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

배전계획용 중장기 부하예측 방법에 대한 고찰 A Study on the Mid-Long Term Load Forecasting Method for Power Distribution Planning

조진태(Jintae Cho) ; 김홍주(Hongjoo Kim) ; 유호성(Hosung Ryu) ; 윤영걸(Yeunggurl Yoon) ; 최승연(Sungyun Choi)

This paper explained a mid-long term load forecasting that can reflect the pattern of increasing loads when is planning the installation of lines and facilities in terms of distribution system. In the case of mid-long term models, unlike short-term models, additional social and economic variables are needed, so input variables should be selected through data analysis on input and output relationships. Then, this paper investigated existing used load forecasting models and analyzed the strengths and weaknesses of them. Finally, this paper proposed a method of load forecasting mode for mid-long term distribution planning.

배전계획을 위한 분산전원 예측모델 장단점 및 사례분석 Analysis of Distributed Power Generation Forecasting Model for Power Distribution Planning

조진태(Jintae Cho) ; 김홍주(Hongjoo Kim) ; 유호성(Hosung Ryu) ; 손용주(Yongju Son) ; 최승연(Sungyun Choi)

This paper researches a model that predicts a growth in distributed power, taking into account the recent increase in renewable energy interconnected in the distribution system. This paper describes the current state of distributed power and discusses the process of selecting input and output variables for the forecasting model. The, this paper defines various models that can be used for distributed power forecasting and analyze strengths and examples. Finally, this paper compares the utilization of input variables and forecasting models that can be used as mid to long-term distributed power forecasting.

신재생에너지 확대에 따른 계통관성 영향성 평가 및 안정도 향상 방안에 관한 연구 A Study on the Evaluation of System Inertia Impact and Stability Improvement Plan According to Renewable Energy Expansion

정진용(Jin-Yong Jung) ; 조윤성(Yoon-Sung Cho)

As the environmental pollution problem becomes serious, interest in renewable energy is increasing around the world, and overseas power companies and domestic companies are also planning to expand renewable energy. With the expansion of renewable energy, the system inertia is decreasing due to the decrease of existing synchronous generators and the increase of inverter-based generators. In this paper, the effect of frequency response due to expansion of renewable energy was evaluated and a method for improving frequency stability was simulated. Based on the 9th power supply and demand plan, a scenario was constructed according to the amount of renewable generation, and the effect for changing and installing the synchronous inertia, frequency reserve, governor droop and ESS was analyzed through frequency response simulation in case of simultaneous generator accidents. The frequency response characteristics are analyzed through those methods to confirm that four methods can be applied as stability improvement measures.

정지기 기반 분산형 전원 연계변압기 결선을 고려한 고장해석 Fault Analysis in the Grid with Inverter-Based Distributed Generation Considering the Interconnection Transformer Topology

윤명석(Myungseok Yoon) ; 이문정(Moonjeong Lee) ; 조남훈(Namhun Cho) ; 최승연(Sungyun Choi)

For conducting the fault analysis in a system with distributed generation, the sequence equivalent circuit is used. Due to the characteristics of distributed generation that reverse currents occur, the size of the fault current can be determined by the path where fault current can flow into the fault point in the negative sequence and zero sequence. In this paper, we calculate and compare the fault currents in the system with inverter-based distributed generation considering the topology of transformer winding. From the results, we can analyze the effect of the interconnection transformer in the fault analysis.

마이크로그리드 간 P2P 에너지 거래를 위한 거래 운영 알고리즘 Transaction Operation Algorithm for Peer to Peer Energy Transaction between Microgrids

나의균(Ui-Kyun Na) ; 김준성(Jun-Sung Kim) ; 정재성(Jae-Sung Jung)

Research on microgrids for efficient use of distributed resources and renewable energy is being actively conducted. In domestic, FIT(Feed-in-Traiff) was applied to increase the penetration rate of renewable energy and distributed resources, and research is being conducted to enable efficient operation through predict of power generation, demand forecast and anomaly detection algorithm by combining with AI to improve the stability of MG operation. A electric power transaction model between MGs, like P2P(peer to peer) trading, has been proposed, but it is still incomplete. In this paper, we propose electric power transaction model between MGs. A correlation and dependence between weather elements and loads is performed and a load prediction model is proposed. In addition, we propose a transaction calculation algorithm that determines the transaction unit price for P2P energy transactions between MGs and a power transaction model which is an optimal matching algorithm for transactions between MGs where both sellers and buyers generate profits.

