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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Electrical Engineering and Technology
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The Korean Institute of Electrical Engineers
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Volume 10, Issue 6 - Nov 2015
Volume 10, Issue 5 - Sep 2015
Volume 10, Issue 4 - Jul 2015
Volume 10, Issue 3 - May 2015
Volume 10, Issue 2 - Mar 2015
Volume 10, Issue 1 - Jan 2015
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Research and Experimental Implementation of a CV-FOINC Algorithm Using MPPT for PV Power System
Arulmurugan, R. ; Venkatesan, T. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1389~1399
DOI : 10.5370/JEET.2015.10.4.1389
This research suggests maximum power point tracking (MPPT) for the solar photovoltaic (PV) power scheme using a new constant voltage (CV) fractional order incremental conductance (FOINC) algorithm. The PV panel has low transformation efficiency and power output of PV panel depends on the change in weather conditions. Possible extracting power can be raised to a battery load utilizing a MPPT algorithm. Among all the MPPT strategies, the incremental conductance (INC) algorithm is mostly employed due to easy implementation, less fluctuations and faster tracking, which is not only has the merits of INC, fractional order can deliver a dynamic mathematical modelling to define non-linear physiognomies. CV-FOINC variation as dynamic variable is exploited to regulate the PV power toward the peak operating point. For a lesser scale photovoltaic conversion scheme, the suggested technique is validated by simulation with dissimilar operating conditions. Contributions are made in numerous aspects of the entire system, including new control algorithm design, system simulation, converter design, programming into simulation environment and experimental setup. The results confirm that the small tracking period and practicality in tracking of photovoltaic array.
Coordinated Voltage-Reactive Power Control Schemes Based on PMU Measurement at Automated Substations
Choi, Yun-Hyuk ; Kang, Sang-Gyun ; Lee, Byongjun ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1400~1407
DOI : 10.5370/JEET.2015.10.4.1400
This paper deals with methodology to control an automatic substation system. The control system can predict the power system condition by a voltage stability index (VSI). The strategies in this paper is called as Voltage-Reactive Power Control (VRPC), which regulates an abnormal voltage of a target substation by using coordination between tap changers and shunt capacitor/reactor. This method is efficient for better voltage profile. The monitoring substation includes whole of substations around the contingency event. The control quantities of the monitoring substations are decided by the calculation of the VSI, called as a Z-index. Case studies with BC Hydro-Quebec system are presented to illustrate this approach using real-time simulator.
The Analysis of Active Power Control Requirements in the Selected Grid Codes for Wind Farm
Kim, Mi-Young ; Song, Yong-Un ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1408~1414
DOI : 10.5370/JEET.2015.10.4.1408
The renewable energies such as photovoltaic power, wind power and biomass have grown to a greater extent as decarbonization techniques. The renewable energies are interconnected to power systems (or electrical grids) in order to increase benefits from economies of scale, and the extra attention is focused on the Grid Code. A grid code defines technical parameters that power plants must meet to ensure functions of power systems, and the grid code determined by considering power system characteristics is various across the country. Some TSO (Transmission System Operator) and ISO (Independent System Operator) have issued grid code for wind power and the special requirements for offshore wind farm. The main purpose of the above grid code is that wind farm in power systems has to act as the existing power plants. Therefore wind farm developer and wind turbine manufacturer have great difficulty in grasping and meeting grid code requirements. This paper presents the basic understanding for grid codes of developed countries in the wind power and trends of those technical requirements. Moreover, in grid code viewpoint, the active power control of wind power is also discussed in details.
Quantum-behaved Electromagnetism-like Mechanism Algorithm for Economic Load Dispatch of Power System
Zhisheng, Zhang ; Wenjie, Gong ; Xiaoyan, Duan ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1415~1421
DOI : 10.5370/JEET.2015.10.4.1415
This paper presents a new algorithm called Quantum-behaved Electromagnetism-like Mechanism Algorithm which is used to solve economic load dispatch of power system. Electromagnetism-like mechanism algorithm simulates attraction and repulsion mechanism for particles in the electromagnetic field. Every solution is a charged particle, and it move to optimum solution according to certain criteria. Quantum-behaved electromagnetism-like mechanism algorithm merges quantum computing theory with electromagnetism-like mechanism algorithm. Superposition characteristic of quantum methodology can make a single particle present several states, and the characteristic potentially increases population diversity. Probability representation of quantum methodology is to make particle state be presented according to a certain probability. And the quantum rotation gates are used to realize update operation of particles. The algorithm is tested for 13-generator system and 40-generator system, which validates it can effectively solve economic load dispatch problem. Through performance comparison, it is obvious the solution is superior to other optimization algorithm.
Reliability Evaluation of Power System Operations Considering Time-Varying Features of Components
Hu, Bo ; Zheng, Ying ; Yang, Hejun ; Xia, Yun ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1422~1431
DOI : 10.5370/JEET.2015.10.4.1422
The reliability of power system components can be affected by a numbers of factors such as the health level of components, external environment and operation environment of power systems. These factors also affect the electrical parameters of power system components for example the thermal capacity of a transmission element. The relationship of component reliability and power system is, therefore, a complex nonlinear function related to the above-mentioned factors. Traditional approaches for reliability assessment of power systems do not take the influence of these factors into account. The assessment results could not, therefore, reflect the short-term trend of the system reliability performance considering the influence of the key factors and provide the system dispatchers with enough information to make decent operational decisions. This paper discusses some of these important operational issues from the perspective of power system reliability. The discussions include operational reliability of power systems, reliability influence models for main performance parameters of components, time-varying reliability models of components, and a reliability assessment algorithm for power system operations considering the time-varying characteristic of various parameters. The significance of these discussions and applications of the proposed techniques are illustrated by case study results using the IEEE-RTS.
Dynamic Economic Dispatch and Control of a Stand-alone Microgrid in DongAo Island
Ma, Yiwei ; Yang, Ping ; Guo, Hongxia ; Wang, Yuewu ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1432~1440
DOI : 10.5370/JEET.2015.10.4.1432
A dynamic economic dispatch and control method is proposed to minimize the overall generating cost for a stand-alone microgrid in DongAo Island, which is integrated with wind turbine generator, solar PV, diesel generator, battery storage, the seawater desalination system and the conventional loads. A new dispatching strategy is presented based on the ranking of component generation costs and two different control modes, in which diesel generator and battery storage alternate to act as the master power source to follow system power fluctuation. The optimal models and GA-based optimization process are given to minimize the overall system generating cost subject to the corresponding constraints and the proposed dispatch strategy. The effectiveness of the proposed method is verified in the stand-alone microgrid in DongAo Island, and the results provide a feasible theoretical and technical basis for optimal energy management and operation control of stand-alone microgrid.
Economic Dispatch Using Hybrid Particle Swarm Optimization with Prohibited Operating Zones and Ramp Rate Limit Constraints
Prabakaran, S. ; Senthilkuma, V. ; Baskar, G. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1441~1452
DOI : 10.5370/JEET.2015.10.4.1441
This paper proposes a new Hybrid Particle Swarm Optimization (HPSO) method that integrates the Evolutionary Programming (EP) and Particle Swarm Optimization (PSO) techniques. The proposed method is applied to solve Economic Dispatch(ED) problems considering prohibited operating zones, ramp rate limits, capacity limits and power balance constraints. In the proposed HPSO method, the best features of both EP and PSO are exploited, and it is capable of finding the most optimal solution for the non-linear optimization problems. For validating the proposed method, it has been tested on the standard three, six, fifteen and twenty unit test systems. The numerical results show that the proposed HPSO method is well suitable for solving non-linear economic dispatch problems, and it outperforms the EP, PSO and other modern metaheuristic optimization methods reported in the recent literatures.
