Sarawut Sujitjorn

Harmonic Identification for Active Power Filters Via Adaptive Tabu Search Method

Harmonic identification by using Adaptive Tabu Search (ATS) Method embedded in the active power filter is proposed in this paper. The use of the ATS identifies harmonic components more accurately and precisely. Besides the accuracy and precision, it is able to select only some particular harmonic orders that cause severe consequences to the system for elimination. This principle thus leads to the reduction in size and cost of hardware implementation + active power filters. In this paper, two test current waveforms are simulated to validate and verify the performance of the proposed algorithm. The satisfactory results obtained by this identification method are also com-pared against those obtained by the d-q axis based harmonic identification method. As a result, the ATS based method has better performance for eliminating only selective harmonic orders over the d-q method. Furthermore, the compensated current from the proposed method has a good transient response while there is the first-cycle delay due to the use of the d-q method.

The DQ Axis With Fourier (DQF) Method for Harmonic Identification

This letter proposes the DQ axis with Fourier (DQF) method for harmonic identification. The method, when used with a parallel active power filter, provides much better results than its predecessors, namely, the DQ axis and the sliding window Fourier analysis methods, in terms of harmonic elimination and phase balancing

Finite Convergence and Performance Evaluation of Adaptive Tabu Search

The naive tabu search (NTS) has been enhanced with two adaptive mechanisms namely back-tracking and adaptive search radius. The proposed search is called adaptive tabu search (ATS). The paper provides convergence and performance analyses of the ATS.

Input weighting optimization for PID controllers based on the adaptive tabu search

Eitelberg introduced a useful method to recover system performance when a direct tuning of the PIDs parameters was prohibited in 1987. Our work herein proposes the use of adaptive tabu search (ATS) to optimally tune the input-weight factors according to Eitelbergs. We illustrate the effectiveness of our proposed method via two motor control problems.

Obtaining an Optimum PID Controller Via Adaptive Tabu Search

An application of the Adaptive Tabu Search (ATS), an intelligent search method in industrial control domain, is presented. The ATS is used to search for the optimum controllers parameters denoted as proportional, integral, and derivative gains. The obtained controllers are tested against some hard-to-be-controlled plants. The results obtained are very satisfactory.

Moving Towards a New Era of Intelligent Protection Through Digital Relaying in Power Systems

This paper presents an intelligent approach for digital relaying de- sign. Due to a powerful search scheme of the selected intelligent method, digi- tal relays are well discriminated to satisfy a large number of constraints, which are so complicated over the ability of the conventional relay setting. Also, the proposed scheme is demonstrated through a small 5-bus power system, in which six digital relays are situated to be smartly discriminated.

Multipath Adaptive Tabu Search for a Vehicle Control Problem

Tabu search has become acceptable worldwide as one of the most efficient intelligent searches applied to various real-world problems. There have been different modifications made to the generic tabu search in recent years to achieve better performances. Among those reviewed in the introduction of this paper, the adaptive tabu search (ATS) has incorporated the backtracking and the adaptive search radius mechanisms that help accelerate the search and release it from a local solution lock. The paper explains an enhancement made to the ATS to accomplish multipath ATS (MATS) algorithms. Performances of the ATS and the MATS are evaluated using surface optimization problems, and results are presented in the paper. Finally, the MATS is applied to solve a real-world vehicle control problem.

State-PID Feedback for Pole Placement of LTI Systems

Pole placement problems are especially important for disturbance rejection and stabilization of dynamical systems and regarded as algebraic inverse eigenvalue problems. In this paper, we propose gain formulae of state feedback through PID-elements to achieve desired pole placement for a delay-free LTI system with single input. Real and complex stable poles can be assigned with the proposed compact gain formulae. Numerical examples show that our proposed gain formulae can be used effectively resulting in very satisfactory responses.

Wavelet-Based Image Watermarking Using the Genetic Algorithm

Image watermarking provides copyright protection of digital image by hiding appropriate information in the original image in such a way that it does not cause degradation of the perceptual image quality and cannot be removed. The watermarking methods for transform domains are usually achieved by using the discrete cosine transform or the discrete wavelet transform. In this paper, we develop a technique for optimizing the image watermarking using the genetic algorithm applied to the wavelet transform domain to improve the quality of the watermarked image and the robustness of the watermark. We then compare our experimental results with the results of previous works.

Torsional resonance suppression via pida controller

A servo motor driving a load through a long shaft or transmission system is widely used in industries. Such a system encounters performance degradation caused by non-homogeneous twist of the shaft. This phenomenon is referred to as torsional resonance. This article describes our work to suppress torsional resonance in a 2-inertia system using accelerated-proportional-integral-derivative (PIDA) controller. A system model obtained from nonparametric identification is the basis for our controller design. We have shown herein with simulation results that our proposed method is very effective for torsional resonance suppression. Fast transient and disturbance rejection can be achieved.