LVDC Microgrid를 위한 웨이브릿 변환 기반 지락고장 검출 Wavelet Transform-based Ground Fault Detection for LVDC Microgrid

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

LVDC Microgrid is a small-scale power grid that can increase the stability and efficiency of power supply in a small area, enabling independent operation and increasing the acceptability of DERs (Distributed Energy Resources). However, this is an ungrounded IT (Isolated Terre) grounding system, and even when a ground fault occurs, there is no fault current path and no significant difference compared to the steady state current, so fault detection is very difficult. WT (Wavelet Transform), an easy tool for transient analysis and signal identification, is to be applied to the detection of ground faults in LVDC Microgrid. In this paper, we propose a Wavelet transform-based ground fault detection method for an ungrounded LVDC Microgrid. By changing the level and order of various MW (Mother Wavelets) using the current collected in the existing pulse injection method, the optimal MW for ground fault detection method is derived. First, an ungrounded LVDC Microgrid is modeled using PSCAD s/w, and ground faults are simulated by varying the fault point and fault resistance. We implement the selected optimal Wavelet transform-based ground fault detection method using Matlab s/w. Finally, performance evaluation is performed through simulation using various collected signals

시간 및 주파수 영역에서 교류 전력선로상 직렬 및 병렬 교류 아크검출기법들에 대한 연구 Study of Series and Parallel AC Arc Detection Techniques on AC Power Lines Based on Time-Domain and Frequency-Domain Approaches

박창주(Chang-Ju Park) ; 김재창(Jae-chang Kim) ; 정재윤(Jae-Yoon Jeong) ; 곽상신(Sangshin Kwak)

In this paper, magnitude and shape of the current flowing on AC line was analyzed when series AC arc and parallel AC arc occur. It was confirmed through experiment that when series AC arc occurs on the AC line, the shape of the current changes more than the magnitude of the current. In addition, in the case of the parallel AC arc, it was confirmed from the experiment that shouldering effect occurred and the line current flowing on the AC line had a distorted current waveform comprising multiple harmonic components, instead of a sinusoidal waveform. To detect series AC arc and parallel AC arc, Zero crossing period (ZCP) and Fast Fourier Transform (FFT) result were used. As a result of analyzing the arc detection capability when the series AC arc and the parallel AC arc occur, in the case of series AC arc, arc detection in time-domain was more effective than in the frequency-domain when the line current was small and detection capability was similar at each domain when the line current was large. In the case of the parallel AC arc, it was confirmed from the experiment that the parallel AC arc was more easily detected than the series AC arc, because the parallel AC arc generates a more distinct current change comparing to the series AC arc.

누적 전하량을 이용한 VRFB 시스템의 용량 추정에 관한 연구 A Study on Capacity Estimation of VRFB System Using Cumulated Charge

임남규(Nam-Gyu Lim) ; 송희욱(Hee-Wook Song) ; 정현홍(Hyeon-Hong Jung) ; 이성준(Seongjun Lee)

VRFB is emerging as a new alternative to ESS batteries applied to renewable power generation systems to solve environmental and resource depletion problems. Currently, lithium batteries are mainly used in ESS, but there is a problem that a fire accident may occur and the lifespan is limited. VRFB has the advantage of being suitable for large-capacity systems because it has a longer lifespan than lithium batteries and has a capacity proportional to the amount of electrolyte. However, there is a disadvantage in that it is difficult to estimate the capacity due to the operating characteristics. Therefore, in this paper, we propose a capacity estimation method by applying the accumulated charge index of VRFB. In addition, the current integration method using the estimated capacity is presented, and the SOC estimation performance results using the long-term charge/discharge cycle experimental data are presented.

