Power and energy management optimization for marine transportation electrification

Abstract

With the prediction of greater reliance on marine transportation for social and economic growth in the future, the development of energy-efficient and environmentally friendly design and operation of the ships are becoming the main focus of research and industry. Furthermore, due to the excessive emission from marine vessels, the International Maritime Organization (IMO) and regulatory authorities impose stringent rules and regulations to limit the overall emission. Over the past few years, the concept of more electrification, renewable energy resources, electrical energy storage integration, and energy optimization in land-based microgrid systems have proven to improve operational efficiency and reliability. Thus, there is an attempt to adapt existing solutions from the land-based microgrid to a more electric ship power system (mobile isolated microgrids). However, unlike its land-based counterparts, deriving power and energy management strategies to improve operational efficiency is a complex and unique problem for a marine vessel. It has to address multiple aspects of ship design and operation to establish a realistic operation scenario for a marine vessel. Furthermore, propulsion architecture selection, task-sequence planning, path selection, voyage scheduling, energy network coordination, short-term maintenance schedules, uncertainty management, and unique load management are additional dimensions of the mobile ship power system that introduce control, power, and energy dispatch complexity.

Hence, the main objective of this thesis is to propose coordinated electric ship power system planning and operation strategies at different temporal stages while considering uncertainty, regulations, energy networks, maintenance requirements, and user-defined operation objectives. In Part II-Chapter 2, a regulation compliance joint rule-based decisions and optimization framework is proposed for propulsion architecture selection. It is based on the operation task sequence planning and energy management decisions. Part III deals with the short-term and day-ahead operation scheduling of the more electric ships. Various energy dispatch objectives such as emission reduction, energy storage degradation (Chapter 3), multi-energy coordination (Chapter 4), and short-term maintenance schedules (Chapter 5) are investigated as multi-objective or time coordinated (day-ahead, hour-ahead, and minute-ahead decisions) mathematical optimization problems in their respective chapters. Methods such as lexicographic augmented epsilon-constraints, goal programming, and weighted sum approach are used to formulate the multi-objective models in these chapters. Uncertainty management methods, such as reactive, robust, and probabilistic, are also discussed. Part IV-Chapter 6 of the thesis addresses the power management issues that arise from the short-duration power-intensive load (winch, crane, war-fighting load, electromagnetic launcher, and towing) in the more electric ship power system. As a result of stringent power quality requirements or objectives (voltage and frequency), power management with the help of energy storage is proposed. A zonal-protection architecture with the energy storage system and a generator is modeled in Simulink. It illustrates a two-stage power management strategy with the first stage as pulse shaping or frequency decoupling and the second stage as fuzzy-logic-based energy storage contribution decisions.

The proposed strategies are demonstrated with various case studies to demonstrate their effectiveness in design, operation, and uncertainty management while improving the overall system operation efficiency. The modularity in the proposed approaches provides flexibility for different types of vessels and even other microgrid applications. The proposed frameworks are employed for the design evaluation and operation planning of various commercial marine projects in the Rolls-Royce Power System.