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31,456 Article Results

Fault Identification of In-Service Power Transformer using Depolarization Current Analysis

10.11591/.v7i2.pp559-567
M.A. Talib , N.A. Muhamad , Z.A. Malek , B.T. Phung
Preventive diagnostic testing of in-service power transformers require system outage and expert’s knowledge and experiences in interpreting the measurement results. The chemical oil analysis may cause significant variance to measurement results due to the different practices in oil sampling, storage, handling and transportation. Thus, a cost effective measuring technique by means of a simpler method that is able provide an accurate measurement results is highly required. The extended application of Polarization and Depolarization Current (PDC) measurement for characterization of different faults conditions on in-service power transformer has been presented in this paper. The oil sample from in-service power transformers with normal and 3 different faults type conditions were sampled and tested for Dissolved Gases Analysis (DGA) and PDC measurement. The DGA results was used to confirm type of faults inside the transformer while the PDC pattern of oil with normal, partial discharge, overheating and arcing were correlated to the oil sample conditions. The analysis result shows that depolarization current provides significant information to defferenciate fault types in power transformer. Thus this finding provides a new alternative in identifying incipient faults and such knowledge can be used to avoid catastrophic failures of power transformers.
Volume: 7
Issue: 2
Page: 559-567
Publish at: 2017-04-01

A Tunable Ferrofluid-based Polydimethylsiloxane (PDMS) Microchannel Inductor for Ultra High Frequency Applications

10.11591/.v7i2.pp926-932
Ahmad Hafiz Mohamad Razy , Mohd Tafir Mustaffa , Asrulnizam Abd Manaf , Norlaili Mohd Noh
In this work, a tunable ferrofluid-based polydimethylsiloxane (PDMS) microchannel inductor with high quality factor and high tuning range is proposed. For this project, PDMS is used to create a microchannel with a width and height of 0.53 mm and 0.2 mm respectively. The microchannel is then used to cover the whole design of a solenoid inductor. A solenoid inductor is designed using wire bonding technique where lines of copper and bond wires are used to form a solenoid winding on top of silicon substrate. A light hydrocarbon based ferrofluid EMG 901 660 mT with high permeability of 5.4 is used. The ferrofluid-based liquid is injected into the channel to enhance the performance of a quality factor. A 3D full-wave electromagnetic fields tool, ANSYS HFSS is used in this work to simulate the solenoid inductor. The results obtained in this work gives a quality factor of more than 10 at a frequency range of 300 MHz to 3.3 GHz (Ultra High Frequency range). The highest quality factor is 37 which occurs at a frequency of 1.5 GHz, provides a high tuning range of 112%.
Volume: 7
Issue: 2
Page: 926-932
Publish at: 2017-04-01

Maximum Power Point Tracking using Particle Swarm Optimization Algorithm for Hybrid Wind-Tidal Harvesting System on the South Coast of Java

10.11591/.v7i2.pp659-666
Fransisco Danang Wijaya , Kukuh Daud Pribadi , Sarjiya Sarjiya
This paper proposes a hybrid wind-tidal harvesting system (HWTHS). To extract maximum power from the wind and tidal, HWTHS implements particle swarm optimization (PSO) algorithm in maximum power point tracking (MPPT) method. The proposed HWTHS had been tested on the range of possible input appropriate to the characteristics of the southern coast of Java. The presented result shows that by using PSO-based MPPT algorithm, maximum power point can be achieved. Thus the efficiency of HWTHS is 92 %, 94 % in wind section and 91 % in tidal section. By using PSO-based MPPT, HWTHS can respond well to changes in wind and tidal speed, whether it's a change from low speed to a higher speed or change from high speed to lower speed wherein time to reach new steady state is ± 0.1 s. At varied wind and tidal speed, PSO algorithm can maintain Cp of the system in the range of 0.47 - 0.48 so that power can be extracted to the maximum.
Volume: 7
Issue: 2
Page: 659-666
Publish at: 2017-04-01

p-Laplace Variational Image Inpainting Model Using Riesz Fractional Differential Filter

10.11591/.v7i2.pp850-857
Sridevi Gamini , S Srinivas Kumar
In this paper, p-Laplace variational image inpainting model with symmetric Riesz fractional differential filter is proposed. Variational inpainting models are very useful to restore many smaller damaged regions of an image. Integer order variational image inpainting models (especially second and fourth order) work well to complete the unknown regions. However, in the process of inpainting with these models, any of the unindented visual effects such as staircasing, speckle noise, edge blurring, or loss in contrast are introduced. Recently, fractional derivative operators were applied by researchers to restore the damaged regions of the image. Experimentation with these operators for variational image inpainting led to the conclusion that second order symmetric Riesz fractional differential operator not only completes the damaged regions effectively, but also reducing unintended effects. In this article, The filling process of damaged regions is based on the fractional central curvature term. The proposed model is compared with integer order variational models and also GrunwaldLetnikov fractional derivative based variational inpainting in terms of peak signal to noise ratio, structural similarity and mutual information.
Volume: 7
Issue: 2
Page: 850-857
Publish at: 2017-04-01

