Estimação paramétrica da impedância de uma rede elétrica conectada a uma geração fotovoltaica

Abstract

Better knowledge of grid impedance is essential to assess stability, improve power quality and control of Distributed Generation Systems (SGDs), as well as perform safe connection or reconnection to the grid grid. As a result of increased network impedance variability, interest in impedance estimation techniques has increased considerably. This work presents a computational method that performs a parametric impedance test on the electrical grid side and online, for a system that contains a photovoltaic generation connected to an electrical grid. The method used in this work requires variations in power injection by the inverter and calculation of network parameters based on numerical analysis on changes in positive sequence phasors extracted from the orientation depth and system currents in the PAC. The numerical search of the network parameters is carried out using classic and recent iterative optimization methods, in order to find a solution for the non-linear search system arising from the technique used. The numerical methods of Newton-Raphson, Broyden, Levemberg-Marquardt, Potra-Pták, Ponto Meio and Chun are used to determine the network parameters and for a subsequent performance comparison between them. A simulation platform containing the entire electrical network together with numerical methods was built in a Simulink/MATLAB® environment to estimate the impedance as the final result of the process. Finally, the results were corroborated with the help of a real-time simulator available in the laboratory