Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers

전력시스템 해석과 교육을 위한 정보시각화 프로그램 개발 - Part 1: 계통도 편집 기능 Information Visualization Program for Analysis and Education of Power Systems - Part 1: Drawing and Editing Functions

차효원(Hyo-Won Cha) ; 김병호(Byoung-Ho Kim) ; 홍민(Min Hong) ; 김규호(Kyu-Ho Kim) ; 김홍래(Hongrae Kim)

In modern power systems, the data for the analysis, monitoring, and operation has become massive. In order to provide the present operating states of the power systems, it is required to have effective visualization methods. In this paper, we present the software to monitor and analyze the power system operations and to show the operating information of the power systems. The program includes the functions for drawing and editing the power system configuration and related information. Automatic drawing function of one line diagram for the power systems is included in the software program, using the geographical information of the buses. The information on buses, lines, transformers and shunt devices can be modified on the diagram and also in the text-based files. The developed software will be used to analyze the operating conditions of the power systems, and also to educate the power system operators.

전력시스템 해석과 교육을 위한 정보시각화 프로그램 개발 - Part II: 전력계통 해석 기능 Information Visualization Program for Analysis and Education of Power Systems - Part II: Power System Analysis Functions

김병호(young-Ho Kim) ; 홍민(Min Hong) ; 김규호(Kyu-Ho Kim) ; 김홍래(Hongrae Kim)

As modern power system has grown rapidly and becomes complex, it is no longer possible to operate and develop the power systems without the help of a computer. By solving the computational problems required for planning, design and operation of the power system using a computer, it is possible to increase the quality of power system analysis, improve the efficiency of the power system operation, and increase the reliability of the power system. EMS (energy management system) includes many power system analysis applications, such as state estimation, power flow, stability analysis, fault analysis, economic dispatch and contingency analysis, which can analyze information for monitoring and control of the power system. In case of state estimation and power flow, their role is very important as application programs that are the basis of power system analysis. Commercial tools for power system analysis provide various visualization techniques for the expression of power system information and applications for grid analysis, but they do not usually include state estimation function as a basic application for power system analysis performed in a real-time environment. In addition, the cost of purchasing and maintaining commercial tools is very expensive. Therefore, it is necessary to use an educational application program that can be easily accessed and used by a user using computer in the educational stage for power system analysis. In this paper, we develop and introduce a program for power system analysis and education with information visualization function.

분산전원 연계 허용용량 개선을 위한 스마트인버터의 전압 무효전력 기능 적용에 따른 영향 분석 A Study on Volt-Var Curve of Smart Inverter to Improve Hosting Capacity

이형진(Hyeong-Jin Lee) ; 윤광훈(Kwang-Hoon Yoon) ; 신중우(Joong-Woo Shin) ; 김재철(Jae-Chul Kim) ; 윤상윤(Sang-Yun Yun)

Herein, This paper analyzed the effect of applying the volt-var curve on the smart inverter to solve the over-voltage problem caused by increasing the distributed generation. To analyze the voltage characteristics due to the increase in distributed power connection, the voltage characteristics at the end of the test model were analyzed while increasing the distributed power capacity. The potential hosting capacity was analyzed by calculating the voltage margin up to the upper limit according to volt-var curve types with different reactive power contributions and dead-band. In addition, mounting the volt-var curve to many distributed generation connected to the distribution system faced a practical limitation. Considering this limitation, the voltage characteristics and hosting capacity margins for the penetration level of the volt-var curve were analyzed. In this paper, the effect of the volt-var curve was analyzed using OpenDSS, a quasi-static time-series simulation, considering the characteristics of the distribution system test model in the worst case.

LNG : 발전 수익성 개선 방안에 관한 연구 변동비 차익 및 제한적 가격입찰제도를 중심으로 A Study on the Profitability Improvement of LNG Generation: Focused on Variable Cost Margin and Restrictive Price Bidding Pool

권규섭(Kyusub Kwon) ; 이주용(Juyong Lee) ; 조영상(Youngsang Cho)

In this study, we analyzed the factors affecting the variable cost margin required for the recovery of investment costs for LNG generators and proposed a restrictive price bidding pool(RPBP). For this, we investigated the issues of Korean LNG generators focusing on the profitability and reviewed some alternatives for overcoming these issues. Next, we calculated the minimum required variable cost margins for 23 Korean LNG generators, and obtained an average of 16.7 KRW/kWh. We also performed multiple regression and found that the investment cost, operation and management cost, and the allocation time for price-setting schedule energy(PSE) have statistically significant effects on the minimum required variable cost margin. Finally, we proposed a RPBP based on the results and analyzed the effect of the RPBP on the electricity market from the perspective of game theory. This study is academically and institutionally meaningful in that it is the first attempt to design the RPBP system using the real-world data of LNG generators.

