A REAL TIME EMULATOR OF VARIABLE PITCH WIND TURBINES USING TORQUE-CONTROLLED INDUCTION MOTORS /
قطاع الدراسات الهندسية / الهندسه الكهربائيه
تخصص البحث : الهندسه الكهربائيه
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 07/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 8
نعيمه منصور محمد
Wind Energy, Wind Turbine Emulator (WTE), Digital Signal Processing (DSP) and Variable Pitch Control.
Owing to the technical difficulties of experimental investigations of real wind turbines, Wind Turbine Emulator (WTE) plays a role for performing such experimental tasks. This facilitates to conduct advanced research efforts for wind energy conversion system applications without reliance on natural wind resources. In this paper, a WTE (able to emulate the steady-state and dynamic wind turbine behavior) is experimentally developed. This represents a chance to validate not only the behavior of the proposed controllers, but also to extensively evaluate the properness of their developed dynamic models as well. For this aim, a motor generator set based two induction motors and Digital Signal Possessing (DSP) board were used to develop the WTE in order to simulate the aerodynamic characteristics of fixed speed-variable pitch wind turbine. The response of the proposed WTE during wind speed variations and the behavior of its related pitch controller are tested and recorded. All presented test results corroborated the efficacy of the developed WTE for profiling the dynamic behavior of variable pitch turbines for analyzing wind farm applications.
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 10/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 7
ساميه محمد محمود
FOC; VR step motor; Advance turn-on; Advance turn-off and Torque per ampere.
Step motors are receiving wide attention in industrial applications which require high performance. They are used in open loop control of position and translation motion but have poor performance. This paper discusses open loop control using field orientation of step motors to improve its dynamic performance. A simplified mathematical model of two phase variable reluctance (VR) stepper motor is introduced. Advance turn-on and advance turn-off is presented to obtain the optimal control angle in order to decrease phase current rise time, produce maximum torque per ampere, elimination of negative torque region, reducing motor losses, and increasing motor efficiency. A drive circuit for two phase VR step motor is implemented. The simulation results of stator current are compared to the experimental results.
STEP-BY-STEP MODELING OF WIND ENERGY CONVERSION SYSTEMS FOR TRANSIENT STABILITY STUDIES /
قطاع الدراسات الهندسية / الهندسه الكهربائيه
تخصص البحث : الهندسه الكهربائيه
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 10/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 7
حسن شعبان محمد إبراهيم( has845@hotmail.com - 01143141159 )
Transient stability, Wind Energy Conversion System, Pitch angle, Fixed speed wind turbine, Synchronous stability and Voltage stability.
Owing to the increasing penetration of renewable energy resources in the electric grids, the need for systematic studies of the impact of wind power on voltage, synchronous (angle) and frequency stability of the grid is encouraged. Unlike the massive literatures for stability issues with conventional energy resources, the corresponding research efforts for Wind Energy Conversion Systems (WECS) are still highly demanded. In this paper, a comprehensive methodology for realizing an efficient, versatile and accurate modeling for grid-integrated WECS for transient stability studies is explored. Details for representing the wind aerodynamics, drive trains, wind generators in addition to other conventional synchronous generators with its control mechanisms are outlined. The presented study is conducted with the known IEEE 3-generator, 9-bus power system network as a simulation example. Some explanation cases are illustrated examining the system voltage, angle and frequency stability.
ROBUST SPEED SENSORLESS CONTROL OF FIVE-PHASE INDUCTION MOTOR DRIVE SYSTEM /
قطاع الدراسات الهندسية / General
تخصص البحث : General
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 10/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 8
زكى محمد البربرى
Five-Phase Induction motor, Sensorless Vector control, Five -phase inverter, MRAS
Five -phase ac motor drives are nowadays considered for various applications, due to numerous advantages that they offer when compared to three-phase motors. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information of the rotor speed is extracted from measured stator currents and voltages at motor terminals. This paper proposes speed estimation method using model reference adaptive system (MRAS) to improve the performance of a sensorless vector controller of five-phase induction motor (IM). In the proposed method, the stator current is used as the state variable to estimate the speed. Since the stator current error is represented as a function of the first degree for the error value in the speed estimation, the proposed method can provide fast speed estimation and is also, more robust to variations in the parameters, compared with other MRAS methods. Consequently, this method can improve the performance of a sensorless vector controller in a low speed region and at zero-speed. The proposed method is verified by simulation using the Matlab/Simulink package. The performance of the proposed system is investigated at different operating conditions. The proposed controller is robust and suitable for high performance five-phase induction motor drives. Simulation results validate the proposed approaches.
