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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 & Issues
Volume 9, Issue 6 - Nov 2014
Volume 9, Issue 5 - Sep 2014
Volume 9, Issue 4 - Jul 2014
Volume 9, Issue 3 - May 2014
Volume 9, Issue 2 - Mar 2014
Volume 9, Issue 1 - Jan 2014
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Study on Current Limiting Characteristics of a Flux-locktype SFCL using Series Connected Two Coils with Twice Triggering Operation
Han, Tae-Hee ; Ko, Seok-Cheol ; Lee, Byongjun ; Lim, Sung-Hun ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 777~781
DOI : 10.5370/JEET.2014.9.3.777
The current limiting characteristics of the flux-lock type superconducting fault current limiter (SFCL) using series connected two coils with twice triggering operation, which consists of series connected two coils and two superconducting (SC) modules with the inserting resistance, was analyzed. The feature of the suggested SFCL is that it can limit the fault current by triggering either one SC module or two SC modules comprising the SFCL depending on the amplitude of the fault current. To verify the current limiting operation of the suggested SFCL, the short-circuits in the fault location with the different fault currents were tested and its useful operations were described through the analysis on the tested results.
Long Term Variation Trend of Wind and its Impact Upon Wind Power Generation in Taiwan
Na, Wang ; Quan, Wan ; Sheng, Su ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 782~788
DOI : 10.5370/JEET.2014.9.3.782
Wind power generation has been viewed as a promising renewable energy to meet challenge of climate change. However, wind power is susceptible to climate change because previous investigation shows there are declining trends of the land surface wind speeds over middle and lower latitudes. Since long term variation trends is notably different from inter-annual random variation and could have notable impact on wind farm from planning perspective, observed meteorological data of Taiwan is investigated to find out long term variation trends of wind speed and its impact on wind power generation. It is discovered that wind speed in majority of stations in west coast of Taiwan have ascending trends while that of all investigated stations in east coast have descending trends. Since east of Taiwan is not suitable for wind power development for its higher likelihood suffering Typhoons and most of established wind farm locate in west coast of Taiwan, it is speculated that long term variation trend of wind do not have notable negative impact on wind power generation in Taiwan.
Risk-Based Allocation of Demand Response Resources Using Conditional Value-at Risk (CVaR) Assessment
Kim, Ji-Hui ; Lee, Jaehee ; Joo, Sung-Kwan ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 789~795
DOI : 10.5370/JEET.2014.9.3.789
In a demand response (DR) market run by independent system operators (ISOs), load aggregators are important market participants who aggregate small retail customers through various DR programs. A load aggregator can minimize the allocation cost by efficiently allocating its demand response resources (DRRs) considering retail customers' characteristics. However, the uncertain response behaviors of retail customers can influence the allocation strategy of its DRRs, increasing the economic risk of DRR allocation. This paper presents a risk-based DRR allocation method for the load aggregator that takes into account not only the physical characteristics of retail customers but also the risk due to the associated response uncertainties. In the paper, a conditional value-at-risk (CVaR) is applied to deal with the risk due to response uncertainties. Numerical results are presented to illustrate the effectiveness of the proposed method.
Ex-ante Evaluation of Economic Costs from Power Grid Blackout in South Korea
Kim, Chang-Seob ; Jo, Manseok ; Koo, Yoonmo ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 796~802
DOI : 10.5370/JEET.2014.9.3.796
South Korea is recently under serious situation in supplying electricity with enough power reserve. A single fault of power plant at a peak-load time may lead to a total blackout for whole area connected by a single electric grid and isolated from other grids. Despite of the seriousness of blackout, however, there are scarce studies with ex-ante analysis of the economic costs from blackout. In order to evocate the seriousness, we calculate the economic costs for both industrial and household sectors with using some survey data and statistical methodologies. As a result, total economic costs are 39.23 trillion KRW (35.83 trillion KRW for industrial sector, 3.40 trillion KRW for household sector).
Decision-Making of Determining the Start Time of Charging / Discharging of Electrical Vehicle Based on Prospect Theory
Liu, Lian ; Lyu, Xiang ; Jiang, Chuanwen ; Xie, Da ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 803~811
DOI : 10.5370/JEET.2014.9.3.803
The moment when Electrical Vehicle (EV) starts charging or discharging is one of the most important parameters in estimating the impact of EV load on the grid. In this paper, a decision-making problem of determining the start time of charging and discharging during allowed period is proposed and studied under the uncertainty of real-time price. Prospect theory is utilized in the decision-making problem of this paper for it describes a kind of decision making behaviors under uncertainty. The case study uses the parameters of Springo SGM7001EV and adopts the historical realtime locational marginal pricing (LMP) data of PJM market for scenario reduction. Prospect values are calculated for every possible start time in the allowed charging or discharging period. By comparing the calculated prospect values, the optimal decisions are obtained accordingly and the results are compared with those based on Expected Utility Theory. Results show that with different initial State-of-Charge (
) and different reference points, the optimal start time of charging can be the one between 12 a.m. to 3 a.m. and optimal discharging starts at 2 p.m. or 3p.m. Moreover, the decision results of Prospect Theory may differ from that of the Expected Utility Theory with the reference points changing.
An Economic Analysis of Potential Cost Savings from the Use of Low Voltage DC (LVDC) Distribution Network
Hur, Don ; Baldick, Ross ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 812~819
DOI : 10.5370/JEET.2014.9.3.812
The proposed technical work attempts to compare the two key technologies of power distribution, i.e. direct current (DC) and alternating current (AC) in a fiscal manner. The DC versus AC debate has been around since the earliest days of electric power. Here, at least four types of a low voltage DC (LVDC) distribution are examined as an alternative to the existing medium voltage AC (MVAC) distribution with an economic assessment technique for a project investment. Besides, the sensitivity analysis will be incorporated in the overall economic analysis model to cover uncertainties of the input data. A detailed feasibility study indicates that many of the common benefits claimed for an LVDC distribution will continue to grow more profoundly as it is foreseen to arise with the increased integration of renewable energy sources and the proliferation of energy storage associated with the enhanced utilization of uninterruptible power supply (UPS) systems.