Impact of Fixed Series Capacitors and SSSC on the LOE Protection of Synchronous Generator
Ghorbani, Amir ; Lima, Hossein Mehryari ; Azadru, Allahverdi ; Mozafari, Babak ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1453~1459
DOI : 10.5370/JEET.2015.10.4.1453
Loss of excitation (LOE) relay is prevalently used to protect synchronous generator. The widely used method for synchronous generator LOE protection is a negative offset mho relay with two zones. The basis of this relay is identical to mho impedance relay. In other words, this relay calculates impedance by measuring voltage and current at the generator terminal. On the other hand, the presence of series compensation, changes measured voltage and current signals during loss of excitation. This paper reveals that the presence of series compensators such as fixed series capacitors (FSCs) and static synchronous series compensator (SSSC) causes a significant delay on the performance of generator LOE relay. It is also shown that the presence of SSSC causes the LOE relay to be under-reached. Different operating modes of the power system, the SSSC and also different percentages of series capacitive compensations have been considered in the modeling. All the detailed simulations are carried out in the MATLAB/Simulink environment using the SimPowerSystems toolbox.
Agent-Based Modeling for Studying the Impact of Capacity Mechanisms on Generation Expansion in Liberalized Electricity Market
Dahlan, N.Y. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1460~1470
DOI : 10.5370/JEET.2015.10.4.1460
This paper presents an approach to solve the long-term generation expansion planning problem of the restructured electricity industry using an agent-based environment. The proposed model simulates the generation investment decisions taken by a particular agent (i.e. a generating company) in a market environment taking into account its competitors’ strategic investment. The investment decision of a particular company is modeled taking into account that such company has imperfect foresight on the future system development hence electricity prices. The delay in the construction of new plants is also explicitly modeled, in order to compute accurately the yearly revenues of each agent. On top of a conventional energy market, several capacity incentive mechanisms including capacity payment and capacity market are simulated, so as to assess their impact on the investment promotion for generation expansion. Results provide insight on the investment cycles as well as dynamic system behavior of long-term generation expansion planning in a competitive electricity industry.
Economic Analysis of Power Transmission Lines using Interval Mathematics
Teegala, Srinivasa Kishore ; Singal, Sunil Kumar ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1471~1479
DOI : 10.5370/JEET.2015.10.4.1471
A major portion of the capital costs in the present day power transmission systems are due to the cost of equipment and construction process. Transmission utilities in the recent years are drawing greater attention towards performing life cycle costing studies for cost management and decision making. However, the data involved in these studies are highly uncertain and the effect of these uncertainties cannot be directly included in the study process, resulting in inaccurate solutions. Interval mathematics provides a method for including these uncertainties throughout the cost analysis and provides final solution range in the form of intervals. In this regard, it is essential and extremely important that significant research has to be carried out in understanding the principles of life cycle costing methodology and its applicability to cost analysis of transmission lines along with uncertainties involved in the cost assessment process. In this paper, economic analysis of power transmission lines using interval mathematics has been studied. Life cycle costing studies are performed using net present value analysis on a range transmission lines used in India and the results are analyzed. A cost break even analysis considering right of way costs was carried out to determine the point of economy indifference.
A New Approach to Short-term Price Forecast Strategy with an Artificial Neural Network Approach: Application to the Nord Pool
Kim, Mun-Kyeom ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1480~1491
DOI : 10.5370/JEET.2015.10.4.1480
In new deregulated electricity market, short-term price forecasting is key information for all market players. A better forecast of market-clearing price (MCP) helps market participants to strategically set up their bidding strategies for energy markets in the short-term. This paper presents a new prediction strategy to improve the need for more accurate short-term price forecasting tool at spot market using an artificial neural networks (ANNs). To build the forecasting ANN model, a three-layered feedforward neural network trained by the improved Levenberg-marquardt (LM) algorithm is used to forecast the locational marginal prices (LMPs). To accurately predict LMPs, actual power generation and load are considered as the input sets, and then the difference is used to predict price differences in the spot market. The proposed ANN model generalizes the relationship between the LMP in each area and the unconstrained MCP during the same period of time. The LMP calculation is iterated so that the capacity between the areas is maximized and the mechanism itself helps to relieve grid congestion. The addition of flow between the areas gives the LMPs a new equilibrium point, which is balanced when taking the transfer capacity into account, LMP forecasting is then possible. The proposed forecasting strategy is tested on the spot market of the Nord Pool. The validity, the efficiency, and effectiveness of the proposed approach are shown by comparing with time-series models
A Study on Voltage Sag Considering Real-Time Traffic Volume of Electric Vehicles in South Korea
Go, Hyo-Sang ; Kim, Doo-Ung ; Kim, Jun-Hyeok ; Lee, Soon-Jeong ; Kim, Seul-Ki ; Kim, Eung-Sang ; Kim, Chul-Hwan ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1492~1501
DOI : 10.5370/JEET.2015.10.4.1492
This paper analyzes the effect of voltage sag on distribution systems due to the connection of Electric Vehicles (EVs). In order to study the impact of the voltage sag on the power system, two scenarios have been selected in this paper. The distribution system and EVs are modeled using the Electro Magnetic Transients Program (EMTP). The numbers of EVs are predicted based on the number of vehicles in distribution system of Seoul. In addition, the number of EVs is set up using real-time traffic in Seoul to simulate Scenario I and II. The simulation results show that voltage sag can occur if the distribution system has more than 30% of the total number of vehicles.
Optimal Shunt Compensation for Improving Voltage Stability and Transfer Capability in Metropolitan Area of the Korean Power System
Choi, YunHyuk ; Lee, Byongjun ; Kim, TaeKyun ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1502~1507
DOI : 10.5370/JEET.2015.10.4.1502
This paper deals with shunt compensation to eliminate voltage violation and enhance transfer capability, which is motivated towards implementation in the Korean power system. The optimal shunt compensation algorithm has demonstrated its effectiveness in terms of voltage accuracy and reducing the number of actions of reactive power compensating devices. The main shunt compensation devices are capacitor and reactor. Effects of control devices are evaluated by cost computations. The control objective at present is to keep the voltage profile of a key bus within constraints with minimum switching cost. A robust control strategy is proposed to make the control feasible and optimal for a set of power-flow cases that may occurs important event from system. Case studies with metropolitan area of the Korean power system are presented to illustrate the method.
Opposition Based Differential Evolution Algorithm for Dynamic Economic Emission Load Dispatch (EELD) with Emission Constraints and Valve Point Effects
Thenmalar, K. ; Ramesh, S. ; Thiruvenkadam, S. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1508~1517
DOI : 10.5370/JEET.2015.10.4.1508
Optimal Power dispatch is the short-term decision of the optimal output of a number of power generation facilities, to meet the system demand, with the objective of Power dispatching at the lowest possible cost, subject to transmission lines power loss and operational constraints. The operational constraint includes power balance constraint, generator limit constraint, and emission dispatch constraint and valve point effects. In this paper, Opposition based Differential Evolution Algorithm (ODEA) has been proposed to handle the objective function and the operational constraints simultaneously. Furthermore, the valve point loading effects and transmission lines power loss are also considered for the efficient and effective Power dispatch. The ODEA has unique features such as self tuning of its control parameters, self acceleration and migration for searching. As a result, it requires very minimum executions compared with other searching strategies. The effectiveness of the algorithm has been validated through four standard test cases and compared with previous studies. The proposed method out performs the previous methods.
Research of the Mechanism of Low Frequency Oscillation Based on Dynamic Damping Effect
Liu, Wenying ; Ge, Rundong ; Zhu, Dandan ; Wang, Weizhou ; Zheng, Wei ; Liu, Fuchao ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1518~1526
DOI : 10.5370/JEET.2015.10.4.1518
For now, there are some low frequency oscillations in the power system which feature low frequency oscillation with positive damping and cannot be explained by traditional low frequency oscillation mechanisms. Concerning this issue, the dynamic damping effect is put forward on the basis of the power-angle curve and the study of damping torque in this article. That is, in the process of oscillation, damping will dynamically change and will be less than that of the stable operating point especially when the angle of the stable operating point and the oscillation amplitude are large. In a situation with weak damping, the damping may turn negative when the oscillation amplitude increases to a certain extent, which may result in an amplitude-increasing oscillation. Finally, the simulation of the two-machine two-area system verifies the arguments in this paper which may provide new ideas for the analysis and control of some unclear low frequency phenomena.
