Open-pit lignite mines contain high-power converter-fed drives whose operating state strongly affects current harmonics and internal power-quality conditions. The primary objective of this study is to experimentally characterize load-dependent voltage and current harmonic regimes in an operating open-pit lignite mining electrical system and to use a simplified MATLAB/Simulink R2021b inverter-motor model only as a trend-interpretation tool. In situ measurements were obtained on the E05 SRS 1300-26/3.5 bucket-wheel excavator and associated conveyor systems. The measurements show low voltage distortion at the monitored internal points (the Total Harmonic Distortion of Voltage (THD_U) below 1.5% in the reported cases) and strongly load-dependent current distortion, including high relative the Total Harmonic Distortion of Current (THD_I) during low-current operation. The simulation reproduces selected qualitative drive-side trends but does not represent the upstream network, feeder impedances, transformer behavior, capacitor-bank interaction, or background supply distortion; it is therefore not presented as an independently validated network model. A separate Battery Energy Storage System (BESS) calculation is retained only as an illustrative resilience scenario based on an assumed four-hour duty profile and is not used as evidence for the measured harmonic findings. The main contribution is an experimentally supported case study of load-dependent harmonic behavior in an operating lignite-mine electrical system, complemented by simulation-assisted physical interpretation and clearly separated prospective modernization implications.

Energy can become an instrument of geopolitical coercion when asymmetric dependencies, infrastructure vulnerabilities, and limited resilience allow energy resources, supplies, prices, technologies, or infrastructure to be strategically exploited. This study examines these mechanisms and their implications for European energy security and NATO strategic preparedness, using Romania as an eastern-flank case study. A coercion–vulnerability–resilience framework is developed by integrating geopolitical assessment, energy-dependency analysis, critical-infrastructure vulnerability, scenario analysis, and quantitative measurement constructs. The study operationalizes energy coercion through a six-stage pathway linking dependence creation, signaling, coercive action, domestic transmission effects, and negotiation. The Romanian case indicates that energy security depends not only on domestic resource availability but also on infrastructure protection, diversification, storage, system flexibility, investment implementation, cybersecurity, and regional interconnection. The composite indices presented in the study are synthetic methodological demonstrations rather than empirically estimated national scores, while the empirical analysis relies on referenced statistical, institutional, and macroeconomic evidence. The framework shows how resilience measures can reduce exploitable dependencies and strengthen Romania’s contribution to European energy security and NATO strategic preparedness.