Power Curve of a Wind Generator Suitable for a Low Wind Speed Site to Achieve a High Capacity Factor
Yoon, Gihwan ; Lee, Hyewon ; Lee, Sang Ho ; Hur, Don ; Cheol, Yong ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 820~826
DOI : 10.5370/JEET.2014.9.3.820
It is well known that energy generated by a wind generator (WG) depends on the wind resources at the installation site. In other words, a WG installed in a high wind speed area can produce more energy than that in a low wind speed area. However, a WG installed at a low wind site can produce a similar amount of energy to that produced by a WG installed at a high wind site if the WG is designed with a rated wind speed corresponding to the mean wind speed of the site. In this paper, we investigated the power curve of a WG suitable for Korea's southwestern coast with a low mean wind speed to achieve a high capacity factor (CF). We collected the power curves of the 11 WGs of the 6 WG manufacturers. The probability density function of the wind speed on Korea's southwestern coast was modeled using the Weibull distribution. The annual energy production by the WG was calculated and then the CFs of all of the WGs were estimated and compared. The results indicated that the WG installed on the Korea's southwestern coast could obtain a CF higher than 40 % if it was designed with the lower rated speed corresponding to the mean wind speed at the installation site.
Fault Response of a DFIG-based Offshore Wind Power Plant Taking into Account the Wake Effect
Kim, Jinho ; Lee, Jinsik ; Suh, Yongsug ; Lee, Byongjun ; Kang, Yong Cheol ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 827~834
DOI : 10.5370/JEET.2014.9.3.827
In order to meet the low voltage ride-through requirement in a grid code, a wind power plant (WPP) has to stay connected to a grid, supporting the voltage recovery for a grid fault. To do this, a plant-level controller as well as a wind generator (WG) controller is essential. The dynamic response of a WPP should be analyzed in order to design a plant-level controller. The dynamic response of a WPP for a grid fault is the collective response of all WGs, which depends on the wind speed approaching the WG. Thus, the dynamic response of a WPP should be analyzed by taking the wake effect into consideration, because different wind speeds at WGs will result in different responses of the WPP. This paper analyzes the response of a doubly fed induction generator (DFIG)-based offshore WPP with a grid fault taking into account the wake effect. To obtain the approaching wind speed of a WG in a WPP, we considered the cumulative impact of multiple shadowing and the effect of the wind direction. The voltage, reactive power, and active power at the point of common coupling of a 100 MW DFIG-based offshore WPP were analyzed during and after a grid fault under various wind and fault conditions using an EMTP-RV simulator. The results clearly demonstrate that not considering the wake effect leads to significantly different results, particularly for the reactive power and active power, which could potentially lead to incorrect conclusions and / or control schemes for a WPP.
Dedicated Cutback Control of a Wind Power Plant Based on the Ratio of Command Power to Available Power
Thapa, Khagendra ; Yoon, Gihwan ; Lee, Sang Ho ; Suh, Yongsug ; Kang, Yong Cheol ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 835~842
DOI : 10.5370/JEET.2014.9.3.835
Cutback control in a grid code is one of the functions of a wind power plant (WPP) that is required to support the system protection and frequency stability. When a cutback control command signal is delivered to the WPP from the system operator, the output of a WPP should be decreased to 20% of the rated power within 5 s. In this paper, we propose a dedicated cutback control algorithm of a WPP based on the ratio of the command power to the available power. If a cutback control signal is delivered, the algorithm determines the pitch angle for the cutback control and starts the pitch angle control. The proposed algorithm keeps the rotor speed at the speed before the start of the cutback control to quickly recover the previous output prior to the cutback control. The performance of the algorithm was validated for a 100 MW aggregated WPP based on a permanent magnet synchronous generator under various wind conditions using an EMTP-RV simulator. The results clearly shows that the proposed algorithm not only successfully reduces the output to the command power within 5 s by minimizing the fluctuation of the pitch angle, but also rapidly recovers to the output level before the cutback control.
Enhancement of On-Resistance Characteristics Using Charge Balance Analysis Modulation in a Trench Filling Super Junction MOSFET
Geum, Jongmin ; Jung, Eun Sik ; Kim, Yong Tae ; Kang, Ey Goo ; Sung, Man Young ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 843~847
DOI : 10.5370/JEET.2014.9.3.843
In Super Junction (SJ) MOSFETs, charge balance is the most important issue of the SJ fabrication process. In order to achieve the best electrical characteristics, such as breakdown voltage and on-resistance, the N-type and P-type drift regions must be fully depleted when the drain bias approaches the breakdown voltage, which is known as the charge balance condition. In conventional charge balance analysis, based on multi-epi process SJ MOSFETs, analytical model has only N, P pillar width and doping concentration parameter. But applying a conventional charge balance principle to trench filling process, easier than Multi-epi process, is impossible due to the missing of the trench angle parameter. To achieve much more superior characteristics of on-resistance in trench filling SJ MOFET, the appropriate trench angle is necessary. So in this paper, modulated charge balance analysis is proposed, in which a trench angle parameter is added. The proposed method is validated using the TCAD simulation tool.
Simulation of Electric Vehicles Combining Structural and Functional Approaches
Silva, L.I. ; Magallan, G.A. ; De La Barrera, P.M. ; De Angelo, C.H. ; Garcia, G.O. ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 848~858
DOI : 10.5370/JEET.2014.9.3.848
In this paper the construction of a model that represents the behavior of an Electric Vehicle is described. Both the mechanical and the electric traction systems are represented using Multi-Bond Graph structural approach suited to model large scale physical systems. Then the model of the controllers, represented with a functional approach, is included giving rise to an integrated model which exploits the advantages of both approaches. Simulation and experimental results are aimed to illustrate the electromechanical interaction and to validate the proposal.
