PERFORMANCE ASSESSMENT OF A PHOTOVOLTAIC SYSTEM FEEDING A DC MOTOR AND CONTROLLED BY A DC-DC CONVERTER /
قطاع الدراسات الهندسية / الهندسه الكهربائيه
تخصص البحث : الهندسه الكهربائيه
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 8
شكرى سعد شكرالله ميخائيل( shokry1saad@yahoo.com - 01006639596 )
Solar Cells, DC-DC Conveter,Cuk Converter, Sepic Converter, Photovoltaic generators, DC-Motor
This paper presents theoretical and experimental analysis of the performance of a photovoltaic system supplying DC loads and controlled by either a cuk or a sepic converter. The nonlinear mathematical model of the system is obtained, considering all operation modes of both converters. A fairly detailed nonlinear simulation was built to assess the performance when system is supplying constant and dynamic loads. Simulation and experimental results are presented illustrating both the steady state and the starting characteristics of the system. The relation between solar irradiation level and the duty ratio for both steady–state and run-up for the cuk and sepic converters have also been given to ensure maximum energy utilization. The results are presented in a comparative form which clearly illustrates that the cuk converter operates over a wider range of irradiation levels. The results also show that with a proper design of photovoltaic generator and careful selection of the dc-dc converter, the performance of a particular application can be optimized by controlling the converter duty ratio.
DESIGN OF A CATHODIC PROTECTION SYSTEM TO PREVENT CORROSION OF METALLIC STRUCTURES USING HYBRID RENEWABLE ENERGY SOURCES /
قطاع الدراسات الهندسية / الهندسه الكهربائيه
تخصص البحث : الهندسه الكهربائيه
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 9
Ashraf I. EL-Alem
Electrical Maintenance Engineer,
This paper presents a study to design a cathodic protection system to protect metallic structures against corrosion using hybrid renewable energy sources. The corrosion of pipelines and storage tanks may cause very dangerous situations such as spills, production interruption and destructions of surrounding environment ending with great explosions. An effective method is to use impressed current cathodic protection system to overcome corrosion. This method can be applied to real systems based on hybrid renewable energy sources. A generic program is developed to design the full system with all details to achieve the best performance including the d.c. source. The possibility of supplying the cathodic protection system by wind and/or small solar panel and few nickel cadmium batteries eliminating the external power is also researched. The results revealed the possibility of designing the impressed current cathodic protection system for different configurations. It will be also possible to obtain better performance for the system through increasing the life time of the system.
CONTROL STRATEGY FOR A HIGH SPEED SRM FED from A PHOTOVOLTAIC SOURCE /
قطاع الدراسات الهندسية / الهندسه الكهربائيه
تخصص البحث : الهندسه الكهربائيه
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 8
أحمد سعيد
SRM, PV system, high speed Controller, Torque Controller, Variable Load
High speed switched reluctance motors (SRMs) have recently been gaining attention as contenders in many variable speed drive applications. This has also been stimulated by recent advances in power electronic technology which enables this drive system for many applications such as high speed water pump and space and military applications. This paper presents the design and control of high speed four phases SRM suitable for high speed water pumping and other high speed variable load applications. The dynamic load characteristic and the SRM operation modes have been studied and a novel cascade control strategy is designed and implemented using the MathLap Simulink. The SRM drive system is tested and encouraging results were obtained. The results are of prime importance in the developments of rural and remote areas and also for space and military applications
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 10
أحمد سعيد
SRM, Sensorless Algorithms, PV system, Performance analysis of SRM.
The paper presents the development and implementation of a new sensorless algorithm for estimating the rotor position of switched reluctance motor (SRM) over a wide range of operating conditions. The algorithm is designed to overcome difficulties in estimating the rotor position at starting as well as at the normal operation region. The algorithm is successfully implemented experimentally using SRM fed from a photovoltaic source which has a nonlinear operating nature. The results show improved performance at starting as well as when step changes in converter duty ratio or insulation levels occur. The results demonstrate clearly that the new algorithm ensures smooth starting without initial hesitation and reduces the torque ripples. The results presented are of prime importance to manufacturing companies leading to low cost reliable SRM drive systems for various industrial applications.
