Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.175
U. Patil, Min Sik Nam, N. Shinde, S. Jun
본 연구에서는 간단한 화학적 합성 방법을 통하여 스테인레스 기판 nano-bud 형성하였다 . 그리고 또 다른 합성 방법인 chemical bath deposition 을 A facile soft chemical synthesis route is used to grow nano-buds of copper hydroxide [Cu(OH) 2 ] thin films on stainless steel substrate[SS]. Besides different chemical methods for synthesis of Cu(OH) 2 nanostructure, the chemical bath deposition (CBD) is attractive for its simplicity and environment friendly condition. The structural, morphological, and electro-chemical properties of Cu(OH) 2 thin films are studied by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurement techniques. The results showed that, facile chemical synthesis route allows to form the polycrystalline, granular nano-buds of Cu(OH) 2 thin films. The electrochemical properties of Cu(OH) 2 thin films are studied in an aqueous 1 M KOH electrolyte using cyclic voltammetry. The sample exhibited supercapacitive behavior with 340 F g -1 specific capacitance. Moreover, electrochemical capacitive measurements of Cu(OH) 2 /SS electrode exhibit a high specific energy and power density about ~83 Wh kg -1 and ~3.1 kW kg -1 , respectively, at 1 mA cm -2 current density. The superior electrochemical properties of copper hydroxide (Cu(OH) 2 /SS) electrode with nano-buds like structure mutually improves pseudocapacitive performance. This work evokes scalable chemical synthesis with the enhanced supercapacitive performance of Cu(OH) 2 /SS electrode in energy storage devices.
본연구에서는간단한화학적합성방법을통하여스테인레스기판nano-bud형성하였다。采用一种简便的软化学合成路线，在不锈钢衬底上生长出氢氧化铜[Cu(OH) 2]纳米芽膜[SS]。化学浴沉积法制备Cu(OH) 2纳米结构的方法多种多样，但化学浴沉积法(CBD)以其简单、环境友好的特点而备受青睐。采用x射线衍射(XRD)、x射线光电子能谱(XPS)、场发射扫描电镜(FESEM)、循环伏安法(CV)和恒流充放电(GCD)测量技术研究了Cu(OH) 2薄膜的结构、形态和电化学性能。结果表明，简单的化学合成路线可以形成多晶、颗粒状的Cu(OH) 2纳米芽薄膜。采用循环伏安法研究了Cu(OH) 2薄膜在1 M KOH水溶液中的电化学性能。样品具有340℉-1的比电容特性。此外，Cu(OH) 2 /SS电极在1 mA cm -2电流密度下具有较高的比能和功率密度，分别为~83 Wh kg -1和~3.1 kW kg -1。具有纳米芽状结构的氢氧化铜(Cu(OH) 2 /SS)电极具有优异的电化学性能，相互提高了赝电容性能。这项工作唤起了可扩展的化学合成，增强了Cu(OH) 2 /SS电极在储能装置中的超电容性能。
{"title":"Facile Chemical Growth of Cu(OH) 2 Thin Film Electrodes for High Performance Supercapacitors","authors":"U. Patil, Min Sik Nam, N. Shinde, S. Jun","doi":"10.18770/KEPCO.2015.01.01.175","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.175","url":null,"abstract":"본 연구에서는 간단한 화학적 합성 방법을 통하여 스테인레스 기판 nano-bud 형성하였다 . 그리고 또 다른 합성 방법인 chemical bath deposition 을 A facile soft chemical synthesis route is used to grow nano-buds of copper hydroxide [Cu(OH) 2 ] thin films on stainless steel substrate[SS]. Besides different chemical methods for synthesis of Cu(OH) 2 nanostructure, the chemical bath deposition (CBD) is attractive for its simplicity and environment friendly condition. The structural, morphological, and electro-chemical properties of Cu(OH) 2 thin films are studied by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurement techniques. The results showed that, facile chemical synthesis route allows to form the polycrystalline, granular nano-buds of Cu(OH) 2 thin films. The electrochemical properties of Cu(OH) 2 thin films are studied in an aqueous 1 M KOH electrolyte using cyclic voltammetry. The sample exhibited supercapacitive behavior with 340 F g -1 specific capacitance. Moreover, electrochemical capacitive measurements of Cu(OH) 2 /SS electrode exhibit a high specific energy and power density about ~83 Wh kg -1 and ~3.1 kW kg -1 , respectively, at 1 mA cm -2 current density. The superior electrochemical properties of copper hydroxide (Cu(OH) 2 /SS) electrode with nano-buds like structure mutually improves pseudocapacitive performance. This work evokes scalable chemical synthesis with the enhanced supercapacitive performance of Cu(OH) 2 /SS electrode in energy storage devices.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129432866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.181
Gyu-sang Park, Chan-ho Kim, Yong-Jae Kim
The non-contact permanent magnet gear has advantages of high efficiency and improved reliability. It has other advantages of no mechanical friction loss, very little noise and vibration, and no need for lubricant. With these advantages, the non-contact permanent magnet gear that solves the physical contact problem of the mechanical gear has drawn attention. Due to this unique non-contact characteristic, the non-contact permanent magnet gear which is capable of non-contact torque transmission has replaced mechanical gear. The mechanical gears which is in many fields of the modern industry, is used mostly for power transmitting mechanical devices. However, it also has the problem of a low torque density, which requires improvement. In this paper, a novel pole piece shape is proposed in order to improve the problem of low torque density of the non-contact permanent magnet gear. The experiment data required for predicting the relationships among them are obtained using finiteelement Operating method based on two-dimensional (2-D) numerical analysis. Therefore, this paper derived an optimal model for thenon-contact permanent magnet gear with the novel pole piece using the Box-Behnken design, and the validity of the optimal design of the proposed pole piece shape through variance analysis and regression analysis demonstrated. In this paper, we performed the thransfer torque analysis in order to improve the torque density and power density, we have performed on optimal design of proposed pole piece shape using box-behnken.
