An optimal and programmable control strategy for
flexible and standard active filtering under non-sinusoidal line voltages
text
article
2013
eng
This paper describes the concept of load compensation under distorted voltages conditions. At these conditions, unity power factor achievement requires the compensated loads to have a current set like the voltages and so it will be non-sinusoidal. Conversely, the perfect compensation of current harmonics will result in a power factor lower than unity. Both the harmonics and power factor compensation are of the well known and very important concepts. This paper introduces several new compensation strategies, which can compromise between power factor and current harmonics. Following these strategies a generalized, optimal and flexible control strategy (OFC) for harmonic compensation of utility lines using Active Power Filter (APF) systems is proposed that can realize a wide range of suitable compensation strategies. The major contribution of this paper is developing the required structure and control algorithm of the needed control system. The control strategy is based on the new compensation concept for power quality improvement under non-sinusoidal line voltage situations. It provides a unified compensation framework and has the ability of programming for perfect current harmonics compensation, or Unity Power Factor (UPF) accomplishment, or other newly defined strategies. One of the defined suitable strategies has the ability of maximizing the power-factor subject to some adjustable constraints on the level of current harmonics and unbalancing via an on-line optimization algorithm to fulfill the IEEE-519 or other desired standards. The strategy guarantees the best achievable power factor and minimum required rating for the compensator. Flexibility of the control strategy has been proved mathematically and verified using extensive simulation results.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
579
596
http://ijste.shirazu.ac.ir/article_1054_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1054
On-line tuning of a fuzzy-logic power system stabilizer
text
article
2013
eng
A scheme for on-line tuning of a fuzzy-logic power system stabilizer (FPSS) is presented. Firstly, a FPSS is developed using speed deviation and accelerating power as the controller input variables. The inference mechanism of the fuzzy-logic controller is represented by a decision table, constructed of linguistic IF-THEN rules. The linguistic rules are available from experts and the design procedure is based on these rules. It is assumed that an exact model of the plant is not available and it is difficult to extract the exact parameters of the power plant. Thus, the design procedure can not be based on an exact model. This is an advantage of fuzzy logic that makes the design of a controller possible without knowing the exact model of the plant. Secondly, two scaling parameters are introduced to tune the FPSS. These scaling parameters are the outputs of another fuzzy-logic system, which gets the operating conditions of the power system as inputs. This mechanism of tuning the FPSS makes the FPSS adaptive to changes in the operating conditions. Therefore, the degradation of the system response, under a wide range of operating conditions, is less compared to the system response with a fixed-parameter FPSS and a conventional (linear) power system stabilizer (CPSS). The tuned stabilizer has been tested by performing nonlinear simulations using a synchronous machine-infinite bus model. The responses are compared with a fixed-parameters FPSS and a CPSS. It is shown that the tuned FPSS is superior to both of them.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
597
604
http://ijste.shirazu.ac.ir/article_1055_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1055
Dynamic modelling of high power single-phase “written pole” motors
text
article
2013
eng
This paper presents a dynamic model to simulate the high power single-phase “Written Pole” motors. The base of this modeling is generalized theory of electrical machines. Based on this theory, first, the required equations governing the dynamic behavior of these motors are obtained. Next, the equations are solved in a special reference frame, which is valid for the unique properties of single-phase “Written Pole” motors. Finally, the comparison of simulating results of the modeling with the experimental ones shows high agreement.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
605
612
http://ijste.shirazu.ac.ir/article_1056_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1056
Analysis of a ridged circular disk microstrip antenna element excited by a microstrip transmission line proximity method using cavity model
text
article
2013
eng
A simple and ridged circular patch antenna element excited by a transmission line proximity method is analyzed. The approach is based on conserving the power action at the ridged position using the cavity model with the assumption of a linear variation of the current distribution on the overlap portion of the line and the patch. The smallest line to ground plane spacing for which a match of the radiator to the line is feasible is found for a given thickness and the patch radius.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
613
622
http://ijste.shirazu.ac.ir/article_1057_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1057
The simulation of a svc and a parallel active filter by
means of transfer function concept of VSI
text
article
2013
eng
In this paper the idea of transfer function of a voltage source inverter (VSI) is used for simulation of a static var compensator (SVC) and a parallel active filter (PAF). This concept makes simulation possible for the above-mentioned converters by generally available simulation software such as student version of Pspice. The idea of transfer function (TF) makes it possible simulation of VSI as a macro-model. In this way, it is not necessary to use semi-conductor switches of VSI or their control circuits. This subject decreases the node number of the circuits, the problem of convergence, the excessive run time and the large memory requirement for output file. The PSCAD/EMTDC simulation package is used as a professional simulation package to satisfy the results. In addition, a new control method for switches of PSCAD/EMTDC simulated converters is presented
