Análise dos impactos dos modos de controle das fontes renováveis interfaceadas por inversores de potência na função de proteção de distância

Abstract

Recent discussions have raised the necessity of increasing the participation of renewable resources into the energy grid in a global level. In Brazil, the response to this necessity has come as the implementation of windfarms and solar powerplants. This kind of generation that benefits from the energy of the wind and the sun are, in majority, interfaced by power electronics equipment that controls the electric variables with the objective of meet the energy quality requirements in the point of connection of the power plants with the high voltage grid. The existence of power inverters in this interface leads to new challenges, like the fault identification at the power grid, since, until this moment, the grid fault analysis was made based in synchronous generator models. Thus, actual protection relays have several difficulties in operate correctly inside systems with high penetration of windfarms and solar powerplants, decreasing the reliability and selectivity of the system. The objective of this dissertation is to conduct a detailed analysis of the impacts of different power converter control modes on distance protection functionality. To achieve this, a numerical simulation was carried out to record the transients caused by faults near wind farms and photovoltaic plants. Single-phase, phase-to-phase, phase-to-phase-to-ground, and three-phase faults were simulated, with variations in fault location, fault resistance, and fault incidence angle. These recordings revealed changes in the short-circuit profile due to the integration of renewable generation sources, such as fault-induced interference in healthy phases. The results were saved in COMTRADE files and applied to a commercial protection relay, allowing the evaluation of protection function behavior in these scenarios through the oscillographic records captured by the relays. The analysis of these records highlighted malfunctions in key components of the distance protection function, such as phase selectors, directional elements, and fault impedance identification.