Design and Implementation of Direct Torque Control Based on an Intelligent Technique of Induction Motor on FPGA
Krim, Saber ; Gdaim, Soufien ; Mtibaa, Abdellatif ; Mimouni, Mohamed Faouzi ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1527~1539
DOI : 10.5370/JEET.2015.10.4.1527
In this paper the hardware implementation of the direct torque control based on the fuzzy logic technique of induction motor on the Field-Programmable Gate Array (FPGA) is presented. Due to its complexity, the fuzzy logic technique implemented on a digital system like the DSP (Digital Signal Processor) and microcontroller is characterized by a calculating delay. This delay is due to the processing speed which depends on the system complexity. The limitation of these solutions is inevitable. To solve this problem, an alternative digital solution is used, based on the FPGA, which is characterized by a fast processing speed, to take the advantage of the performances of the fuzzy logic technique in spite of its complex computation. The Conventional Direct Torque Control (CDTC) of the induction machine faces problems, like the high stator flux, electromagnetic torque ripples, and stator current distortions. To overcome the CDTC problems many methods are used such as the space vector modulation which is sensitive to the parameters variations of the machine, the increase in the switches inverter number which increases the cost of the inverter, and the artificial intelligence. In this paper an intelligent technique based on the fuzzy logic is used because it is allows controlling the systems without knowing the mathematical model. Also, we use a new method based on the Xilinx system generator for the hardware implementation of Direct Torque Fuzzy Control (DTFC) on the FPGA. The simulation results of the DTFC are compared to those of the CDTC. The comparison results illustrate the reduction in the torque and stator flux ripples of the DTFC and show the Xilinx Virtex V FPGA performances in terms of execution time.
Sensorless Detection of Position and Speed in Brushless DC Motors using the Derivative of Terminal Phase Voltages Technique with a Simple and Versatile Motor Driver Implementation
Carlos Gamazo Real, Jose ; Jaime Gomez, Gil ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1540~1551
DOI : 10.5370/JEET.2015.10.4.1540
The detection of position and speed in BLDC motors without using position sensors has meant many efforts for the last decades. The aim of this paper is to develop a sensorless technique for detecting the position and speed of BLDC motors, and to overcome the drawbacks of position sensor-based methods by improving the performance of traditional approaches oriented to motor phase voltage sensing. The position and speed information is obtained by computing the derivative of the terminal phase voltages regarding to a virtual neutral point. For starting-up the motor and implementing the algorithms of the detection technique, a FPGA board with a real-time processor is used. Also, a versatile hardware has been developed for driving BLDC motors through pulse width modulation (PWM) signals. Delta and wye winding motors have been considered for evaluating the performance of the designed hardware and software, and tests with and without load are performed. Experimental results for validating the detection technique were attained in the range 5-1500 rpm and 5-150 rpm under no-load and full-load conditions, respectively. Specifically, speed and position square errors lower than 3 rpm and between 10º-30º were obtained without load. In addition, the speed and position errors after full-load tests were around 1 rpm and between 10º-15º, respectively. These results provide the evidence that the developed technique allows to detect the position and speed of BLDC motors with low accuracy errors at starting-up and over a wide speed range, and reduce the influence of noise in position sensing, which suggest that it can be satisfactorily used as a reliable alternative to position sensors in precision applications.
A New Cascaded Multilevel Inverter Topology with Voltage Sources Arranged in Matrix Structure
Thamizharasan, S. ; Baskaran, J. ; Ramkumar, S. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1552~1557
DOI : 10.5370/JEET.2015.10.4.1552
The paper unleashes a new idea to arrive at reduced switch count topological structures configured in the form of a matrix for a cascaded Multi level inverter (CMLI). The theory encircles to minimize the number of switches involved in the conduction path and there from acclaim reduced input current distortion, lower switching losses and electromagnetic interference. The focus extends to standardize the number of power devices required for reaching different levels of output voltage from the same architecture. It includes appropriate pulse width modulation (PWM) strategy to generate firing pulses and ensure the desired operation of the power modules. The investigative study carries with it MATLAB based simulation and experimental results obtained using suitable prototypes to illustrate the viability of the proposed concept. The promising nature of the performance projects a new dimension in the use of single phase MLIs for renewable energy related applications.
Support Vector Machine Based Bearing Fault Diagnosis for Induction Motors Using Vibration Signals
Hwang, Don-Ha ; Youn, Young-Woo ; Sun, Jong-Ho ; Choi, Kyeong-Ho ; Lee, Jong-Ho ; Kim, Yong-Hwa ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1558~1565
DOI : 10.5370/JEET.2015.10.4.1558
In this paper, we propose a new method for detecting bearing faults using vibration signals. The proposed method is based on support vector machines (SVMs), which treat the harmonics of fault-related frequencies from vibration signals as fault indices. Using SVMs, the cross-validations are used for a training process, and a two-stage classification process is used for detecting bearing faults and their status. The proposed approach is applied to outer-race bearing fault detection in three-phase squirrel-cage induction motors. The experimental results show that the proposed method can effectively identify the bearing faults and their status, hence improving the accuracy of fault diagnosis.
High Step-Up Converter with Hybrid Structure Based on One Switch
Hwu, K.I. ; Peng, T.J. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1566~1577
DOI : 10.5370/JEET.2015.10.4.1566
A novel high step-up converter is presented herein, which combines the conventional buck-boost converter, the charge pump capacitor and the coupling inductor. By doing so, a quite high voltage conversion ratio due to not only the turns ratio but also the duty cycle, so as to increase design feasibility. It is noted that the denominator of the voltage conversion ratio is the square of one minus duty cycle. Above all, there is no voltage spike across the switch due to the leakage inductance and hence no passive or active snubber is needed, and furthermore, the used switch is driven without isolation and hence the gate driving circuit is relatively simple, thereby upgrading the industrial application capability of this converter. In this paper, the basic operating principles and the associated mathematical deductions are firstly described in detail, and finally some experimental results are provided to demonstrate the effectiveness of the proposed high step-up converter.
Improved KY Converter
Hwu, K.I. ; Jiang, W.Z. ; Chen, H.M. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1578~1588
DOI : 10.5370/JEET.2015.10.4.1578
In this paper, an improved KY converter is presented, which is constructed mainly by one charge pump capacitor and one central-tapped coupling inductor. Besides, a passive clamping snubber is added to this converter to improve the efficiency above half load. As compared to the KY converter, the voltage conversion ratio of the proposed converter is upgraded significantly. In this paper, the basic operating principles and mathematical deductions of the proposed converter are described, along with some experimental results provided to demonstrate the feasibility and effectiveness of the proposed converter.
A Novel Active Damping Control of a Three-phase PWM Inverter with LC Filter
Kim, Kwang-Seob ; Hyun, Dong-Seok ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1589~1596
DOI : 10.5370/JEET.2015.10.4.1589
A novel control method of a three-phase PWM inverter with LC filter is proposed. The transfer function of LC filter is the same as that of 2nd order low pass filter(2nd LPF) which has a zero damping ratio. A simple method of implementing 2nd LPF with damping ratio is to add resistor to inductor or capacitor of LC filter. In an industrial application, it is not practical to adopt damping resistor because it results in losses being proportional to square of current flowing through resistor. Instead of using damping resistors, the proposed active damping control(ADC) utilizes all pass filter(APF) and considers inherent processing delay of digital controller. The overall transfer function of the proposed method is the same as a 2nd LPF and its damping ratio is also controllable via control variables. Detailed design and implementation of controller is also presented. Experiments are conducted with a 7.5kVA induction motor drive system controlled by PWM converter and inverter. Test waveforms are also presented to verify the proposed LC filter control algorithm.
