SERBIAN JOURNAL OF ELECTRICAL ENGINEERING
Vol. 15, No. 3, October 2018

CONTENTS


Neelamsetti Kirn Kumar, Vairavasundaram Indragandhi
Analysis on Various Optimization Techniques used for Load Frequency Control in Power System
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DOI: https://doi.org/10.2298/SJEE1803249K
Abstract: In a unified power system the Load Frequency Control (LFC) is taken for review looking at all aspects with various optimization techniques for optimizing the parameters of PI, PID and Fuzzy controllers. The power system with multi area consists of conventional, renewable and combination of both with some energy devices like SMES, battery sources is analyzed specifically in this manuscript. The controllers are designed for a deregulated environment of a power system for LFC. The Model Predictive Control (MPC) and some other control techniques are used to control LFC under various disturbances like GRC and dead band control. For the readers ease of understanding the time response comparison graph of the controller for single and multiple areas of power system is depicted.
Keywords: Automatic generation control, Area control error, Load frequency control, Optimization, Controllers.

Maruti Rendale, Shrihar Mathad, Vijaya Puri
Resonance Shifting by Ferrite Thick Film Superstrate
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DOI: https://doi.org/10.2298/SJEE1803275R
Abstract: Fritless thick films of Ni-Co-Zn ferrites were fabricated by screen printing technique on alumina substrates. Structural analysis was undertaken using X-ray diffraction and Scanning electron microscopy techniques. A new approach for the determination of complex permittivity ( and ) using microwave property perturbation is unveiled. Ag thick film microstrip ring resonator (MSRR) with and without the thick film substrate was used for the microwave transmission studies in the frequency region of 812 GHz. The microwave conductivity of the thick films lies in the range of 1.779 S/cm to 2.296 S/cm. The penetration depth is also reported within the X-band of microwave frequencies.
Keywords: Thick films, Microstrip ring resonator (MSRR), Complex permittivity, Penetration depth.

Mahamkali Ranjit, Teegala Bramhananda Reddy, Munagala Suryakalavathi
Decoupled Centric and Non-Centric PWM Techniques for Open-End Winding Induction Motor Drive
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DOI: https://doi.org/10.2298/SJEE1803275R
Abstract: This article proposes the space vector based decoupled centric and non-centric PWM techniques for open-end winding induction motor drive. To make the proposed configuration, 2-coventional inverters are fed on either side of open-circuited stator winding of induction motor. Therefore three level output is achieved. To obtain the control pulses for inverters in the proposed configuration reference sinusoids are used. All the proposed PWM techniques use the equal switching frequency. To obtain the validation for the proposed work various theoretical and simulation analysis is carried out using v/f control and the corresponding output voltage is verified experimentally using 1HP asynchronous motor.
Keywords: Centric PWM (CPWM), Decoupled, Non-centric PWM (NCPWM), Open-end winding Induction Motor (OEWIM).

Madhavsingh Indoonundon, Tulsi Pawan Fowdur
An Unequal Error Protection Scheme for Non-Binary LDPC using Statistical QAM and Prioritized Mapping
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DOI: https://doi.org/10.2298/SJEE1803301I
Abstract: Low Density Parity Check (LDPC) codes are among the most popular channel codes used nowadays because of their ability to achieve near channel capacity performances. However, with the ever-increasing demand for reliable transmission of data at higher data rates, there is a need to narrow down the gap between the performance of LDPC codes and the channel capacity. LDPC codes and Quadrature Amplitude Modulation (QAM) have been widely deployed in wireless communication standards such as the IEEE 802.11n and Digital Video Broadcasting-Second Generation Terrestrial (DVB-T2). Recently, several Unequal Error Protection (UEP) schemes have been used to enhance the performance of LDPC codes. In this paper an UEP scheme is proposed for Non-Binary LDPC codes with QAM. The scheme uses the statistical distribution of the source symbols to obtain a more efficient statistical QAM constellation. Additionally, it uses the degree distribution of the nodes of the LDPC codeword to achieve prioritized QAM mapping. Simulations revealed that the proposed scheme can provide Eb/N0 gains of up to 0.78 dB and 1.24 dB with 16-QAM and 64-QAM respectively in the range BER≤10-2.
Keywords: Unequal Error Protection, Non-Binary, Low Density Parity Check, IEEE 802.11n, Quadrature Amplitude Modulation.

