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Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers
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분산전원 수용률 향상을 위한 전압 및 무효전력 제어 알고리즘 Voltage and Reactive Power Control Algorithm to Improve Hosting Capacity of Distributed Generation

https://doi.org/10.5370/KIEE.2022.71.11.1533

고석일(Seok-Il Go)

In this paper, a global measurement-based voltage and reactive power control algorithm using a linear equation is proposed. For linear optimization, the voltage control characteristics of the voltage controllers of the distribution system are expressed in a linear form. It was divided according to the characteristics of each control device and expressed in a linear expression, and the final voltage was expressed as the sum of each control device from the principle of superposition. The voltage equation expressed as a linear expression was formulated as a quadratic programming method (QP). The optimal solution was derived using the mixed integer quadratic programming (MIQP, Mixed-Integer Quadratic Programming), which is a mixed integer nonlinear programming (MINLP), for the objective function expressed by the quadratic programming method. The proposed algorithm was verified through simulation

하이브리드 고장률을 이용한 태양광 발전 시스템의 설비 유지보수 시점 결정에 관한 연구 A Study on Determination of Facility Maintenance Timing for Photovoltaic System Using Hybrid Failure Rate

https://doi.org/10.5370/KIEE.2022.71.11.1541

남태양(Tae-Yang Nam) ; 윤광훈(Kwang-Hoon Yoon) ; 문원식(Won-Sik Moon) ; 김재철(Jae-Chul Kim) ; 신중우(Joong-Woo Shin)

Recently, the PV(Photovoltaic) penetration has increased rapidly in Republic of Korea. And quite a lot of PV systems has been installed in small capacity. And the PV systems have difficult to have its own maintenance planning system due to difficulties in securing economic feasibility. Therefore the maintenance planning method for PV systems that can be generally applied are attracting considerable. Although the age replacement policy, one of the traditional RCM(Reliability Centered Maintenance) methodology, is excellent for determining the replacement cycle of facilities. But It evaluates that the facilities as good as new after maintenance. In this paper, the maintenance planning method for PV system facilities based on RCM has been proposed. To evaluate the failure rate after the imperfective maintenance, hybrid model has been applied. In addition, the economic feasibility of maintenance has been compared by considering investment cost and loss of the implementation for preventive maintenance policy.

배전계통에 있어서 태양광전원의 수용성 향상을 위한 SVR 및 ESS의 운용방안 An Operation Strategy of SVR and ESS to Enhance Hosting Capacity of PV Systems in Distribution System

https://doi.org/10.5370/KIEE.2022.71.11.1552

이세연(Se-Yeon Lee) ; 김지명(Ji-Myung Kim) ; 한병길(Byeong-Gill Han) ; 김기영(Ki-Young Kim) ; 노대석(Dae-Seok Rho)

According to the 3020 RE policy of korean government, renewable sources including PV and WP systems have been actively installed and operated in distribution systems. However, if large-scale PV systems are interconnected in distribution system, hosting capacity in PV systems may be reduced because they may violate the allowable voltage limits(220±13V) due to reverse power flow of PV systems. Under these circumstances, this paper proposes the operation algorithms of SVR(step voltage regulator) and ESS(energy storage system) to improve the hosting capacity of PV systems. Specifically, optimal LDC setting values are obtained by calculation algorithm of LDC setting values for SVR using the Least-squares method that minimizes the error for the entire time interval based on the distribution characteristics of upper and lower limits for the sending voltage of SVR considering the reverse power flow by PV systems. In addition, the minimum introduction capacity of ESS is obtained by evaluation algorithm of the required capacity of ESS to maintain the customer voltage within the allowable voltage limits for each time interval. From the simulation results, it is confirmed that the proposed algorithms are useful and practical tool to improve the hosting capacity of PV system.

동해안 지역 재생에너지원 접속에 따른 과도안정도 여유 분석 및 발전제약 산정 연구 A Study on Analysis of Margin of Transient Stability and Calculation of Power Generation Constraints According to Renewable Energy Sources in the East Coast

https://doi.org/10.5370/KIEE.2022.71.11.1564

정인주(Injoo Jeong) ; 오승찬(Seungchan Oh) ; 송지영(Jiyoung Song) ; 구현근(Hyunkeun Ku) ; 배문성(Moonsung Bae) ; 곽은섭(Eun-Sup Kwak) ; 민재현(Jae-Hyun Min) ; 신정훈(Jeonghoon Shin)

Increasing renewable energy resources can lead to critical stability problems in power systems. Specially in Korean power system, since the power generation complex is concentrated on the coast, there are constraints on transmitting to the load. If a connection of renewable energy resources near generator buses continues to grow, specially in the east cost, transient stability problems may arise due to shortage of transmission lines. Therefore, it is necessary to evaluate how much renewable energy access at each site can affect the power system by some stability index such as critical clearing time. This paper shows how to assess or calculate the margin of dynamic stability and verify the methodology through assessment of a practical power system. Based on the methodology, this paper analyzes the practical system and draws conclusions.