STABILITY OF A MULTI-MACHINE POWER SYSTEM EQUIPPED WITH LQG CONTROLLERS /
قطاع الدراسات الهندسية / الهندسه الكهربائيه
تخصص البحث : الهندسه الكهربائيه
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 12
أحمد سعيد
LQR controller , LQG controller, power system stabilizer and multi-machine power system
This paper presents the design of a novel control strategy of a Power System Stabilizer (PSS) for generators in multimachine electric power systems using the Linear Quadratic Gawssian (LQG) control technique. The controller combines both the excitation and governor control loops. The technique is applied using a sample power system which includes a number of generators connected to a large power system. An optimal full state controller has been designed and a state observer is included using Kalman Filter theory. A comprehensive stability analysis and time domain performance analysis of the system with the new controller have been presented. The results prove the robustness and powerful of proposed LQG controller in improve stability margins and adding positive with a noticeable reduction in settling time.
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 6
Hassan mahmoud
SRMs.
Switched Reluctance Machines (SRMs) are receiving significant attention from industries in the last decade. SRMs are rather inexpensive, reliable and weigh less than other machines of comparable power outputs. The goal of this paper is to investigate how to estimate the maximum and minimum inductance of the switched reluctance machine by the flux map method.
In this paper, the conjugate conduction-free convection heat transfer from a horizontal cylinder is numerically and experimentally investigated. In the theoretical study, the unsteady two-dimensional conduction equation for the cylindrical wall and the unsteady laminar two-dimensional governing equations for the flowing fluid are solved simultaneously using the finite-difference method. The effects of controlling parameters, such as Rayleigh number, thermal conductivity ratio and diameter ratio on heat transfer process have been investigated. The study has shown that the heat transfer rate increases with increasing Rayleigh number and thermal conductivity ratio. The study has also discussed the existence of critical radius for some Rayleigh numbers and thermal conductivity ratios. The streamlines and isotherms are plotted for some cases to show the details of the velocity and thermal fields. For verification of the numerical model, the present numerical results are compared with previously published experimental and theoretical data where good agreements were found. In the experimental study, the heat transfer from a hollow horizontal aluminum cylinder with diameter ratio of 2 and heated from its inner surface at constant temperature is investigated. The obtained experimental results are used to further assess the validity of the numerical results and acceptable agreement has been found.
SOME HEURISTIC RULES FOR JOB SHOP SCHEDULING PROBLEM /
قطاع الدراسات الهندسية / الهندسه الكهربائيه
تخصص البحث : الهندسه الكهربائيه
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 8
A. A. Boushaala
Job-shop scheduling problem (JSSP), Dispatching rules, Heuristics
Scheduling job shop problem is searching for good schedule or optimization with the goal of finding the best schedule. The main objective of this paper is to develop some heuristic rules for job shop scheduling problem. These heuristic rules are developed and tested in their scheduling performances with other common rules in benchmark problems. Six measures are considered for performance evaluation. Seventy instance cases are used as jobs for scheduling process. The results are compared with eighteen common heuristic rules for the considered test cases. The proposed heuristics are found to be promising in their effectiveness in scheduling job shop problem. A computer program could be designed to test the validity of the proposed heuristics.
Productivity Improvement by Using Time and Motion Study Techniques in Lotus High Tech Company /
قطاع الدراسات الهندسية / الهندسه الميكانيكيه
تخصص البحث : الهندسه الميكانيكيه
Engineering Research Journal \ / Vol. 36, No. 2 - April 2013
تاريخ تقديم البحث 14/11/2013
تاريخ قبول البحث 14/11/2013
عدد صفحات البحث 7
H. H. Abdel-Maksoud
Time and Motion Study, Method Improvement, Production Processes, Flow Charts, Flow Process Analysis, Productivity.