에폭시/실리카 콤포지트의 수분 흡수 및 건조에 따른 전기적 유전특성에 관한 연구 A Study on the Electrical Dielectric Properties of Epoxy Micro Silica Composites by Moisture Absorption and Drying

승오탁(O-Tak Seung)

Epoxy-based microcomposites are currently used in a variety of high-voltage-based heavy electric machines (CT/PT, mold transformers, distribution insulators, etc.). Samples were prepared with three types of micro-silica-filled composites (W12est_65wt%, M10_65wt%) and epoxy prototype samples based on epoxy resin. The moisture absorption and drying properties of the three samples were evaluated. The moisture absorption process was performed until the moisture absorption of the sample was saturated in distilled water at 95°C, and the drying process was performed in a drying oven at 105°C until the moisture was saturated without any change. In the evaluation, the relationship between water absorption (M) and dielectric properties was evaluated under the conditions of steady state, moisture absorption and dry conditions. And dielectric characteristics (dielectric constant, dielectric loss and electrical conductivity) were evaluated according to the frequency change at room temperature as an evaluation environment. A large amount of water absorption resulted in a large increase in dielectric constant, dielectric loss, and electrical conductivity. In addition, it was found that the dielectric properties were restored because the dry state was based on the physical bonding with the absorbed water.

Arc Ion Plating 법으로 형성된 TiAlN 박막의 버퍼층에 따른 특성 연구 A Study on the Properties by Buffer Layer of TiAlN Films Deposited by Arc Ion Plating Method

정운조(Woon-Jo Jeong)

In this study, using the AIP method, a TiAlN thin film was grown on a WC-5Co alloy using the buffer layer as TiAl, TiN, and CrN. The preferred orientation according to the XRD analysis showed a pattern with the growth directions of (111) and (110) in almost coating conditions. In the case of the thin film using TiN and CrN as buffer layers, (220) was more prominent than that of other specimens. The adhesion of the TiAlN layer showed a tendency to be affected by the buffer layer and surface roughness. The TiN buffer layer showed the highest adhesion of 130 [N], while the TiAl buffer layer showed a low adhesion of 20[N]. And to examine the high-temperature oxidation resistance, heat treatment was performed. In the case of the specimen using TiN and CrN as buffer layers and coating the TiAlN upper layer for 60 minutes, nitrogen was not replaced with oxygen even at 900[℃] and the nitride thin film was maintained as it is.

능동형 메타물질 표면을 이용한 반사파 주파수 변환 Frequency Conversion of Reflected Wave using an Active Metasurface

한희제(Heeje Han) ; 박순우(Soonwoo Park) ; 김홍준(Hongjoon Kim)

By employing varactor diodes in a metasurface, the surface impedance can be changed by a bias voltage, as the resonant frequency altered. In order to convert the frequency of a reflected wave, 360° reflection phase variation is required. This study presents the related theory and demonstrates the frequency conversion through the experimental results. We achieved the reflection frequency conversion which is increased by 50 kHz more than the incident wave of 2.65 GHz, and its SFDR and conversion loss are 7.38 dBc and 5.62 dB, respectively. The proposed metasurface can contribute an efficient improvement in anti-RADAR system fields.

적대적 생성 신경망을 사용한 유기 행동 검출 Abandonment Behavior Detection Using Ganerative Advesarial Networks

정광희(Kwanghee Jeong) ; 서기성(Kisung Seo)

Abandoned luggage items in public areas will be a potential threat caused by bombs or biological warfare. We present a method for real-time automatic detection of abandoned luggage in video captured by surveillance cameras. Most works for abandoned objects detection use a preliminary step to detect foreground regions or objects, and use various techniques including deep learning to distinguish between abandoned luggage items and other objects. These object detection-based methods require direct learning of characteristics of different types of objects. However, it is difficult to detect a new type of unlearned object, and there is insufficient detection of the instantaneous situation in which an object is abandoned. In order to solve these problems, we propose reconstruction-based anomaly detection to identify unusual patterns that do not conform to expected behavior such as abandoning objects. The approach is comprised of two stages - first, static object detection based on YOLOv4 and second, abandoned luggage recognition based on anomaly detection using Ganerative Advesarial Networks (GAN). We demonstrate the proposed GAN-based anomaly detection for abandonment behavior by performing experiments on Abnormal Event CCTV Video Dataset.

