Abstract
Abstract In the coming years, seaports will undergo significant electrification process, moving away from fossil fuels. In such new reality, obtaining accurate electricity load forecasting is critical for reducing costs, planning infrastructure improvements, and ensuring a stable energy supply. However, studies specifically addressing this need in ports are scarce. This paper presents several novel Long Short-Term memory (LSTM) models for forecasting the electricity demand of a highly electrified port, using the Port of Sines as a case study. These models incorporate operational data, such as vessel arrival schedules and quay crane usage, to enhance forecasting accuracy. Our results show that including these variables significantly improves forecast accuracy, reducing the Mean Absolute Percentage Error (MAPE) from 10.55% to 3.59% compared to models relying solely on historical data. This research provides a robust framework for ports to improve energy management and supports the broader goals of energy efficiency and sustainability in the maritime industry.

Abstract
This paper presents an experimental evaluation of the dielectric performance of a synthetic ester-based insulating fluid (Midel 7131) for power transformers subjected to lightning impulse voltages. The study is motivated by the search for sustainable and environmentally friendly alternatives to conventional mineral oils, particularly under extreme electrical stress conditions. A test setup was developed using Rogowski-type electrodes immersed in the fluid and subjected to positive and negative standard lightning impulses, following IEC 60060-1 and 60247. The dielectric dissipation factor (tan d) and partial discharge (PD) activity were measured before and after the impulses. Results showed that Midel 7131 maintained low dielectric loss values and exhibited stable PD behavior, even after repeated high-voltage (HV) impulses. These findings confirm the technical feasibility of synthetic esters as reliable insulating fluids for HV equipment, supporting sustainable practices in the electrical energy sector. © 2025 IEEE.

Abstract
Mineral oil has long been the standard insulating fluid in power transformers due to its excellent dielectric and thermal properties. However, growing environmental and safety concerns have sparked interest in alternative, eco-friendly insulating fluids. Esters have emerged as promising candidates due to their high biodegradability, flame retardance, and lower ecological impact. This paper compares two such insulating fluids-a natural ester (Envirotemp FR3) and a synthetic ester (Midel 7131)-under the influence of lightning impulse voltages, representing a critical stress condition for transformer insulation. High voltage tests, including dielectric loss factor (delta tangent) measurements, were performed before and after applying standardized impulse sequences. Results indicate that both esters maintained dielectric performance within acceptable limits, with the synthetic ester demonstrating superior stability under impulse stress. The findings confirm the technical feasibility of ester-based insulating oils as viable and sustainable alternatives to mineral oil in power transformers, supporting broader environmental and operational safety goals in modern power systems. © 2025 IEEE.

Abstract
The rapid expansion of offshore wind farms and the development of energy islands for green hydrogen production have introduced futuristic off-grid systems. These systems can experience total shutdowns, necessitating black start solutions to ensure reliable restoration capabilities for isolated offshore wind farms. This paper investigates a grid-forming converter sizing strategy to enable black start capabilities in off-grid offshore wind farms. The study evaluates the impact of different energization strategies on battery energy storage system (BESS) sizing, focusing on soft energization with droop control in wind turbines and electrolyzers, the effects of wind turbine ramp rates on BESS requirements, and the role of switchable shunt reactors at the offshore substation for reactive power management. A comparative analysis is conducted between soft + hard and pure soft energization sequences to assess their impact on BESS converter sizing. Results demonstrate that the combined soft + hard energization strategy significantly reduces BESS converter size, offering a more cost-effective black start solution compared to pure soft energization.

Abstract
Local flexibility markets are a promising solution to aid system operators in managing the network as it faces the growth of distributed resources and the resulting impacts on voltage control, among other factors. This paper presents and simulates a proposal for an intra-day local flexibility market based on grid segmentation. The design provides a market-based solution for distribution system operators (DSOs) to address near-real-time grid issues. The grid segmentation computes the virtual buses that represent each zone and the sensitivity indices that approximate the impact of activating active power flexibility in the buses within the zone. This approach allows DSOs to manage and publish their flexibility needs per zone and enables aggregators to offer flexibility by optimizing their resource portfolios per zone. The simulation outcomes allow for the assessment of market performance according to the number of zones computed and show that addressing overloading and voltage control through zonal approaches can be cost-effective and counterbalance minor errors compared to node-based approaches.