Low-Pass Filter Circuit
Zhou, Rui ; Zhang, Run-Fan ; Chen, Di-Yi ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1597~1609
DOI : 10.5370/JEET.2015.10.4.1597
This paper introduces the fundamentals of the conventional LC low-pass filter circuit in the fractional domain. First, we study the new fundamentals of fractional-order LC low-pass filter circuit including the pure real angular frequency, the pure imaginary angular frequency and the short circuit angular frequency. Moreover, sensitivity analysis of the impedance characteristics and phase characteristics of the LC low-pass filter circuit with respect to the system variables is studied in detail, which shows the greater flexibility of the fractional-order filter circuit in designs. Furthermore, from the filtering property perspective, we systematically investigate the effects of the system variables (LC, frequency f and fractional orders) on the amplitude-frequency characteristics and phase-frequency characteristics. In addition, the detailed analyses of the cut-off frequency and filter factor are presented. Numerical experimental results are presented to verify the theoretical results introduced in this paper.
Hybrid Cascaded MLI topology using Ternary Voltage Progression Technique with Multicarrier Strategy
Venugopal, Jamuna ; Subarnan, Gayathri Monicka ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1610~1620
DOI : 10.5370/JEET.2015.10.4.1610
A major problem in conventional multilevel inverter is that an increase in power semiconductor switches causes an increase in cost and switching losses of the inverter. The multicarrier strategy adopted for the multilevel inverters has become more popular due to reduced cost, lower harmonic distortion, and higher voltage capability than the conventional switching strategy applied to inverters. Various topologies and modulation strategies have been reported for utility and drive applications. Level shifted based pulse width modulation techniques are proposed to investigate the performance of the multilevel inverter. The proposed work focuses on reducing the utilized switches so that the cost and the switching losses of the inverter do not go up and the consistent efficiency could be achieved. This paper presents the detailed analysis of these topologies. The analysis is based on the number of switches, DC sources, output level, maximum voltage, and the efficiency. As an illustration, single phase cascaded multilevel inverter topologies are simulated using MATLAB/SIMULINK and the experimental results demonstrate the viability of these inverters.
An Innovative Solution for the Power Quality Problems in Induction Motor by Using Silica and Alumina Nano Fillers Mixed Enamel for the Coatings of the Windings
Mohanadasse, K. ; Sharmeela, C. ; Selvaraj, D. Edison ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1621~1625
DOI : 10.5370/JEET.2015.10.4.1621
Power quality has always been a concern of power engineers. Certainly an argument can be successfully made that most parts of power engineering have the ultimate objective to improve power quality. AC motors were widely used in industrial and domestic applications. Generally, AC motors were of two types: Induction and Synchronous motors. In motor many parameters like different load cycling, switching, working in hot weather and unbalances creates harmonics which creates major reasons for temperature rise of the motors. Due to high peak value of voltage, harmonics can weaken insulation in cables, windings and capacitors and different electronic components. Higher value of harmonics increase the motor current and decrease the power factor which will reduce the life time of the motor and increase the overall rating of all electrical equipments. Harmonics reduction of all the motors in India will save more power. Coating of windings of the motor with nano fillers will reduce the amount of harmonics in the motor. Based on the previous project works, actions were taken to use the enamel filled with various nano fillers for the coating of the windings of the different AC motors. Ball mill method was used to convert the micro particles of Al
and ZnO into nano particles. SEM, TEM and XRD were used to augment the particle size of the powder. The synthesized nano powders were mixed with the enamel by using ultrasonic vibrator. Then the enamel mixed with the nano fillers was coated to the windings of the several AC motors. Harmonics were measured in terms of various indices like THD, VHD, CHD and DIN by using Harmonic analyzer. There are many other measures and indices to describe power quality, but none is applicable in all cases and in many instances, these indices may hide more than they show. Sometimes power quality indices were used as a basis of comparison and standardization. The efficiency of the motors was increased by 5 – 10 %. The thermal withstanding capacity of the motor was increased by 5º to 15º C. The harmonics of the motors were reduced by 10 – 50%.
Optimization of Parameters for LCL Filter of Least Square Method Based Three-phase PWM Converter
Zheng, Hong ; Liang, Zheng-feng ; Li, Meng-shu ; Li, Kai ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1626~1634
DOI : 10.5370/JEET.2015.10.4.1626
LCL filters are widely used in three-phase PWM converter for its advantages of small volume, low cost and inhibition of high frequency current harmonic. However, it is difficult to optimize its design because its parameters are mutually influenced while the value of each parameter for LCL filter has impacts on the converter`s cost and size. In this paper, the target of optimization is to minimize the parameter values of LCL filter, and an optimization method for parameters of LCL filter of three-phase PWM converter based on least square method is proposed. With this method, a quantitative calculation of the harmonic component of the converter’s side phase voltage is performed first, and then the quantitative relationship between phase voltage harmonics and grid phase current harmonics is analyzed. After that, the attenuation requirement of each harmonic is obtained by taking into account the requirements for each harmonic component of grid current. Then according to the optimization objective, the objective function with minimum harmonic attenuation deviation is established, and least squares method is adopted for three-dimensional global searching of parameters for LCL filter. Thus, the designed harmonic attenuation curve approximates the minimum attenuation requirements, and the optimized LCL filter parameters are obtained. Finally, the effectiveness of the method is verified by the experiments.
High-Performance Voltage Controller Design Based on Capacitor Current Control Model for Stand-alone Inverters
Byen, Byeng-Joo ; Choe, Jung-Muk ; Choe, Gyu-Ha ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1635~1645
DOI : 10.5370/JEET.2015.10.4.1635
This study proposes high-performance voltage controller design that employs a capacitor current control model for single-phase stand-alone inverters. The single-phase stand-alone inverter is analyzed via modeling, which is then used to design the controller. A design methodology is proposed to maximize the bandwidth of the feedback controller. Subsequently, to compensate for the problems caused by the bandwidth limitations of the controller, an error transfer function that includes the feedback controller is derived, and the stability of the repetitive control scheme is evaluated using the error transfer function. The digital repetitive controller is then implemented. The simulation and experimental results show that the performance of the proposed controller is high in a 1.5 kW single-phase stand-alone inverter prototype.
Single-Switch ZVZCS Quasi-Resonant CLL Isolated DC-DC Converter for 32`` LCD TV
Ryu, Seung-Hee ; Ahn, Jung-Hoon ; Cho, Kwang-Seung ; Lee, Byoung-Kuk ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1646~1654
DOI : 10.5370/JEET.2015.10.4.1646
In this paper, a single-switch ZVZCS quasi-resonant CLL isolated DC-DC converter for driving a low-power (less than 100 W) 32`` LED backlighting liquid crystal display television (LCD TV) is proposed. The proposed converter exhibits both forward and flyback operational characteristics. All semiconductors are activated and deactivated under the soft switching conditions during the switching transition without additional active devices. The switching frequency varies less than about 10 kHz for load variations, leading to minimizing the efficiency reduction under light load. Furthermore, the low di/dt and dv/dt by soft switching enhance the electromagnetic interference (EMI) performance above 1 MHz. A theoretical analysis is described in detail, and a 72-W prototype converter verifies the validity of the analysis.
An Efficient FPGA based Real-Time Implementation Shunt Active Power Filter for Current Harmonic Elimination and Reactive Power Compensation
Charles, S. ; Vivekanandan, C. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1655~1666
DOI : 10.5370/JEET.2015.10.4.1655
This paper proposes a new approach of Field Programmable Gate Array (FPGA) controlled digital implementation of shunt active power filter (SAPF) under steady state and dynamic operations. Typical implementations of SAPF uses microprocessor and digital signal processor (DSP) but it limited for complex algorithm structure, absence of feedback loop delays and their cost can be exceed the benefit they bring. In this paper, the hardware resources of an FPGA are configured and implemented in order to overcome conventional microcontroller or digital signal processor implementations. This proposed FPGA digital implementation scheme has very less execution time and boosts the overall performance of the system. The FPGA controller integrates the entire control algorithm of an SAPF, including synchronous reference frame transformation, phase locked loop, low pass filter and inverter current controller etc. All these required algorithms are implemented with a single all-on chip FPGA module which provides freedom to reconfigure for any other applications. The entire algorithm is coded, processed and simulated using Xilinx 12.1 ISE suite to estimate the advantages of the proposed system. The coded algorithm is also defused on a single all-on-chip Xilinx Spartan 3A DSP-XC3SD1800 laboratory prototype and experimental results thus obtained match with simulated counterparts under the dynamic state and steady state operating conditions.