Minimization of a Cogging Torque for an Interior Permanent Magnet Synchronous Machine using a Novel Hybrid Optimization Algorithm
Kim, Il-Woo ; Woo, Dong-Kyun ; Lim, Dong-Kuk ; Jung, Sang-Yong ; Lee, Cheol-Gyun ; Ro, Jong-Suk ; Jung, Hyun-Kyo ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 859~865
DOI : 10.5370/JEET.2014.9.3.859
Optimization of an electric machine is mainly a nonlinear multi-modal problem. For the optimization of the multi-modal problem, many function calls are required with much consumption of time. To address this problem, this paper proposes a novel hybrid algorithm in which function calls are less than conventional methods. Specifically, the proposed method uses the kriging metamodel and the fill-blank technique to find an approximated solution in a whole problem region. To increase the convergence speed in local peaks, a parallel gradient assisted simplex method is proposed and combined with the kriging meta-model. The correctness and usefulness of the proposed hybrid algorithm is verified through a mathematical test function and applied into the practical optimization as the cogging torque minimization for an interior permanent magnet synchronous machine.
Brushless DC Motor Electromagnetic Torque Estimation with Single-Phase Current Sensing
Cham, Chin-Long ; Samad, Zahurin Bin ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 866~872
DOI : 10.5370/JEET.2014.9.3.866
The purpose of this paper was to find an effective method for measuring electromagnetic torque produced by a brushless DC motor with single-phase current sensing in real-time. A torque equation is derived from the theory of brushless DC motor. This equation is then validated experimentally with a motor dynamometer. A computer algorithm is also proposed to implement the electromagnetic torque estimation equation in real-time. Electromagnetic torque is a linear function of phase current. Estimating the electromagnetic torque in real-time using single-phase current is not appropriate with existing equations, however, because of the rectangular alternating-pulse nature of the excitation current. With some mathematical manipulation to the existing equations, the equation derived in this paper overcame this limitation. The equation developed is simple and so it is computationally efficient, and it takes only motor torque constant and single-phase current to evaluate the electromagnetic torque; no other parameters such as winding resistances, inductances are needed. The equation derived is limited to the three-phase brushless DC motor. It can, however, easily be extended to the multiphase brushless DC motor with the technique described in this paper.
Sensorless Vector Control of Induction Motors for Wind Energy Applications Using MRAS and ASO
Jeong, Il-Woo ; Choi, Won-Shik ; Park, Ki-Hyeon ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 873~881
DOI : 10.5370/JEET.2014.9.3.873
Speed sensorless modes of operation are becoming standard solution in the area of electric drives. This paper presents flux estimator and speed estimator for the speed sensorless vector control of induction motors. The proposed sensorless methods are based on the model reference adaptive system (MRAS) observer and adaptive speed observer (ASO). The proposed speed estimation algorithm can be employed in the power control of grid connected induction generator for wind power applications. Two proposed schemes are verified through computer simulation PSIM and compared their simulation results.
Thermal Analysis of IPMSM with Water Cooling Jacket for Railway Vehicles
Park, Chan-Bae ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 882~887
DOI : 10.5370/JEET.2014.9.3.882
In this paper, the water cooling method among the forced coolant cooling methods is considered to be applied to the 110kW-class IPMSM for railway vehicles. First, basic thermal property analysis of the IPMSM is conducted using the three-dimensional thermal equivalent network method. Then, based on the results of the basic thermal property analysis, some design requirements for the water cooling jacket are deduced and a basic design of the water cooling jacket is carried out. Finally, thermal equivalent circuit of the water cooling jacket is attached to the IPMSM's 3D thermal equivalent network and then, the basic thermal and effectiveness analysis are conducted for the case of applying the water cooling jacket to the IPMSM. In the future, the thermal variation trends inside the IPMSM by the application of the water cooling jacket is expected to be quickly and easily predicted even at the design step of the railway traction motor.
A Stress Analysis Method for the Rotor Design of an IPMSM Considering Radial Force
Kim, Won-Ho ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 888~892
DOI : 10.5370/JEET.2014.9.3.888
In the design of the rotor of an interior permanent magnet synchronous motor (IPMSM), the bridge between the permanent magnets helps prevent the scattering of permanent magnets and pole pieces during high-speed operation. In the design of a motor, if the bridge is too thick, its performance will be largely degraded because of flux leakage. Additionally, if the bridge is too thin, its mechanical safety cannot be guaranteed. Thus, an accurate analysis method is required to determine the thickness of the bridge. Conventional stress analysis methods determine the thickness of the bridge by only considering the centrifugal force of the rotors. In this study, however, a method that additionally considers the radial force generated by the air-gap flux density based on the conventional methods is proposed and reflected in the design of a traction motor for electric vehicles. Finally, the validity of this study is verified through a reliability test related to high-speed operation.
Thermal Analysis of Water Cooled ISG Based on a Thermal Equivalent Circuit Network
Kim, Kyu-Seob ; Lee, Byeong-Hwa ; Jung, Jae-Woo ; Hong, Jung-Pyo ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 893~898
DOI : 10.5370/JEET.2014.9.3.893
Recently, the interior permanent synchronous motor (IPMSM) has been applied to an integrated starter and generator (ISG) for hybrid electric vehicles. In the design of such a motor, thermal analysis is necessary to maximize the power density because the loss is proportional to the power of a motor. Therefore, a cooling device as a heat sink is required internally. Generally, a cooling system designed with a water jacket structure is widely used for electric motors because it has advantages of simple structure and cooling effectiveness. An effective approach to analyze an electric machine with a water jacket is a thermal equivalent network. This network is composed of thermal resistance, a heat source, and thermal capacitance that consider the conduction, convection, and radiation. In particular, modeling of the cooling channel in a network is challenging owing to the flow of the coolant. In this paper, temperature prediction using a thermal equivalent network is performed in an ISG that has a water cooled system. Then, an experiment is conducted to verify the thermal equivalent network.
