In this paper, an improve robust UPFC controller is designed based on Lyapunov direct method which enhances the power flow and DC voltage regulation of a power system. The proposed controller is robust and produces an optimal response in the presence of unknown bounds of system parameter uncertainty and disturbances. The magnitudes of the uncertainty and disturbances are identified online and the information obtained is then used to tune the controller. The performance of the proposed controller is simulated on a Kundur power system and compared with a state feedback controller with integral control, called state feedback PI controller. Comparative results indicate satisfactory performance of the proposed controller in dealing with the uncertainties and disturbances considered.
In this paper, an adaptive nonlinear controller for transient stabilization and voltage regulation of wind power systems based Double Fed Induction Generator (DFIG) in multimachine environment is described using a classical third order dynamical model of the DFIG. Estimation of non measurable time derivative signals (quadrature stator current component of the DFIG, mechanical input power, unknown transient open circuit time constant for direct axis) and an online computing technique for the operating points (e.g. power angle and its reference) are presented. The major advantage of the proposed control law is its robustness with respect to large disturbances, parameter variations and change of the operating point. Simulation results in the case of 4-machine power systems show the performance of the proposed control scheme and its heftiness properties.
<p style='text-indent:20px;'>This paper focuses on the dynamical analysis of the permanent magnet asynchronous motor with the aim of subsequently designing effective robust control laws for the indirect field-oriented control (IFOC) devices. We first perform some tasks which demonstrate the existence of chaos phenomenon in the IFOC using relevant indicators such as phase portraits, bifurcations diagrams and Lyapunov exponents. Chaotic signature and some striking transitions are revealed such as period-doubling, torus, period-adding and chaos when an accessible parameter of the IFOC motor is changed. More interestingly, a certain range of the parameter space corresponds to the transient chaos. This behavior was not reported previously and can be considered as an enriching contribution. Secondly, due to the great interest to reduce the upper bound of uncertainties and interference, conventional sliding mode control (SMC) has been abundantly investigated for fault-tolerant control (FTC) systems. However, this approach presents several drawbacks in terms of overshoot, less robustness, transient state error, large chattering and speed of convergence that limit its use for industrial applications. For these reasons, the integral sliding mode control (ISMC) and the fuzzy sliding mode control (FISMC) are proposed to keep the IFOC motor in the regular operation zone. The optimal feedback gains and a sufficient condition are proposed for the stability of the overall IFOC system is drawn based on the linear quadratic regulator (LQR) method. To highlight the effectiveness and applicability of the proposed control scheme, numerical simulation results are presented. This analysis allows us a great knowledge of engineers for interpreting the operation of the IFOC motor. To highlight the effectiveness and the applicability of the proposed control scheme, numerical simulations results are presented and clearly demonstrated the feasibility of these techniques.</p>
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