Design of an Electromagnet with Low Detent Force and its Control for a Maglev Super-speed Vehicle
Lim, Jaewon ; Kim, C.H. ; Han, J.B. ; Han, H.S. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1667~1673
DOI : 10.5370/JEET.2015.10.4.1667
The vibration and noise caused by the dynamic interaction between electromagnetic suspension and the linear synchronous motor stator beneath a flexible guideway remain problems in designing attractive Maglev trains. One possible method to reduce the sources of vibration is to minimize the detent force in the linear synchronous motor that creates variations in both lift force and thrust. This paper proposes lowering detent force by using separated core instead of single united core. The magnet is designed to adapt to the deflected guideway at a speed of 550km/h. This study will analyze the electromagnetic field and control performance, and how they relate to lift forces and dynamic responses.
Improved Method for Calculating Armature-Reaction Field of Surface-Mounted Permanent Magnet Machines Accounting for Opening Slots
Zhou, Yu ; Li, Huaishu ; Wang, Qingyu ; Xue, Zhiqiang ; Cao, Qing ; Zhou, Shi ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1674~1681
DOI : 10.5370/JEET.2015.10.4.1674
This paper presented an improved analytical method for calculating armature-reaction field in the surface-mounted permanent magnet machines accounting for opening slots. The analytical model is divided into two types of subdomains. The current of the armature is centralized in the center of the slots. The field solution of each subdomain is obtained by applying the interface and boundary conditions of the model. Two 30-pole/36-slot prototype machines with different slot-opening width are used for validation. The FE (finite element) results confirm the validity of the analytical results with the proposed model. The investigation shows that the wider the slot-opening width is, the smaller the peak value of radial and circumferential components of flux density, and the analytical armature-reaction field produced by centralized current in the slots is similar with the armature-reaction field produced by distributed current in the slots in the FE.
Real time Implementation of SHE PWM in Single Phase Matrix Converter using Linearization Method
Karuvelam, P. Subha ; Rajaram, M. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1682~1691
DOI : 10.5370/JEET.2015.10.4.1682
In this paper, a real time implementation of selective harmonic elimination pulse width modulation (SHEPWM) using Real Coded Genetic Algorithm (RGA), Particle Swarm Optimization technique (PSO) and a new technique known as Linearization Method (LM) for Single Phase Matrix Converter (SPMC) is designed and discussed. In the proposed technique, the switching frequency is fixed and the optimum switching angles are obtained using simple mathematical calculations. A MATLAB simulation was carried out, and FFT analysis of the simulated output voltage waveform confirms the effectiveness of the proposed method. An experimental setup was also developed, and the switching angles and firing pulses are generated using Field Programmable Gate Array (FPGA) processor. The proposed method proves that it is much applicable in the industrial applications by virtue of its suitability in real time applications.
Analysis of MOSFET Failure Modes in Bi-directional Phase-Shift Full-Bridge Converters
Oh, Chang-Yeol ; Sung, Won-Yong ; Kim, Yun-Sung ; Lee, Byoung-Kuk ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1692~1699
DOI : 10.5370/JEET.2015.10.4.1692
This paper presents an analysis of the mechanism of failure modes in bi-directional phase-shift full-bridge converters, composed of MOSFET, based on the circuit operation and parasitic parameters of MOSFET. In addition, the relation between circuit operation and parameters is suggested through an experimental comparison. From this relation, the suitable ranges of parameters for stable performance are analyzed. The design criteria of the bi-directional phase-shift full-bridge converter are presented and evaluated from the experimental verification.
Electrical and Thermal Characterization of Organic Varnish Filled with ZrO
Nano Filler Used in Electrical Machines
Selvaraj, D. Edison ; Vijayaraj, R. ; Sugumaran, C. Pugazhendhi ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1700~1711
DOI : 10.5370/JEET.2015.10.4.1700
In the last decade it has been witnessed significant developments in the area of nano particles and nano scale fillers on electrical, thermal, and mechanical properties of polymeric materials such as resins, varnishes, enamel and bakelites. The electric and thermal properties were more important in the electrical equipments for both steady state and transient state conditions. This paper deals with the characterization of the electric and thermal properties of the pure varnish and zirconia (ZrO
) filler mixed varnish. The electric properties such as dielectric loss (tan δ), dielectric constant (ε), dielectric strength and partial discharge voltage were analyzed and detailed for different samples. It was observed that zirconia nano filler mixed varnish has the superior dielectric and thermal properties when compared to those of standard varnish. It has shown that at power frequency the 1wt% nano composite sample has the higher permittivity value when compared to other samples. It has been examined that the 1wt% sample was having higher inception and extinction voltages when compared to other samples. It has been observed that 1wt% sample has higher dielectric strength when compared with other samples. There has been an improvement of thermal property by adding few weight percent of zirconia nano fillers. There was not much variation in glass transition among the nano mixed composites. The weight loss was improved at 1wt% of the zirconia nano fillers.
Enhancement of Dielectric Properties of Polyamide Enamel Insulation in High Voltage Apparatuses Used in Medical Electronics by Adding Nano Composites of SiO
Biju, A.C. ; Victoire, T. Aruldoss Albert ; Selvaraj, D. Edison ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1712~1719
DOI : 10.5370/JEET.2015.10.4.1712
In recent days, there was a significant development on the electrical, thermal, mechanical, physical, chemical, magnetic and optical properties of the polyamide enamel, varnish and other insulating materials by the addition of nano fillers to it. Enamel was used in High Voltage Apparatuses used in Medical Electronics as insulation. Insulating materials determine the life time of the electrical apparatuses. The life time of the insulating materials was improved by the addition of nano fillers to it. Hence the life time of the electrical apparatuses was improved by the mixing of nano fillers to the enamel. In this research, the basic dielectric properties of the enamel and enamel mixed with nano composites of silica and alumina were analyzed and compared with each other. The addition of nano fillers has improved the quality factor and capacitance of the enamel. It was also observed that the addition of nano fillers has reduced the dissipation factor and dielectric losses of the enamel. Heat produced by the dielectric losses was also reduced by adding nano fillers to it.
Capacitance Swing and Capacitance Ratio of GaN-Based Metal-Semiconductor-Metal Two-Dimensional Electron Gas Varactor with Different Dielectric Films
Tien, Chu-Yeh ; Kuei, Ping-Yu ; Chang, Liann-Be ; Hsu, Chien-Pin ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1720~1725
DOI : 10.5370/JEET.2015.10.4.1720
The performance of the AlGaN/GaN MSM-2DEG varactor with different dielectric films deposited by the E-beam deposition is investigated in detail. The capacitance swing and the capacitance ratio of the varactor without dielectric film as well as with, SiO
, and Si
films, respectively, are determined by electrodes of varying areas. The maximum capacitance, the minimum capacitance and the capacitance ratios are proportional to the increasing of the electrode areas. The capacitance ratio determined by the maximum and the minimum capacitance is found to be 18.35 (with Si
dielectric film) and 149.51 (without dielectric film), respectively. The transition voltages of the fabricated varactors are almost the same for a bias voltage of about ±5 V and leakage current can be lower three orders of magnitude while the varactors with dielectric films. The tunability of the capacitance ratio makes the AlGaN/GaN MSM-2DEG varactor with a dielectric film highly useful in multirange applications of a surge free preamplier.
An Experimental and Numerical Study of Corona in a Cage with Sandy and Dusty Flow in High Altitude Area
Lv, Yukun ; Ge, Zekun ; Liu, Yunpeng ; Zhu, Lei ; Wei, Shaoke ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1726~1733
DOI : 10.5370/JEET.2015.10.4.1726
In order to study the effect of the high-altitude and dusty weather in northwest of China on the corona characteristics of transmission lines, a corona caged based experimental system with sandy and dusty flow condition is numerically investigated and designed. This system overcomes the difficulties caused by harsh environment and offers easy usage for off-site tests. The design parameters are mainly determined by the characteristics of strong sandstorm in northwest region and test requirements. By the comparison of numerical simulation of the particle diffusion in four programs with rectangular or circular air-duct, a practical technology, which introduces swirl to control the particle diffusion length, is obtained. Accordingly, the structure of round air-duct with swirl elbow in inlet and outlet of high level segment is selected as final program. Systems of control and measurement are designed at the same time. Field tuning results show that the test system could ensure the range of sandy and dusty coverage. The wind speed, sandy and dusty concentration could be controlled and meet the requirements of accuracy. The experimental system has many features, such as simple structure, easy to be assembled, disassembled, transported and operated, small space occupied.
