Identification of Factors Influencing the Improvement of Long-Term Operational Reliability of Centralized Inverters

Abstract

Relevance: in power supply systems based on renewable energy sources, centralized inverters represent a key functional component. Their reliable and stable operation plays a decisive role in ensuring the efficiency of electricity generation and economic sustainability. Under real operating conditions, inverters are influenced by load variations, harmonic distortions, grid voltage quality, thermal regimes, mechanical impacts, and maintenance levels. These factors accelerate component degradation, increase the probability of failures, and reduce the remaining useful life. Therefore, identifying the electrical, thermal, mechanical, and operational factors affecting the reliability of centralized inverters and evaluating their interrelationships through correlation analysis is of significant scientific and practical importance.

Aim: to identify the main electrical, thermal, mechanical, and operational factors influencing the long-term reliability of centralized inverters; to evaluate their relationships with the reliability index and remaining useful life (RUL) using correlation analysis; and to establish a hierarchical structure of dominant parameters that have the greatest impact on degradation processes.

Methods: key operational parameters were selected based on IEC, IEEE, GOST, and ISO standards. Current, voltage, power, total harmonic distortion (THD), temperature, vibration, and maintenance indicators were collected using monitoring systems. Thermal, load, and harmonic effects were evaluated using mathematical models. The reliability function R(t), mean time between failures (MTBF), and failure intensity λ were calculated. Relationships between parameters were analyzed using Pearson (r) and Spearman (ρ) correlation coefficients. The results were visualized using heat maps. Dominant factors were identified, and their impact on reliability was evaluated using a comprehensive approach.

Results: the study identified the main factors affecting the reliability of centralized inverters, and their interrelationships were quantitatively evaluated. Correlation analysis revealed that internal temperature (T_in), harmonic distortion (THD), number of temperature cycles (Ncycle), rate of temperature change (dT/dt), and voltage deviation (ΔU) exhibit strong negative correlations with the reliability index. Heat map analysis confirmed that T_in is the central driver of degradation. The efficiency of the cooling system and the quality of maintenance were shown to be critical factors in improving reliability. The proposed approach enables prediction of the remaining useful life, optimization of preventive maintenance, and reduction of operational risks.