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Articles by Rosli Omar
Total Records ( 4 ) for Rosli Omar
  Rosli Omar , Nasrudin Abd Rahim and Marizan Sulaiman
  The Dynamic Voltage Restorer (DVR) was a power electronics device that was able to compensate voltage sags on critical loads dynamically. The DVR consists of VSC, injection transformers, passive filters and energy storage (lead acid battery). By injecting an appropriate voltage, the DVR restores a voltage waveform and ensures constant load voltage. There were so many types of the control techniques being used in DVR for mitigating voltage sags. The efficiency of the DVR depends on the efficiency of the control technique involved in switching the inverter. Problem statement: Simulation and experimental investigation toward new algorithms development based on SVPWM. Understanding the nature of DVR and performance comparisons between the various controller technologies available. The proposed controller using space vector modulation techniques obtain higher amplitude modulation indexes if compared with conventional SPWM techniques. Moreover, space vector modulation techniques can be easily implemented using digital processors. Space vector PWM can produce about 15% higher output voltage than standard Sinusoidal PWM. Approach: The purpose of this research was to study the implementation of SVPWM in DVR. The proposed control algorithm was investigated through computer simulation by using PSCAD/EMTDC software. Results: From simulation and experimental results showed the effectiveness and efficiency of the proposed controller based on SVPWM in mitigating voltage sags in low voltage distribution systems. It was concluded that its controller also works well both in balance and unbalance conditions of voltages. Conclusion/Recommendations: The simulation and experimental results of a DVR using PSCAD/EMTDC software based on SVPWM technique showed clearly the performance of the DVR in mitigating voltage sags. The DVR operates without any difficulties to inject the appropriate voltage component to correct rapidly any anomaly in the supply voltage to keep the load voltage balanced and constant at the nominal value.
  Rosli Omar , Mohammed Rasheed , Marizan Sulaiman and Wahidah Abd Halim
  In this study, modified multilevel inverters based on Newton Raphson (NR) and Particle Swarm Optimization (PSO) techniques were presented. A NR and PSO techniques were presented for Selective Harmonics Elimination (SHE) solution in a modified Cascaded H Bridge Multilevel Inverter (CHB-MLI). The Selective Harmonic Elimination Pulse-Width Modulation (SHE-PWM) is a powerful technique for harmonic minimization in multilevel inverter. The proposed design was used to charge the energy storage such as battery, super capacitor. NR and PSO techniques were used to determine the switching angles by solving the non-linear equation’s analysis of the output voltage waveform of the modified CHB-MLI in order to control the fundamental component. The proposed techniques based on NR and PSO techniques are capable to minimize the Total Harmonic Distortion (THD) of output voltage of the modified CHB-MLI within allowable limits. A comparison has been made between NR and PSO techniques related to optimization in order minimize harmonic distortion. The main aims of this study cover design, modeling, construction and testing of a laboratory the modified topology of the CHB-MLI for a single-phase prototype for nine levels. The experimental results of the prototype were also, illustrated. The controllers based on NR and PSO were applied to the modified multilevel inverter. The Digital Signal Processing (DSP) TMS320F2812 is used to implement these modified inverters control schemes using NR and PSO method. The proposed controller was then coded into a DSP TMS320F2812 board. The inverter offers much less THD using PSO scheme compared with the NR scheme.
  Mohammed Rasheed , Rosli Omar , Marizan Sulaiman , Wahidah Abd Halim and Moataz M.A. Alakkad Majeda
  In this study, Artificial Intelligence (AI) technique is applied to determine the switching angles for a uniform step asymmetrical modifiedmultilevel inverter by eliminating specified higher-order harmonics while maintaining the required fundamental voltage and current waveform. Artificial intelligence technique based on Selective Harmonic Elimination (SHE) method in a modifiedmultilevel inverter has been proposed in this study. The Selective Harmonic Elimination Pulse-Width Modulation (SHE-PWM) is a powerful technique for harmonic minimization in multilevel inverter. The proposed a five-level Modified Cascaded H-Bridge Multilevel Inverter (M-CHBMI) with Artificial Neural Network (ANN) controller to improve the output voltage and current performance and achieve a lower Total Harmonic Distortion (THD). The main aims of this study cover design, modeling, prediction for real-time generation of optimal switching angles in five level modified topology of the CHB-MLI for a single-phase. Real-time application of Selective Harmonic Elimination-Pulse Width Modulation (SHE-PWM) technique is limited due to the heavy computational cost involved in solving aspecified number of transcendental nonlinear equations known as Selective Harmonic Elimination (SHE) equations that contain trigonometric functions. Simulation of a 5-level inverter in MATLAB/Simulink reveals that the proposed method is highly efficient for harmonic reduction in modified multilevel inverter.
  Rosli Omar , Tan Zi Hao , Mohammed Rasheed and Marizan Sulaiman
  The distorted waveforms due to highly uses of the non-linear load, especially, the current that is considered the main issues need to be addressed seriously. The issues of the distorted waveforms for the current have attracted many researchers to recover them in the electrical system. There are so, many electronic devices that have been used in order to protect the waveform of the current from distorted as it is very dangerous and may cause the main supply to shut down or burnt. The main aims of this project is to design and develop a shunt active power filter for the purposes to mitigate the distorted of current waveform produced by the different types of non-linear loads using the controller of the SRF. The software MATLAB/Simulink will be used to design and develop shunt active power filter and its controller. Finally, the performance of the shunt active power filter and its controller at different types of non-linear loads will be evaluated through the waveforms of the currents produced by different types of non-linear loads and the Total Harmonic Distortion (THD) will be monitored and observed whether meets to the International Electrical Committee (IEC) standard or not.
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