Enhanced Time of Use Electricity Pricing for Industrial Customers in Malaysia

10.11591/ijeecs.v6.i1.pp155-159
Nur Azrina Mohd Azman , Md Pauzi Abdullah , Mohammad Yusri hasan , Dalila Mat Said , Faridah Hussin
New Time of Use (ToU) tariff scheme known as Enhanced ToU (EToU) has been introduced on 1st January 2016 for industrial customers in Malaysia. EToU scheme is the advanced version of current ToU where the daily time frame is divided into six period blocks, as compared to only two in the existing ToU. Mid-peak tariff is introduced on top of peak-hour and off-peak tariff. The new scheme is designed to reduce Malaysia’s peak hour electricity demand. On customer side, they could be benefited from the low off-peak tariff by simply shifting their consumption. However, it depends on their consumption profile and their flexibility in shifting their consumption. Since EToU scheme is voluntary, each customer needs to perform cost-benefit analysis before deciding to switch into the scheme. This paper analyzes this problem by considering EToU tariff scheme for industry and customer’s electricity consumption profile. Case studies using different practical data from different industries are presented and discussed in this paper.
Volume: 6
Issue: 1
Page: 155-159
Publish at: 2017-04-01

Power Quality Enhancement in Grid Connected PV Systems using High Step Up DC-DC Converter

10.11591/.v7i2.pp720-728
V S Prasadarao K , K V Krishna Rao , P Bala Koteswara Rao , T. Abishai
Renewable energy sources (RES) are gaining more importance in the present scenario due to the depletion of fossil fuels and increasing power demand. Solar energy is the one of the most promising as it is clean and easily available source. The voltage obtained from the PV system is low. This voltage is increased by high step up dc-dc converter which uses only one switch leads to low switching losses and hence the efficiency of this converter is high. To get the good response this converter is operated in closed loop manner. Integration of PV system with existing grid has so many issues like distorted voltage, current and reactive power control etc. This paper presents a four leg inverter which works on hysteresis current control technique to address the power quality issues like reactive power compensation, balanced load currents and compensation of neutral current. The switching to the inverter is designed in such a way that it supplies the extra current to stabilise the current of the grid that is being supplied to the loads. Finally, the proposed technique is validated by using mat lab/Simulink software and corresponding results are presented in this paper.
Volume: 7
Issue: 2
Page: 720-728
Publish at: 2017-04-01

The Effect of Plasma-Treated Boron Nitride on Partial Discharge Characteristics of LDPE

10.11591/.v7i2.pp568-575
N.A Awang , M.H Ahmad , Y.Z. Arief , I.H. Zakaria , N.A. Ahmad
Power supply reliability is a key factor in a country economic stability. It is contributed by the reliable power distributor via transmission lines, overhead or underground cables. However, the power cables and accessories are always exposed to pre-breakdown phenomena known as partial discharges (PD) which commonly occur in microvoids, defects or protrusions inside the insulation. To improve the performance of the cable insulation against PD, nanofillers are added into the insulating materials. However, to achieve superior performance of PD resistance, the nanofillers must be homogeneously dispersed into the polymer matrices with tightly bonded interfacial zones. Therefore, this could be achieved by employing method of surface functionalization by using cold atmospheric plasma to strengthen the filler/polymer interfaces. In view of foregoing, this study investigated the effects of surface treated boron nitride (BN) nanoparticles in Low Density Polyethylene (LDPE) on the PD characteristics by following CIGRE Method II at 7 kVrms applied voltage. The phase resolved PD characteristics were performed. The results revealed that by treating the nanofillers with cold plasma, the PD resistance of LDPE were highly achieved compared with the untreated BN nanofillers.
Volume: 7
Issue: 2
Page: 568-575
Publish at: 2017-04-01

