PRECISION ASSESSMENT OF GRID IMPEDANCE ESTIMATION METHOD BASED ON PQ VARIATIONS APPLIED TO A THREE-PHASE PHOTOVOLTAIC CONVERTER UNDER VARIOUS GRID AND WEATHER CONDITIONS

MATHEUS SOARES; MARCELLO NEVES; THIAGO TRICARICO; FELIPE  DICLER; GUSTAVO  GONTIJO; MAURICIO  AREDES

doi:10.20906/CBA2022/279

MATHEUS SOARES Universidade Federal do Rio de Janeiro
MARCELLO NEVES Universidade Federal do Rio de Janeiro
THIAGO TRICARICO Universidade Federal do Rio de Janeiro
FELIPE DICLER Universidade Federal do Rio de Janeiro
GUSTAVO GONTIJO Universidade Federal do Rio de Janeiro
MAURICIO AREDES Universidade Federal do Rio de Janeiro

DOI: https://doi.org/10.20906/CBA2022/279

Keywords: Photovoltaic generation, Grid impedance estimation, Islanding detection

Abstract

An electrical grid equivalent impedance, specially in the context of microgrids, may be time- varying due to disconnections. Therefore, online grid impedance monitoring is deemed important to detect islanding and to allow for adaptive control schemes. In this context, a series of methods for grid impedance estimation using active and reactive power orders variations has been proposed in the last decade. The objective of this work is to use simulations to analyze the precision of the three-phase, synchronous frame based version of this method when implemented in a grid-tie inverter for a photovoltaic system. Various combinations of short-circuit MVA and X/R ratios are tested. Estimation under multiple solar radiation conditions is also studied. Finally, the method is applied as an islanding detection algorithm and the compliance with the test setup required by IEEE 1547 is veried.