국내 기업의 재생에너지 조달을 위한 녹색전력 구매계약제도 설계에 관한 제언 A Proposal for Design of Green Tariff Programme for Corporate Renewables Procurement in Korea

정구형(Koo-Hyung Chung) ; 허돈(Don Hur)

As global interests in climate change are growing, international credit rating agencies and investors allow for individual enterprises’ action plans for that issue as a key indicator for their corporate competitiveness. As such, multinational companies promote their efforts into the energy transition by unveiling their objectives and attainment of voluntary renewable energy 100% (RE 100). The establishment of their goals for RE 100 is likely to obligate their business partners to encourage wider use of renewables while the corporate sourcing conditions for renewables and institutional strategies in Korea are still nascent. Accordingly, the arrangement of both effective measures to facilitate corporate renewable energy procurement and reasonable standards to validate the renewable electricity consumption is now required to keep domestic industries immensely competitive, simply not to fulfill the national target of green gas emissions. Though multiple procurement pathways vary across countries based on how they are implemented and detailed market rules and regulations, utility green tariffs, which have emerged recently in U.S. markets, are highly regarded as economical and stable options to meet renewable energy demand from corporations. Typically, in utility green tariffs, the utility procures renewable energy on behalf of the electricity customers, and they pay a special utility green tariff rate for the renewable energy service. Compared with other potential opportunities, utility green tariffs have an overwhelming advantage of reduced financial burdens on renewable energy purchases by realizing the renewable energy offerings with overall cost savings through enabling renewable generators to seek assurances that their investments in renewables should be returned on a long-term basis. Finally, this paper purports to come up with a viable and vibrant green tariff mechanism in Korean electric power transaction frameworks and, at the same time, the overarching insights into various requirements considered to trigger this scheme in an amicable manner.

PV ESS 연계 의 최적 사업모델 및 용량 산정을 위한 설계 프로그램 Techno-Economic Evaluation Software for Optimal Business Model and Sizing of Photovoltaic Power Station-Linked Energy Storage System

조경희(Kyeong-Hee Cho) ; 김슬기(Seul-Ki Kim) ; 조형철(Hyung-Chul Jo) ; 손완빈(Wanbin Son) ; 김응상(Eung-Sang Kim) ; 박준호(June Ho Park)

Under the Korea government’s Energy Transition Roadmap, energy transition is underway with the gradual reduction of nuclear power plants and the expansion of renewable energy. Moreover, in the Third Energy Master Plan, the target share of renewable energy by 2040 was increased to 30-35%. The increase in the capacity of small-and medium-sized photovoltaic power stations (PV) is the highest among different renewable energy sources. As the output of PV power stations varies considerably, linking them with energy storage systems(ESSs)is attracting attention. When designing a PV-ESS, as the investment costs are high and the applicable support policies vary with the purpose of operation, it is important to review the economic feasibility of various models before installation. However, conducting this review might be very complex and difficult for the operator. Accordingly, the present study introduces a design program for distributed resources (MODDER) that can select the optimal capacity and business model considering the domestic policies and the operating characteristics of the distributed resources. The program comprises a database of weather information, load patterns according to application, sales unit costs, electricity rate unit costs, and renewable energy system specifications and can conveniently analyze the economic feasibility of a PV-ESS by selecting and configuring it according to the user’s purpose. Accordingly, the program helps determine the optimal capacity and business model. To verify the effectiveness of the proposed program, through a case study, simulations of a demand side management business and a renewable energy generation sale business were conducted based on actual industrial customers, and the results were analyzed. The developed program can be used to maximize the return on investment of renewable power generation and ESSs, thereby reducing investment risk and contributing to improving the acceptance of renewable energy.

