Joint voyage scheduling and economic dispatch for all-electric ships with virtual energy storage systems

As a special mobile microgrid, an all-electric ship (AES) utilizes diesel generators and energy storage systems to provide electric propulsion and service loads. Unlike previous studies of the minimization of the AES operation using auxiliary energy storage systems, this paper exploits existing shipboard thermal storage and thermal load as a virtual energy storage system to reduce both operating cost and greenhouse gas emissions. To achieve this goal, a joint optimization model is developed optimally to coordinate the voyage scheduling and power generation of the AES under various load conditions. Thermal load and propulsion load optimization are considered in demand-side management. The problem is formulated mathematically as a multi-objective economic dispatch problem and solved by the particle swarm optimization (PSO) algorithm combined with non-dominated sorting genetic algorithm II (NSGA-II). A typical navigation route is selected for the case studies and simulation results demonstrate that the proposed joint optimization method reduces cost and greenhouse gas emissions by 17.4% and 23.6%, respectively, from those achieved using current fixed voyage generation scheduling methods. The environment friendliness and energy efficiency are further improved by coordinated penetration of the thermal storage dispatch into generation and voyage scheduling.