Fault-Tolerant Control of Five-Phase Induction Motor Under Single-Phase Open
Kong, Wubin ; Huang, Jin ; Kang, Min ; Li, Bingnan ; Zhao, Lihang ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 899~907
DOI : 10.5370/JEET.2014.9.3.899
This paper deals with fault-tolerant control of five-phase induction motor (IM) drives under single-phase open. By exploiting a decoupled model for five-phase IM under fault, the indirect field-oriented control ensures that electromagnetic torque oscillations are reduced by particular magnitude ratio currents. The control techniques are developed by the third harmonic current injection, in order to improve electromagnetic torque density. Furthermore, Proportional Resonant (PR) regulator is adopted to realize excellent current tracking performance in the phase frame, compared with Proportional Integral (PI) and hysteresis regulators. The analysis and experimental results confirm the validity of fault-tolerant control under single-phase open.
Adaptive-Predictive Controller based on Continuous-Time Poisson-Laguerre Models for Induction Motor Speed Control Improvement
Boulghasoul, Z. ; El Bahir, L. ; Elbacha, A. ; Elwarraki, E. ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 908~925
DOI : 10.5370/JEET.2014.9.3.908
Induction Motor (IM) has several desirable features for high performance adjustablespeed operation. This paper presents the design of a robust controller for vector control induction motor drive performances improvement. Proposed predictive speed controller, which is aimed to guarantee the stability of the closed loop, is based on the Poisson-Laguerre (PL) models for the association vector control drive and the induction motor; without necessity of any mechanical parameter, and requires only two control parameters to ensure implicitly the integrator effect on the steady state error, load torque disturbances rejection and anti-windup effect. In order to improve robustness, insensitivity against external disturbances and preserve desired performance, adaptive control is added with the aim to ensure an online identification of controller parameters through an online PL models identification. The proposed control is compared with the conventional approach using PI controller. Simulation with MATLAB/SIMULINK software and experimental results for a 1kW induction motor using a dSPACE system with DS1104 controller board are carried out to show the improvement performance.
Parametric Analysis and Experimental Testing of Radial Flux Type Synchronous Permanent Magnet Coupling Based on Analytical Torque Calculations
Kang, Han-Bit ; Choi, Jang-Young ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 926~931
DOI : 10.5370/JEET.2014.9.3.926
This paper presents the torque calculation and parametric analysis of synchronous permanent magnet couplings (SPMCs). Based on a magnetic vector potential, we obtained the analytical magnetic field solutions produced by permanent magnets (PMs). Then, the analytical solutions for a magnetic torque were obtained. All analytical results were extensively validated with the non-linear a two-dimensional (2D) finite element analysis (FEA). In particular, test results such as torque measurements are presented that confirm the analysis. Finally, using the derived analytical magnetic torque solutions, we carried out a parametric analysis to determine the influence of the design parameters on the SPMC's behavior.
Autonomous Underwater Vehicles with Modeling and Analysis of 7-Phase BLDC Motor Drives
Song, Sang-Hoon ; Yoon, Yong-Ho ; Lee, Byoung-Kuk ; Won, Chung-Yuen ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 932~941
DOI : 10.5370/JEET.2014.9.3.932
In this paper, a simulation model for 7-phase BLDC motor drives for an Autonomous Underwater Vehicles (AUV) is proposed. A 7-phase BLDC motor is designed and the electrical characteristics are analyzed using FEA program and the power electronics drives for the 7-phase BLDC motor are theoretically analyzed and the actual implementation has been accomplished using Matlab Simulink. PI controller and fuzzy controller are compared for verifying the validity of the proposed model and the informative results are described in detail. Especially A fuzzy controller is used to characterize 7-phase BLDC motor, drive systems under normal and fault operating conditions.
Low Cost Design Study of Brushless DC Motor for Electric Water Pump Application
Jung, Tae-Uk ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 942~949
DOI : 10.5370/JEET.2014.9.3.942
We studied about the rotor design change using a Ferrite ring magnet to reduce material cost in the condition of the same stator core design. However, this design direction has many weak points such as the decrease of BEMF, the low maximum output, the irreversible demagnetization characteristics of a permanent magnet and so on. In order to mitigate such disadvantages, an optimization design of the BLDC motor has been developed by changing each design parameter and by improving the electromagnetic structure. In the proposed water pump SPM BLDC motor using Ferrite magnet, the outer and inner diameter of stator is fixed to the value of the conventional IPM BLDC motor using Nd-Fe-B magnet. The design specification requirements should be satisfied with the same output power and efficiency characteristics in the same dimension. As a result of this study, the design comparison results considering driving performances and material cost are represented. Through the actual experiment with the prototype of the designed motor, the simulations results are verified.
Specialized Sensors and System Modeling for Safety-critical Application
Jeong, Taikyeong Ted ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 950~956
DOI : 10.5370/JEET.2014.9.3.950
Special purpose sensor design using MEMS (Micro-Electro-Mechanical Systems) technique is commonly used in Nondestructive Testing (NDT) research for the evaluation of existing structures and for the safety control and requirements. Various sensors and network have been developed for general infrastructures as well as safety-critical applications, e.g., aerospace, defense, and nuclear system, etc. In this paper, one of sensor technique using Fiber Bragg Gratings (FBG) and Finite Element Method (FEM) evaluation is discussed. The experimental setup and data collection technique is also demonstrated. The factors influencing test result and the advantages/limitations of this technique are also reviewed using various methods.
