Fotis D. Kanellos

New challenges emerged from the development of more efficient electric energy generation units

The current trends in ship technology are turning ships into more energy efficient ones. Thus, the extensive electrification of ship systems, including propulsion, is a most appealing alternative as, the more electrified a ship, the greener and more efficient it turns. In this paper, a brief overview of novel trends regarding electric energy generator schemes is made, and it is shown that these result in new challenges leading to amendments of the traditional concepts dominating over design and operation standards. The discussion is supported by the results of a model comprising a ship generic power grid with multi-type supply units.

Control system for fuel consumption minimization–gas emission limitation of full electric propulsion ship power systems

Environmental pollution caused by ships’ green house gas emissions and worldwide concern about air quality and oil supplies have led to stricter emissions regulations and fuel economy standards. In this regard, respective limits are set, while efforts to provide general guidelines for the achievement of economic and green ship operation with an urge to ship operators to apply them and return feedback. Also, specific design and operation indicators have been proposed in order to ensure compliance with new emissions regulations and fuel economy standards. Up to now, these indices are limited to ships comprising conventional propulsion systems, while full electric propulsion systems are not examined. In this article, an integrated control system that attains economically optimized and environmentally friendly operation is proposed. Moreover, appropriate reformulation of energy efficiency operation indicator is proposed for real-time assessment of gas emissions. The study is supported with the presentation of results obtained from the simulation of the operation of a ship power system comprising full electric propulsion.

Optimal Demand-Side Management and Power Generation Scheduling in an All-Electric Ship

The worldwide effort for the development of more efficient and environmentally friendly ships has led to the development of new concepts. Extensive electrification is a very promising technology for this purpose. Together with optimal power management can lead to a substantial improvement in ship efficiency ensuring, at the same time, compliance with the environmental constraints and enhancing ship sustainability. In this paper, a method for optimal demand-side management and power generation scheduling is proposed. Demand-side management is based on the adjustment of the power consumed by ship electric propulsion motors, and no energy storage facility is exploited. Dynamic programming algorithm subjected to ship operation and environmental and travel constraints is used to solve the problem for all-electric ships (AESs). Simulation results prove that the proposed method ensures cost minimization of ship power system operation, greenhouse gas (GHG) emissions limitation, and compliance with all technical and operational constraints.

Short Term Load Forecasting in Electric Power Systems with Artificial Neural Networks

The demand in electric power should be predicted with the highest possible accuracy as it affects decisively many of power system’s operations. Conventional methods for load forecasting were built on several assumptions, while they had to cope with relations between the data used that could not be described analytically. Artificial Neural Networks (ANNs) gave answers to many of the above problems and they became the predominant load forecasting technique. In this chapter the reader is first introduced to Artificial Neural Networks and their usage in forecasting the load demand of electric power systems. Several of the major training techniques are described with their pros and cons being discussed. Finally, feed- forward ANNs are used for the short-term forecasting of the Greek Power System load demand. Various ANNs with different inputs, outputs, numbers of hidden neurons etc. are examined, techniques for their optimization are proposed and the obtained results are discussed.

Optimal Active Power Management in All Electric Ship Employing DC Grid Technology

Extensive electrification and the use of dc distribution grid are recently proved to be very promising technologies for the development of more efficient and environmentally friendly ships. Onboard dc grids present several advantages such as, improved efficiency, easy integration of different types of power sources, reduced size and rating of switchboard, elimination of reactive power flow, increased reconfiguration capability etc. All electric ship (AES) concept, dc distribution grid and optimal power management can lead to a substantial improvement of ship efficiency and compliance with the environmental constraints. In this paper, a method for optimal demand side management and power generation scheduling is proposed for AES employing dc grid. Demand side management is based on the adjustment of the power consumed by ship electric propulsion motors. Dynamic programming algorithm subject to operation, environmental and travel constraints is used to solve the above problem.

Real-Time Control Based on Multi-Agent Systems for the Operation of Large Ports as Prosumer Microgrids

Full electrification of large ports and intelligent energy networks compose a very promising solution, not only for limiting the in-port greenhouse gas emissions but also for the improvement of their efficiency and electric power system operation support. Large ports comprise a variety of flexible loads like refrigerated containers, electric vehicles, onshore electric power supply to ships at berth, and so on, while they usually have great potential for local energy generation from renewable energy resources, like offshore wind, tides, waves, and so on. Smart grids can be proved very efficient in increasing port power demand flexibility and controllability. The main goal of this paper is to propose an innovative decentralized demand response method that eventually turns a port comprising flexible loads and power generation from renewable energy sources to a prosumer Microgrid. The proposed method is applied to a realistic case study of a large port comprising a large number of flexible loads and one offshore wind park. The efficiency of the proposed method is evaluated by detailed simulations.

A Method for Optimal Operation of Complex Ship Power Systems Employing Shaft Electric Machines

The electrification of ships and, particularly, of their propulsion is an area of intense research nowadays. A very appealing option that allows partial electrification of ship propulsion system is the use of shaft electric machines. Moreover, power dispatch is implemented in ships by using simplistic methods, in contrast to continental power systems where sophisticated optimal power dispatch methods are applied. In this paper, a novel optimal power management algorithm that considers the use of shaft electric machines, the technical and operation limitations of the ship, and the environmental restrictions enforced by the international maritime organization is presented. Several ship propulsion and power generating configurations are analyzed and compared by using technical data from actual diesel engines, alternators, shaft generators, prime, and auxiliary movers. The results clearly indicate the benefits from the application of the proposed algorithm and the obtained cost reduction in the ship power system operation.

Analysis of various power quality phenomena in a highly electrified vessel

This paper deals with analyzing and resolving Power Quality (PQ) issues in electric energy systems of ships with extensive electrification. Within this framework, optimized configurations of critical subsystems are studied in depth: shaft generators, thrusters, pods and protection against lightning. The anticipated results obtained from a large scale research project are summarized as aiming at a greener, safer and more reliable ship.

Ship to shore connection — Reliability analysis of ship power system

Worldwide concern about air quality and greenhouse gas emissions has led to stricter emissions regulations in ship industry. The pollutant emissions in a port mainly come from the electric power generation system of the ships at berth. If cold ironing facilities are provided then the power supply comes from the shore electric power system through the proper interconnection. Many techno-economic studies have been carried out about the interconnection issues, but the reliability of the power system has not been adequately investigated. This will be analyzed in this paper taking into consideration the forced outage rate (FOR) of ship electric generators and shore connection, as well as the parameters which influence the FOR. The behavior of power generation system in different case studies is examined based on reliability indicators of the expected loss of load power (LOLP) and of the expected loss of load energy (LOLE).

Comparison of ship power systems from an optimal economic operation point of view

For many years, the predominant concept on board ships was to have separate propulsion and generator engines. However, more recently, the adoption of hybrid installations with shaft generators, is becoming increasingly common. In this paper, a case study is presented where measurements from actual equipment are used to compare the propulsion and power plants of a typical ship to a hybrid one. Also, a new algorithm for electrical load distribution is introduced and examined in this case.