Nonlinear Disturbance Attenuation Control Research Articles

The design of nonlinear disturbance attenuation controller for TCSC robust model of power system

The control problem of the single machine infinite bus system with TCSC is dealt with. Based on the maximization of the external disturbances on the system model, an adaptive nonlinear controller for large disturbance attenuation and a parameter updating law are designed by using the backstepping method. The parameter uncertainty of the transmission line is considered, as well as the influences of large external disturbances to the system output are mainly discussed. The nonlinear controller does not have the sensitivity to the influences of external disturbances, but also has strong robustness for system parameters variation. The simulation results show that the control effect of the large disturbance attenuation controller more advantages by comparing with the control performance of conventional nonlinear robust controller.

Nonlinear disturbance attenuation control for four-leg active power filter based on voltage source inverter

Active power filter (APP) based on voltage source inverter (VSI) is one of the important measures for handling the power quality problem. Mathematically, the APF model in a power grid is a typical nonlinear one. The idea of passivity is a powerful tool to study the stabilization of such a nonlinear system. In this paper, a state-space model of the four-leg APF is derived, based on which a new H-infinity controller for current tracking is proposed from the passivity point of view. It can achieve not only asymptotic tracking, but also disturbance attenuation in the sense of L2-gain. Subsequently, a sufficient condition to guarantee the boundedness and desired mean of the DC voltage is also given. This straightforward condition is consistent with the power-balancing law of electrical circuits. Simulations performed on PSCAD platform verify the validity of the new approach.

Nonlinear disturbance attenuation control of static phase shifter in sense of L2‐gain

AbstractStatic phase shifters (SPS) have the abilities to optimize power flow and to improve transient stability of power systems. In this paper, improving transient stability of the power system using the static phase shifter is considered. First, a nonlinear robust model of the power system including SPS is established. Then a Backstepping method is used to construct the storage function, and a disturbance attenuation controller in the sense of L2‐gain is achieved consequently. The controller reflects the nonlinearity of the system and attenuates disturbances explicitly. Simulations have proved the effectiveness of the nonlinear disturbance attenuation controller.

Hamiltonian modelling and nonlinear disturbance attenuation control of TCSC for improving power system stability

To tackle the obstacle of applying passivity-based control (PBC) into power systems, an affine non-linear system widely existing in power systems is formulated as a standard Hamiltonian system using a pre-feedback method. The port controlled Hamiltonian with dissipation (PCHD) model of TCSC is then established corresponding with a revised Hamiltonian function. Furthermore, employing the modified Hamiltonian function directly as the storage function, a non-linear adaptive L2 gain control method is proposed to solve the problem of L2 gain disturbance attenuation for this Hamiltonian system with parametric perturbations. Finally, simulation results are presented to verify the validity of the proposed controller.

ON NONLINEAR DISTURBANCE ATTENUATION FOR HYDRAULIC DIFFERENTIAL CYLINDERS VIA TRACKING CONTROL

Hydraulic actuators are well described by nonlinear system modeling. Nonlinear control for differential cylinders may be realized in order to obtain disturbance decoupling. However, such a system cannot be decoupled from the disturbance and therefore it is necessary to compute a nonlinear disturbance attenuation controller that reduces the influence of the disturbance with respect to the system output. The controller synthesis of nonlinear disturbance attenuation is based on linear error dynamics. Measurements on a testbed represent the basis of this contribution and show the mode of operation for the disturbance attenuation controller under real conditions. The measurements yield very good tracking performance for the cylinder piston position up to a particular disturbance force margin.