한우 체중 추정을 위한 딥러닝 기반의 영상 분할 알고리즘 적용 Application of Deep Learning-based Image Segmentation Algorithm for Korean Cattle Weight Estimation

이창복(Chang-bok Lee) ; 조현종(Hyun-chong Cho)

Image-based weight measurement is a novel approach for reducing the manpower consumption of Korean cattle farms without causing stress to animals. In this paper, the weight was predicted by measuring the area of Korean cattle and estimating the weight correlation factors. Using the histogram sum from the acquired image data, repeated data was removed and learning efficiency was improved, and the Mask R-CNN model was trained with the selected data. Mask R-CNN uses RoIAlign and is a model capable of precise segmentation by replacing the Softmax activation function of FCN with sigmoid. The result of territorial division of Korean cattle in the background of an actual barn reached an average precision of 0.88 with confidence standards of average IoU 0.88 and 0.85. The size of the mask obtained as a result of segmentation had a maximum correlation of 0.88 with the body weight, and the minor axis length and major axis length of the optimal ellipse calculated through the mask had a correlation of 0.35 and 0.56, respectively. The weighted average of the error rate of the weight prediction results using these three weight correlation factors was 0.07.

배전 자산 상태예측 모델 성능 개선을 위한 기계학습 데이터 관리 시스템 개발 Development of Machine Learning Data Management System for Improving Electric Distribution Asset Condition Prediction Model

이해성(Hae-Sung Lee) ; 이병성(Byung-Sung Lee)

The predictive information provided through the electric distribution asset failure prediction model is used as key information for transmission and distribution investment plans in consideration of new and renewable energy, distribution line capacity analysis, or distributed power location analysis. The predictive performance of the distribution asset failure prediction model is affected by the quality of the training data. Also, due to the characteristics of the highly volatile electrical distribution line, the electric distribution asset failure prediction model should maintain the predictive performance at a certain level by performing periodical machine learning on newly generated data. In this paper, we develop an automated system for machine learning data quality management in order to continuously manage machine learning data and efficiently improve electric distribution asset condition prediction model. As a result, our system make it possible to effectively shorten the development time and the cost of the electric distribution asset failure prediction model through the provision of high-quality data for training the prediction model. And the system developed in this paper will be able to improve the accuracy of electric distribution asset condition prediction model.

RGB영상과 깊이영상을 이용한 3D 휴먼 골격 키포인트 탐지 3D Human Skeleton Keypoint Detection Using RGB and Depth Image

정근석(Jeongseok Jeong) ; 박병준(Byeongjun Park) ; 윤경로(Kyoungro Yoon)

As computing technology advances, tasks those are used to judge human behavior with the eyes are turning into tasks those computers try to judge human behavior through keypoint detection. Accordingly, in this paper, we propose a 3D human skeleton keypoint detection system using RGB and Depth images acquired by Azure Kinect's RGB camera and Depth camera, respectively. The 3D human skeleton keypoint detection system proposed in this paper detects 2D human skeleton keypoints from RGB images, and uses depth value acquired to project the detected 2D human skeleton keypoints onto the depth image. However, when detecting 3D human skeleton keypoints in such method, the human skeleton keypoints are projected onto the surface of human body. To solve this problem, the skeleton keypoints provided by Azure Kinect is used to calibrate the depth value of the extracted keypoints.

