Showing papers by "Nasrudin Abd Rahim published in 2008"

Modeling and simulation for voltage sags/swells mitigation using dynamic voltage restorer (DVR)

Abstract: This paper describes the problem of voltage sags and swells and its severe impact on non linear loads or sensitive loads. The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags and swells. The control for DVR based on dqo algorithm is discussed. The proposed control scheme is simple to design. Simulation results carried out by Matlab/Simulink verify the performance of the proposed method.

Digital PI current control for grid connected PV inverter

Abstract: This paper describes a digital proportional-integral (PI) control method for single-phase grid-connected photovoltaic (PV) system. The control algorithm is implemented in digital signal processor (DSP) TMS320F2812. A detail analysis of system control and mathematic formation of digital PI control is presented to show that this control method provides robust current regulation and operates at near to unity power factor. The PI current control method is implemented in a single-phase grid-connected PV inverter to convert DC power from the solar modules into AC power to be transferred to the grid. Simulation and experimental results are provided to demonstrate the effectiveness of the design.

Implementation of single-phase grid connected inverter using TMS320F2812

Abstract: This paper describes a digital control method for single-phase grid-connected inverter system with an LCL filter for distributed generation application. Digital PI Current Controller is applied as the control method. The control algorithm is implemented in low cost Digital Signal Processor (DSP) TMS320F2812 eZdsp board. The control method provides robust current regulation and achieve unity power factor. Simulation and experimental results are provided to demonstrate the effectiveness of the design.

Adaptive Notch Filter for Harmonic Current Mitigation

Abstract: This paper presents an effective technique for harmonic current mitigation using an adaptive notch filter (ANF) to estimate current harmonics. The proposed filter consists of multiple units of ANF connected in parallel structure; each unit is governed by two ordinary differential equations. The frequency estimation is carried out based on the output of these units. The simulation and experimental results show the ability of the proposed tracking scheme to accurately estimate harmonics. The proposed filter was implemented digitally in TMS320F2808 and used in the control of hybrid active power filter (HAPF). The theoretical expectations are verified and demonstrated experimentally.

Self-tuning fuzzy-based dispatching strategy for elevator group control systems

Abstract: Fuzzy logic is recognized as an intelligent approach to complex problems demanding fulfillment of several criteria. A smart solution for an elevator group control system is one complex problem. This paper discusses a fuzzy logic dispatching strategy for elevator group control that uses a self-tuning fuzzy logic controller to tune membership functions and adjust fuzzy rule sets. Computer simulation evaluates, in three traffic peaks, the strategypsilas effectiveness. The results, when compared with other strategies that use conventional controllers, show considerable overall improvements in both waiting time and riding time.

Dynamic and control of fuel cell system

Abstract: In this paper, dynamic simulation of a fuel cell system studied using MATLAB/SIMULINK. The paper presents the dynamic model of proton exchange membrane fuel cell (PEMFC). The fuel cell output voltage is proportional to the change of the current drawn from the fuel cell model. Phase control full bridge dc/dc converter considered to match the unregulated voltage produced by the fuel cell model to the needed application voltage. PID controller has been selected to regulate the fuel cell output voltage. PWM-based inverter serves as the interface between the dc/dc converter and the ac load. Three-phase inverter used to drive three phase load. Third harmonic injection pulse width modulation used to drive the three-phase inverter so that minimum harmonic distortion and maximum usage of the fuel cell voltage on the three-phase inverter output. Simulation results provided to validate the design.

A neural network approach for contrast enhancement image

Abstract: Tuberculosis infection is a serious disease which could be controlled by early diagnosis A commonly used technique for detecting the TB bacilli is by analyzing sputum smear Now days, image recognition systems have several applications in enormous fields This paper uses an artificial neural network to enhance color images of Ziehl-Neelsen stained smear for the purpose of detecting TB bacilli The first necessary step is the captured images are converted into usable format (RGB values) and pass the RGB values to neural network for training to emulate the contrast enhancement technique The training is based on back-propagation algorithm It is found that the proposed neural network approach could emulate contrast enhancement technique quite well

Development and Testing of Hybrid Fuzzy Logic Controller for Car Suspension System Using Magneto-Rheological Damper

Abstract: In this paper, the development of a novel semi-active suspension control of quarter car model using fuzzy logic based controller has been done. The proposed quarter car model can be described as a nonlinear two degrees of freedom system, which is subject to system disturbances from different road profiles. In order to implement the suspension system experimentally, the magneto rheological (MR) fluid has been used as adjustable damper. The MR damper is a control device that consists of a hydraulic cylinder filled with magnetically polarizable particles suspended in a liquid. The MR dampers rapidly dissipate vibration by absorbing energy. In this work, a proportional integral derivative, a fuzzy logic and hybrid controllers are used to control the semi-active car suspension system. Results show that both fuzzy logic and hybrid controllers are quite suitable to eliminate road disturbances to the suspension system considerably as compared to the conventional PID controller.

Neural network based detection in switched capacitor filter for harmonic mitigation

Abstract: In this paper, neural network technique used in digital based control for switched capacitor filter (SCF) is proposed. The SCF is an alternative tool to mitigate harmonic distortion in the AC supply system as it has only small capacitor size and low switching frequency. Harmonic detection by using neural network technique is developed to determine harmonic component and hysteresis control is used to generate compensated current. The digital signal processor (DSP) is used to implement digital based control. Simulation and experimental work is carried out to evaluate its control performance. The results show the ability of this technique to achieve desirable harmonic mitigation.

Colour image enhancement for Ziehl-Neelsen slide images

Abstract: The recognition of tuberculosis (TB) bacilli base on a color image processing is one of the most challenging tasks in image processing. The problems increase if the captured images are blurred or have low contrast. This paper proposes partial contrast and saturation technique methods to enhance color images of Ziehl-Neelsen stained smear for the detection of TB bacilli. The partial contrast and saturation techniques have been tested using seven different images. It is shown that the TB bacilli are easier to be detected after applying these techniques.

Parallel connected inverter for fuel cell system

Abstract: This paper presents the design and analysis of a new configuration of parallel connected inverter suitable for fuel cell system application. The configuration consists of DC/DC converter and parallel three-phase DC/AC inverter. Series resistors added to the inverter output to maintain same current in each inverter of the two parallel inverters, and to reduce the circulating current in the parallel inverters to minimum. Third harmonic injection PWM (THIPWM) reduces the total harmonic distortion and to make maximum use of the voltage source. DSP was used to create the THIPWM and the control algorithm for the converter. PID controller is applied on the full-bridge DC/DC converter side to maintain the ac voltage to the required level. Experimental results have been shown to validate the proposed system.