H2/H∞ formulation of LQR controls based on LMI for continuous-time uncertain systems

Caun, Rodrigo da Ponte; Assunção, Edvaldo; Teixeira, Marcelo Carvalho Minhoto

doi:10.1080/00207721.2020.1836283

Cited by 11 publications

(2 citation statements)

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“…Since power conversion systems should be operated with high efficiency as well as improved flexibility and profitability, many authors have a tendency to focus on robust algorithm, adaptive algorithm or learning algorithm to obtain the stabilization of the entire system even in the presence of harsh conditions of the utility grid [6,[11][12][13][14][15][16]. The linear quadratic regulators (LQR) were proposed as a method to determine the optimal controller gains by means of a cost function minimization [17,18].…”

Section: Introductionmentioning

confidence: 99%

“…Even though these studies provide satisfactory performance under parametric uncertainties, several external disturbances such as grid voltage imbalance degrade the current controller operations. Another approach [12] employs H∞ control to cope with the additional grid impedance caused by the weak grid. The robust performance of H∞ control is guaranteed even under parametric uncertainties.…”

Section: Introductionmentioning

confidence: 99%

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Robust EMPC-Based Frequency-Adaptive Grid Voltage Sensorless Control for an LCL-Filtered Grid-Connected Inverter

Kim,

Tran,

Kim

2024

Electronics

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A robust explicit model predictive control (EMPC)-based frequency-adaptive grid voltage sensorless control is developed for a grid-connected inverter (GCI) via a linear matrix inequality (LMI) approach under the model parametric uncertainties as well as distorted and imbalanced grid voltages. In order to ensure the quality of grid currents injected into the utility grid even when the system model parameters vary, the proposed control scheme is accomplished by an enhanced prediction model rather than the conventional prediction model obtained by fixed parameters. Furthermore, an LMI-based observer is integrated with the disturbance observer to improve the reference tracking performance and to reject disturbances. The proposed observer is employed for the grid frequency-adaptive control without the need for grid voltage sensors. The proposed current controller and observer employ the LMI scheme to maintain a stable and robust operation of the GCI. The discrete-time frequency response and pole-zero map analyses are utilized to examine the system performance including the stability and robustness against parametric uncertainties. Comprehensive simulation and experimental tests as well as theoretical analyses clearly validate the robustness of the proposed control scheme under various harsh test conditions with non-ideal and unexpected grid and system parametric uncertainties.

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