다수의 얼굴 인식을 통한 자동출석체크 시스템 Automatic Attendance Check System Through Multiple Face Recognition

이상훈(Sang-Hun Lee) ; 윤경로(Kyoung-Ro Yoon)

Non-contact biometric identification technology is once again receiving social attention these days when untact technology is required due to the Covid-19. Face recognition technology is being used in a variety of platforms such as airport immigration systems, hospital patient management systems, financial self-authentication systems, criminal suspect detection systems, and personal authentication systems for mobile devices, and is showing its effectiveness. In this paper, multiple face recognition technology is applied to the automatic attendance system. Unlike when only one person is recognized, multiple face recognition results in lower accuracy and slower processing speed. In this paper, a frontal face detection algorithm is proposed. Using the frontal face detection algorithm, only the frontal face was used for recognition, and when 36 people were recognized, 97.2% accuracy was achieved. In addition, we proposed an erasing multiple face recognition method and increased the average number of frames processed per second as the recognition completion rate increased

재진입 표적추적을 위한 복수 레이더 2단계 정보융합 기법 Two-Stage Multi-radar Data Fusion for Re-entry Target Tracking

정보영(Boyoung Jung) ; 이찬석(Chan-Seok Lee) ; 서의석(Ui-Suk Suh) ; 나원상(Won-Sang Ra)

This paper proposes a two-stage track-to-track fusion algorithm for re-entry target tracking using multiple radars. The existing track-to-track fusion strategy relying only on the kinematic information shows unreliable target tracking performance when the target of interest is adjacent with other objects. To prevent tracking performance degradation due to false track fusion, the track paring hypothesis is evaluated using both the feature data and the kinematic data provided by radars. A recursive Bernoulli filter is desinged to discriminate the target identity by fusing binary decision data which correspond to the most probable track pairing hypothesis. Since our approach exploits the statistical property of the available decision data, it can enhance the target tracking and identification performance. Through the computer simulations for a typical re-entry target tracking scenario, the effectiveness of the suggested data fusion scheme is demonstrated.

다중 레이더 배치를 위한 폐쇄형 표적추적 성능지표 산출 Closed-Form Target Tracking Performance Measure for Multi-Radar Placement

조형찬(Hyung-Chan Cho) ; 정보영(Bo-Young Jung) ; 서의석(Ui-Suk Suh) ; 김영원(Young-Won Kim) ; 나원상(Won-Sang Ra)

This paper suggests the closed-form target tracking performance measure which is necessary for formulating a multi-radar placement problem. It is well-known that there is no analytic solution to the DRE(differential Riccati equation) of a nonlinear target tracking filter, which makes the problem intractable. As a fundamental resolution to this technical issue, the line-of-sight frame equivalents of the given nonlinear filter are exploited. For such case, unlike the existing numerical method, the analytic solutions to the corresponding DREs can be readily derived. This idea was based on the fact that the Fisher information is preserved regardless of the coordinates system in which a tracking filter is designed. The proposed approach allows us to clearly describe the tracking performance measure as a function of the radars’ positions as well as their specification. Simulations confirm that our scheme is beneficial for reducing the inherent complexity of a multi-radar placement problem.

이선아크 최소화를 위한 직류 강체전차선로 도시철도차량 집전방식에 관한 고찰 A Study on the Current Collecting Method of Urban Railroad Vehicle on DC Rigid Bar for Minimizing contact loss and Arc

박원찬(Weon-Chan Park) ; 이동호(Dong-Ho Lee) ; 최용은(Yong-Eun Choi) ; 강정원(Jeong-Won Kang) ; 김재문(Jae-Moon Kim)

In this paper, when the single-arm pantograph is applied as a single current collecting method, the interface problem between the contact wire and the pantograph was derived and the cause of this was considered. In the case of a test driving of a new urban railway vehicle consisting of a single-arm pantograph (3 units) as a single current collecting method, arc melting damage to the contact wire and pantograph occurred due to a contact loss. On the other hand, when the parallel current collecting method was applied and the single arm pantograph was tested 4 times, it satisfies within 1% of the allowable standard for the contact loss rate. Based on these results, it is suggested that the parallel current collecting method is suitable for the pantograph of an urban railroad vehicle operating on the DC rigid bar.