The purpose of this research is to improve productivity in Lotus High Tech Company (LHTC). This research used time and motion study techniques to improve the production process at LHTC. The research objectives towards accomplishing this study is to identify problems in the current method and improve it in terms of production time, number of process and production layout by proposing a new method to the manufacturing product. The current method in the manufacturing of garment in the production line involved some unnecessary steps, where the materials and components take a very long and roundabout path on their journey to the workstation, which adversely affect productivity. The proposed method eliminates these steps, which reduces production time, number of processes, and the overall increase in productivity is about 72.6%.
On the road of minimizing air pollution and global warming by reducing the Portland cement content in Portland cement based mixes, this experimental study was conducted. Maximizing the percentage of Portland cement replaced by silica fume was tried using lime-water instead of water in mixing. That will help availability of CH crystals at early ages for pozzolanic reaction instead of waiting up to C3S and C2S hydration products. The conducted Portland cement based materials included three groups; cement pastes, cement mortars and cement concrete mixes. The main parameters were; type of mixing solution (water or lime-water) as well as the percentages of Portland cement replaced by silica fume. Times of initial and final settings, compressive strength development, existence and intensity of CH crystals with age, pozzolanic activity as well as efficiency of the investigated matrices to delay the corrosion of embedded steel bars were the investigated properties. Test results show that using lime-water in mixing delays both of initial and final setting times compared with traditional water due to the common ion effect principals. Moreover, combination use of lime-water and silica fume enhances the pozzolanic reaction that was reflected by the strength development at both early and later ages. The existence of CH crystals for higher percentages of silica fume (up to 30%) for further reaction at later ages was observed by XRD results. Moreover, combined use of silica fume and lime-water ensures a high alkaline media around steel bars from the moment of ingredients mixing as long as later ages despite of pozzolanic reaction that was identified from results of chloride attack.
Experimental investigations to study the efficiency of using single non destructive test and combined methods to predict the concrete compressive strength have been conducted. Different concrete mixes including different types of coarse aggregates and mix proportions are considered. Concrete age’s ranges from one to sixty days were covered. The statistical analysis of the results reveals that; with a reasonable correlation coefficient, rebound hammer and ultrasonic pulse velocity tests could be implemented individually to measure the compressive strength of concrete at age rang from one to sixty days. Moreover, the use of both the rebound hammer and the ultrasonic pulse velocity tests as a combined method produces more reliable results that are closer to the actual compressive values compared to the use of one of the implemented methods individually. A proposed equation combines both rebound hammer and ultrasonic pulse velocity tests could be implemented securely for in situ concrete strength assessment has been established
جميع البيانات التي يتم تسجيلها على النظام هي ملك للجهة صاحبة هذه البيانات
لا يتم الاطلاع على هذه البيانات من قبل مهندسي المركز إلا للضرورة القصوى ولغرض الدعم الفني وبالاتفاق مع الجهة صاحبة البيانات شفوياً أو كتابياً
لا يتم إعطاء أي بيان من بيانات النظام لأي فرد او جهة فرعية تنتمي للجهة صاحبة البيانات او لأي جهة أخرى إلا بموافقة كتابية من الجهة صاحبة البيانات
يمكن استخدام البيانات المسجلة على النظام بهدف عمل إحصائيات يستفاد منها فى قياس اداء النظام وكفاءة استخدامه من قبل مستخدميه
يتم تأمين جميع البيانات الخاصة بالنظام من خلال تأمين الحاسب الخادم الذي يستضيف البيانات ومن خلال تأمين انتقال البيانات بين جهاز المستخدم والحاسب الخادم وكذلك تأمين واجهة النظام التي يستخدمها المستخدم
كل مستخدم للنظام مسئول مسئولية كاملة عن كلمة المرور الخاصة به وعليه اتخاذ كافة الاحتياطات الممكنة حتى لا يستطيع أى شخص آخر الحصول عليها
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