Renewable energy includes a wide variety of technologies that may provide electric energy without releasing greenhouse gases. However, due to the intermittent nature of renewable energy sources, relying on a single source cannot ensure a steady energy supply, making it essential to combine multiple renewable energies with thermal generators to meet the required energy demand. Furthermore, the economic feasibility of renewable energy can vary significantly across different geographical regions. These challenges can be addressed successfully through the global electricity grid concept. It enables the efficient transmission of clean energy over long distances, and it allows nations to capitalize on their unique renewable energy strengths, facilitating the seamless exchange of clean energy to meet global demand while optimizing the use of renewable resources worldwide. This paper examines global and regional initiatives aimed at fostering a sustainable energy future, highlighting the benefits and challenges associated with globally interconnected power grids and intercontinental transmission networks. Although the challenges and opportunities of the global electricity grid are well understood, the quantification of its costs, benefits, and environmental impacts remains in its infancy, leaving a significant gap in the current literature.

The paper presents the defined conception of the agent structure of the multi-agent system that performs the tasks of power system protection. The required input data sets and the input agents that provide observability of the power system were determined. The paper also proposes the agent input data acquisition ways that allow fast access to power system status information. The proposal of agents' attributes that define their functionality in spatially and layered distributed structure of the multi-agent systems was also discussed. The paper presents also the simulation results evolving from the implementation of the agents' functionalities in the digital power line distance protections.

Complex phase shifting transformer protection scheme and complexity of the object itself created a need to use simulation programs for their analysis. Often phase shifting transformer (PST) are modeled as a simplified series impedance and quadrature voltage source which cannot be used for power system protection analysis, especially in a transient condition. Therefore, the procedure of building realistic PST model was presented by using available transformer models with calculation of their parameters including interconnections between units. Paper consist calculations based on case study with symmetrical dual-core PST example. Additionally, theoretical background of PST principle, operation, and their impact of power system protection were introduced with numerus examples of PST model verification.

Following a number of studies that have employed different forms of neural network models to perform dissolved gas-in-oil analysis (DGA) of transformer bushings, this manuscript focuses on evaluating the relevance of the parameters that form part of the model input space. Using a multilayer neural network initially populated with all the 10 input parameters (10V-Model), a matrix containing causal information about the possible relevance of each input parameter is obtained. The information from this matrix is proven to be valid through the construction and testing of another two, separate, multilayer networks. One network's input space is populated with the 5 most relevant parameters (MRV-Model), while the other is populated with the 5 least relevant parameters (LRV-Model). The obtained classification accuracy values are as follows: 100% for the 10V-Model, 98.5% for the MRV-Model, and 53.0% for the LRV-Model.

Paper presents an innovative concept for automatic selection of an optimal tap of the phase shifting transformer (PST) before its switching-on. The purpose of the system is to enable the switching-on of the PST without sudden changes in power network operating conditions. For the investigation of the underlying phenomena during switching, a test power network containing the accurate dynamic model of the PST was developed. The investigations were performed for different scenarios of changes in the power network parameters and control options of the PST. This allowed determining the desired functionality and structure of the automation system for selecting an optimal tap of the PST before its switching-on. The developed automation system is based on synchronous measurements, and this represents a novel implementation of such measurements. Verification simulation studies indicate that the proposed concept achieves the stated objectives. It is expected that the practical application of this automation system can resolve the transient overcurrent in the adjoining network components arising from PST switching. Overall this will enable significant minimization of negative effects of PST switching-on the power network operating conditions.