Analysis of Insulating Characteristics of Cl
-He Mixture Gases in Gas Discharges
Tuan, Do Anh ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1734~1737
DOI : 10.5370/JEET.2015.10.4.1734
Insulating characteristics of Cl
-He mixture gases in gas discharges were analysed to evaluate ability of these gases for using in medium voltage and many industries. These are electron transport coefficients, which are the electron drift velocity, density-normalized longitudinal diffusion coefficient, and density-normalized effective ionization coefficient, in Cl
-He mixtures. A two-term approximation of the Boltzmann equation was used to calculate the electron transport coefficients for the first time over a wide range of E/N (ratio of the electric field E to the neutral number density N). The limiting field strength values of E/N, (E/N)
, for these binary gas mixtures were also derived and compared with those of the pure SF
Radiation Characteristics of a Probe-Fed Microstrip Patch Antenna on a Finite Grounded High Permittivity Substrate
Kwak, Eun-Hyuk ; Yoon, Young-Min ; Kim, Boo-Gyoun ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1738~1745
DOI : 10.5370/JEET.2015.10.4.1738
Radiation characteristics of a probe-fed rectangular microstrip patch antenna printed on a finite grounded high permittivity substrate are investigated systematically for various square grounded dielectric substrate sizes with several thicknesses and dielectric constants by experiment and full wave simulation. The effect of the substrate size on the radiation characteristics of a rectangular patch antenna is mainly determined by the effective dielectric constant of surface waves on a grounded dielectric substrate. As the effective dielectric constant of surface waves increases, the substrate sizes for the maximum broadside gain and the required onset for a large magnitude of squint angle decrease, while the variations of the broadside gain, the front-to-back ratio, and the magnitude of squint angle versus the substrate size increase due to the increase of the power of the surface wave.
The Characteristic Study of Plasma Electrolytic Oxidation in AZ31B Magnesium Alloy
Yu, Jae-Yong ; Choi, Soon-Don ; Yu, Jae-In ; Yun, Jae-Gon ; Ko, Hoon ; Jung, Yeon-Jae ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1746~1751
DOI : 10.5370/JEET.2015.10.4.1746
In this study low voltage Plasma Electrolytic Oxidation (PEO) was utilized to eliminate high voltage PEO drawbacks such as high cost, dimensional deformation and porosity. Low voltage PEO produces a thin coating which causes low corrosion resistance. In order to solve such problem, 0.1~0.6M pyrophosphates were added in a bath containing 1.4M NaOH, and 0.35M Na
. 70 V PEO was conducted at 25℃ for 3 minutes. Chemical composition, morphology and corrosion resistance of the anodized coating were analyzed. The anodized film was composed of MgO, Mg
, and Mg
. The morphology of film showed appropriately dense structure and low porosity in the anodized layers. It is found that low voltage Plasma Electrolytic Oxidation in cooperation with phosphating treatment can provide a good corrosion protection for the AZ31B magnesium alloy.
Comparison of High Frequency Detailed Generator Models for Partial Discharge Localization
Hassan Hosseini, S.M. ; Hosseini Bafghi, S.M. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1752~1758
DOI : 10.5370/JEET.2015.10.4.1752
This paper presents partial discharge localization in stator winding of generators using multi-conductor transmission line (MTL) and RLC ladder network models. The high-voltage (HV) winding of a 6kV/250kW generator has been modeled by MATLAB software. The simulation results of the MTL and the RLC ladder network models have been evaluated with the measurements results in the frequency domain by applying of the Pearson’s correlation coefficients. Two PD generated calibrator signals in kHz and MHz frequency range were injected into different points of generator winding and the signals simulated/measured at the both ends of the winding. For partial discharge localization in stator winding of generators is necessary to calculate the frequency spectrum of the PD current signals and then estimate the poles of the system from the calculated frequency spectrum. Finally, the location of PD can be estimated. This theory applied for the above generator and the simulation/measured results show the good correlation for PD Location for RLC ladder network and MTL models in the frequency range of kHz (10kHz<f<1MHz) and MHz (1MHz<f<5MHz) respectively.
Suppression of Glow Corona on Streamer and Influence of Thin Wire on its Inception
Sima, Wenxia ; Fan, Shuochao ; Yang, Qing ; Wang, Qi ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1759~1764
DOI : 10.5370/JEET.2015.10.4.1759
Glow corona is a kind of streamer-free corona that can suppress upward leaders in transmission lines. Thus, it has good application potential in lightning protection. This paper investigates its corona characteristics. The suppression characteristic of glow corona on streamer is studied in air gap under negative DC voltage by wrapping thin wires on the electrode. The effect of thin wire winding patterns on the gap breakdown voltage is analyzed. Results are considered to be attributed to the inception condition of glow corona. Thus an inception test of glow corona is also conducted, and the inception voltage is obtained. Results show that the inception voltage decreases with short winding pitch. Thus an investigation on the inception of glow corona influenced by thin wire is conducted, and an influential factor is proposed to evaluate the influence. The inception regular of thin wire glow corona presented in this paper has certain reference value for the application of glow corona in transmission lines.
Application of Joint Electro-Chemical Detection for Gas Insulated Switchgear Fault Diagnosis
Li, Liping ; Tang, Ju ; Liu, Yilu ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1765~1772
DOI : 10.5370/JEET.2015.10.4.1765
The integrity of the gas insulated switchgear (GIS) is vital to the safety of an entire power grid. However, there are some limitations on the techniques of detecting and diagnosing partial discharge (PD) induced by insulation defects in GIS. This paper proposes a joint electro-chemical detection method to resolve the problems of incomplete PD data source and also investigates a new unique fault diagnosis method to enhance the reliability of data processing. By employing ultra-high frequency method for online monitoring and the chemical method for detecting SF6 decomposition offline, the acquired data can form a more complete interpretation of PD signals. By utilizing DS evidence theory, the diagnostic results with tests on the four typical defects show the validity of the new fault diagnosis system. With higher accuracy and lower computation cost, the present research provides a promising way to make a more accurate decision in practical application.
Comparison of Insulation Coordination Between ±800kV and ±1100kV UHVDC Systems
Wang, Dong-ju ; Zhou, Hao ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1773~1779
DOI : 10.5370/JEET.2015.10.4.1773
Insulation coordination is a key problem in UHVDC systems in terms of safety and cost. Although high-voltage ±1100kV UHVDC projects are being planned in China, the characteristics and key points of high-voltage systems have not yet been analyzed. This study aims to improve the safe, effective operation of these high-voltage power transmission systems. First, we analyzed two typical insulation coordination schemes used in ±800kV UHVDC systems in China. Next, we used the two typical ±800kV insulation coordination schemes as a reference to analyze the ±1100kV UHVDC system. Finally, we compared these schemes and proposed an effective insulation coordination solution, as well as developing principles for ±1100kV UHVDC systems. Our findings indicate that the points enduring the highest voltage in the system should be protected separately by special arresters. Our analysis of the insulation coordination of ±800kV and ±1100kV UHVDC systems concluded that, in ±1100kV UHVDC systems, the main goal of insulation coordination is to lower the insulation level of points enduring the highest voltage. However, in a ±800kV UHVDC system, the main goal is to reduce the cost of manufacture for arresters, as well as the space occupation in the valve hall, with an acceptable insulation level.