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
623
628
http://ijste.shirazu.ac.ir/article_1058_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1058
Probe-position error correction for time-domain planar near-field antenna measurements
text
article
2013
eng
In order to construct the far-field pattern of an antenna in the time domain from its near-field samples, uniform sampling techniques have been widely used. If a signal is unequally sampled due to probe position error, the reconstruction of far-field can not be obtained correctly. Therefore, we propose a method that first recovers uniformly spaced samples of the near-fields from their unequally spaced samples by 2-dimensional nonuniform interpolation techniques, and then proceeds to the computation of the far-field by near-field to far-field transformation. In this paper a comparative survey of some recent interpolation techniques is presented for finding their advantages and disadvantages of using them in our method.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
629
638
http://ijste.shirazu.ac.ir/article_1059_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1059
Assessment of the complexity/regularity of transient brain waves (EEG) during sleep, based on wavelet theory and the concept of entropy
text
article
2013
eng
In this paper we describe a new approach to quantify the concepts of order and complexity of EEG signals during sleep. Based on the concepts of entropy and wavelet transform, we introduce a measure named Wavelet-Entropy and we will show the results of its application to real sleep EEG signals and artificial data. The definition of wavelet entropy is very similar to the definition of entropy in information theory or spectral entropy in signal processing but its most important difference is the usage of time-frequency representation of the signal and its wavelet coefficients. Time-frequency methods proved to be very useful for signals like EEG with fast changing dynamics and high non-stationarity. This characteristic of EEG limits the usage of other complexity evaluation methods like chaos analysis and parameters like correlation dimension or Lyapunov exponent.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
639
646
http://ijste.shirazu.ac.ir/article_1060_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1060
Cross-talk and intermediate frequency deviation effects on phase-shift range finder
text
article
2013
eng
In this paper, design and assembly of a new phase-shift range finder and also the cross-talk effect and the effect of intermediate frequency (IF) deviation on the range finder, is presented. Using the heterodyne technique, the system was able to measure very small phase-shifts, hence, considerably increasing the accuracy of the distance measurements. Since the major error in such systems is due to the phase measurement (counter-clock pulse), related to the cross-talk and the frequency shift, it was necessary to take especial steps to decrease these errors. Therefore, after testing the system, practically a simulation of the system was also carried out. Using the simulation results, the error due to the cross-talk was about 2% in the worst condition. The error related to the frequency changes was about zero, and the resolution due to the counter-clock pulse became 21 mm. Considering the signal to noise ratio of 20dB and the noise current of 42.8pA at the input current to voltage inverter, the lowest detectable optical power at the APD input, which the noise could be ignored, was 23 pW
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
647
654
http://ijste.shirazu.ac.ir/article_1061_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1061
Vertical optical directional coupler: modeling, fabrication and test
text
article
2013
eng
A physical model is develpoed for operation of a functional quantum well optoelectronic integrated device (QW-OEID). Based on the model, static and dynamic characteristics of the device is analyzed numerically considering the effects of parameters such as internal optical feedback and lateral diffusion of carriers for both amplification and switching modes of operations.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
665
672
http://ijste.shirazu.ac.ir/article_1062_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1062
A physical model for characteristics of an optical amplifier-switch integrated device
text
article
2013
eng
A physical model is develpoed for operation of a functional quantum well optoelectronic integrated device (QW-OEID). Based on the model, static and dynamic characteristics of the device is analyzed numerically considering the effects of parameters such as internal optical feedback and lateral diffusion of carriers for both amplification and switching modes of operations.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
665
672
http://ijste.shirazu.ac.ir/article_1063_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1063
Utilizing a direct model reference adaptive controller for a cardiovascular system
text
article
2013
eng
The objective of this study is to design robust direct model reference adaptive controller (DMRAC) for a non-linear cardiovascular model over a range of plant parameters representing a variety of physical conditions. The direct adaptive controllers used here require the plant to be almost strictly positive real (ASPR), that is, for a plant to be controlled there must exist a feedback gain such that the resulting closed-loop system is strictly positive real. We designed new compensator so that the system composed of the cardiovascular plant and the compensator satisfies the ASPR condition.
