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Dariusz Horla

On Directional Change and Anti-Windup Compensation in Multivariable Control Systems

The paper presents a novel description of the interplay between the windup phenomenon and directional change in controls for multivariable systems (including plants with an uneven number of inputs and outputs), usually omitted in the literature. The paper also proposes a new classification of anti-windup compensators with respect to the method of generating the constrained control signal.

Open access

D. Horla

Abstract

The paper presents the phenomenon of directional change in LQG control of multivariable systems with amplitude constraints, as well as the impact of the latter on control performance. The interplay of directional change of the computed control vector with control performance has been thoroughly investigated, and is a result of the presence of constraints imposed on the applied control vector for different proportions of the number of control inputs to plant outputs. The impact of directional change phenomenon on the control performance has been defined, stating that performance deterioration is not tightly coupled with preservation of direction of the computed control vector. The statement has been supported by numerous simulation results for different types of plants with different LQG controller parameters.

Open access

Adam Owczarkowski and Dariusz Horla

Abstract

Essential ingredients for robust control are the ability to cope with different types of system behavior following modeling imperfections and the ability to assure a certain performance level. In this paper, we propose to use an actuator fault-tolerant control law to govern, during experiments, the stabilization of a bicycle robot with an inertial wheel in order to take into account unmodeled uncertainty introduced by using a linearized model in an LQR fashion. Our proposal is illustrated by signal plots and the values of performance indices obtained from a set of experiments.

Open access

Talar Sadalla, Dariusz Horla, Wojciech Giernacki and Piotr Kozierski

Abstract

The paper aims at presenting the influence of an open-loop time delay on the stability and tracking performance of a second-order open-loop system and continuoustime fractional-order PI controller. The tuning method of this controller is based on Hermite- Biehler and Pontryagin theorems, and the tracking performance is evaluated on the basis of two integral performance indices, namely IAE and ISE. The paper extends the results and methodology presented in previous work of the authors to analysis of the influence of time delay on the closed-loop system taking its destabilizing properties into account, as well as concerning possible application of the presented results and used models.

Open access

Piotr Kozierski, Marcin Lis and Dariusz Horla

Abstract

The influence of wrong information about transition and measurement models on estimation quality has been presented in the paper. Two methods of a particle filter, with and without the Population Monte Carlo modification, and also the extended and unscented Kalman filters methods have been compared. A small 5-bus power system has been used in simulations, which have been performed based on one data set, and this data set has been chosen from among 100 different - to draw the most general conclusions. Based on the obtained results it has been found that for the particle filter methods the implementation of the slightly higher standard deviation than the true value, usually increases the estimation quality. For the Kalman filters methods it has been concluded that optimal values of variances are equal to the true values.

Open access

Piotr Kozierski, Marcin Lis, Adam Owczarkowski and Dariusz Horla

Abstract

An approach to power system state estimation using a particle filter has been proposed in the paper. Two problems have been taken into account during research, namely bad measurements data and a network structure modification with rapid changes of the state variables. For each case the modification of the algorithm has been proposed. It has also been observed that anti-zero bias modification has a very positive influence on the obtained results (few orders of magnitude, in comparison to the standard particle filter), and additional calculations are quite symbolic. In the second problem, used modification also improved estimation quality of the state variables. The obtained results have been compared to the extended Kalman filter method