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Impedance Measurement of Three Phase Systems in DQ-Domain: Applying MIMO-Identification Techniques

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


Original languageEnglish
Title of host publication8th Annual IEEE Energy Conversion Congress & Exposition (ECCE 2016)
ISBN (Electronic)978-1-5090-0738-7
Publication statusPublished - 2016
Publication typeA4 Article in a conference publication
EventIEEE Energy Conversion Congress and Exposition -
Duration: 1 Jan 1900 → …


ConferenceIEEE Energy Conversion Congress and Exposition
Period1/01/00 → …


Grid impedance and the output impedance of grid-connected inverter are important parameters for the operation of grid-connected systems, such as solar, wind, and other distributed-generation resource systems. The impedance mismatch between the grid and the interfacing circuit often generates harmonic resonances that lead to reduced power quality. Since the impedances usually vary over time with many parameters, online measurements are required for adaptive control of the inverters. Several methods have been proposed for quick, accurate measurements of impedances, but the use of multiple-input multiple-output (MIMO) identification techniques have not been considered. Applying the MIMO techniques, different components of the inverter output impedance or grid impedance can be simultaneously measured during a single measurement cycle. Therefore, the operating conditions of the system can be kept constant during the measurements, and the overall measurement time is significantly reduced. This paper shows the use of orthogonal binary sequences to simultaneously measure the d- and q-components of grid-connected inverter output impedance. Experimental results based on a three-phase grid-connected inverter are presented and used to demonstrate the effectiveness of the proposed methods.

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