A Study on a Gain-Enhanced Antenna for Energy Harvesting using Adaptive Particle Swarm Optimization
Kang, Seong-In ; Kim, Koon-Tae ; Lee, Seung-Jae ; Kim, Jeong-Phill ; Choi, Kyung ; Kim, Hyeong-Seok ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1780~1785
DOI : 10.5370/JEET.2015.10.4.1780
In this paper, the adaptive particle swarm optimization (APSO) algorithm is employed to design a gain-enhanced antenna with a reflector for energy harvesting. We placed the reflector below the main radiating element. Its back-radiated field is reflected and added to the forward radiated field, which could increase the antenna gain. We adopt the adaptive particle swarm optimization (APSO) algorithm, which improves the speed of convergence with a high frequency solver. The result shows that performance of the optimized design successfully satisfied the design goal of the frequency band, gain and axial ratio.
Experimence Study of Trace Water and Oxygen Impact on SF
Decomposition Characteristics Under Partial Discharge
Zeng, Fuping ; Tang, Ju ; Xie, Yanbin ; Zhou, Qian ; Zhang, Chaohai ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1786~1795
DOI : 10.5370/JEET.2015.10.4.1786
It is common practice to identify the insulation faults of GIS through monitor the contents of SF
decomposed components. Partial discharges (PD) could lead to the decomposition of SF
dielectric, so new reactions usually occur in the mixture of the newly decomposed components including traces of H
O and O
. The new reactions also cause the decomposed components to differ due to the different amounts of H
O and O
even under the same strength of PD. Thus, the accuracy of assessing the insulation faults is definitely influenced when using the concentration and corresponding change of decomposed components. In the present research, a needle-plate electrode was employed to simulate the PD event of a metal protrusion insulation fault for two main characteristic components SO
, and to carry out influence analysis of trace H
O and O
on the characteristic components. The research shows that trace H
O has the capability of catching an F atom, which inhibits low-sulfide SF
from recombining into high-sulfide SF
. Thus, the amount of SOF
strongly correlates to the amount of trace H
O, whereas the amount of SO
is weakly related to trace H
O. Furthermore, the dilution effect of trace O
obviously exceeds that of SO
Mathematical Modeling on AC Pollution Flashover Performance of Glass and Composite Insulator
Prakash, N.B. ; Parvathavarthini, M. ; Madavan, R. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1796~1803
DOI : 10.5370/JEET.2015.10.4.1796
While considering the current scenario, in this world power demand goes on increases day by day. Frequent power outages occur in high voltage transmission line due to the deprived performance of polluted insulators; this affects overall operation of power system and may indirectly impinge on the growth of production sector. Many researchers are keenly taking efforts to provide highly reliable and stable power to neediest. In this paper, A.C pollution flashover performance of disc type glass insulator and composite long rod insulators investigation under various artificial pollutions by varying Equivalent Salt Density Deposition (ESDD) levels. Here, we use different types of pollution methods like binding method, dipping method and spraying methods with different types of pollutants concentration. Based on dimensional analysis, four different Mathematical models have been developed to predict the A.C pollution Flashover Voltage (FOV) of insulators. Both the experimental and mathematically modeled results are compared; it`s observed that mathematical model 3 yields better results.
Numerical Simulation of the Characteristics of Electrons in Bar-plate DC Negative Corona Discharge Based on a Plasma Chemical Model
Liu, Kang-Lin ; Liao, Rui-Jin ; Zhao, Xue-Tong ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1804~1814
DOI : 10.5370/JEET.2015.10.4.1804
In order to explore the characteristics of electrons in DC negative corona discharge, an improved plasma chemical model is presented for the simulation of bar-plate DC corona discharge in dry air. The model is based on plasma hydrodynamics and chemical models in which 12 species are considered. In addition, the photoionization and secondary electron emission effect are also incorporated within the model as well. Based on this model, electron mean energy distribution (EMED), electron density distribution (EDD), generation and dissipation rates of electron at 6 typical time points during a pulse are discussed emphatically. The obtained results show that, the maximum of electron mean energy (EME) appears in field ionization layer which moves towards the anode as time progresses, and its value decreases gradually. Within a pulse process, the electron density (ED) in cathode sheath almost keeps 0, and the maximum of ED appears in the outer layer of the cathode sheath. Among all reactions, R1 and R2 are regarded as the main process of electron proliferation, and R
plays a dominant role in the dissipation process of electron. The obtained results will provide valuable insights to the physical mechanism of negative corona discharge in air.
Performance Improvement Using an Automation System for Segmentation of Multiple Parametric Features Based on Human Footprint
Kumar, V.D. Ambeth ; Malathi, S. ; Kumar, V.D. Ashok ; Kannan, P. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1815~1821
DOI : 10.5370/JEET.2015.10.4.1815
Rapid increase in population growth has made the mankind to delve in appropriate identification of individuals through biometrics. Foot Print Recognition System is a new challenging area involved in the Personal recognition that is easy to capture and distinctive. Foot Print has its own dimensions, different in many ways and can be distinguished from one another. The main objective is to provide a novel efficient automated system Segmentation using Foot Print based on structural relations among the features in order to overcome the existing manual method. This system comprises of various statistical computations of various foot print parameters for identifying the factors like Instep-Foot Index, Ball-Foot Index, Heel- Index, Toe- Index etc. The input is naked footprint and the output result to an efficient segmentation system thereby leading to time complexity.
Approximate and Three-Dimensional Modeling of Brightness Levels in Interior Spaces by Using Artificial Neural Networks
Sahin, Mustafa ; Oguz, Yuksel ; Buyuktumturk, Fuat ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1822~1829
DOI : 10.5370/JEET.2015.10.4.1822
In this study, artificial neural networks were used to determine the intensity of brightness in interior spaces. The illumination elements to illuminate indoor spaces were considered, not individually, but as a system. So, during the planned maintenance periods of an illumination system, after its design and installation, simple brightness level measurements must be taken. For a three-dimensional evaluation of the brightness level in indoor spaces in a speedy and accurate manner, the obtained brightness level measurement results and artificial neural network model were used. Upon estimation of the most suitable brightness level for indoor spaces by using the artificial neutral network model, the energy demands required by the illumination elements decreased. Consequently, in this study, with estimations of brightness levels, the extent to which the artificial neutral networks become successful was observed and more correct results have been obtained in terms of both economy and usage.
Automatic Registration of Two Parts using Robot with Multiple 3D Sensor Systems
Ha, Jong-Eun ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1830~1835
DOI : 10.5370/JEET.2015.10.4.1830
In this paper, we propose an algorithm for the automatic registration of two rigid parts using multiple 3D sensor systems on a robot. Four sets of structured laser stripe system consisted of a camera and a visible laser stripe is used for the acquisition of 3D information. Detailed procedures including extrinsic calibration among four 3D sensor systems and hand/eye calibration of 3D sensing system on robot arm are presented. We find a best pose using search-based pose estimation algorithm where cost function is proposed by reflecting geometric constraints between sensor systems and target objects. A pose with minimum gap and height difference is found by greedy search. Experimental result using demo system shows the robustness and feasibility of the proposed algorithm.
A Clustering Scheme for Discovering Congested Routes on Road Networks
Li, He ; Bok, Kyoung Soo ; Lim, Jong Tae ; Lee, Byoung Yup ; Yoo, Jae Soo ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1836~1842
DOI : 10.5370/JEET.2015.10.4.1836
On road networks, the clustering of moving objects is important for traffic monitoring and routes recommendation. The existing schemes find out density route by considering the number of vehicles in a road segment. Since they don’t consider the features of each road segment such as width, length, and directions in a road network, the results are not correct in some real road networks. To overcome such problems, we propose a clustering method for congested routes discovering from the trajectories of moving objects on road networks. The proposed scheme can be divided into three steps. First, it divides each road network into segments with different width, length, and directions. Second, the congested road segments are detected through analyzing the trajectories of moving objects on the road network. The saturation degree of each road segment and the average moving speed of vehicles in a road segment are computed to detect the congested road segments. Finally, we compute the final congested routes by using a clustering scheme. The experimental results showed that the proposed scheme can efficiently discover the congested routes in different directions of the roads.
