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All Journal International Journal of Power Electronics and Drive Systems (IJPEDS) Indonesian Journal of Electrical Engineering and Computer Science
Walid Emar
Isra University
Control & Systems Engineering Electrical & Electronics Engineering

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Modeling and simulation of a stand-alone wind turbine supplying an inductive load through a long cable Zakaria Al-Omari; Walid Emar
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 13, No 3: September 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijpeds.v13.i3.pp1654-1665

Abstract

This paper considers the principles of modeling, control, and simulation of variable speed wind turbines (VSWTs), based on a stand-alone doubly fed induction generator (DFIG). The DFIG is used to feed a three-phase highly inductive load through a long cable via a three-phase multi-level frequency converter (MLFC). The proposed MLFC increases the number of voltage levels with less power electronic components as compared to the conventional back-to-back AC/DC/AC converter. The length of the cable (transmission line TL) influences a mismatch between the load and TL impedances; therefore, a reflected signal will occur. If the "incident signal" is a "continuous AC waveform", these waveforms will mix with another oncoming "incident waveform", creating stationery waveforms called "standing waves". The simulation process shows that the value of the transient’s over-voltage that appears either on the windings of the DFIG or across the load reaches twice the DC-link voltage periodically, which may cause premature failure of the DFIG windings and cable insulations. Usually, this is produced by generating high harmonics within the loads. Therefore, the main benefit of using the MLFC is the significant reduction of the total harmonic distortion and enhancement of the load voltage waveforms. This was verified, primarily by using the "MATLAB/Simulink, Simplorer 7" simulation software.
Analysis of inventory management of slow-moving spare parts by using ABC techniques and EOQ model-a case study Walid Emar; Zakaria Anas Al-Omari; Sami Alharbi
Indonesian Journal of Electrical Engineering and Computer Science Vol 23, No 2: August 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v23.i2.pp1159-1169

Abstract

Computer spare parts (CSPs) inventory management (IM) is very important for many companies. Excess inventory leads to high storage costs. On the other hand, the lack of CSP has a strong impact on the quality of service. This study was conducted by Power-One Jordan Computer Hardware-Software company (POJCHSC), Amman, Jordan. The focus area was the IM department and the target sample was employees working in the management department. The results showed that factors influencing the management of slow moving CSPs include production costs, obsolescence and CSPs dependence availability and transportation costs. By forecasting during the study, the results showed that the demand for adapters and chargers would increase by 20%. This demand forecast was performed using the economical order quantity (EOQ) model. The percentage of profits made by this company is 48%, and this requires some intervention to prevent losses. The results of this study are useful to the company, as well as to other similar industries that deal with slow-moving items. These results will help to simplify IM of slow-moving items. When we focused on POJCHSC manufacturers, the disadvantages of using the traditional ABC classification model were identified. Therefore, there is a need to have an ABC classification that is improved and which takes into consideration the criticality of the slow-moving CSP.
Co-Authors Sami Alharbi Zakaria Al-Omari Zakaria Anas Al-Omari