Análise e mitigação da distorção harmônica em sistemas industriais com inversores de frequência.

Abstract

The quality of electrical energy has become an increasingly relevant topic given the significant growth of non-linear loads in electrical systems, especially in industrial environments. Decades ago, most electrical loads connected to the electrical system were linear in nature; however, with the advancement of studies in power electronics and the growing application of semiconductor devices in industry, the number of non-linear loads has increased significantly, intensifying the challenges related to electrical disturbances in the network. These electronic components distort the voltage and current waveform of the system, as occurs in equipment such as rectifiers, switched-mode power supplies, and, mainly, frequency inverters. Industrial environments, especially in the mining sector, have a high use of frequency inverters in their production processes, making them susceptible to the presence of harmonics in the electrical network. In this context, this work aims to investigate and reduce the impacts of harmonics generated by frequency inverters in the substation of Herculano Mineração, located in the city of Itabirito/MG. These harmonics modify fundamental characteristics of the electrical network, impacting the load curve of the substation transformer. Initially, the calculation procedures and analysis of the electrical measurements performed on the system are presented, with emphasis on the evaluation of voltage and current parameters associated with power quality indicators. Thus, with the case study addressed, it is noted that the use of active filters contributes significantly to the reduction of Total Harmonic Distortion (THD). The measurements performed on the 2.5 MVA transformer indicated voltage THD values ​​around 18% and current THD values ​​close to 100%, exceeding the limits recommended by the standard (IEEE 519, 2022) (10% and 20%, respectively), in addition to an average inductive power factor of 0.79, lower than the minimum limit of 0.92 established by (ANEEL REN 1000, 2021). Based on the sizing and application of the filter, a reduction in the harmonic components of the system was observed, with a decrease in DHTi to values ​​close to 20% and an increase in the power factor to approximately (0.93), meeting regulatory limits and demonstrating the effectiveness of the proposed solution in mitigating harmonic distortions, contributing to improved energy efficiency, greater operational reliability of the network and increased equipment lifespan.