An Asymmetric Perturbation Signal for Enhanced Perturbation Injection Capabilities of a Grid-connected Converter

Abstract

Impedance estimation is an important tool for gridconverter interaction evaluation. Using existing grid-connected converters for perturbation injection enables grid impedance estimation during operation without additional hardware (namely dedicated perturbation injection equipment). However, such equipment (e.g. converters for PV systems, BESS, EV charging stations...) have limited voltage reserve, leading to reduced perturbation injection capabilities (i.e. perturbation magnitude) with conventional perturbation signals (pseudo-random binary signals or chirp signals). To enhance the perturbation capabilities of those converters, an asymmetric signal is proposed that increases the perturbation magnitude at a maximum operating point. An extension to a wide-bandwidth chirp signal is then presented.