{"title":"Study on Analysis of Transfer Torque and Improvement of Transfer Torque in Non-Contact Permanent Magnet Gear","authors":"Gyu-sang Park, Chan-ho Kim, Yong-Jae Kim","doi":"10.18770/KEPCO.2015.01.01.181","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.181","url":null,"abstract":"The non-contact permanent magnet gear has advantages of high efficiency and improved reliability. It has other advantages of no mechanical friction loss, very little noise and vibration, and no need for lubricant. With these advantages, the non-contact permanent magnet gear that solves the physical contact problem of the mechanical gear has drawn attention. Due to this unique non-contact characteristic, the non-contact permanent magnet gear which is capable of non-contact torque transmission has replaced mechanical gear. The mechanical gears which is in many fields of the modern industry, is used mostly for power transmitting mechanical devices. However, it also has the problem of a low torque density, which requires improvement. In this paper, a novel pole piece shape is proposed in order to improve the problem of low torque density of the non-contact permanent magnet gear. The experiment data required for predicting the relationships among them are obtained using finiteelement Operating method based on two-dimensional (2-D) numerical analysis. Therefore, this paper derived an optimal model for thenon-contact permanent magnet gear with the novel pole piece using the Box-Behnken design, and the validity of the optimal design of the proposed pole piece shape through variance analysis and regression analysis demonstrated. In this paper, we performed the thransfer torque analysis in order to improve the torque density and power density, we have performed on optimal design of proposed pole piece shape using box-behnken.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130015816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.099
S. Sohn, Dong-Hwan Kim, Wook-ryun Lee, Jae-Raeyang Koo, Jing Hong
In this study, it has been initiated to investigate the specific abnormal vibration signal that has been captured in the power equipment. Array Microphone can be used in order to detect the direction and the position of the noise source. It is possible to track the abnormal mechanical noise in the power plant by utilizing the program and the microphone array system developed from this research. Array microphone system can be operated as a constant monitoring system
{"title":"Development of Noise Source Detection System using Array Microphone in Power Plant Equipment","authors":"S. Sohn, Dong-Hwan Kim, Wook-ryun Lee, Jae-Raeyang Koo, Jing Hong","doi":"10.18770/KEPCO.2015.01.01.099","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.099","url":null,"abstract":"In this study, it has been initiated to investigate the specific abnormal vibration signal that has been captured in the power equipment. Array Microphone can be used in order to detect the direction and the position of the noise source. It is possible to track the abnormal mechanical noise in the power plant by utilizing the program and the microphone array system developed from this research. Array microphone system can be operated as a constant monitoring system","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128145749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.001
Seok-kon Kim, Y. An, B. Jang, Jong-kee Choi, N. Lee, Jung-yeol Han, Youjin Lee
