Metaheuristic Optimization based Coordinated Electric Ferry Charging Impacts on Distribution Network

The global maritime industry significantly contributes to greenhouse gas emissions in marine environments. To address this, there is a growing global initiative to adopt renewable-powered electric marine vessels, where storage plays a crucial role. This study delves into the potential impacts of charging electric ferries in coordinated mode on local distribution network by metaheuristic optimization. Using Gladstone Marina in Queensland, Australia, as a test case, the research employs DIgSILENT PowerFactory for power flow analysis, based on actual load data. The simulated network includes four BESSs (Battery Energy Storage Systems) representing proposed charging stations. For analysis, MATLAB Simulink based BESS’s dynamic model is included in the simulated network of DIgSILENT. A novel control algorithm is used for controlling and optimizing the operation of BESSs according to load demand and status of network’s system parameters. Python based control algorithm implements a balanced hybrid GA-PSO-BFO (Genetic Algorithm-Particle Swarm Optimization-Bacterial Foraging Optimization) metaheuristic optimization which ensures sequential operation of BESSs according to their SOC (State of Charge) in coordinated mode. Initially, power flow analysis is conducted without BESS integration, termed as the base case, at 50% and 80% load capacities of transformers. For impact analysis, power flow analysis is performed by integrating BESSs to simulate fully utilized charging stations at 50% and 80% load increment in coordinated charge-discharge and only charge coordinated modes. Results show a 1%-1.5% increase in bus voltages in coordinated modes as load escalates. Transformer loading decreases by 3%-4% in coordinated charge-discharge mode, while line loading drops by 2.5%-3.5%, contributing to reduced system current and power. The transformer loading and line loading remain same to base case in only charge coordinated mode. The findings from the time-based quasi-dynamic mode in DigSilent suggest that coordinated charge-discharge imposes beneficial effect on the system parameters of the test network. By aligning charge-discharge times with load demand, coordinated mode enables BESSs to participate in peak shaving of the test distribution network. This peak shaving strategy indicates that electric ferries at dockyards can serve as a spinning reserve for the shore-side distribution network.