Fator de agregação em estudos de qualidade da energia elétrica para usinas fotovoltaicas com inversores STRIN.

Abstract

Due to reduced installation costs, abundance of solar resource, environmental appeal and simplicity of installation, the photovoltaic solar energy use is rising. In Brazil, the installed capacity in 2021 reached 10,429 MW, representing 2.1% of the entire national power matrix. However, the solar source has elements with non­linear characteristics, such as current inverters that, when converting from direct current (DC) to alternating current (AC), can cause disturbances in the Quality of Electric Power (QEE), among which, harmonic voltage distortions are highlighted. Therefore, in Brazil, the National Electric System Operator requires the execution of theoretical studies and field measurements of QEE, according to guidelines, criteria and assumptions established in the Network Procedures documented in Sub­modules (ONS, 2021) of the National Interconnected System (SIN), and in the specific instructions published by the ONS. In such a way, lining up with these guidelines, criteria and assumptions, this work aims to carry out a comparative study of two methodologies to point out the harmonic distortion in a real solar complex, connected to the Basic Network at 230 kV, with 135 MWac of nominal installed power. Therefore, the compared methodologies are: simple aggregation (algebraic sum of harmonic currents) and vector aggregation (applying the aggregation factor). In the simulations, the program HarmZs is used – Harmonic Behavior Studies and Modal Analysis of Electric Networks, developed and maintained by CEPEL, for modeling the solar complex and to obtain the results. It is verified from the results obtained, that: for a simple aggregation, there is a greater amount of harmonic components that surpassed the individual limits established by the ONS, as well as the total harmonic distortion limit. On the other hand, using vector aggregation, the results are different and indicate smaller amounts of harmonic components that surpassed the individual limits, and the total harmonic distortion is lower. Hence, it is concluded that, there may be an unnecessary dimensioning of harmonic filters depending on the methodology used. Due to different results, it is necessary make measurements in field, in order to validate the methodologies and results presented here.