ORIGINAL_ARTICLE
DIGITAL SIGNAL PROCESSOR CONTROL ALGORITHM FOR PWM INVERTER
Recent developments in power electronic device technology promises faster switching capability at high power. The hybrid pulse width modulation method which requires two of the four switches in a full bridge inverter are used, and enable pulse pattern operation at high frequency. The use of two level switching instead of three level switching enables the use of higher frequency for given computation time delay. The proposed control scheme is implemented using bi-polar junction transistors (BJT) controlling an inverter to produce a very low frequency (THD) sinusoidal output voltage. Simulation and experimental results are presented to verify the performance.
https://erjm.journals.ekb.eg/article_72442_09e275234edbce26d134330ef7bf7915.pdf
1999-10-01
1
12
10.21608/erjm.1999.72442
A. A.
Heggo
1
Minufiya University, Faculty of Engineering, Shebin El-Kom
AUTHOR
ORIGINAL_ARTICLE
SCADA BASED POWER SYSTEM CONTROL
Computerised supervisory control systems have been in operation in manycountries for the past 10 to 15 years. The systems performance requirementsare influenced by an arena of rapidly advancing technologies and a highlycompetitive business environment. There is multitasking of the use ofmicroprocessors in power system control. This paper concerns four criticalapplications of the use of SCADA, system protection, metering, high-speeddata exchange and distribution network automation. Specific information isgiven concerning system hardware. The advantages of the use of SCADA areexplained and discussed. The detail of a power system under study ispresented and commented on.
https://erjm.journals.ekb.eg/article_72749_3b3e68c7ea80a8842c4efcaa1181f62d.pdf
1999-10-01
13
23
10.21608/erjm.1999.72749
A. A.
Heggo
1
-
AUTHOR
ORIGINAL_ARTICLE
DYNAMIC AND STEADY-STATE PERFORMANCE OF A PWM CONVERTER-FED SERIES MOTOR
This paper introduces an analytical and experimental investigation for both dynamics and steady-state of a dc series motor fed from a single-phase AC to DC pulse width modulated (PWM) voltage source converter. The source impedance as well as the saturation effects were taken into consideration. The differential equations describing the system behavior in the different modes of operation are given. Solving these equations using fourth order Runge-Kutta method enabled the prediction of the motor performance in both transient and steady-state conditions. The large chopping frequency facilitate the input filter requirements of the supply current. The supply current, which is considered sinusoidal, can be controlled with a near unity power factor. The complete performance is verified expcrimentally where close agreement between the computed and test results is achieved.
https://erjm.journals.ekb.eg/article_72448_5820d3e8be29d2c6f3e5e35b92570868.pdf
1999-10-01
25
39
10.21608/erjm.1999.72448
M. M.
Khater
1
Department of Electrical Engineering, Faculty of Engineering, Menoufiya University, Shebin El-Kom
AUTHOR
S. S.
Shokralla
2
Department of Electrical Engineering, Faculty of Engineering, Menoufiya University, Shebin El-Kom
AUTHOR
ORIGINAL_ARTICLE
A Novel Approach To Improve The Performance Of FuzzyLogic Based Controllers For Systems With Wide Range disturbances And Uncertain Parameters
Applications offuzzy logic controllers have proved that a tuning algorithm must be added to improve its perfomance against the system disturbances. The tuning methodr represent an additional costs and complexiry for implementation. This paper, presents a novel method which implies a self-tuned controh capable of damping the system oscillations whatever the disturbance changes. Moreover, this controller is robust to a degree that permits more than 2500% parameters uncertainties to be considered. The idea of this approach is to combine two control signals, one from a conventional stabilizer, e.g. lead lag compensator, and the other from a fuzzy logic controller. The stabilizer is designed based on modal techniques for the worst case of oscillations and is independent on the system disturbance. On the other side, the ranges of membership firnetions requiredfor the design of fuzzy logic controller are selected based on the worst experience of the input/output behavior. Thefinal controller is testedfor diflerent disturbances and system parameters and the results show a satisfactoory perfomance and robustness.
https://erjm.journals.ekb.eg/article_72449_49b23c624c8b03a1a1deb19fb293fc12.pdf
1999-10-01
41
56
10.21608/erjm.1999.72449
A.M.
