State Observer for Grid-Voltage Sensorless Control of a Converter Equipped with an LCL Filter: Direct Discrete-Time Design

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Synchronization with the power system is an essential part of control of grid-connected converters. This paper proposes a grid-voltage sensorless synchronization and control scheme for a converter equipped with an LCL filter, measuring only the converter currents and the dc voltage. A discrete-time pole-placement design method is used to formulate an adaptive full-order observer for the estimation of the frequency, angle, and magnitude of the grid voltage. The proposed discrete-time design method enables straightforward implementation and suits low sampling rates better than its continuous-time counterpart. The analytically derived design is experimentally validated, and the results demonstrate rapid convergence of the estimated quantities. Moreover, the experimental tests show that grid-voltage sensorless operation is possible under balanced and unbalanced grid disturbances and distorted grid conditions.


Original languageEnglish
Article number7433435
Pages (from-to)3133-3145
Number of pages13
JournalIEEE Transactions on Industry Applications
Issue number4
Publication statusPublished - 1 Jul 2016
MoE publication typeA1 Journal article-refereed

    Research areas

  • Active front-end rectifier, adaptive observer, distributed generation, line-voltage sensorless, small-signal linearization, state feedback, synchronization

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