Abstract When the line and switchgear of the substation system are disconnected, ferro-resonance can occur. This happens even if the capacitive reactance and inductive reactance are not equal, which are not common resonance conditions. Resonance conditions vary depending on the busbar configuration environment. Although the damping resistance method applying the existing saturable reactor to cope with ferro-resonance has been su ccessfully applied on site, th ere can be loss of normal function during long-term operat ion. The reason is because the rise in the operating frequency of saturable reactors means the saturation number is increased. Therefore, it can no longer function as saturable reactor since the resistor having inadequate capacity is burned out. To address this problem, in this paper, an EMTP-based simulation test was performed by designing and applying a dual reactor method, which adds an extended divergence reactor to the 1st side of the VT. The test result confirms that when the divergence reactor is inserted, the voltage and current values obtained at the 1st side and 2nd side of the VT as well as current values of divergence reactor part were stabilized from the transient phenomena and return to normal values. When compared with existing measures, although this method is similar in adding having a reactor added to a system regarding ferro-resonance, it has the advantage of being able to prevent ferro-resonance in advance since the reactor is added before the system is s aturated. In addition, because it does not use damping resistance, it can extend the equ ipment life and stabilize its operation. Therefore, there are a lot of differences in terms of its operating characteristics and achivement of goal between the conventional method and new divergence reactor method.
{"title":"Study on EMTP Simulation Applying Dual Reactor for Prevention of the Ferro-resonance and VT Burnout in Substation System","authors":"Seok-kon Kim, Y. An, B. Jang, Jong-kee Choi, N. Lee, Jung-yeol Han, Youjin Lee","doi":"10.18770/KEPCO.2015.01.01.001","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.001","url":null,"abstract":"Abstract When the line and switchgear of the substation system are disconnected, ferro-resonance can occur. This happens even if the capacitive reactance and inductive reactance are not equal, which are not common resonance conditions. Resonance conditions vary depending on the busbar configuration environment. Although the damping resistance method applying the existing saturable reactor to cope with ferro-resonance has been su ccessfully applied on site, th ere can be loss of normal function during long-term operat ion. The reason is because the rise in the operating frequency of saturable reactors means the saturation number is increased. Therefore, it can no longer function as saturable reactor since the resistor having inadequate capacity is burned out. To address this problem, in this paper, an EMTP-based simulation test was performed by designing and applying a dual reactor method, which adds an extended divergence reactor to the 1st side of the VT. The test result confirms that when the divergence reactor is inserted, the voltage and current values obtained at the 1st side and 2nd side of the VT as well as current values of divergence reactor part were stabilized from the transient phenomena and return to normal values. When compared with existing measures, although this method is similar in adding having a reactor added to a system regarding ferro-resonance, it has the advantage of being able to prevent ferro-resonance in advance since the reactor is added before the system is s aturated. In addition, because it does not use damping resistance, it can extend the equ ipment life and stabilize its operation. Therefore, there are a lot of differences in terms of its operating characteristics and achivement of goal between the conventional method and new divergence reactor method.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134079161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.141
Heesun Kim, Young-Hee Han, Seongeun Yang, Seung-Duck Yu, B. Park, Kijun Park, Jaeun Yoo, Hye-Rim Kim, S. In, Y. Hong, H. Yeom
The superconducting fault current limiter (SFCL) is an electric power device that limits the fault current immediately in a power grid. Korea Electric Power Corporation (KEPCO) has been developing a 154 kV, 2 kA SFCL since 2011 to protect power grids from increasing fault current and improve the stability and quality of electric power. This SFCL adopts 2G YBCO wires and operates at 71 K and 5 bars. In this paper, a cooling system for the 154 kV SFCL and its cooling test results are reported. This cooling system uses a Stirling-type cooler to make sub-cooled liquid nitrogen (LN2), which cools the superconductor modules of the SFCL. The LN2 is circulated between the cooler and the cryostat that contains superconductor modules. The LN2 also plays the role of a high voltage insulator between the modules and the cryostat, so the pressure was maintained at 5 bars for high insulation performance. After installation in a test site, the cooling characteristics of the system were tested. In this operation test, some important data were measured such as temperature distribution in LN2, pressure change, performance of the heat exchanger, and cooling capacity of the total system. Consequently, the results indicate that the cooling system operates well as designed.