일체형 플라이휠 구동용 내장형 전동기의 최적 설계에 관한 연구 A Study on the Optimal Design of Built-in Electric Motor for Driving Integrated Flywheel

김성안(Sung-An Kim)

The gyro stabilizer that reduces the lateral fluctuation of a ship generates a precession torque of the gimbal using the flywheel moment of inertia. An electric motor is needed to drive the flywheel. The conventional gimbal has a problem of a increase in installation space and weight because the fastening between the flywheel and the motor is made of a belt pulley. Therefore, this paper proposes an integrated structure in which the motor is installed inside the flywheel and presents the optimal design of the built-in motor to improve performance. The mechanical and electrical effectiveness of the proposed gimbal was verified through stress analysis, electromagnetic analysis and thermal analysis.

GaN FET IPT ZCS 적용 시스템의 동작 특성 분석 Analysis of ZCS Operation Characteristics of GaN FET-based IPT System

안철용(Chul-Yong Ahn) ; 김종수(Jong-Soo Kim)

This paper presents the feasibility of GaN FET as a method to solve the problems caused by bifurcation of IPT system. In the IPT system, bifurcation can occur for various reasons, and when bifurcation occurs, the operating area is shifted from ZVS to ZCS. In this process, the large reverse recovery charge of the MOSFET causes a very large current spike, which can cause the device to burn out. To avoid this, an additional sensor and a switching frequency shift algorithm must be applied. To solve this, the characteristics of the GaN FET, which is known to have a reverse recovery charge amount close to 0, are compared with that of a silicon MOSFET, and the spike current generation during ZCS region transition due to bifurcation is analyzed through simulation. The validity of the analysis is verified experimentally through a 2 kW prototype IPT system, and the experimental results shows that the current spike generated under bifurcation conditions is reduced by about 75% compared to the silicon MOSFET.

육상대비 수면의 냉각효과에 의한 수상태양광 출력계수 도출 The Deduction of Generation Efficiency Coefficient of the Floating PV Systems with the Cooling Effect of Water Surface

권오극(Ogeuk Kwon) ; 권진성(Jinseong Kwon) ; 조현식(Hyunsik Jo) ; 차한주(Hanju Cha)

he efficiency of PV systems varies in performance due to several factors, such as module efficiency, PV arrays, PCS, solar irradiation, ambient temperature, and wind speed. In this study the cooing effect of floating PV is mainly discussed. In order to examine the cooling effect of reservoirs, three laboratory experiments are performed by controlling chamber temperature. The first experiment was conducted to determine the amount of light reflected from the water surface compared to the ground. Secondly, the representative temperature and humidity were set for each season and the temperature difference of module between ground and water conditions is measured. The third experiment was a comparative experiment of the generation amount between ground and floating PVs according to the change of the outside temperature. In addition, a mathematical model was selected and compared with experiment results.

액상 실리콘 고무의 조성에 따른 기계적 내트래킹 특성 연구 Study on the Mechanical and Tracking Resistance Properties of Liquid Silicone Rubber with Variation to its Composition

이지희(Ji-hee Lee) ; 홍영기(Young-Gi Hong) ; 박재준(Jae-Jun Park)

Liquid silicone rubber containing 20wt% of nano-silica was prepared with the molar ratio of [Si-H] / [Vinyl] to 3.0, 4.9, 7.8, and 11.0, respectively, in order to develop insulating materials for ultra-high voltage insulators for HVDC. The crosslink density, swelling rate and gel content were measured to evaluate the properties of the prepared samples, and mechanical strength (tensile strength, elongation, 100% elasticity) and DC inclined plane tracking performance were evaluated.

다중커널 중첩기법을 이용한 기반 병렬 GPGPU MFCC GPGPU-Based Parallel MFCC using a Multi-Kernel Overlapping

윤상혁(SangHyeuk Yoon) ; 박능수(Neungsoo Park)

Recently, machine learning applications using audio data are increasing. MFCC is widely used as a feature extraction technique to utilize audio data. It takes a long execution time to compute MFCC with a large amount of audio data. Also, a fast MFCC computation method is necessary for real-time inference. In this study, a GPU-based parallel MFCC using a multi-kernel overlap is proposed to fast compute MFCC. The proposed GPGPU-based parallel MFCC is 434 times faster than CPU-based MFCC. When processing 800 audio data, the proposed GPU-based MFCC using multi-kernel overlap was 2.87 times faster than the previous GPU-based MFCC. Besides, in case processing a long single streaming audio data, the proposed one achieved 1.3 times speed-up compared with the previous one.