Chaos in PID Controlled Nonlinear Systems
Ablay, Gunyaz ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1843~1850
DOI : 10.5370/JEET.2015.10.4.1843
Controlling nonlinear systems with linear feedback control methods can lead to chaotic behaviors. Order increase in system dynamics due to integral control and control parameter variations in PID controlled nonlinear systems are studied for possible chaos regions in the closed-loop system dynamics. The Lur’e form of the feedback systems are analyzed with Routh’s stability criterion and describing function analysis for chaos prediction. Several novel chaotic systems are generated from second-order nonlinear systems including the simplest continuous-time chaotic system. Analytical and numerical results are provided to verify the existence of the chaotic dynamics.
Multiscale Spatial Position Coding under Locality Constraint for Action Recognition
Yang, Jiang-feng ; Ma, Zheng ; Xie, Mei ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1851~1863
DOI : 10.5370/JEET.2015.10.4.1851
– In the paper, to handle the problem of traditional bag-of-features model ignoring the spatial relationship of local features in human action recognition, we proposed a Multiscale Spatial Position Coding under Locality Constraint method. Specifically, to describe this spatial relationship, we proposed a mixed feature combining motion feature and multi-spatial-scale configuration. To utilize temporal information between features, sub spatial-temporal-volumes are built. Next, the pooled features of sub-STVs are obtained via max-pooling method. In classification stage, the Locality-Constrained Group Sparse Representation is adopted to utilize the intrinsic group information of the sub-STV features. The experimental results on the KTH, Weizmann, and UCF sports datasets show that our action recognition system outperforms the classical local ST feature-based recognition systems published recently.
A Singular Perturbation-Like Approach to EDFA Gain Control Based on Observer Techniques
Song, Seong-Ho ; Chang, Dong Eui ; Lee, Kwang Y. ; Kim, Ho-Chan ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1864~1876
DOI : 10.5370/JEET.2015.10.4.1864
In this paper, we propose a singular perturbation-like approach to EDFA gain controller design and analysis. Considering a three-level model of EDFA, a gain controller containing a state observer and a channel add/drop estimator is designed based on a singular perturbation - like concept. The proposed design methodology is shown to be effective and advantageous not only in theoretically verifying the asymptotic stability of systems with multi-time scales such as EDFA but also in designing an asymptotic estimator for channel add/drops which does not satisfy the matching condition.
Nearest-Neighbors Based Weighted Method for the BOVW Applied to Image Classification
Xu, Mengxi ; Sun, Quansen ; Lu, Yingshu ; Shen, Chenming ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1877~1885
DOI : 10.5370/JEET.2015.10.4.1877
This paper presents a new Nearest-Neighbors based weighted representation for images and weighted K-Nearest-Neighbors (WKNN) classifier to improve the precision of image classification using the Bag of Visual Words (BOVW) based models. Scale-invariant feature transform (SIFT) features are firstly extracted from images. Then, the K-means++ algorithm is adopted in place of the conventional K-means algorithm to generate a more effective visual dictionary. Furthermore, the histogram of visual words becomes more expressive by utilizing the proposed weighted vector quantization (WVQ). Finally, WKNN classifier is applied to enhance the properties of the classification task between images in which similar levels of background noise are present. Average precision and absolute change degree are calculated to assess the classification performance and the stability of K-means++ algorithm, respectively. Experimental results on three diverse datasets: Caltech-101, Caltech-256 and PASCAL VOC 2011 show that the proposed WVQ method and WKNN method further improve the performance of classification.
Block and Fuzzy Techniques Based Forensic Tool for Detection and Classification of Image Forgery
Hashmi, Mohammad Farukh ; Keskar, Avinash G. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1886~1898
DOI : 10.5370/JEET.2015.10.4.1886
In today’s era of advanced technological developments, the threats to the authenticity and integrity of digital images, in a nutshell, the threats to the Image Forensics Research communities have also increased proportionately. This happened as even for the ‘non-expert’ forgers, the availability of image processing tools has become a cakewalk. This image forgery poses a great problem for judicial authorities in any context of trade and commerce. Block matching based image cloning detection system is widely researched over the last 2-3 decades but this was discouraged by higher computational complexity and more time requirement at the algorithm level. Thus, for reducing time need, various dimension reduction techniques have been employed. Since a single technique cannot cope up with all the transformations like addition of noise, blurring, intensity variation, etc. we employ multiple techniques to a single image. In this paper, we have used Fuzzy logic approach for decision making and getting a global response of all the techniques, since their individual outputs depend on various parameters. Experimental results have given enthusiastic elicitations as regards various transformations to the digital image. Hence this paper proposes Fuzzy based cloning detection and classification system. Experimental results have shown that our detection system achieves classification accuracy of 94.12%. Detection accuracy (DAR) while in case of 81×81 sized copied portion the maximum accuracy achieved is 99.17% as regards subjection to transformations like Blurring, Intensity Variation and Gaussian Noise Addition.
Optimal Hyper Analytic Wavelet Transform for Glaucoma Detection in Fundal Retinal Images
Raja, C. ; Gangatharan, N. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1899~1909
DOI : 10.5370/JEET.2015.10.4.1899
Glaucoma is one of the most common causes of blindness which is caused by increase of fluid pressure in the eye which damages the optic nerve and eventually causing vision loss. An automated technique to diagnose glaucoma disease can reduce the physicians’ effort in screening of Glaucoma in a person through the fundal retinal images. In this paper, optimal hyper analytic wavelet transform for Glaucoma detection technique from fundal retinal images is proposed. The optimal coefficients for transformation process are found out using the hybrid GSO-Cuckoo search algorithm. This technique consists of pre-processing module, optimal transformation module, feature extraction module and classification module. The implementation is carried out with MATLAB and the evaluation metrics employed are accuracy, sensitivity and specificity. Comparative analysis is carried out by comparing the hybrid GSO with the conventional GSO. The results reported in our paper show that the proposed technique has performed well and has achieved good evaluation metric values. Two 10- fold cross validated test runs are performed, yielding an average fitness of 91.13% and 96.2% accuracy with CGD-BPN (Conjugate Gradient Descent- Back Propagation Network) and Support Vector Machines (SVM) respectively. The techniques also gives high sensitivity and specificity values. The attained high evaluation metric values show the efficiency of detecting Glaucoma by the proposed technique.
Human Posture Recognition: Methodology and Implementation
Htike, Kyaw Kyaw ; Khalifa, Othman O. ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1910~1914
DOI : 10.5370/JEET.2015.10.4.1910
Human posture recognition is an attractive and challenging topic in computer vision due to its promising applications in the areas of personal health care, environmental awareness, human-computer-interaction and surveillance systems. Human posture recognition in video sequences consists of two stages: the first stage is training and evaluation and the second is deployment. In the first stage, the system is trained and evaluated using datasets of human postures to ‘teach’ the system to classify human postures for any future inputs. When the training and evaluation process is deemed satisfactory as measured by recognition rates, the trained system is then deployed to recognize human postures in any input video sequence. Different classifiers were used in the training such as Multilayer Perceptron Feedforward Neural networks, Self-Organizing Maps, Fuzzy C Means and K Means. Results show that supervised learning classifiers tend to perform better than unsupervised classifiers for the case of human posture recognition.
Design and Development of a Functional Safety Compliant Electric Power Steering System
Lee, Kyung-Jung ; Lee, Ki-Ho ; Moon, Chanwoo ; Chang, Hyuk-Jun ; Ahn, Hyun-Sik ;
Journal of Electrical Engineering and Technology, volume 10, issue 4, 2015, Pages 1915~1920
DOI : 10.5370/JEET.2015.10.4.1915
ISO 26262 is an international standard for the functional safety of electric and electronic systems in vehicles, and this standard has become a major issue in the automotive industry. In this paper, a functional safety compliant electronic control unit (ECU) for an electric power steering (EPS) system and a demonstration purposed EPS system are developed, and a software and hardware structure for a safety critical system is presented. EPS is the most recently introduced power steering technology for vehicles, and it can improve driver’s convenience and fuel efficiency. In conformity with the design process specified in ISO 26262, the Automotive Safety Integrity Level (ASIL) of an EPS system is evaluated, and hardware and software are designed based on an asymmetric dual processing unit architecture and an external watchdog. The developed EPS system effectively demonstrates the fault detection and diagnostic functions of a functional safety compliant ECU as well as the basic EPS functions.