Robust Control Based on Observed States Designed by Means of Linear Matrix Inequalities for Grid-Connected Converters

Gustavo G. Koch (), Caio R. D. Osório, Ricardo C. L. F. Oliveira and Vinícius F. Montagner
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Gustavo G. Koch: Power Electronics and Control Research Group, Federal University of Santa Maria—UFSM, Santa Maria 97105-900, RS, Brazil
Caio R. D. Osório: Typhoon HIL—Applications Team, 400771 Novi Sad, Serbia
Ricardo C. L. F. Oliveira: School of Electrical and Computer Engineering, University of Campinas—UNICAMP, Campinas 13083-852, SP, Brazil
Vinícius F. Montagner: Power Electronics and Control Research Group, Federal University of Santa Maria—UFSM, Santa Maria 97105-900, RS, Brazil

Energies, 2023, vol. 16, issue 4, 1-24

Abstract: This paper provides a procedure to design robust controllers based on observed states applied to three-phase inverters with LCL filters connected to a grid with uncertain and possibly time-varying impedances, which can arise in renewable energy systems and microgrid applications. Linear matrix inequalities are used to rapidly compute, off-line, based only on the choice of two scalar parameters for pole location, sets of gains for the controller and the observer, and also to provide a theoretical certificate of the closed-loop stability, including a limit for the rate of variations of the grid impedances. The proposed design procedure allows the easy implementation of robust state feedback controllers with a reduced number of sensors, ensuring good performance for different sets of grid impedances. Additionally, larger regions of guaranteed stability are provided by the proposed procedure, when compared with a similar condition from the literature. The control law using the observed states can ensure grid currents with low harmonic content, complying with the IEEE 1547 Standard requirements, with negligible loss of performance concerning the feedback of the measured state variables. Three optimal state feedback controllers from the literature are reproduced here and successfully implemented using the observed state variables based on the proposed procedure. In all cases, the viability of the proposal was confirmed by simulations and experimental results.

Keywords: grid-connected converters; state observers; uncertain parameters (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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