{"title":"Development and Test of a Cooling System for a 154 kV Superconducting Fault Current Limiter","authors":"Heesun Kim, Young-Hee Han, Seongeun Yang, Seung-Duck Yu, B. Park, Kijun Park, Jaeun Yoo, Hye-Rim Kim, S. In, Y. Hong, H. Yeom","doi":"10.18770/KEPCO.2015.01.01.141","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.141","url":null,"abstract":"The superconducting fault current limiter (SFCL) is an electric power device that limits the fault current immediately in a power grid. Korea Electric Power Corporation (KEPCO) has been developing a 154 kV, 2 kA SFCL since 2011 to protect power grids from increasing fault current and improve the stability and quality of electric power. This SFCL adopts 2G YBCO wires and operates at 71 K and 5 bars. In this paper, a cooling system for the 154 kV SFCL and its cooling test results are reported. This cooling system uses a Stirling-type cooler to make sub-cooled liquid nitrogen (LN2), which cools the superconductor modules of the SFCL. The LN2 is circulated between the cooler and the cryostat that contains superconductor modules. The LN2 also plays the role of a high voltage insulator between the modules and the cryostat, so the pressure was maintained at 5 bars for high insulation performance. After installation in a test site, the cooling characteristics of the system were tested. In this operation test, some important data were measured such as temperature distribution in LN2, pressure change, performance of the heat exchanger, and cooling capacity of the total system. Consequently, the results indicate that the cooling system operates well as designed.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121463698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.157
Ji-Young Lee, Seyeon Lee, Yungil Kim, Sang Ho Park, Kyeongdal Choi, Ji-kwang Lee, Woo-Seok Kim
대용량 초전도 Magnetic Energy Storage, could be reduced to 0.1 percent of that by the 3-dimensional numerical calculation.
通过三维数值计算，可以将磁能存储降低到0.1%。
{"title":"Study on the 2G High Temperature Superconducting Coil for Large Scale Superconducting Magnetic Energy Storage Systems","authors":"Ji-Young Lee, Seyeon Lee, Yungil Kim, Sang Ho Park, Kyeongdal Choi, Ji-kwang Lee, Woo-Seok Kim","doi":"10.18770/KEPCO.2015.01.01.157","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.157","url":null,"abstract":"대용량 초전도 Magnetic Energy Storage, could be reduced to 0.1 percent of that by the 3-dimensional numerical calculation.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123367660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.169
S. Park, I. Lee, D. Bae, Jungtae Nam, B. Park, Young-Hee Han, K. Kim
In this research, pristine graphene was synthesized using methane () gas, and N-doped graphene was synthesized using pyridine () liquid source by chemical vapor deposition (CVD) method. Basic optical properties of both pristine and N-doped graphene were investigated by Raman spectroscopy and XPS (X-ray photoemission spectroscopy), and electrical transport characteristics were estimated by current-voltage response of graphene channel as a function of gate voltages. Results for CVD grown pristine graphene from methane gas show that G-peak, 2D-peak and C1s-peak in Raman spectra and XPS. Charge neutral point (CNP; Dirac-point) appeared at about +4 V gate bias in electrical characterization. In the case of pyridine based CVD grown N-doped graphene, D-peak, G-peak, weak 2D-peak were observed in Raman spectra and C1s-peak and slight N1s-peak in XPS. CNP appeared at -96 V gate bias in electrical characterization. These result show successful control of the property of graphene artificially synthesized by CVD method.