Hungarian-Puzzled Text with Dynamic Quadratic Embedding Steganography

10.11591/.v7i2.pp799-809
Ebrahim Alrashed , Suood Suood Alroomi
Least-Significant-Bit (LSB) is one of the popular and frequently used steganography techniques to hide a secret message in a digital medium. Its popularity is due to its simplicity in implementation and ease of use. However, such simplicity comes with vulnerabilities. An embedded secret message using the traditional LSB insertion is easily decodable when the stego image is suspected to be hiding a secret message.  In this paper, we propose a novel secure and high quality LSB embedding technique. The security of the embedded payload is employed through introducing a novel quadratic embedding sequence. The embedding technique is also text dependent and has non-bounded inputs, making the possibilities of decoding infinite. Due to the exponential growth of and quadratic embedding, a novel cyclic technique is also introduced for the sequence that goes beyond the limits of the cover medium. The proposed method also aims to reduce the noise arising from embedding the secret message by reducing bits changed. This is done by partitioning the cover medium and the secret message into N partitions and artificially creating an assignment problem based on bit change criteria. The assignment problem will be solved using the Hungarian algorithm that will puzzle the secret message partition for an overall least bit change.
Volume: 7
Issue: 2
Page: 799-809
Publish at: 2017-04-01

Design of Pervasive Discovery, Service and Control for Smart Home Appliances: An Integration of Raspberry Pi, UPnP Protocols and Xbee

10.11591/.v7i2.pp1012-1022
Sabriansyah Rizqika Akbar , Maystya Tri Handono , Achmad Basuki
Pervasive technology is an important feature in smart home appliances control. With pervasive technology, the user is able to discover and control every device and each service without initialization configuration and setup. Since single-board computer often used in smart home appliances, combining pervasive technology and microcomputer/single-board computer will be important to be applied and make a possibility to create a smart home system based on the requirement of it users that will be beneficial for the smart home users and the developers. This paper proposed a design of pervasive discovery, service, and control system for smart home appliances by integrating Raspberry Pi, UPnP protocols, and Xbee that able to control an RGB LED services such as switching, dimming, change color and read a temperature sensor as an example in smart home appliances. This paper enriched the raspberry Pi GPIO function to be able to control via TCP/IP network with UPnP protocol and receive information from a temperature sensor node via Xbee communication. Service control time is measured with UPnP round trip time by subtracting HTTP response arrival with HTTP request time. GPIO processing time measured at the application level by counting a timer that starts before GPIO process and ended after GPIO successfully executed.
Volume: 7
Issue: 2
Page: 1012-1022
Publish at: 2017-04-01

A New Instrumentation Amplifier Architecture Based on Differential Difference Amplifier for Biological Signal Processing

10.11591/.v7i2.pp759-766
Zainul Abidin , Koichi Tanno , Shota Mago , Hiroki Tamura
In this paper, a new Instrumentation Amplifier (IA) architecture for biological signal pro-cessing is proposed. First stage of the proposed IA architecture consists of fully balance differential difference amplifier and three resistors. Its second stage was designed by using differential difference amplifier and two resistors. The second stage has smaller number of resistors than that of conventional one. The IA architectures are simulated and compared by using 1P 2M 0:6-m CMOS process. From HSPICE simulation result, lower common-mode voltage can be achieved by the proposed IA architecture. Average common-mode gain (Ac) of the proposed IA architecture is 31:26 dB lower than that of conventional one under 3% resistor mismatches condition. Therefore, the Ac of the proposed IA architecture is more insensitive to resistor mismatches and suitable for biological signal processing.
Volume: 7
Issue: 2
Page: 759-766
Publish at: 2017-04-01

Fuzzy Recursive Least-Squares Approach in Speech System Identification: A Transformed Domain LPC Model

10.11591/.v7i2.pp842-849
Kah Wai Cheah , Noor Atinah Ahmad
In speech system identification, linear predictive coding (LPC) model is often employed due to its simple yet powerful representation of speech production model. However, the accuracy of LPC model often depends on the number and quality of past speech samples that are fed into the model; and it becomes a problem when past speech samples are not widely available or corrupted by noise. In this paper, fuzzy system is integrated into the LPC model using the recursive least-squares approach, where the fuzzy parameters are used to characterize the given speech samples. This transformed domain LPC model is called the FRLS-LPC model, in which its performance depends on the fuzzy rules and membership functions defined by the user. Based on the simulations, the FRLS-LPC model with this special property is shown to outperform the LPC model. Under the condition of limited past speech samples, simulation result shows that the synthetic speech produced by the FRLS-LPC model is better than those produced by the LPC model in terms of prediction error. Furthermore with corrupted past speech samples, the FRLS-LPC model is able to provide better reconstructed speech while the LPC model is failed to do so.
Volume: 7
Issue: 2
Page: 842-849
Publish at: 2017-04-01

Size Reduction and Gain Enhancement of a Microstrip Antenna using Partially Defected Ground Structure and Circular/Cross Slots

