Frequency Response of Grid-Forming and Following Inverters-Based Microgrid Supplied by Onshore Electrified Ships

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.