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 10/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 14
محمد أحمد حسين
Cavitation, erosion.
In the present paper a power- law relationship between erosion rate and cumulative erosion for cavitation has been presented. In order to verify this relationship, erosion tests were conducted in a closed circuit water tunnel in which pure aluminum test specimens were mounted in the wake of cavitating source. Erosion was determined by weight loss on the side wall specimens. The erosion tests were conducted for four sizes of 600 symmetric wedges at wide range of flow velocities and cavitation numbers. The present experimental data confirm the proposed power-law relationship. Moreover, data from various previous investigations of cavitation and liquid impingement devices confirm this relation. The present analysis supports the view that the predominate erosion mechanism appear to be the same in all types of erosion. from the proposed relationship it is possible to predict the magnitude of erosion in a field system with the data from a laboratory device or to predict how much material will be lost in a number of years or how long it will take to lose a certain amount of material for adequate, performance of the component.
SCOUR IN FRONT OF THE LATERAL INTAKES DUE TO USING SINGLE ROW OF SUBMERGED VANES /
قطاع الدراسات الهندسية / General
تخصص البحث : General
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 10/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 7
سمير أحمد إبراهيم
Local Scour, Submerged vanes, Lateral Intake, Physical model, Sedimentation
Submerged vanes can be used to create sufficient depth for navigation, to mitigate bank erosion or to divert sediment away of lateral intakes. Besides these intended effects, submerged vanes also produce local scour, which may interfere with the intended morphological correction and which is relevant to the structural stability of the vanes. The present paper shows an experimental study that was executed in order to investigate the local scour that induced in front of the lateral intakes due to using a single row of submerged vanes to minimize the sediment that entered the intake channel. Sixty experiments were carried out using a single row of vanes, considering various vane heights, angles, and positions under different flow conditions. A case of flat floor without vanes was included to estimate the influence of the submerged vanes on the scour in front of the diversions. Obtained results were analyzed and graphically presented, and also provide simple formulas to compute the maximum scour depth in vicinity of the single submerged vanes at different flows entering the lateral intake.
DEVELOPMENT OF COMPRESSIVE STRENGTH AND MICROSTRUCTURE FOR CEMENT PASTE AND MORTAR CONTAINING Cu-Zn NANO-FERRITES /
قطاع الدراسات الهندسية / General
تخصص البحث : General
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 10/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 9
منير محمد كمال( prof_mounir@yahoo.com - 01065641276 )
Nano ferrite (N.F), TEM, SEM, microstructure, compressive strength, Nano ferrite/cement composites (NFCC).
Nano ferrite/cement composites (NFCC) have been prepared by adding different weight ratios of Nano ferrite (N.F) ranging from (1 up to 4%) cement. This study is aimed to evaluate the effect of addition of N.F on the mechanical behavior of NFCC and study the performance of cement pastes and cement mortars mixed with Nano ferrite (N.F) when exposed to elevated temperatures of 200 oC and 400 oC, for firing period of two hours. Compressive strength test showed valuable enhancement in mechanical properties of NFCC with increasing N.F loading ratio. The obtained minerals of Cu-Zn ferrites nanoparticles were identified by using X-ray diffraction (XRD) and the morphology of N.F was determined using transmission electron microscopy (TEM). The microstructure of the NFCC was characterized by means of scanning electron microscope (SEM) analysis. The addition of N.F by about 1% enhanced the compression strength to about 52 % for cement paste and1% enhanced the compression strength to about 35% for cement mortar. The results indicated that cement pastes and cement mortars mixedwith N.F are more able to resist elevated temperature than pure cement pastes.