Abdel-Hamid
1
Department of Electrical Engineering, Faculty of Engineering, El-Monoufia University. Shebin El-Kom, Egypt
AUTHOR
ORIGINAL_ARTICLE
ACCURACY OF THE CONVERGENT PHOTOGRAPHY
There is no doubt that the number and variety of the photogrammetric - applications are growing. Convergent case photogrammetry is the most commonly used in analytical photogrammetry . The present formulas which are used to kstimate the accuracy of convergeit case photogrammetry do not give good results, Special at the edge of photograph therefor, the simulation is used for estimating the accuracy of the convergent case of close range photogrammetry . The accuracy obtained in practical experiments closely matches the estimated accuracy from simulation.The disadvantages of the simulation are : The method needs an experience and skilled photogrammetrist, The optimal solution is missed and The si;nulation technique is costly and complicated. This paper gives the mathematical proofs of a newly developed formulas for estimating the accuracy of convergent case.
https://erjm.journals.ekb.eg/article_72450_27681ac0732796c67466466128b6f0c0.pdf
1999-10-01
57
69
10.21608/erjm.1999.72450
Abo El -Hassan M.
Rahil
1
Faculty of Eng. Schebin El - Kom, Minufiya University, Egypt
AUTHOR
ORIGINAL_ARTICLE
New Phylosophy for pole amplitude modulation in the three phase induction machines.
The induction motor is considered to be one of the best elecmcal motors However up to now,it is difficult to control its speed by an ideal method, or even by a method close to that of direct current motors. In spite of this disadvantage, this motor is widely used when the load is not in need of control of its speed over a wide range. Some loads need to change the speed by a ratio of two or three times the rated value. In this case, it is possible to use the Pole Amplitude Modulation to control the method of speed . This method does not need high cost and keeps the motor characteristics in a high grade. The previous papers on this subject mentioned that this technique can be carried out by different methods of modulating the connections of motor winding parts. There is a contradiction between theory and practice seemed when verifying these connections experimentally on an actual motor, so that the predicted speeds could not be obtained. So the motor performance has been analyzed mathematically and physically. From these results, the conditions necessary for motor windings, their distribution and the method of connection have been obtained.
https://erjm.journals.ekb.eg/article_72452_d3f4be51a2d467c1885681691a042a44.pdf
1999-10-01
87
102
10.21608/erjm.1999.72452
F.E
Abdel-kader
1
Dept. of Elect. Eng., Faculty of Eng. Minufiya University, Shebien El-Kom, Egypt
AUTHOR
A.E.
Abou Mobarka
2
Dept. of Elect. Eng., Faculty of Eng. Minufiya University, Shebien El-Kom, Egypt
AUTHOR
W.S.
Abouel-Fadl
3
Dept. of Elect. Eng., Faculty of Eng. Minufiya University, Shebien El-Kom, Egypt.
AUTHOR
ORIGINAL_ARTICLE
Sliding Mode Controller Design For Direct Self Control of Induction Motor For Traction Drive Applications
A control system with fast torque response is important in traction drive applications, where direct self control is highly desirable. A direct self control (DSC) of induction motor is presented using a sliding mode controller. The instantaneous values of the flux and torque are calculated from only the primary variables and controlled in a hysteresis band fashion. In this system the errors in the torque and flux along with the flux position are directly used to choose the optimized switching states of the base drive circuit. New torque and flux controllers are proposed to improve the dynamic response of the drive system. The results demonstrate the superior performance of such a drive system.
https://erjm.journals.ekb.eg/article_72454_26e6946b0d5012e726a49fd9efb7fc89.pdf
1999-10-01
103
114
10.21608/erjm.1999.72454
Direct self control- Induction motor- Space vector modulation
E .E.
El-Kholy
1
Electrical Engineering Department, Faculty of Engineering, Shebin El-Kom, Minufiya University.
AUTHOR
S. A.
Mahmoud
2
Electrical Engineering Department, Faculty of Engineering, Shebin El-Kom, Minufiya University.
AUTHOR
Abdou. M.
El-refay
3
Elect. Tech. Dept., Industrial Education College (IEC), Cairo
AUTHOR
F.
