Microgrids and nanogrids are increasingly deployed to support decentralized generation, local resilience, and renewable integration. However, their growing reliance on digital control, communication networks, cloud services, and IT–OT integration exposes them to diverse cybersecurity threats. Unlike traditional utility-scale systems, microgrids and nanogrids often operate under resource constraints, heterogeneous architectures, and limited cybersecurity expertise, making direct application of large-scale security frameworks impractical. This paper proposes a structured cybersecurity assessment framework for small- and medium-scale energy systems, supporting systematic risk identification,... More >

In large-scale 2D finite element steady-state thermal models for underground cable ampacity calculations, where the lateral and lower boundaries are adiabatic, the ground surface may be represented by isothermal Dirichlet, convective Robin, or coupled convection–radiation conditions. In such cases, the soil temperature at depths significantly below the cables tends to be equal or to exceed the temperature of reference soil or air. This paper proposes a novel approach addressing this issue by dividing the native soil into two layers, introducing an effective thermal conductivity for the upper layer, and assuming distinct reference soil temperatures at the cable depth and at the lower bounda... More >

This paper proposes the two-step approach for improving the voltage profile of the distribution network (DN) using the optimal integration of photovoltaic-battery energy storage (PV-BES) system. In the first step of the approach the optimal location of the PV-BES system in the DN and its optimal powers are determined, considering the topology and the load of the DN. This is done to improve the voltage profile of the DN using the meta-heuristic wild horse optimization method (WHO) and genetic algorithm (GA). The second step of the approach determines the optimal sizing of the PV-BES system, by taking into account the optimal powers obtained in the first step, the solar irradiance diagram and... More >

This paper analyzes the lightning protection of a 110 kV underground cable line connecting two overhead transmission lines with a 110 kV substation. The transition from two overhead lines to two underground cable lines is implemented at a special double-circuit overhead line tower located approximately 2.4 km from the 110 kV substation. Lightning transients are calculated at: (i) both cable terminations, first at the transition tower and second at the substation, (ii) at the first (more critical) cable joint, (iii) at the cable sheath to the surrounding soil and objects. The latter analysis is performed to assess the risk of outer cable insulation breakdown between the sheath and the transi... More >

The accumulation of atmospheric and industrial pollution of high-voltage insulators is one of the frequent problems and a pattern of failures in transmission systems. In this paper, a two-phase approach based on deep learning is proposed for the detection of pollution of high-voltage insulators. The proposed approach automatically detects three types of pollution (salt, soot and excrement) based on UAV images. In addition to detection, the classification of pollution is automatically done into three levels (low, medium and high pollution). In the first phase, the You Only Look Once (YOLO) detector is used for precise detection and isolation of insulators, where an average accuracy of [email protected]... More >

U.S. Treasury Department’s Office of Foreign Assets Control (OFAC) placed sanctions on Russian petroleum companies in January 2025, but for the petroleum industry of Serbia (NIS JSC Novi Sad), they were postponed repeatedly before finally took effect on October 9, 2025. In particular, PJSC Gazprom Neft owns 44.85% of NIS JSC Novi Sad, followed by Serbian government with 29.87%, JSC Intelligence with 11.3%, and small shareholders with 13.98%. Because of this, Pančevo Oil Refinery ran out of crude oil and stopped its operation on December 2, 2025. However, NIS JSC Novi Sad produces not only petroleum derivatives but also significant amounts of electricity. Part of this electricity is used b... More >

The increasing integration of digital technologies into electric power networks has transformed traditional grids into complex cyber-physical systems. Yet, the level of digital maturity across operators remains uneven, lacking a unified assessment framework. This paper proposes a structured model for evaluating the degree of digitalization in power grids, integrating technological, organizational, and analytical dimensions. The model introduces six core domains, technological infrastructure, data and analytics, operational processes, cybersecurity, organizational culture, and distributed energy integration, each evaluated across four maturity levels. A weighted scoring system is used to comp... More >

This paper presents a procedure for calculating switching overvoltage on the main circuit breaker of a medium-voltage (MV) cable feeder, to which induction and/or synchronous generators are connected, during a three-phase short circuit. When a fault occurs, the feeder is disconnected by the circuit breaker located at its beginning. After the set operating time of the relay protection, since islanded operation is not permitted, the connected distributed generators will also be disconnected. It is shown that, during the period when the network is disconnected while the generators remain connected, the overvoltage factor reaches values between 2.2 and 2.5, depending on the types of generators a... More >