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Optimal robust stabilizer design based on UPFC for interconnected power systems considering time delay

Koofigar H. R., Isazadeh G.

Archives of Electrical Engineering

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2017

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Vol. 66, nr 3

459--474

EN

A robust auxiliary wide area damping controller is proposed for a unified power flow controller (UPFC). The mixed H2 /H∞ problem with regional pole placement, resolved by linear matrix inequality (LMI), is applied for controller design. Based on modal analysis, the optimal wide area input signals for the controller are selected. The time delay of input signals, due to electrical distance from the UPFC location is taken into account in the design procedure. The proposed controller is applied to a multimachine interconnected power system from the IRAN power grid. It is shown that the both transient and dynamic stability are significantly improved despite different disturbances and loading conditions.

2

Adaptive fuzzy control for a class of constrained nonlinear systems with application to a surface vessel

Jamalzade M S., Koofigar H. R., Ataei M.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 3

987--1000

EN

In this paper, adaptive control for a class of uncertain nonlinear systems with input constraints is addressed. The main goal is to achieve a self-regulator PID controller whose coefficients are adjusted by using some adaptive fuzzy rules. The constraints on the control signal are taken into account as a saturation operator. The stability of the closed-loop system is analytically proved by using the Lyapunov stability theorem. The proposed method is then applied to a surface vessel with uncertain dynamic equations. The simulation results show the effectiveness of the proposed control strategy.

3

Decentralized fuzzy-integral-sliding control for a class of TITO uncertain nonlinear systems with application to a 2-DOF helicopter model

Zare K., Koofigar H. R.

Journal of Theoretical and Applied Mechanics

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2014

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Vol. 52 nr 4

959--969

EN

In this paper, a novel fuzzy-integral-sliding controller (FISC) is designed for coupled nonlinear two-input two-output (TITO) systems. Decomposing the original system into two subsystems, the coupling effects are modelled as uncertainties. In order to ensure the robustness properties with respect to system uncertainties and external disturbances, the sliding mode technique with a proportional integral (PI) sliding surface is adopted. On the other hand, to avoid the chattering phenomenon, the Takagi-Sugeno fuzzy rules are incorporated into the control algorithm, which forms a fuzzy sliding controller. The stability analysis is also presented based on the Lyapunov stability theorem. The proposed FISC is then applied to control the elevation and azimuth angles of Humusoft CE150, as a two degree of freedom (DOF) laboratory helicopter model with highly cross-coupled dynamics. The simulation results are also presented to demonstrate the performance of the proposed control scheme.

4

Robust adaptive vibration control for a general class of structures in the presence of time-varying uncertainties and disturbances

Koofigar H. R., Amelian S.

Journal of Theoretical and Applied Mechanics

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2013

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Vol. 51 nr 3

533--541

EN

The problem of active vibration suppression in a wide class of smart structures is addressed. The dynamical model of a structure may be perturbed by uncertain time-varying parameters and external disturbances. A novel adaptive-based control algorithm is presented here to satisfy robustness properties with respect to model uncertainties and environmental disturbances. Reflecting practical situations, the upper bound of perturbations is not required for controller design. The analytical stability of a closed-loop system is presented based on the Lyapunov stability theorem. Furthermore, numerical analysis is also provided to show the effectiveness of the proposed method.