딥러닝 기반의 동풍 예측 및 강수 분류 Deep Learning Based Prediction for Easterly Wind and Classification of Precipitation

정광희(Kwanghee Jeong) ; 이성준(Sungjun Lee) ; 서기성(Kisung Seo)

Understanding the characteristics of the easterly-related weather phenomena in the eastern coast in Korean Peninsula is very important to analyze abnormal atmospheric phenomena such as heavy rain, heavy snow, and hot-dry wind. As data science techniques have steadily improved, a data driven prediction models are becoming more powerful in the quantitative forecasting weather. In this paper, we apply the LSTM based deep learning method to predict the velocity of the easterly wind around the Korean peninsula. Bi-directional data shape of input data and cascaded LSTM structure are proposed. The modified LSTM based method for prediction of easterly wind is experimented in years form 2013 to 2017 for the Korean Peninsula and East Sea using ERA5 data. Experiments of precipitation classification for Gangwon and Gyeongsang area are executed in years form 2008 to 2017

선형 및 원형 편광 이미지 감지를 이용한 타원형 편광 추정 Estimating Elliptical Polarization with Linear and Circular Polarization in Image Sensing

김진수(Jinsoo Kim) ; 김대은(DaeEun Kim)

Investigating light polarization for a camera image has been a challenging issue. Linear and circular polarization properties have been investigated separately. We introduce how to estimate the elliptical polarization for a camera image. Linear polarization and circular polarization properties are combined to obtain the elliptical polarization. By observing a series of polarization-filtered images, we can estimate the full range of polarization direction as well as the magnitude for each direction for the elliptical polarization. The elliptical polarization can be applied to estimate linear and circular polarization properties together and also measure complex patterns of light on the surface of materials.

휴대용 손가락 측정 기기 및 심장 건강 모니터링 시스템의 사용성 평가 예비연구 Pilot Study on the Feasibility of Portable Fingertip ECG Measurement Device and Heart Health Monitoring System

장승완(Seung-wan Jang) ; 김영(Young Kim) ; 왕창원(Chang-won Wang) ; 호종갑(Jong-Gab Ho) ; 김대겸(Dae-Gyeom Kim) ; 민세동(Se-Dong Min)

As we entered the aging society, personal health has become more important and various technologies for easier use of electrocardiograms (ECG) have been developed. According to the national statistics, heart disease is a major cause of death in Korea. Considering the risk factors and characteristics of heart diseases, constant monitoring of hear conditions is essential for the patients with cardiovascular diseases. This study designed and implemented a portable ECG measurement device (PEMD) that can monitor heart health in everyday life by wearing the device on a fingertip. To evaluate the performance of this portable heart health monitoring system, two different commercial sensors that measure heart rate and blood pressure were selected for correlation analysis. For the feasibility study experiment, 5 healthy volunteers in their 20s were recruited. To induce changes in the subjects’ heart rate (HR) and R-R interval time, 5 experimental conditions (at rest (C), right after running (E1), right after drinking a shot of espresso (E2), 10 minutes after espresso (E3), 20 minutes after espresso (E4)) were randomly selected for each subject. To evaluate PEMD’s detection performance of the R peak and R-R intervals in ECG signals, Bland-Altman plots and ANOVA were used to analyze the differences in the 5 conditions of 5 subjects. Results showed a very high consistency (95%) between the values measured by the three sensor devices, suggesting that PEMD and its monitoring system tested in this study are able to detect meaningful changes in HR, R peak, and R-R interval times after running on a treadmill and taking caffeine. Further study considering personal lifestyle and amount of daily coffee intake on more number of people together with higher level of signal processing and noise filtering functions of the sensor are needed.

태양광 적용을 위한 푸쉬풀 컨버터의 차측 인덕터에 따른 -ESS 2 독립형 전원장치의 효율 특성 고찰 Efficiency Characteristics Review of Stand-alone Power Device with respect to the Secondary Inductor in the Push-pull Converter for PV-ESS

이현재(Hyun-Jae Lee) ; 전해옥(Hai-Ok Jeon) ; 손성용(Sung-Yong Son) ; 손진근(Jin-Geun Shon)

This paper analyzes stand-alone power device efficiency for the presence or absence of an inductor using a single-phase inverter based on a push-pull converter. Experiments were conducted using the push-pull converter based single-phase inverter. It showed higher power conversion efficiency of up to 2.2[%] than when no inductor was present. It is determined that these results can affect power efficiency depending on whether or not there is an inductor on the secondary side of the push-pull converter. When designing an inverter for high efficiency, it is considered that the inductor of the converter can be considered as an important factor.