Along with the emergence of renewable energy sources in harbors, microgrids are required in the harbor area, which has been subjected to wide development on the mainland and islands. However, besides numerous benefits such as reducing greenhouse gas emissions and enhancing energy security, it could pose some challenges, such as high-power requirements and energy policy framework, particularly related to the variability and intermittency of renewable generation. This paper provides an enhanced microgrid model and control comprising a promising technology - grid-forming inverters (GFMI) followed by grid-following inverters (GFLI) that are supplied by an electrified on-shore ship and the conventional generator. The microgrid model is constructed on Matlab/Simulink by the energetic macroscopic representation (EMR) method. The novelty of the paper is to apply the EMR tool to organize the system model and develop the control scheme. Considering the impact of transmission lines and a comprehensive frequency deviation analysis is provided under various conditions using the phase-locked loop (PLL) and fast Fourier transform (FFT) algorithms. The primary contribution of the study is on the effect of the line impedance on the fast and slow dynamic frequency oscillation. Finally, the challenges to the system and future works for this study are discussed.

This paper proposes a novel integrated multiport bidirectional back-to-back power converter for a type-4 wind turbine that accommodates a battery and supercapacitor for energy storage. The circuit topology reduces 4 switches compared to the traditional configuration. Moreover, owing to the dual-buck structure embedded in the phase leg, the circuitry has no short-circuit path, therefore it withstands short-circuited events for a much longer time than the normal phase-leg and prevents the reverse current in turn-off recovery. The use of a hybrid energy storage system with battery and supercapacitor helps smooth out the power output under wind gusts and stabilizes the DC-link voltage under grid fault conditions. The case studies are carried out with a 1.5 MW wind turbine system. Simulation results are provided for the theoretical validation.

This paper proposes a novel integrated multiport bidirectional dc-dc converter to interface the battery, the ultra-capacitor, the fuel cell, or other energy sources with the dc-link capacitor of the hybrid energy systems such as the hybrid electric vehicle (HEV) and fuel cell vehicle (FCV) applications. The proposed converter can be applied to the distributed generation systems which include local energy sources, storage, and loads. It can perform both buck and boost functions with fewer switches. In addition, it is extendable when more inputs and/or outputs are required. The operating principle and control strategy of the proposed converter will be analyzed in detail. For verification, simulation, and experimental results of the four utilized operating modes of an HEV/FCV are provided.

The real-time models of offshore wind turbines are proposed in this study, which are developed in compliance with the Western Electricity Coordinating Council (WECC) standard to meet the industry requirements. In addition to basic functionalities of the generic WECC turbine model such as power curtailment and voltage ride through, the sequence current control and sequence current limit are designed for future electromagnetic transient (EMT) testing and control of offshore wind farms. Both average-value and switching detailed models are modeled in the Opal-RT simulator. Both balanced and unbalanced faults are studied to show the feasibility of the proposed turbine models. The models are validated against the WECC second-generation generic wind turbine model. The active and reactive power results for low-voltage ride through cases validated the turbine model’s performance against WECC generic model in the balanced system. In addition, the models provide extended capability in mitigating the active power oscillation during unbalanced fault conditions.

Cyber-physical systems (CPS) refers to the integrative system consisting of interconnected computing and control devices interacting with the physical infrastructure via sensors and actuators. Recently, there is a swift growth of CPSs ranging from smart grids to smart buildings, robotics, and other industrial control systems. They have formed the keystone of the sustainable growth of the economy, manufacturing, and smart and connected communities. Due to extensive applications of CPSs, their resilience, reliability, and security are paramount. Many factors, however, pose significant threats to CPSs and lead to high economic losses and social impacts. Software defects also make CPSs vulnerable to security attacks and coordinated cyber and physical attacks. To address this issue, emerging technologies and methods for understanding and improving the resilience, reliability, and security of CPSs are needed. This Special Section aims to provide a platform to help define, understand, and quantify the resilience, reliability, and security of CPSs.