Two Factors Failure Model of Oil-Paper Insulation Aging under Electrical and Thermal Multistress
Li, Jian ; Wang, Yan ; Bao, Lianwei ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 957~963
DOI : 10.5370/JEET.2014.9.3.957
Converter transformers play important roles in high-voltage direct current transmission systems. This paper presents experimental and analysis results of the combined electrical and thermal aging of oil-impregnated paper at pulsating DC voltages. Breakdown voltages and time-to-breakdown of oil-paper specimens were measured by using short-time and constant-stress tests. The breakdown characteristics of combined electrical and thermal aging on insulation system were discussed. According to the relationship between failure time and aging temperature, the two-parameter Weibull model was improved. On the basis of the competing risk algorithm and the improved Weibull model, the two factors failure model was calculated. And the influence of temperature in the insulation system has been analyzed. This model performs better than the two-parameter Weibull model when both time and temperature are considered as variables in estimating the lifetime of oil-paper insulation.
Design and Fabrication of Super Junction MOSFET Based on Trench Filling and Bottom Implantation Process
Jung, Eun Sik ; Kyoung, Sin Su ; Kang, Ey Goo ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 964~969
DOI : 10.5370/JEET.2014.9.3.964
In Super Junction MOSFET, Charge Balance is the most important issue of the trench filling Super Junction fabrication process. In order to achieve the best electrical characteristics, the N type and P type drift regions must be fully depleted when the drain bias approaches the breakdown voltage, called Charge Balance Condition. In this paper, two methods from the fabrication process were used at the Charge Balance condition: Trench angle decreasing process and Bottom implantation process. A lower on-resistance could be achieved using a lower trench angle. And a higher breakdown voltage could be achieved using the bottom implantation process. The electrical characteristics of manufactured discrete device chips are compared with those of the devices which are designed of TCAD simulation.
Junction Temperature Prediction of IGBT Power Module Based on BP Neural Network
Wu, Junke ; Zhou, Luowei ; Du, Xiong ; Sun, Pengju ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 970~977
DOI : 10.5370/JEET.2014.9.3.970
In this paper, the artificial neural network is used to predict the junction temperature of the IGBT power module, by measuring the temperature sensitive electrical parameters (TSEP) of the module. An experiment circuit is built to measure saturation voltage drop and collector current under different temperature. In order to solve the nonlinear problem of TSEP approach as a junction temperature evaluation method, a Back Propagation (BP) neural network prediction model is established by using the Matlab. With the advantages of non-contact, high sensitivity, and without package open, the proposed method is also potentially promising for on-line junction temperature measurement. The Matlab simulation results show that BP neural network gives a more accuracy results, compared with the method of polynomial fitting.
Experimental Investigation on Dielectric and Thermal Characteristics of Nanosized Alumina Filler Added Polyimide Enamel
Sugumaran, C. Pugazhendhi ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 978~983
DOI : 10.5370/JEET.2014.9.3.978
The polymer nano composite possess good priority recently for engineering applications. Especially the electrical insulating materials attract the high performance of nano composites. In this work the ballmill synthesiation process of nano sized Alumina (
), the preparation of new nano composite material with an content of enamel and synthesized Alumina as 1wt%, 3wt% and 5wt%. Experimental investigation has been carried out for the prepared nano composites materials with respect to dielectric parameter measurements such as dielectric loss (tan
), dielectric constant (
), dielectric strength under various temperature. The partial discharge level also measured for all the samples and the PD inception voltage is also observed and compared. Weight loss of the material has been analyzed through TGA. It has been experimentally proved that 3wt% of Alumina nano filler added enamel has significant improvement in the dielectric and thermal properties.
Property Enhancement of SiR-EPDM Blend Using Electron Beam Irradiation
Deepalaxmi, R. ; Rajini, V. ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 984~990
DOI : 10.5370/JEET.2014.9.3.984
Polymers are the most commonly used di-electrics because of their reliability, availability, ease of fabrication and cost. The commercial and industrial demand for advanced polymeric materials which are capable of being used in harsh environment is need of the hour. The study of the effect of electron beam irradiation on polymeric materials is an area of rapidly increasing interest. This paper discusses the resultant beneficial effects of electron beam irradiation on the SiR-EPDM blend having 50:50 composition. The changes in mechanical and electrical properties of SiR-EPDM blend which are exposed to three different doses of electron beam radiation namely 5 Mrad, 15 Mrad and 25 Mrad are presented. The irradiated blends are analyzed for their electro-mechanical and physico chemical properties. The electrical changes induced by irradiation are investigated by arc resistance, surface resistivity and volume resistivity measurements as per ASTM standards. The mechanical changes are observed by the measurement of tensile strength and elongation at break. Physico chemical investigation has been done using the FTIR, in order to investigate the irradiation induced chemical changes.
Assessment of Magnetic Field Mitigation and Electrical Environmental Effects for Commercially Operating 154kV Transmission Lines with Passive Loop
Lee, Byeong-Yoon ; Myung, Sung-Ho ; Ju, Mun-No ; Cho, Yeun-Gyu ; Lee, Dong-Il ; Lim, Yun-Seog ; Kim, Sang-Beom ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 991~996
DOI : 10.5370/JEET.2014.9.3.991
Power frequency magnetic field is still a critical problem for new construction of overhead power transmission lines in Korea because most people have been concerned about possibly carcinogenic effects of it. Although reference level of power frequency(60Hz) magnetic field has been set to 200uT in ICNIRP guidelines published in 2010, Korean government has no intention of adjusting 83.3uT specified by law in 2006 to this new reference level in consideration of people's concerns for the time being. Regardless of the current regulated magnetic field value, electric utility company has been trying to reduce magnetic field in the residential area in the vicinity of overhead power transmission lines to take into account of public concerns on the long-term effect of magnetic fields. In an effort to reduce magnetic field, engineering side has made considerable efforts to develop passive loop based, cost-effective mitigation technique of power frequency magnetic field more than ten years. In order to verify developed power frequency magnetic field mitigation technique based on passive loop, a horizontal type of passive loop was designed and installed for commercially operating 154kV overhead power transmission line for the first time in Korea. The measurement results before and after the installation of passive loop showed that magnetic field could be reduced to about 20%. The electrical environmental effects such as AN, RI and TVI were assessed before and after the installation of passive loop and these values were complied with the requirements specified by electric utility. It has been confirmed from the field test results that passive loop could be commercially and cost-effectively utilized to mitigate power frequency magnetic field.
