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

2 - 모선 계통의 위상각 없는 전압 전력방정식 An Exact Voltage-Power Equation with no Angle Terms for an AC Two-bus System

https://doi.org/10.5370/KIEE.2020.69.5.637

이상중(SangJoong Lee) ; 김주철(Ju-Chul Kim)

This paper presents a voltage-power equation for a two-bus system with a complex load S=P+jQ connected through a transmission line with admittance Y=G-jB. The proposed formula is represented by the magnitudes of bus voltages, active and reactive load power and transmission line admittance. No angle terms are included in the formula and no complex number calculation is needed. Sample calculations for bus voltages using proposed formula show exact solutions, which are compared with existing calculation methods.

V2G 기술을 활용한 배전계통 신뢰도 향상에 관한 연구 A Study on the Improvement of Distribution System Reliability using V2G Technology

https://doi.org/10.5370/KIEE.2020.69.5.644

오병찬(Byeong-Chan Oh) ; 김성열(Sung-Yul Kim)

Reliability is an important indicator that determines the quality of service provided to consumers. Reliability evaluation is essential in power system planning and operation perspective in oder to stably supply high quality electricity for consumers with continuous increase in power demand. Therefore, this paper proposes a technique using EV to improve the reliability of the distribution system. in addition, the load priority is calculated to minimize ECOST according to the failure section per time. this paper presents a method to improve the reliability of the distribution system by calculating the optimal location of EVs through the hourly load priority

강원지역 재생에너지원의 기반 데이터를 이용한 영향 평가 FRT Influence Evaluation using PMU based Data of Renewable Energy Sources in Gangwon Area

https://doi.org/10.5370/KIEE.2020.69.5.650

이경민(Kyung-Min Lee) ; 박철원(Chul-Won Park)

Recently, as the grid connection capacity of renewable energy sources in Gangwon area is rapidly increasing, research on the construction of monitoring and control system based on real-time precision data based on time synchronization has been conducted. This paper is about FRT influence evaluation of renewable energy sources using PMU and F/R based data. First, the PMU and F/R based monitoring analysis system established in wind-linked Hoenggye substation and solar-linked Yeongwol substation will be briefly introduced. Next, the format of the time-synchro based data collected is reviewed. It also briefly describes the subject and principle of domestic FRT application. Finally, we describe whether FRT regulation of renewable energy source is satisfied using PMU based data.

FRT를 고려한 마이크로그리드 보호기기의 적응형 이중 정정 방법에 관한 연구 A Study on the Adaptive Dual Setting Method of the Microgrid Protective Devices Considering FRT

https://doi.org/10.5370/KIEE.2020.69.5.657

이우식(Woo-Sik Lee) ; 김지수(Ji-Soo Kim) ; 송진솔(Jin-Sol Song) ; 신광수(Gwang-Su Shin) ; 김철환(Chul-Hwan Kim)

Microgrid (MG) has emerged as an effective way of distributed generations (DGs) integration. MGs can be operated as a grid-connected or islanded mode. During the fault situation, fault current magnitudes will vary depending on the MG operating mode. Consequently, protecting the MG using conventional methods is a challenging problem. Also, the Fault Ride Through (FRT) concept has not been introduced in the Korean distribution system. FRT is a grid code to maintain the connection of the DG for a while and to support the distribution system by injecting a reactive power when the fault occurs in the power system. Therefore, in this paper, the relay setting values of the MG connected to the DG is proposed considering the FRT. Moreover, using the Hilbert-Transform (HT) of operation mode about the energy of power flow, and adaptive dual setting method is proposed. Finally, the proposed method is validated using the Electro-Magnetic Transients Program (EMTP).

