Standardization of power quality indicators and the causes of their deviations from established norms

The aim of this study is a comprehensive investigation into the standardization and assurance of electric power quality under modern challenges, particularly the active integration of distributed energy resources, microgrids, electromobility, and the widespread use of power electronics. The article focuses on systematizing current regulatory requirements for power quality indicators and identifying the main causes of their deviation from established standards. The methods. The study employs a critical analysis of international and national standards (EN 50160, IEEE 1159, IEEE 519, IEC 61000), as well as a review of scientific literature and practical case studies related to the detection, classification, and mitigation of power quality disturbances. Typical PQ issues, their root causes, and preventive measures are generalized. Findings. The paper presents a list of key power quality parameters (frequency, voltage, flicker, harmonics, unbalance, short-term events), their permissible values according to standards, and specific monitoring features in modern power networks. It also discusses the physical causes of quality deterioration, such as faults, nonlinear loads, motor startups, load fluctuations, and weather phenomena. The impact of emerging technologies (DG, RES, EV charging) on PQ is analyzed. The originality. A holistic approach is proposed to analyze the regulatory and technical framework of power quality, considering modern energy trends. For the first time, both normative aspects and practical influencing factors are consolidated in a single study with detailed mechanisms of their manifestation. Practical implementation. The findings can serve as a foundation for updating local standards, improving monitoring systems, implementing intelligent compensation devices, and educating power system personnel in power quality management.