Numerous technical papers have considered a small range of gain variations of the cardiovascular system. In most of these works, the controller was designed based on the variations in either time delay or plant gains. Many of the papers have treated the cardiovascular system as a single-input single-output (SISO) plant in which the control output was mean arterial pressure (MAP). We treated the cardiovascular system as a multi-input multi-output (MIMO) plant in which both the MAP and cardiac output (CO) are controlled.
We presented a new linear model that provides better approximation than the original linear model. By doing so and utilizing the DMRAC algorithm, we could satisfy the stability conditions for the model, and obtained satisfactory responses in every possible condition for the cardiovascular nonlinear model.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
673
678
http://ijste.shirazu.ac.ir/article_1064_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1064
A high quality multi-level voltage source inverter suitable for high power/high voltage applications
text
article
2013
eng
In this paper new magnitudes for DC side capacitors’ voltages of a multi level voltage source inverter (MLVSI) are presented. Using these magnitudes of DC side capacitors voltages allow generation of steps of AC output voltage by cascade connection of only N single-phase full bridge inverter (FBI). This subject has resulted in almost sinusoidal output voltage waveform. Approximated equal area pulse amplitude modulation (AEAPAM) technique is used to calculate the duration of each step of voltage, which has resulted in reduction of complexity of control circuit. A simple closed-loop controller is developed for controlling the voltages of DC side capacitors. Harmonic analysis and capacitor calculations are presented, too. Simulation results have been used to verify the overall operation of the proposed MLVSI in feeding a R-L load with a stepped sinusoidal waveform.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
679
686
http://ijste.shirazu.ac.ir/article_1065_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1065
Development of a stand-alone lighting system for 70 W HPS lamps
text
article
2013
eng
A stand-alone photovoltaic lighting system is reported in this paper. The system uses a 70 W HPS lamp with a DC bus voltage of 12 V. An efficient electronic ballast, which makes possible the use of 70 W HPS lamp in photovoltaic applications is reported. Design of the ballast is discussed. The ballast has an efficiency of more than 87 percent for the operating load range. The performance of the HPS lamp with the electronic ballast is reported and compared with passive ballast.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
687
692
http://ijste.shirazu.ac.ir/article_1066_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1066
A genetic-neuro algorithm for tiling problems with rotation and/or reflection of figures
text
article
2013
eng
This paper describes an algorithm for tiling with polyminoes that consider rotation and/or reflection of figures in the steps of 90o. First, we review the previous parallel algorithms for tiling problems. Next, we propose a hybrid approach that is based on genetic algorithms (GA) and artificial neural networks (ANN). In this approach, the production of new members in GA and their evaluation are performed by a Hopfield neural network. Finally we compare our method with the previous works, and show that our method can produce global minima for many problems. The algorithm can be used for solving a variety of 2D-packing problems.
Iranian Journal of Science and Technology Transactions of Electrical Engineering
Shiraz University
2228-6179
26
v.
4
no.
2013
693
700
http://ijste.shirazu.ac.ir/article_1067_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijste.2013.1067