Reducing the Interference in Compact MIMO Antennas of CRLH-TL-Based Broadside-Capacitive and Slot Couplings
Jang, Kyeongnam ; Kahng, Sungtek ; Yang, Inkyu ; Kim, Hyeongseok ; Wu, Qun ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 997~1001
DOI : 10.5370/JEET.2014.9.3.997
In this paper, the interference in small MIMO antennas having two identical composite right- and left-handed transmission-line(CRLH-TL)-based radiating elements is remarkably decreased. The radiating element has the broadside-capacitive coupling as well as slots to be equivalent to the CRLH-TL to prevent the size from increasing for an LTE high band. The suspended line bridging the two radiating elements is optimized to lower the interference between them down to -23 dB, while the overall MIMO antenna system is compact and its antenna performance is acceptable. The design is tested for 2.5 GHz.
Insulation Design and Reliability Evaluation of ±80kV HVDC XLPE Cables
Jung, Chae-Kyun ; Park, Hung-Sok ; Kang, Ji-Won ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1002~1008
DOI : 10.5370/JEET.2014.9.3.1002
This paper describes insulation design and its reliability evaluation of
HVDC XLPE cable. Recently, the construction of HVDC transmission system, which is combined overhead line with underground cable, has been completed. This system is installed with existing 154 kV AC transmission line on the same tower. In this paper, the lightning transient analysis is firstly reviewed for selection of basic impulse insulation level and nominal insulation thickness. Then the electrical performance tests including load cycle test and superimposed impulse test based on CIGRE TB 496 are performed to evaluate the reliability of newly designed HVDC cable. There is no breakdown for
HVDC XLPE cable during electrical performance test. Finally, this system is installed in Jeju island based on successful electrical performance test (Type test). After installation tests are also successfully completed.
Se-loss-induced CIS Thin Films in RTA Process after Co-sputtering Using CuSe
Kim, Nam-Hoon ; Jun, Young-Kil ; Cho, Geum-Bae ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1009~1015
DOI : 10.5370/JEET.2014.9.3.1009
(CIS) thin films were prepared without Se- / S-containing gas by co-sputtering using
selenide-targets and rapid thermal annealing. The grain size increased to a maximum of 54.68 nm with a predominant (112) plane. The tetragonal distortion parameter
decreased and the inter-planar spacing
increased in the RTA-treated CIS thin films annealed at a
, which indicates better crystal quality. The increased carrier concentration of RTA-treated p-type CIS thin films led to a decrease in resistivity due to an increase in Cu composition at annealing temperatures
. The optical band gap energy (
) of CIS thin films decreased to 1.127 eV in RTA-treated CIS thin films annealed at
due to the improved crystallinity, elevated carrier concentration and decreased In composition.
Real-time Virtual-viewpoint Image Synthesis Algorithm Using Kinect Camera
Lee, Gyu-Cheol ; Yoo, Jisang ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1016~1022
DOI : 10.5370/JEET.2014.9.3.1016
Kinect is a motion sensing camera released by Microsoft in November 2010 for the Xbox360 that is used to produce depth and color images. Because Kinect uses an infrared pattern, it generates holes and noises around an object's boundaries in the obtained images. The flickering phenomenon and unmatched edges also occur. In this paper, we propose a real time virtual-view video synthesis algorithm which results in a high quality virtual view by solving these problems stated above. The experimental results show that the proposed algorithm performs much better than the conventional algorithms.
Virtual View Generation by a New Hole Filling Algorithm
Ko, Min Soo ; Yoo, Jisang ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1023~1033
DOI : 10.5370/JEET.2014.9.3.1023
In this paper, performance improved hole-filling algorithm which includes the boundary noise removing pre-process that can be used for an arbitrary virtual view synthesis has been proposed. Boundary noise occurs due to the boundary mismatch between depth and texture images during the 3D warping process and it usually causes unusual defects in a generated virtual view. Common-hole is impossible to recover by using only a given original view as a reference and most of the conventional algorithms generate unnatural views that include constrained parts of the texture. To remove the boundary noise, we first find occlusion regions and expand these regions to the common-hole region in the synthesized view. Then, we fill the common-hole using the spiral weighted average algorithm and the gradient searching algorithm. The spiral weighted average algorithm keeps the boundary of each object well by using depth information and the gradient searching algorithm preserves the details. We tried to combine strong points of both the spiral weighted average algorithm and the gradient searching algorithm. We also tried to reduce the flickering defect that exists around the filled common-hole region by using a probability mask. The experimental results show that the proposed algorithm performs much better than the conventional algorithms.
Expanded Guide Circle-based Obstacle Avoidance for the Remotely Operated Mobile Robot
Park, Seunghwan ; Kim, Gon-Woo ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1034~1042
DOI : 10.5370/JEET.2014.9.3.1034
For the remote operation of the mobile robot, the human operator depends fully on the sensory information which is the partial information of the workspace of the mobile robot. It is usually very hard to fully manually operate the mobile robot in this situation. We propose the efficient guidance navigation method for improving the efficiency of the remote operation with the expanded guide circle using the sensory information. The guidance command is generated from the proposed algorithm using the expanded guide circle. We evaluated the performance of the proposed algorithm using the experiments.
Cyber Threat and a Mitigation Method for the Power Systems in the Smart Grid
Kim, Myongsoo ; Kim, Younghyun ; Jeon, Kyungseok ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1043~1050
DOI : 10.5370/JEET.2014.9.3.1043
Obsolescent control systems for power systems are evolving into intelligent systems and connecting with smart devices to give intelligence to the power systems. As networks of the control system are growing, vulnerability is also increasing. The communication network of distribution areas in the power system connects closely to vulnerable environments. Many cyber-attacks have been founded in the power system, and they could be more critical as the power system becomes more intelligent. From these environment, new communication network architecture and mitigation method against cyber-attacks are needed. Availability and Fault Tree analysis used to show that the proposed system enhances performance of current control systems.