Nenad Marković, Jeroslav Živanić, Zoran Lazarević, Bratislav Iričanin
The Mathematical Model for Analysis and Evaluation of the Transient Process of the three‒phase Asynchronous Machine Performance
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DOI: https://doi.org/10.2298/SJEE1803319M
Abstract: This paper describes an adopted method which could be used in transient process modelling of three‒phase asynchronous machines on the computer. Converter asynchronous electric machine feeding requires a detailed research of the transient process influence and the dynamic states of energy exchange between the electrical circuit feeding and the machine itself. A mathematical model has been formulated in order to solve the transient process of the three-phase asynchronous electric machine referring to the two asynchronous machines and containing two matrix models defined by Park’s components. In the system of symmetrical components the state and the operation of the first machine was defined based on relations and operation conditions of a direct sequence system and of other machines based on relations and operation conditions of an inverse sequence system. The new method has been derived from the existing psbpwm MATLAB package. The new model simulates the state and operation of a single machine with identical parame-ters through the state and operation of the two machines with identical parameters: the first in a direct sequence system and the others in an inverse sequence system. Operation analysis of the three‒phase induction machine is limited to a transient process occurring in the right angled shape of voltage feeding. The new presented model can, with certain limitations, be applied not only to a three‒phase asynchro-nous machine model but to other alternating current machines which have a stator and a rotor. The experiment has been performed following an example of asym-metrical feeding followed by inverse component phenomena of electrical and mechanical values in the machine.
Keywords: Mathematical Model, One-phase Interruption, Asymmetric Mode, Three-Phase Asynchronous Machine.

Miloš Antonijević, Goran Shimic, Aleksandar Jevremović, Mladen Veinović, Slađana Arsić
The Potential for the Use of EEG Data in Electronic Assessments
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DOI: https://doi.org/10.2298/SJEE1803339A
Abstract: One of the most important goals of electronic assessments is to achieve the smallest measurement error with tests that are as simple and short as possible. The psychological state of an examinee is typically ignored, both in the process of designing the tests and during the exam itself. Using the developed framework, we tested 35 participants in an experiment to obtain as much data as possible about the emotional states of the students depending on the different types of question posed. In this paper, we present our current results from an examination of the potential of using EEG data towards applying artificial intelligence for improvement of electronic assessments, as well as a technical platform for this purpose..
Keywords: EEG, Electronic assessment, Online testing, Human-computer interaction, Analytics.

Valentin Fedosov, Andrey Legin, Anna Lomakina
Adaptive Algorithm for Wireless Data Transmission (Including Images) Based on SISO System and OFDM Technique
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DOI: https://doi.org/10.2298/SJEE1803353F
Abstract: The efficiency of wireless systems to transmit information in a complex interference situation is one of the main indicators of the effectiveness of the system, which can be characterized by the probability of an error in the transmitted message. This characteristic depends on the interference situation of the communication channel and the nature of the signals propagation in the medium. If the medium has a multi-path character, the signal interferes with the receiving antenna, causing signal fading. So the developer of wireless communication devices is faced with the task of increasing the noise immunity of the system. It can be increased in various ways, for example, by using adaptive processing algorithms for spatio-temporal signals. In this paper we solve the problem of improving noise immunity in wireless communication systems by applying an algorithm of adaptive spatial-temporal signal processing in the receiver based on an adaptive antenna array, which allows spatial filtering under conditions of a complex pattern of signal propagation in a channel with reflections. Calculation of weights for the adaptation algorithm in the article is based on the theory of eigenvalues and vectors of the spatial correlation matrix.
Keywords: Antenna array (AA), SISO, Multipath, Adaptive algorithm, Coding, OFDM.

Vladimir Marchuk
Reducing of Noise Structure Influence on an Accuracy of a Desired Signal Extraction
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DOI: https://doi.org/10.2298/SJEE1803365M
Abstract: In the paper, the issues regarding the analysis of the noise component structure are addressed and methods for reducing the error in estimating of the mathematical expectation of the noise component are proposed. The use of the proposed method of “noise purification” makes possibility to reduce the error introduced by the noise structure when estimating the mathematical expectation and dispersion of the noise component during research. The main scientific contribution in this paper in accuracy increasing of random processes parameters estimation. These theoretical results can be applied in different spheres of data analyzing and signal processing when random processes have some structure.
Keywords: Noise, Multiplication of estimates, Signal extraction, Mathematical expectation estimation, Signal smoothing.

Milić Djekić
Corrigendum
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DOI: https://doi.org/10.2298/SJEE1803371E

Milić Djekić
Retraction Notice to Spatio – Temporal Image Inpainting for Video Applications
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DOI: https://doi.org/10.2298/SJEE1803373E



©2018 Serbian Journal of Electrical Engineering