonding, interactions between HVSC bonding and cathodic protection systems, bonding opportunity, and electrical safety aspects related to bonding issues in case of large earth fault currents in port facilities

Hybrid-electric solutions for the propulsion of a luxury sailing yacht

The application of hybrid-electric solutions for the propulsion of pleasure crafts is increasing in recent years. The more restrictive regulations on pollutants and the growing sensibility of the people on greenness make this solution even more attractive. In case the craft is stationing in a marine equipped with renewable energy sources, the attractiveness of such a solution increases even more. Besides, a hybrid-electric configuration can reduce the consumptions and, consequently, the operative costs against an initial higher investment. Therefore, hybrid-electric propulsion could give a benefit to raise a stationary market, as the pleasure craft one. This study compares in terms of consumptions three different solutions, besides conventional diesel one, for the propulsion of a sailing yacht

Feasibility Study of a DC Hybrid-Electric Catamaran for River Navigation

The sustainable growth is becoming every day more present and even mandatory in the framework of global decarbonization and Green House Gases (GHG) reduction. In such a context, electric powering offers important advantages while offering reliable and greener solutions for private-public urban transport. By considering this scenario, in this paper, an electric catamaran equipped with a DC hybrid module is proposed as effective in passenger transport along the Po river, in the Turin urban environment. The study encompasses many challenging aspects, which, in the end, improve the overall ship performance. For instance, the vessel shall be suitable for a quick hauling to the land in case of emergency with a crane truck. Secondly, the DC voltage distribution must provide safe power delivery by maintaining low weights. In this paper, the design is presented, along with the scenario constraints that have defined the peculiarities and addressed the technical choices

Next-Generation Shipboard DC Power System: Introduction Smart Grid and dc Microgrid Technologies into Maritime Electrical Networks

In recent years, evidence has suggested that the global energy system is on the verge of a drastic revolution. The evolutionary development in power electronic technologies, the emergence of high-performance energy storage devices, and the ever-increasing penetration of renewable energy sources (RESs) are commonly recognized as the major driving forces of the revolution. The explosion in consumer electronics is also powering this change. In this context, dc power distribution technologies have made a comeback and keep gaining a commendable increase in research interest and industrial applications. In addition, the concept of flexible and smart distribution has also been proposed, which tends to exploit distributed generation and pack together the distributed RESs and local electrical loads as an independent and self-sustainable entity, namely a microgrid. At present, research in the area of dc microgrids has investigated and developed a series of advanced methods in control, management, and objective-oriented optimization that would establish the technical interface enabling future applications in multiple industrial areas, such as smart buildings, electric vehicles, aerospace/aircraft power systems, and maritime power systems