{"title":"Controlling the Properties of Graphene using CVD Method: Pristine and N-doped Graphene","authors":"S. Park, I. Lee, D. Bae, Jungtae Nam, B. Park, Young-Hee Han, K. Kim","doi":"10.18770/KEPCO.2015.01.01.169","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.169","url":null,"abstract":"In this research, pristine graphene was synthesized using methane () gas, and N-doped graphene was synthesized using pyridine () liquid source by chemical vapor deposition (CVD) method. Basic optical properties of both pristine and N-doped graphene were investigated by Raman spectroscopy and XPS (X-ray photoemission spectroscopy), and electrical transport characteristics were estimated by current-voltage response of graphene channel as a function of gate voltages. Results for CVD grown pristine graphene from methane gas show that G-peak, 2D-peak and C1s-peak in Raman spectra and XPS. Charge neutral point (CNP; Dirac-point) appeared at about +4 V gate bias in electrical characterization. In the case of pyridine based CVD grown N-doped graphene, D-peak, G-peak, weak 2D-peak were observed in Raman spectra and C1s-peak and slight N1s-peak in XPS. CNP appeared at -96 V gate bias in electrical characterization. These result show successful control of the property of graphene artificially synthesized by CVD method.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131849923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.055
YooJin Kwon
Denial of Service (DoS) attack is to interfere the normal user from using the information technology services. With a rapid technology improvements in computer and internet environment, small sized DoS attacks targeted to server or network infrastructure have been disabled. Thus, Distributed Denial of Service (DDoS) attacks that utilizes from tens to several thousands of distributed computers as zombie PC appear to have as one of the most challenging threat. In this paper, we categorize the DDoS attacks and classify existing countermeasures based on where and when they prevent, detect, and respond to the DDoS attacks. Then we propose a comprehensive defense mechanism against DDoS attacks in Control System to detect attacks efficiently.
{"title":"A Survey on Defense Mechanism against Distributed Denial of Service (DDoS) Attacks in Control System","authors":"YooJin Kwon","doi":"10.18770/KEPCO.2015.01.01.055","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.055","url":null,"abstract":"Denial of Service (DoS) attack is to interfere the normal user from using the information technology services. With a rapid technology improvements in computer and internet environment, small sized DoS attacks targeted to server or network infrastructure have been disabled. Thus, Distributed Denial of Service (DDoS) attacks that utilizes from tens to several thousands of distributed computers as zombie PC appear to have as one of the most challenging threat. In this paper, we categorize the DDoS attacks and classify existing countermeasures based on where and when they prevent, detect, and respond to the DDoS attacks. Then we propose a comprehensive defense mechanism against DDoS attacks in Control System to detect attacks efficiently.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131053802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.073
Taesik Park, Nohong Kwak, Chaeju Moon, S. Cha, Seongchul Kwon
Abstract Offshore wind farms extend a distance from an onshore grid to increase their generating power, but long distance and high power transmissions raise a lot of cost challenges. LFAC (Low Frequency AC) transmission is a new promising technology in high power and low cost power transmission fields against HVDC (High Voltage DC) and HVAC (High Voltage AC) transmissions. This paper presents an economic comparison of LFAC and HVDC transmissions for large offshore wind farms. The economic assessments of two different transmission technologies are analyzed and compared in terms of wind farm capacities (600 MW and 900 MW) and distances (from 25 km to 100 km) from the onshore grid. Based on this comparison, the economic feasibility of LFAC is verified as a most economical solution for remote offshore wind farms. Keywords: LFAC, HVDC, Offshore, wind farm I. INTRODUCTION In recent years, energy systems based on wind power have rapidly enlarged their