가상관성을 적용한 분산전원의 동 특성 분석 Transient Response Characteristics Analysis of Distributed Generation based on Virtual Inertia

https://doi.org/10.5370/KIEE.2020.69.5.664

유형준(Hyeong-Jun Yoo) ; 김경훈(Gyeong-Hun Kim) ; 전진홍(JinHong Jeon)

The distributed generations(DGs) such as wind turbine, photovoltaic(PV), fuel cells, and energy storage system(ESS) are normally connected through power conversion system interface to power system. The high penetration of DGs will bring significant challenges to the power system. The power conversion systems have no rotating inertia or damping mechanism, thus the inertia and damping can’t be provided to power system, which makes the power system have a low inertia, and weakness the frequency stability and regulation capability. In addition, there is a constant voltage constant frequency(CVCF) converter in microgrid. So, if a CVCF converter fails, the system can be shut down. In this paper, the virtual inertia was applied to the power conversion system of ESS and PV system for analyzing transient response characteristics when the disturbance occur in microgrids. Especially, when the microgrid operation mode was switched from the grid-connected mode to the islanded mode and CVCF converter fail, the transient response has been compared under with virtual inertia and without virtual inertia. The simulation results are presented using MATLAB/SIMULINK.

매입형 영구자석 모터의 코일형상에 따른 저항 분석 Analysis of AC Resistance according to Coil Shape of an Interior-Permanent Magnet Motor

https://doi.org/10.5370/KIEE.2020.69.5.671

이기주(Gi-Ju Lee) ; 이호영(Ho-Young Lee) ; 이의천(Eui-Chun Lee) ; 박수환(Soo-Hwan Park) ; 권순오(Soon-O Kwon) ; 최홍순(Hong-Soon Choi) ; 서장호(Jangho Seo)

As the motor becomes smaller, it is an effective way to consider the AC resistance when analyzing. Motor analysis is usually interpreted as a stranded type. If it is a low speed analysis with the type, the AC resistance cannot be considered. Therefore, in this paper, we analyze the AC resistance of Round-Coil, MSO-Coil, and Stranded models and check the difference between them.

원가 절감을 위한 분할 접합용 태양전지의 전극 패턴 설계 Electrode Pattern Design of Dividing and Bonding Solar Cells for Cost Reduction

https://doi.org/10.5370/KIEE.2020.69.5.677

오원제(Won-Je Oh) ; 박지수(Su-Ji Park) ; 이재형(Jea-Hyeong Lee)

Shingled PV modules are manufactured by dividing and bonding solar cells. This method uses a laser to cut the solar cell and bond the solar cell using Electrically Conductive Adhesives (ECA). This module has a bus bar-free structure that can eliminate shadowing loss and have high output. However, this module is more expensive than conventional modules because it has additional processes. Therefore, it is essential to reduce the unit cost to secure the economical efficiency of the shingled module. We focused on the metal grid of the solar cell to reduce the cost. The metal grid for solar cells was designed to reduce the amount of silver paste used. Conventional-type grid and paste reduction-type grid were simulated and compared. The metallization of the solar cell used the screen printing method. The weight of the silver paste of the produced solar cell was measured. As a result of comparing with the paste reduction-type pattern and the conventional-type pattern, the paste was reduced by 43.556%.

자산관리시스템을 위한 변전소 변압기 수명 계산 방법 Life Evaluating Method of Substation Transformers for Asset Management System

https://doi.org/10.5370/KIEE.2020.69.5.682

권동진(Dongjin Kweon) ; 김용현(Yonghyun Kim) ; 이온유(Onyou Lee) ; 강형구(Hyoungku Kang) ; 이준호(JuneHo Lee)

A method for evaluating replacement life of substation transformers required to build an asset management system is presented. The electrical utilities are replacing the transformers at the time when the failure rate of the transformers increases to prevent sudden failures. In this study, the mean time to failure of the transformers was defined as the technical end of life, and 52 years was calculated by analyzing the cumulative density function of the failure data. The replacement time of the transformers was defined as the strategic end of life, and 32 years was calculated by failure rate (Bathtub curve) analysis. These lives of the substation transformers are calculated based on 154kV three-phase transformers with sufficient failure data, and the lives of 154kV single-phase transformers applied since 1995 should be recalculated when failure data is sufficiently collected. In addition, the replacement life of the transformers should be strategically decided according to the business value of the company and the risk associated with the failure of the transformer.

