This study presents a comparative techno-economic and environmental assessment of three leading stationary energy storage technologies: lithium-ion batteries, lead-acid batteries, and hydrogen systems (electrolyzer–tank–fuel cell). The analysis integrates Life Cycle Assessment (LCA) and Levelized Cost of Storage (LCOS) to provide a holistic evaluation. The LCA covers the full cradle-to-grave stages, while LCOS accounts for capital and operational expenditures, efficiency, and cycling frequency. The results indicate that lithium-ion batteries achieve the lowest LCOS (120–180 EUR/MWh) and high round-trip efficiency (90–95%), making them optimal for short- and medium-duration storage. Lead-acid batteries, though characterized by low capital expenditures (CAPEX) and high recyclability (>95%), show limited cycle life and lower efficiency (75–80%). Hydrogen systems remain costly (>250 EUR/MWh) and less efficient (30–40%), yet they demonstrate clear advantages for long-term and seasonal storage, particularly under scenarios with “green” hydrogen production and reduced CAPEX. These findings provide practical guidance for policymakers, investors, and industry stakeholders in selecting appropriate storage solutions aligned with decarbonization and sustainability goals.

These days, with the significant increase in the use of renewable energy sources as additional energy sources connected to the distribution network, many challenges and difficulties arise in ensuring sustainability and reliability. The generation, transmission and distribution, in the current state of the electricity system, are facing quite dynamic changes. They are the result of the liberalization of the energy market, the increased use of renewable energy sources such as photovoltaic systems, wind turbines and the charging stations for hybrid and electric vehicles. The most important factors are related to the balancing of the energy system, the analysis of voltage stability, overcoming the consequences of the increase in short-circuit currents, increasing the transmission capacities of the system forming and distribution networks, as well as the accurate forecasting of the development of loads and consumption over the coming years. This article presents an analysis of the voltage stability in a smart microgrid for two different scenarios. The studied cases describe a linear low-voltage p-type microgrid with loads connected to it at different nodes. Data on the type and cross-section of the conductors of the studied power line are presented. Simulation studies were carried out to determine the limits of grid voltage stability when connecting photovoltaic plants with a set power. The simulation results are commented on and an analysis of the optimal operating mode of the system is realized. The model studies were implemented in the NEPLAN program environment. The research carried out allows an evaluation of the permissible limits for network stability when connecting photovoltaic plants. Through this evaluation, it can be determined how many and at which node the loads should be connected without causing an imbalance in the network. This is useful from the point of view of ensuring the sustainability and reliability of electrical energy in a microgrid.

When selecting the grounding mode of the neutral of power transformer in electric grids, the important factors are the overvoltages in the single-phase earth faults transient, the magnitude of the earth connection currents, the selective action of the relay protections, etc. The publication discusses the variation of the regime parameters for single-phase earth faults in medium voltage combined-earth networks. In the case of combined earthing of the neutral, the earthing mode through a reactor and a parallel switch on of active resistance at single-phase earth faults are normally used. In some of the distribution networks, the earthing mode is already used, in which a reactor and active resistance are normally switched on and in the case of non-selective action of the relay protection the active resistance is switched off. The variation of the regime parameters is considered depending on the compensation and the magnitude of the transient resistance at single-phase earth faults. The changes in the multiplicity of the overvoltages of the undamaged phases and in the neutral were investigated in case of combined earthing through a reactor and subsequent activation of active resistance and with active resistance and a reactor and subsequent exclusion of active resistance depending on the compensation and overvoltage single-phase earth faults for the tested electrical networks.

With the development of smart grids in recent years in the medium-voltage grids have been increasingly introduced renewable energy sources, such as photovoltaics, wind generators and biomass. These power capacities are designed and built in the vicinity of the electricity consumers. Therefore, they are connected to the nearest existing power lines. The power lines supplying these smart users are calculated to the limit capacity to ensure their power supply. For the connection of new power generation and consumers of power energy from renewable energy sources, it is necessary to reassess the setting of the existing overcurrent relay protection. The publication assesses the requirements for selectivity and sensitivity of an overcurrent relay protection against phase to phase faults at connection of renewable energy sources.

This report presents new concept for modelling of high-voltage and extra-high voltage transmission systems, which provide higher accuracy for modelling of underground cables. The growing worldwide demand for electricity influences the transmission system in a way that requires the upgrade and construction of new transmission lines. Also, the high degree of urbanization, the growth of the cities and the social discontent with living nearby overhead lines leads to gradual transition from overhead lines to underground cables at all voltage levels. This paper presents the discrepancies between the real-world situation and the mathematical model due to the specific operation, construction and environment of the cable lines.

This study investigates the physical and cyber-physical resilience of smart grids with a high share of renewable energy sources (RESs) dominated by permanent magnet synchronous generators (PMSGs). The originality of this work lies in the development and unified evaluation of five integrated control strategies, the PLL with grid following, VSG with grid shaping, VSG+BESS, VSG+STATCOM, and VSG+BESS+STATCOM, implemented within a coherent simulation framework based on Python. Unlike previous works that analyze these methods in isolation, this study provides a comprehensive quantitative comparison of their dynamic characteristics, including frequency root mean square deviation, maximum deviation, and composite resilience index (RI). To extend the analysis beyond static conditions, a multi-generator (multi-PMSG) scenario with heterogeneous inertia constants and variable load profiles is introduced. This dynamic model allows the evaluation of natural inertia diversity and the effects of inter-generator coupling compared to the synthetic inertia emulation provided by VSG-based control. The combined VSG+BESS+STATCOM configuration achieves the highest synthetic resilience, improving frequency and voltage stability by up to 15%, while the multi-PMSG system demonstrates comparable or even higher RI values due to its inherent mechanical inertia and decentralized response behavior. In addition, a cyber-physical scenario is included to evaluate the effect of communication delays and false data injection (FDI) on VSG frequency control. The results show that a communication delay of 50 ms reduces RI by approximately 0.2%, confirming that even minor cyber disturbances can affect synchronization and transient recovery. However, hybrid control architectures with local energy buffering (BESS) show superior resilience under such conditions. The main technical contribution of this work is the establishment of an integrated analytical and simulation framework that enables the joint assessment of synthetic, natural, and cyber-physical resilience in converter-dominated smart grids. This framework provides a unified basis for the analysis of dynamic stability, hybrid control interaction, and the impact of cyber uncertainty, thereby supporting the design of low-inertia, resilient, and secure next-generation power systems.