Multi-Sensor Signal based Situation Recognition with Bayesian Networks
Kim, Jin-Pyung ; Jang, Gyu-Jin ; Jung, Jae-Young ; Kim, Moon-Hyun ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1051~1059
DOI : 10.5370/JEET.2014.9.3.1051
In this paper, we propose an intelligent situation recognition model by collecting and analyzing multiple sensor signals. Multiple sensor signals are collected for fixed time window. A training set of collected sensor data for each situation is provided to K2-learning algorithm to generate Bayesian networks representing causal relationship between sensors for the situation. Statistical characteristics of sensor values and topological characteristics of generated graphs are learned for each situation. A neural network is designed to classify the current situation based on the extracted features from collected multiple sensor values. The proposed method is implemented and tested with UCI machine learning repository data.
An Improved EEG Signal Classification Using Neural Network with the Consequence of ICA and STFT
Sivasankari, K. ; Thanushkodi, K. ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1060~1071
DOI : 10.5370/JEET.2014.9.3.1060
Signals of the Electroencephalogram (EEG) can reflect the electrical background activity of the brain generated by the cerebral cortex nerve cells. This has been the mostly utilized signal, which helps in effective analysis of brain functions by supervised learning methods. In this paper, an approach for improving the accuracy of EEG signal classification is presented to detect epileptic seizures. Moreover, Independent Component Analysis (ICA) is incorporated as a preprocessing step and Short Time Fourier Transform (STFT) is used for denoising the signal adequately. Feature extraction of EEG signals is accomplished on the basis of three parameters namely, Standard Deviation, Correlation Dimension and Lyapunov Exponents. The Artificial Neural Network (ANN) is trained by incorporating Levenberg-Marquardt(LM) training algorithm into the backpropagation algorithm that results in high classification accuracy. Experimental results reveal that the methodology will improve the clinical service of the EEG recording and also provide better decision making in epileptic seizure detection than the existing techniques. The proposed EEG signal classification using feed forward Backpropagation Neural Network performs better than to the EEG signal classification using Adaptive Neuro Fuzzy Inference System (ANFIS) classifier in terms of accuracy, sensitivity, and specificity.
Coordinated Droop Control for Stand-alone DC Micro-grid
Kim, Hyun-Jun ; Lee, Yoon-Seok ; Kim, Jae-Hyuk ; Han, Byung-Moon ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1072~1079
DOI : 10.5370/JEET.2014.9.3.1072
This paper introduces a coordinated droop control for the stand-alone DC micro-grid, which is composed of photo-voltaic generator, wind power generator, engine generator, and battery storage with SOC (state of charge) management system. The operation of stand-alone DC micro-grid with the coordinated droop control was analyzed with computer simulation. Based on simulation results, a hardware simulator was built and tested to analyze the performance of proposed system. The developed simulation model and hardware simulator can be utilized to design the actual stand-alone DC micro-grid and to analyze its performance. The coordinated droop control can improve the reliability and efficiency of the stand-alone DC micro-grid.
Optimization of Wind Power Dispatch to Minimize Energy Storage System Capacity
Nguyen, Cong-Long ; Lee, Hong-Hee ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1080~1088
DOI : 10.5370/JEET.2014.9.3.1080
By combining a wind turbine with an energy storage system (ESS), we are able to attenuate the intermittent wind power characteristic making the power derived from a wind farm dispatchable. This paper evaluates the influence of the phase delay of the low-pass filter in the conventional smoothing power control on the ESS capacity; longer phase delays require a larger ESS capacity. In order to eliminate the effect of the phase delay, we optimize the power dispatch using a zero-phase low-pass filter that results in a non-delayed response in the power dispatch. The proposed power dispatching method significantly minimizes the ESS capacity. In addition, the zero-phase low-pass filter, which is a symmetrical forward-reverse finite impulse response type, is designed simply with a small number of coefficients. Therefore, the proposed dispatching method is not only optimal, but can also be feasibly applied to real wind farms. The efficacy of the proposed dispatching method is verified by integrating a 3 MW wind turbine into the grid using wind data measured on Jeju Island.
Operation Planning of Reserve in Microgrid Considering Market Participation and Energy Storage System
Lee, Si Young ; Jin, Young Gyu ; Kim, Sun Kyo ; Yoon, Yong Tae ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1089~1095
DOI : 10.5370/JEET.2014.9.3.1089
Innumerable microgrids would be operated independently by individual operators in a future smart grid. This kind of decentralized power system requires entirely different operation scheme in the actual power system and electricity market operation. Especially, frequency regulation is very important for successive energy trade in this multi-microgrid circumstance. This paper presents an optimal energy and reserve market participation strategy and operation strategy of energy storage system (ESS) by a microgrid operator (MGO). For definite evaluation of the proposed strategy, we postulate that the MGO should participate in the Power Exchange for Frequency Control (PXFC) market, which was devised by Maria Ilic and her coworkers and is suitable to the decentralized operation circumstances. In particular, optimal reserve capacity of the frequency control market and optimal market participation ratio of ESS between frequency control market and energy market are derived theoretically and evaluated by simulations utilizing Nordic Pool Elspot price data.