LERP IT2TSK 기반 퍼지 예측시스템을 이용한 일별 최대 전력부하 예측 Daily Peak Electric Power Load Forecasting using LERP-based IT2TSK Fuzzy Prediction System

https://doi.org/10.5370/KIEE.2020.69.5.688

방영근(Young-Keun Bang) ; 이철희(Chul-Heui Lee)

Analyzing and forecasting the daily peak electric power load in summer season in Korea, which changes rapidly, is very important because it is very closely associated with the maximum load value and electric power reserve rate. To properly deal with patterns and uncertainty hidden in these data, we suggest an IT2TSK FPS of which the LERP and IT2TSK FLS are used. The LERP can provide more information to analyze the patterns of the data and to identify the parameters of each rule, and IT2TSK FLS can make it handle properly the uncertainty due to the rapidly changing data. In each design step, two fuzzy sets, KM algorithm, and LSM are used respectively and simply. With these method, not only the design process of the prediction system can be simple, but also the patterns and uncertainty can be treated effectively. Finally, through forecasting the daily peak electric load data in summer season, 2014 and 2015, this paper verifies the performance and usefulness of the proposed design method.

전방향 이동이 가능한 차동 구동 로봇 A Differential Drive Mobile Robot with Omnidirectionality

https://doi.org/10.5370/KIEE.2020.69.5.698

김민찬(Min Chan Kim) ; 성영휘(Young Whee Sung)

In this paper, we propose a new type of differential drive mobile robot that has omni-directional mobility. The proposed mobile robot has two wheels which can be controlled independently by two separate motors. These motors are in a housing, to which a shaft is perpendicularly attached. This shaft can be connected or disconnected to the robot body by using an electric brake which is attached to the robot body. When the shaft is connected to the robot body, the robot is same to conventional differential drive mobile robot. When the shaft is disconnected to the robot body, the wheels of the robot can rotate without causing any motion of the robot body. The proposed mobile robot can show omnidirectionality by properly controlling the electric brake and the two motors. Generally, omni-directional mobile robot require specially designed omni-directional wheels. However, the proposed robot adopts ordinary wheels so, it can move with high speed and can be employed in outdoor applications. We verified that the proposed mobile robot has omni-directionality by several experiments.

실시간 산불 모니터링을 위한 이벤트 처리 기반 저전력 저비용 무선 센서 네트워크 Event Processing-based Low-Power Low-Cost Wireless Sensor Network for Real Time Wildfire Monitoring

https://doi.org/10.5370/KIEE.2020.69.5.706

최상호(Sangho Choe) ; 유정화(Jeong-Hwa Yoo) ; 폰수게수라니(Ponsuge Surani Shalika Tissera) ; 강조인(Jo-In Kang) ; 양희경(Hee-Kyung Yang)

In this paper, we propose an event-driven low-power low-cost wireless sensor network (WSN) for real time wildfire monitoring. The proposed system will be mainly deployed and operated in a fire alert (or monitoring) area that could be divided into several sectors, each sector consisting of a controller (AP: access point) and its controlled nodes. For the evaluation of the proposed system, we implement a test bed (TB) using Arduino Uno board that has a smoke detector and a ZigBee module. The presented sensor nodes that are operated in power saving mode (PSM) during most of idle period have a longer battery life. Once a node detects smoke sample (which is termed as sensData) that is larger than a given threshold, it will generate a transmission message, called msgSensInfo (msgSensInfo1 for node fusion or msgSensInfo2 for AP fusion), and transmit that message to the AP and then the remote server. When a sensing event or a wake-up message event occurs, the presented node system is woken up from PSM, and gives a prompt (real-time) response including sensing message msgSensInfo generation and its transmission to AP. The proposed system has a data fusion algorithm collecting and synthesizing either multiple spatial samples (in case of AP fusion) or multiple time samples (in case of node fusion) that improves the fire detection performance further. Therefore, compared to existing low-cost WSN schemes, the proposed low-cost WSN scheme would be better at the perspective of real time performance, cost-effectiveness, and life-cycle such that it would be a good candidate for wildfire prevention as well as initial fire fighting.

