Abstract. The article examines key aspects of electrical energy losses and power quality indicators in electric power systems. It analyzes the causes of technical and non-technical losses, methods for their calculation and mitigation, as well as power quality indicators such as voltage and frequency deviations, harmonics, phase load imbalances, reactive power, and power factor. Furthermore, the study addresses issues related to losses in transformers and power lines, load regimes, compensation equipment, and energy efficiency. It highlights the role of SCADA and Smart Grid technologies in detecting losses and improving power quality through real-time monitoring. The paper is based on a theoretical and practical overview of energy losses and power quality issues in electric power systems, rather than on measurements taken from a specific network.

Keywords: electric power system, electrical energy losses, power quality, energy efficiency, voltage, harmonics.