전차선로 해빙시스템을 위한 발열시험을 통한 전차선 온도상승 특성평가 Evaluation of temperature rising characteristics for catenary deicing system through heating test

정호성(Hosung Jung) ; 김주욱(Joouk Kim) ; 김형철(Hyungchul Kim)

This paper analyzes the temperature rising characteristics of the deicing catenary system in winter. For the composition of the deicing system, the deicing system is constructed according to the combination of various trolley wires and messenger wires applied at Korea. To compare of temperature rising characteristics, the current distribution ratio between trolley wire and messenger wire are measured and the wire temperature is measured according to the deicing current using a catenary heating test device. In case of current distribution ratio test, the current distribution ratio is measured in 82.1%: 18.9% similar to the theoretical ratio in DC supplying. As a result of temperature rising test, the temperature of Cu 150 ㎟ is increased by 1.26 °C/m at a wind speed of 0.5 m/s and 0.92 °C/m at 2.0 m/s when supplying DC 350 A, And in case of Bz 65 ㎟, when DC 95 A is supplied, the temperature rose at 0.74° C/m at 0.5 m/s, and 0.56 °C/m at 2.0 m/s. In the comparison between the theoretical equation and test result, the difference is at most 0.7 ℃. Therefore, it is confirmed that it would be appropriate to use the theoretical equation in the design of the deicing system.

도시철도 부하 패턴 기반 ESS 최대 용량 산정 및 동작 알고리즘 연구 Study on ESS Maximum Capacity Calculation and Operation Algorithm based on Load Pattern of Substations in Urban Railway

윤치명(Chi-Myeong Yun) ; 조규정(Gyu-Jung Cho) ; 김형철(Hyungchul Kim) ; 김철환(Chul-Hwan Kim) ; 정호성(Hosung Jung)

Abstract - In this paper, we introduce the method of reducing only the morning peak of the ESS and the method of calculating the maximum ESS capacity according to the method of reducing the entire day by using the characteristic that the load of the urban railway substation shows a different load pattern depending on weekdays, weekends, and holidays. Furthermore, an operation method suitable for urban railroad is introduced using the operation algorithm for each of the five points of time of the ESS according to the load pattern. To verify the introduced maximum capacity calculation method and ESS operation algorithm, power analysis program, PSCAD/EMTDC was used

태양광발전 및 압전에너지 하베스팅 하이브리드 전원시스템 개발 Development of Hybrid Power System using Photovoltaic Generation and Piezoelectric Energy Harvesting Module

이동희(Dong-Hee Lee) ; 최형진(Hyung-Jin Choe) ; 김용욱(Yong-Wook Kim) ; 김동완(Dong-Wan Kim)

This paper presents a hybrid power system using PV(Photovoltaic) and piezoelectric energy harvesting modules. In the proposed hybrid power system, the main power is supplied by the PV, and the assistant power can be added by the piezoelectric energy harvesting modules. Furthermore, the buck-boost dc-dc converter for the PV and the piezoelectric energy harvesting modules are designed for the parallel connection of two power inputs. For the parallel connection of multi-source power system, the different MPPT(Maximum Power Point Tracking) curves are selected by the input source in the proposed power system. The outputs of two converters are parallel connected to the battery. In the simulation and the experimental results show the effectiveness of the proposed hybrid power system using PV and piezoelectric energy harvesting modules.

리액터 기동 유도전동기의 가속 시간에 관한 연구 Research on Acceleration Time of Reactor Starting Induction Motor

김종겸(Jong-Gyeum Kim)

Induction motors have a simple structure, easy maintenance, and constant speed operation, so they are most often used as driving equipment for fluid loads such as pumps. Induction motors have a disadvantage that voltage drops occur due to high current generation during startup. In order to overcome this problem, various starting methods are applied according to the motor capacity. In the case of medium and large induction motors, the reactor starting method is widely applied. The calculation of the acceleration time by the reactor starting is important for the electrical quality analysis of the system. The calculation of acceleration time is complicated because it must go through the process of differential and speed integration for the torque difference between the motor and the load. Therefore, in this study, we compared and analyzed the calculation of the acceleration time through the introduction of the simplified calculation of the acceleration torque and the simulation of the actual model through the electromagnetic transient analysis program.