application areas, especially towards large offshore wind farms (over 100 MW) and micro grid systems. The conventional onshore wind farms have small power generation and short distance power transmission to a power grid. However, for a large remote wind farms, a new power transmission system is required to provide high energy density and low loss power transmission characteristics with low investments. So, how to connect large remote wind farms to the onshore micro grid with low power losses and economic benefits is the prime concerns of researchers, and its economic power system and wind farm layouts for transmitting high power and long distance has gained more attentions. The conventional HVAC (High Voltage AC) system consists of wind generators, transformers, transmission cables and reactive power compensators, and the generated power is converted to a very high voltage (154 kV or 345 kV) by transformers. The HVAC power system transmits the power through 3 cores XPLE cables through underwater, but the transmission distance of the HVAC power system is the most critical factor against power transmission capability because reactive power losses are proportional to the distance. Therefore, HVAC transmission system is not adequate to long distance large offshore wind farms. Recently, new technologies for power systems have been reported [1]-[15] to provide alternative ways to maximize the power transmission capability. The most outstanding technology is HVDC power system, which has high economic benefits for long distant applications because HVDC power system has no limitation of the transmission capability. HVDC Transmission does not suffer from the reactive losses found in the transmission of HVAC system. However, in order to transmit DC power from a remote wind farms the generated AC power must be converted to the DC power and must be converted back to the AC power for a grid connection. Converting the AC power into the DC power requires an expensive AC to DC converter station to be installed at the remot
海上风电场通过与陆上电网的距离扩展来提高发电能力，但长距离和高功率传输带来了许多成本挑战。LFAC (Low Frequency AC)输电技术是一种相对于HVDC (high Voltage DC)和HVAC (high Voltage AC)输电而言，在大功率低成本输电领域具有发展前景的新技术。本文对大型海上风电场的LFAC和HVDC输电进行了经济比较。根据风电场容量(600兆瓦和900兆瓦)和距离(从25公里到100公里)，对两种不同输电技术的经济评估进行了分析和比较。基于这种比较，LFAC的经济可行性被验证为偏远海上风电场最经济的解决方案。近年来，以风电为基础的能源系统的应用领域迅速扩大，特别是向大型海上风电场(100mw以上)和微电网系统发展。传统的陆上风电场发电量小，输电网距离短。然而，对于大型偏远风电场，需要一种新的输电系统，以提供高能量密度、低损耗、低投资的输电特性。因此，如何将大型远程风电场以低损耗、低经济效益的方式接入陆上微电网是研究人员关注的首要问题，其经济的电力系统和大功率长距离传输的风电场布局也受到了越来越多的关注。传统的HVAC (High Voltage AC)系统由风力发电机、变压器、输电电缆和无功补偿器组成，产生的电力通过变压器转换成非常高的电压(154千伏或345千伏)。HVAC电力系统通过3芯XPLE电缆通过水下传输电力，但由于无功损耗与距离成正比，HVAC电力系统的传输距离是影响电力传输能力的最关键因素。因此，暖通空调传输系统不适用于长距离大型海上风电场。最近，电力系统的新技术已经被报道，以提供可选的方式来最大化电力传输能力。其中最突出的技术是高压直流电力系统，由于高压直流电力系统不受输电能力的限制，在远距离应用中具有很高的经济效益。高压直流输电不存在暖通空调系统输电中存在的无功损耗。然而，为了从远程风电场传输直流电源，必须将产生的交流电源转换为直流电源，并必须将其转换回交流电源以连接电网。将交流电源转换为直流电源需要在偏远的风电场区域安装一个昂贵的交直流换流站，并且在电网之前在接收端安装一个直流到交流电源换流站。一种替代技术是LFAC(低频交流)传输系统。LFAC传输系统使用的频率(50/ 3hz或60/ 3hz)低于电网频率(50或60hz)，不需要海上电力换流站，只需要陆上换流站。LFAC传输系统具有比传统HVAC传输系统更大的传输距离和传输能力。然而，LFAC系统会产生一些可听噪声，并且存在变压器饱和和尺寸问题。为了使大型远程海上风电场采用最佳的电力系统拓扑，需要对高压直流输电和LFAC系统进行经济分析。然而，经济投资直接取决于电力系统的配置、距离和传输能力。因此，本文提出了HVDC和LFAC电力系统配置，并对大型海上风电场LFAC和HVDC输电进行了经济评估和比较。根据拟议的电力配置，分析了两种不同传输技术的经济评估，并根据风电场的容量(600兆瓦和900兆瓦)和距离(从25公里到100公里)与陆上电网进行了比较。通过比较，验证了LFAC的经济可行性，是大型海上风电场最经济的解决方案。
{"title":"Economic Assessments of LFAC and HVDC Transmissions for Large Offshore Wind Farms","authors":"Taesik Park, Nohong Kwak, Chaeju Moon, S. Cha, Seongchul Kwon","doi":"10.18770/KEPCO.2015.01.01.073","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.073","url":null,"abstract":"Abstract Offshore wind farms extend a distance from an onshore grid to increase their generating power, but long distance and high power transmissions raise a lot of cost challenges. LFAC (Low Frequency AC) transmission is a new promising technology in high power and low cost power transmission fields against HVDC (High Voltage DC) and HVAC (High Voltage AC) transmissions. This paper presents an economic comparison of LFAC and HVDC transmissions for large offshore wind farms. The economic assessments of two different transmission technologies are analyzed and compared in terms of wind farm capacities (600 MW and 900 MW) and distances (from 25 km to 100 km) from the onshore grid. Based on this comparison, the economic