Power Smoothening Control of Wind Farms Based on Inertial Effect of Wind Turbine Systems
Nguyen, Thanh Hai ; Lee, Dong-Choon ; Kang, Jong-Ho ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1096~1103
DOI : 10.5370/JEET.2014.9.3.1096
This paper proposes a novel strategy for attenuating the output power fluctuation of the wind farm (WF) in a range of tens of seconds delivered to the grid, where the kinetic energy caused by the large inertia of the wind turbine systems is utilized. A control scheme of the two-level structure is applied to control the wind farm, which consists of a supervisory control of the wind farm and individual wind turbine controls. The supervisory control generates the output power reference of the wind farm, which is filtered out from the available power extracted from the wind by a low-pass filter (LPF). A lead-lag compensator is used for compensating for the phase delay of the output power reference compared with the available power. By this control strategy, when the reference power is lower than the maximum available power, some of individual wind turbines are operated in the storing mode of the kinetic energy by increasing the turbine speeds. Then, these individual wind turbines release the kinetic power by reducing the turbine speed, when the power command is higher than the available power. In addition, the pitch angle control systems of the wind turbines are also employed to limit the turbine speed not higher than the limitation value during the storing mode of kinetic energy. For coordinating the de-rated operation of the WT and the storing or releasing modes of the kinetic energy, the output power fluctuations are reduced by about 20%. The PSCAD/EMTDC simulations have been carried out for a 10-MW wind farm equipped with the permanent-magnet synchronous generator (PMSG) to verify the validity of the proposed method.
Method to Prevent the Malfunction Caused by the Transformer Magnetizing Inrush Current using IEC 61850-based IEDs and Dynamic Performance Test using RTDS Test-bed
Kang, Hae-Gweon ; Song, Un-Sig ; Kim, Jin-Ho ; Kim, Se-Chang ; Park, Jong-Soo ; Park, Jong-Eun ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1104~1111
DOI : 10.5370/JEET.2014.9.3.1104
The digital substations are being built based on the IEC 61850 network. The cooperation and protection of power system are becoming more intelligent and reliable in the environment of digital substation. This paper proposes a novel method to prevent the malfunction caused by the Transformer Magnetizing Inrush Current(TMIC) using the IEC 61850 based data sharing between the IEDs. To protect a main transformer, the current differential protection(87T) and over-current protection(50/51) are used generally. The 87T IED applies to the second harmonic blocking method to prevent the malfunction caused by the TMIC. However, the 50/51 IED may malfunction caused by the TMIC. To solve that problem, the proposed method uses a GOOSE inter-lock signal between two IEDs. The 87T IED transmits a blocking GOOSE signal to the 50/51 IED, when the TMIC is detected. The proposed method can make a cooperation of digital substation protection system more intelligent. To verify the performance of proposed method, this paper performs the real time test using the RTDS (Real Time Digital Simulator) test-bed. Using the RTDS, the power system transients are simulated, and the TMIC is generated. The performance of proposed method is verified in real-time using that actual current signals. The reaction of simulated power system responding to the operation of IEDs can be also confirmed.
Autonomous Micro-grid Design for Supplying Electricity in Carbon-Free Island
Hwang, Woo-Hyun ; Kim, Sang-Kyu ; Lee, Jung-Ho ; Chae, Woo-Kyu ; Lee, Je-Ho ; Lee, Hyun-Jun ; Kim, Jae-Eon ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1112~1118
DOI : 10.5370/JEET.2014.9.3.1112
In island and backcountry areas, electrical power is usually supplied by diesel generators. It is difficult for small scale diesel generators to have an economy of scale owing to the usage of fossil fuels to produce electricity. Also, there is a problem of carbon dioxide emissions that brings some environmental pollution to the entire region of the area. For solving those, this paper proposes a design method of autonomous micro-grid to minimize the fossil fuels of diesel generator, which is composed of diesel generator, wind turbine, battery energy storage system and photovoltaic generation system. The proposed method was verified through computer simulation and micro-grid operation system.
An Effective Control Scheme of a Back-to-Back Converter with Shunt-Connected HTS SMES for Frequency Regulation of an Islanded Microgrid
Dinh, Minh-Chau ; Park, Minwon ; Kim, Gyeong-Hun ; Yu, In-Keun ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1119~1124
DOI : 10.5370/JEET.2014.9.3.1119
High temperature superconducting magnetic energy storage (HTS SMES) is known as an effective solution to significantly decrease the voltage and power fluctuations of grid connected wind power generation system (WPGS). This paper implements an effective control scheme of a back-toback converter with shunt-connected HTS SMES for the frequency regulation of an islanded microgrid. The back-to-back converter is used to connect the WPGS to the grid. A large-scale HTS SMES is linked to the DC side of the back-to-back converter through a two-quadrant DC/DC chopper. An adaptive control strategy is implemented for the back-to-back converter and the two-quadrant DC/DC chopper to improve the efficiency of the whole system. The performance of the proposed control system was evaluated in a test power system using PSCAD/EMTDC. The simulation results clearly show that the back-to-back converter with shunt-connected HTS SMES operates effectively with the proposed control strategy for stabilizing the power system frequency fluctuations.
Investigating the Impacts of Different Price-Based Demand Response Programs on Home Load Management
Rastegar, Mohammad ; Fotuhi-Firuzabad, Mahmud ; Choi, Jaeseok ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1125~1131
DOI : 10.5370/JEET.2014.9.3.1125
Application of residential demand response (DR) programs are currently realized up to a limited extent due to customers' difficulty in manually responding to the time-differentiated prices. As a solution, this paper proposes an automatic home load management (HLM) framework to achieve the household minimum payment as well as meet the operational constraints to provide customer's comfort. The projected HLM method controls on/off statuses of responsive appliances and the charging/discharging periods of plug-in hybrid electric vehicle (PHEV) and battery storage at home. This paper also studies the impacts of different time-varying tariffs, i.e., time of use (TOU), real time pricing (RTP), and inclining block rate (IBR), on the home load management (HLM). The study is effectuated in a smart home with electrical appliances, a PHEV, and a storage system. The simulation results are presented to demonstrate the effectiveness of the proposed HLM program. Peak of household load demand along with the customer payment costs are reported as the consequence of applying different pricings models in HLM.
Load Dispatching Control of Multiple-Parallel-Converters Rectifier to Maximize Conversion Efficiency
Orihara, Dai ; Saitoh, Hiroumi ; Higuchi, Yuji ; Babasaki, Tadatoshi ;
Journal of Electrical Engineering and Technology, volume 9, issue 3, 2014, Pages 1132~1136
DOI : 10.5370/JEET.2014.9.3.1132
In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.