성긴 시스템 환경에서 빠른 수렴 속도 달성을 위한 새로운 인접 투사 알고리즘 A Novel Affine Projection Algorithm for Fast Convergence of Sparse System

https://doi.org/10.5370/KIEE.2020.69.5.719

유진우(JinWoo Yoo)

This paper proposes a novel affine projection algorithm (APA) based on L0-norm constraint for improving the convergence rate in a sparse system. The proposed APA guarantees a fast convergence rate owing to the effect of L0-norm constraint. Experimental results confirm that implementing the proposed APA enhances the performance of adaptive filter for sparse system identification.

UAV환경에서 스테레오 비전을 활용한 딥러닝 기반 시차맵 추정 Deep Learning based Disparity Map Estimation using Stereo Vision for UAV

https://doi.org/10.5370/KIEE.2020.69.5.723

이예지(Yegi Lee) ; 윤경로(Kyoungro Yoon)

Recently, UAVs(Unmanned Aerial Vehicles) are used in various industries such as military, transportation, agriculture and reconnaissance. However, it is very likely to cause an accident such as a collision or fall, due to external environmental factors, and research is needed to increase safety. To prevent such risks, UAVs are often equipped with sensors such as laser scanners or cameras. But laser scanners are very heavy and consume high power. Stereo cameras are much lighter and use less power than laser scanners, making them ideal for use in small UAV environments. Therefore, in this paper, we introduce a method for estimating the disparity map using a stereo camera and deep learning without using a LiDAR(Lighting Detection And Ranging). The proposed method constructs semi-supervision based neural network to estimate disparity maps. This algorithm can estimate more precise disparity maps than existing matching algorithms.

Hellinger 거리를 이용한 다중 이동 객체 추적 방법 Multiple Moving Object Tracking Method Using Hellinger Distance

https://doi.org/10.5370/KIEE.2020.69.5.729

류권무(Kwon Moo Ryu) ; 한영진(Young Jin Han) ; 주영훈(Young Hoon Joo)

In this paper, we propose a novel multi-object tracking method using the Hellinger distance as a method for continuously recognizing and tracking moving objects. To do this, we propose method for recognizing moving objects using GMM, label merging, and histogram matching. And then, the moving object is continuously tracked by determining the overlapping of the moving object, analyzing the moving direction, and analyzing the similarity based on the Hellinger distance. Finally, the propose method is demonstrated its availability and feasibility through real experiments.

자가진단과 자산관리법을 통한 변압기 잔여수명 예측에 대한 연구 A Study on the Prediction of Residual Life of Transformer through Self Diagnosis and Asset Management

https://doi.org/10.5370/KIEE.2020.69.5.738

이현우(Hyun-Woo Lee) ; 장경배(Kyung-Bae Jang)

This paper presents a residual life prediction method that combines a self - diagnostic evaluation of a transformer with An Approach to Power Transformer Asset Management Using Health Index. The asset management method analyzes the health of the transformer through a variety of precise diagnoses and predicts the remaining service life. The self-diagnostic evaluation analyzes the soundness of the electrical equipment and proposes precise diagnosis and emergency repair. By combining the self-diagnostic evaluations with the asset management, more accurate soundness analysis and residual life prediction can be achieved than before. Also, by changing evaluation score of the self-diagnostic, confirm that the causality between health and the life of the transformer.