El-Kady
4
Elect. Tech. Dept., Industrial Education College (IEC), Cairo
AUTHOR
ORIGINAL_ARTICLE
BOUNDARY LAYER-TRIPPING STUDIES ON CHARACTERISTICS OF NEAR-WAKE BEHIND A CAMBERlED AIRFOIL
This paper presents an experimental study to the effects of boundary layer-tripping on the aerodynamic performance and the near-wake which generates immediately behind the trailing edge of NACA-2415 airfoil sections. The airfoil was tripped by separately placing two different trip wires near the leading edge as an artificial roughness to induce rapid transition. The tripped and untripped airfoil were tested at different angles of attack to indicate the effects of pressure gradient and streamline curvature on its aerodynamic performance and the wake development behind the airfoil sections. Measurements included lift and drag coefficients, static pressure distributions, and mean velocity profiles in the wake region at Reynolds numbers between 3.5~10~ and 1.92~10~. The results of this experimental investigation showed that the aerodynamic performance of the airfoil is sensitive to the tripping mechanism. The drag coefficient of the airfoil increases due to the distorted velocity profiles in the wake region caused by the boundary layer tripping. The boundary layer tripping did not affect strongly the wake velocity profiles in the case of negative angles of attack and the wake velocity distributions are symmetric. Asymmetric velocity profiles are observed in the wake region as the angle of attack increases, for both tripped and untripped airfoils. The results indicated also that, the pressure gradient and the separation location on airfoil surfaces significantly control the growth of the wake. The effect of the boundary layer tripping on the growth of the wake width, the decay of the maximum velocity defect and similarity of wake profiles are discussed.
https://erjm.journals.ekb.eg/article_72455_5ad9ecadde0358b56d2fdc490b649560.pdf
1999-10-01
115
133
10.21608/erjm.1999.72455
Cambered airfoil
Boundary layer tripping
Wake properties
Aerodynamic
H.A.
Abdalla
1
Department of Mechanical Power Engineering, Faculty of Engineering, Minufiya University, Shebin El-Kom, Egypt
AUTHOR
ORIGINAL_ARTICLE
CONTROL AND STABILITY ANALYSIS OF A SUPERCONDUCTING GENERATOR IN A MULTI-MACHINE POWER SYSTEM
The paper describes a frquency domain technique for the controller design and stability analysis of multi-machine power system indud& a superconducting genertor (SCG). An equivalent model for each generator is obtained, taking into account the dynamic interaction between units, and is used as a base for controller design, the air-cored nature of the SCG and its very long field time constant renders that the governor control is to be considered only. The design technique enables the controller designers to add the required phase at the machine electromechanical frequency, ensuring a satisfactory transient response and prevent the possibilities of system failure.
https://erjm.journals.ekb.eg/article_72457_cd56262eae0e3bf3e2c528e97a6640a2.pdf
1999-10-01
135
149
10.21608/erjm.1999.72457
G.A.
MORSY
1
Electrical Engineering Department, Faculty of Engineering, Menoufiya Univesity, Shebin el-Kom, EGYPT.
AUTHOR
ORIGINAL_ARTICLE
TRANSIENT STABILITY ANALYSIS OF MULTlMACHINE POWER SYSTEM CONSIDERING GENERATOR FLUX DECAY
In the paper, transient stabw analysis of an N-machine power system is carried out using the decomposition-aggregation via vector Lyapunov fimction method. It is considered in the anatysis, transfer conductances, non-uniform mechanical damping, and generators flux decay effect. Each of the system generators 1s represented by a more sophisticated model, that is, the one-axis model in which the generator internal voltage component Elq is assumed to be changed with time. Note that, using the stability direct methods the voltage Elq is usually assumed, for simplicity, constant. The III&~&c~ model of the whole system is derived and is decomposed into [(N-1) 1 3 ] eleventh-order interconnected subsystems, each of them includes tbree machines in addition to the reference machine. The system aggregation is carried out using a constructed vector Lyapunov fimction whose elements are scalar Lygunov functions, each in the form of" quadratic form + sum of thc integrals of six noniincar fimctions". It is obtained a square aggregation matriv of the order [(N-1) 131, and stabii of this matrix implies asymptotic stabiity of the system equilibrium. In a numerical example, the developed stabihty approach is used to cany out transient stability studies of a 10-machine,ll-bus power system The stablhty computations are canied out assuming occurrence of a 3 - phase short circuit fault near a bus, and also for connection of a pulsating load to one of the system buses. In addition it is assumed two composite faults defined as, disconnection of two tie-lines (due to false openRion of circuit breakers near fault location), or addition of a pulsating load, just after clearing a 3-phase short circuit fault (the faulted line is switched off) at two different locations. It is found that the developed stability approach is suitable and can be easily used for practical, and on-line stability studies of large- scale power systems (number of machincs may be more than 10)
https://erjm.journals.ekb.eg/article_72458_af2503915061e5f559996566b7ea447b.pdf
1999-10-01
151
168
10.21608/erjm.1999.72458
H.
Shaaban
1
Faculty of Engineering, Shebin El-Kom, Egypt
AUTHOR