10.11591/.v7i2.pp894-898
Nada N. Tawfeeq
Microwave engineers have been known to designedly created defects in the shape of carved out patterns on the ground plane of microstrip circuits and transmission lines for a long time, although their implementations to the antennas are comparatively new. The term Defected Ground Structure (DGS), precisely means a single or finite number of defects. At the beginning, DGS was employed underneath printed feed lines to suppress higher harmonics. Then DGS was directly integrated with antennas to improve the radiation characteristics, gain and to suppress mutual coupling between adjacent elements. Since then, the DGS techniques have been explored extensively and have led to many possible applications in the communication industry. The objective of this paper is to design and investigate microstrip patch antenna that operates at 2.4 GHz for Wireless Local Area Network WLAN IEEE 802.11b/g/n, ,Zigbee, Wireless HART, Bluetooth and several proprietary technologies that operate in the 2.4 GHz band. The design of the proposed antenna involves using partially Defected Ground Structure and circular/cross slots and compare it to the traditional microstrip patch antenna.  The results show improvement in both the gain of 3.45 dB and the S11 response of -22.3 dB along with reduction in the overall dimensions of the antenna. As a conclusion, the performance of the antenna has been improved through the incorporation with the DGS and slots structures regarding the S11 response and the gain. The proposed antenna become more compact. Finally, the radiation pattern of proposed antenna has remained directional in spite of adding slots on the ground plane.
Volume: 7
Issue: 2
Page: 894-898
Publish at: 2017-04-01

Energy Performance of LDPC Scheme in Multi-Hop Wireless Sensor Network with Two base Stations Model

10.11591/.v7i2.pp933-941
Younes El Assari , Mounir Arioua , Imad Ez-zazi , Ahmed El Oualkadi
Conservation of the energy is one of the main design issues in wireless sensor networks. The limited battery power of each sensor node is a challenging task in deploying this type of network. The challenge is crucial in reliable wireless network when implementing efficient error correcting scheme with energy consuming routing protocol. In this work, we investigated the energy performance of LDPC code in multi-hop wireless sensor network. We proposed a model of two base stations to prolong the lifetime and build a reliable and energy-efficient network. Through performed MATLAB simulations, we examine the energy effectiveness of multiple base stations model on reliable wireless sensor network performance in different network dimensions.
Volume: 7
Issue: 2
Page: 933-941
Publish at: 2017-04-01

Characterization of Acrylonitrile Butadiene Styrene for 3D Printed Patch Antenna

10.11591/ijeecs.v6.i1.pp116-123
Norun Abdul Malek , Athirah Mohd Ramly , Atiah Sidek , Sarah Yasmin Mohamad
3D printing is one of the additive manufacturing technology that has gain popularity for time saving and complex design. This technology increases a degree of flexibility for potential 3D RF applications such as wearable and conformal antennas. This paper demonstrates a circular patch antenna fabricated on 3D printed Acrylonitrile Butadiene Styrene (ABS) filament. The main reason of using a 3D printer is that it is accurate, easy to fabricate of a complex geometry and the ability to create new antennas that cannot be made using conventional fabrication techniques. The ABS material has a tangent loss of 0.0051 and the relative permittivity is 2.74. The thickness of the substrate is 1.25 mm. The simulation has been performed using Computer Simulation Technology (CST). The return loss from simulation software is in good match with measurement which is 12.5dB at 2.44GHz. Hence, from the results obtained, the ABS could be used as a substrate for an antenna.
Volume: 6
Issue: 1
Page: 116-123
Publish at: 2017-04-01

Voltage Compensation In Wind Power System Using STATCOM Controlled By Soft Computing Techniques

10.11591/.v7i2.pp667-680
Bineeta Mukhopadhyay , Rajib Kumar Mandal , Girish Kumar Choudhary
When severe voltage sags occur in weak power systems associated with grid-connected wind farms employing doubly fed induction generators, voltage instability occurs which may lead to forced disconnection of wind turbine. Shunt flexible AC transmission system devices like static synchronous compensator (STATCOM) may be harnessed to provide voltage support by dynamic injection of reactive power. In this work, the STATCOM provided voltage compensation at the point of common coupling in five test cases, namely, simultaneous occurrence of step change (drop) in wind speed and dip in grid voltage, single line to ground, line to line, double line to ground faults and sudden increment in load by more than a thousand times. Three techniques were employed to control the STATCOM, namely, fuzzy logic, particle swarm optimization and a combination of both. A performance comparison was made among the three soft computing techniques used to control the STATCOM on the basis of the amount of voltage compensation offered at the point of common coupling. The simulations were done with the help of SimPowerSystems available with MATLAB / SIMULINK and the results validated that the STATCOM controlled by all the three techniques offered voltage compensation in all the cases considered.
Volume: 7
Issue: 2
Page: 667-680
Publish at: 2017-04-01
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