feasibility of LFAC is verified as a most economical solution for remote offshore wind farms. Keywords: LFAC, HVDC, Offshore, wind farm I. INTRODUCTION In recent years, energy systems based on wind power have rapidly enlarged their application areas, especially towards large offshore wind farms (over 100 MW) and micro grid systems. The conventional onshore wind farms have small power generation and short distance power transmission to a power grid. However, for a large remote wind farms, a new power transmission system is required to provide high energy density and low loss power transmission characteristics with low investments. So, how to connect large remote wind farms to the onshore micro grid with low power losses and economic benefits is the prime concerns of researchers, and its economic power system and wind farm layouts for transmitting high power and long distance has gained more attentions. The conventional HVAC (High Voltage AC) system consists of wind generators, transformers, transmission cables and reactive power compensators, and the generated power is converted to a very high voltage (154 kV or 345 kV) by transformers. The HVAC power system transmits the power through 3 cores XPLE cables through underwater, but the transmission distance of the HVAC power system is the most critical factor against power transmission capability because reactive power losses are proportional to the distance. Therefore, HVAC transmission system is not adequate to long distance large offshore wind farms. Recently, new technologies for power systems have been reported [1]-[15] to provide alternative ways to maximize the power transmission capability. The most outstanding technology is HVDC power system, which has high economic benefits for long distant applications because HVDC power system has no limitation of the transmission capability. HVDC Transmission does not suffer from the reactive losses found in the transmission of HVAC system. However, in order to transmit DC power from a remote wind farms the generated AC power must be converted to the DC power and must be converted back to the AC power for a grid connection. Converting the AC power into the DC power requires an expensive AC to DC converter station to be installed at the remot","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133133575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-30DOI: 10.18770/KEPCO.2015.01.01.105
Jong-an Kim, J. Woo, I. Choi
A digital Governor (GOV) has been developed for being used for a Francis hydro turbine, and the validity of the GOV has been tested. As for the hardware system for the GOV, we purchased a basic digital control system that already had proven its reliability in the power industry. We developed a set of new GOV software and integrated it with the hardware system, and finally verified the performance of the whole GOV system. For the human-machine interface (HMI), we configured and implemented appropriate graphic interfaces for the turbine operations. This paper describes the major GOV control functions, approaches we took in developing the GOV control logics, and the validity tests and the results.
{"title":"Development of a Hydro Turbine Governor and Validation Test","authors":"Jong-an Kim, J. Woo, I. Choi","doi":"10.18770/KEPCO.2015.01.01.105","DOIUrl":"https://doi.org/10.18770/KEPCO.2015.01.01.105","url":null,"abstract":"A digital Governor (GOV) has been developed for being used for a Francis hydro turbine, and the validity of the GOV has been tested. As for the hardware system for the GOV, we purchased a basic digital control system that already had proven its reliability in the power industry. We developed a set of new GOV software and integrated it with the hardware system, and finally verified the performance of the whole GOV system. For the human-machine interface (HMI), we configured and implemented appropriate graphic interfaces for the turbine operations. This paper describes the major GOV control functions, approaches we took in developing the GOV control logics, and the validity tests and the results.","PeriodicalId":445819,"journal":{"name":"KEPCO Journal on electric power and energy","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117171143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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