The main aim of this paper is to explore the impact of highway geometric characteristics on capacity at tangents and horizontal curves as well as on capacity loss at the change from tangent to curve. Vehicle speeds and flows on the two successive elements (tangent and curve) were recorded for each five-minute intervals during the survey period, for twelve rural two-lane road sites. A capacity estimation method based on extrapolation from a fundamental diagram representing the relationship between traffic flow and density was used. The effect of different vehicle types was considered by converting them into equivalent passenger car units. Regression analysis was used to investigate the relationships between geometric characteristics and capacity for tangents, curves and capacity loss between the two elements. The significant independent variables for tangents are lane width, shoulder width and tangent length. In the case of curves, the significant independent variables are curve radius and lane width. The best model that shows the relationship between capacity loss and geometry characteristics includes only curve radius. Based on this model, a curve radius with 600 m appears to be the threshold value to diminish the capacity loss between tangent and succeeding curve. The models are very useful and can be used to deal with capacity analysis and evaluation, especially for the area under study.
المعايير التصميمية لمستشفيات الأمراض النفسية فى مص /
قطاع الدراسات الهندسية / General
تخصص البحث : General
Engineering Research Journal \ / Vol. 35, No. 1 - January 2012
تاريخ تقديم البحث 10/11/2013
تاريخ قبول البحث 10/11/2013
عدد صفحات البحث 9
إيمان محمد عيد عطية( emanprof@hotmail.com - 01223271549 )
رغدة السيد حسب الله
المعايير التصميمية لمستشفيات
تقدم مستشفيات الأمراض النفسية الرعاية الصحية للمرضى النفسيين المقيمن و المترددين من الخارج كمرضى العيادة الخارجية و الذين لا يحتاجون إلى رعاية صحية مركزة كالحالات الحرجة أو إجراء عمليات جراحية . و مع ذلك فإن الغالبية العظمى من مستشفيات الأمراض النفسية فى مصر لا تعطى فرصاً جيدة لتحسين خدمات العلاج و الرعاية لهؤلاء المرضى ، و قد يرجع أحد أسباب عدم تجاوب المرضى النفسيين مع العلاج جزئياً إلى عدم ملائمة مبانى المستشفيات النفسية المخصصة للعلاج لإحتياجاتهم الوظيفية و النفسية مما يكون له تأثيراً سلبياً على العملية العلاجية ، و هو ما يمثل تحدياً لمصممى هذه المستشفيات الذى يجب أن يراعوا النواحى الوظيفية و النفسية جيداً دون أن يطغى أحدهما على الآخر. و من هنا جاءت أهمية تلك الدراسة التى ترسخ مجموعة من المفاهيم الخاصة بأهمية وجود فراغات للمريض النفسى بمواصفات خاصة، و إلقاء الضوء على الأسس التصميمية الواجب تطبيقها و اتباعها فى تصميم فراغات مستشفى الأمراض النفسية من قبل المصمم المعمارى الذى له دور حقيقى و فعال فى تأثيره على المريض النفسى بحيث يمكن أن يجعل علاج هؤلاء المرضى يتحقق من خلال تصميمه ، و ما يمكن أن يحدثه من تأثير للمنظور الخاص برؤية المريض لما حوله ، من خلال توفير المساندة اللازمة للمرضى و المساعدة على احتواء السلوكيات الشاذة التى قد تصدر منهم ، و توفير الخصوصية اللازمة للمريض النفسى من خلال مراعاة ذلك فى تصميم الفراغات المختلفة ، و كذلك توفير أسلوب سهل لمراقبة المرضى من قبل الهيئة المعالجة لتوفير الأمن و الآمان لهم بطريقة غير ملحوظة حتى لا يشعر المرضى بأنهم مراقبون ، مما يساعد فى رعاية هؤلاء المرضى و احتواء أى أزمة قبل حدوثها ، الإستخدام السليم لمواد التشطيبات بما يزيد من الشعور بالمناخ العائلى ، و تأكيد الإتصال بين البيئة الداخلية و الخارجية.
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