행위자-기반 기법을 이용한 불완비정보 전력시장에서의 균형상태 해석 Agent-Based Nash Equilibrium Analysis on Electricity Market with Incomplete Information

https://doi.org/10.5370/KIEE.2022.71.11.1571

이광호(Kwang-Ho Lee)

This paper presents a methodology of finding Nash Equilibrium (NE) by using an agent-based approach. A game theoretic method to solve the NE is applicable under the assumption of complete information on the electricity market and the participants. In the real market, however, Generation Companies (Gencos) submit supply bids to the Market Operator (MO) with incomplete information. Agent-based approaches are more suitable for the electricity market with incomplete information than the microeconomic method. In this paper, the payoff matrices are used as key information for deciding strategic bids. In the process of repeated auction with incomplete information, each agent can calculate efficient partial payoff matrix by using the results after each auction. The Best Response (BR) technique is applied to the partially constructed payoff matrices for finding the NE. The simulation process is divided into three modes, first is a preliminary step of constructing the payoff matrices, second is a step of tracking the NEs, and the third is a step of applying to the varying load pattern. The simulation results show that this methodology is applicable to the electricity market with incomplete information.

주말 전력수요 예측을 위한 머신러닝 알고리즘 적용 연구 A Machine Learning Based Algorithm for Short-Term Weekends Load Forecasting

https://doi.org/10.5370/KIEE.2022.71.11.1578

심상우(Sang Woo Shim) ; 이다한(Da Han Lee) ; 노재형(Jae Hyung Roh) ; 박종배(Jong-Bae Park)

This paper presents a methodology for forecasting short-term weekends hourly loads using feature selection and hyperparameter. It starts with setting features necessary for forecasting loads and the peculiarity is that weather data divided by region are used as weather data across the country based on the number of people in each region. In order to improve the performance of forecasting, important variables are extracted through the SHAP(SHapley Additive exPlanations) method and Pearson Correlation Coefficient, and then optimized XGBoost parameters are found and applied through grid search. This paper tried to predict for every weekend of 2021, and the paper shows results for four weekends in September, or eight days. Errors are expressed through NMAE, MAPE and NRMSE to show the performance of the prediction model in various ways. Later studies will be conducted on forecasting algorithms for special days such as holidays as well as general weekends, and sensitivity analysis for each feature will also be considered.

방열판의 온도를 이용한 IGBT 모듈 및 공랭시스템의 상태 모니터링 Condition Monitoring of IGBT Module and Forced Air Cooling System Using Heatsink Temperature

https://doi.org/10.5370/KIEE.2022.71.11.1585

조인혁(In-Hyck Cho) ; 김건영(Geon-Young Kim) ; 김용욱(Yong-Uk Kim) ; 김중균(Joong Kyun Kim)

The insulated gate bipolar transistor (IGBT) is one of the weakest components in the converter. Therefore, high reliability is very important in terms of price. However, it is very difficult to monitor IGBT’s condition because it is not easy to directly measure the junction temperature in practice. And cooling system also important element of converter, but additional method should be used to monitor cooling system. This paper proposes a method of monitoring the condition of IGBT module and cooling system at once by heatsink temperature that is easy to measure. Advantage of proposed method is very easy to implement without interfering operation of IGBT. Simulation tests were conducted to verify the effectiveness and accuracy of this proposed method. The results show that the proposed method can improve accuracy of the reliability of power converter.

극/슬롯 조합에 따른 영구자석 동기전동기의 전자기 및 NVH 특성 비교 분석 Comparative study of electromagnetic and NVH characteristics of permanent magnet synchronous motors according to pole/slot combinations

https://doi.org/10.5370/KIEE.2022.71.11.1591

이영근(Young-Keun Lee) ; 방태경(Tae-Kyoung Bang) ; 조성태(Seong-Tae Jo) ; 김수민(Su-Min Kim) ; 이정인(Jeong-In Lee) ; 이훈기(Hoon-Ki Lee) ; 신경훈(Kyung-Hun Shin) ; 최장영(Jang-Young Choi)

In this paper, electromagnetic noise sources of permanent magnet synchronous motors with 8-pole 9-slot and 12-slot fractional slot concentrated windings were analyzed through finite element analysis, and the radiated noise/vibration levels were compared through structural-acoustic analysis. Electromagnetic noise sources are classified into cogging torque, torque ripple, magnetic pull force, and unbalanced magnetic force, and the main values of electromagnetic excitation forces are different according to the pole/slot combination. In particular, the effect of electromagnetic noise sources on vibration/noise was analyzed in the frequency domain through the electromagnetic-mechanical coupling analysis. The noise level according to the speed was compared with the noise characteristics for each frequency using the waterfall diagram.

전기펄스 제빙시스템의 전자기-구조변형-회로 결합 다물리 해석 기법 Mutiphysics Analysis for Electromagnetics-Structural Deformation-Circuit Coupled Problem of Electromagnetic Expulsive De-icing System

https://doi.org/10.5370/KIEE.2022.71.11.1599

강성준(Sung-Jun Kang) ; 이준성(Jun-Sung Lee) ; 노승은(Seung-Eun Rho) ; 박종오(Jong-Oh Park) ; 정은채(Eun-Chae Jung) ; 박일한(Il-Han Park)

One of the ice protection systems for flights above medium altitudes is the electromagnetic explusive deicing system(EEDS). EEDS is composed of a coil which is structurally deformed by electromagnetic repulsion of electric current supplied by external circuit, a complex multiphysics phenomenon requiring electromagnetic, structural, and circuit analysis simultaneously. In this paper, we suggest electromagnetic(EM)-structural deformation-circuit coupled lumped parameter system for the analysis of EEDS. The results of the numerical analysis using the coupled lumped parameter system is compared with the results of measuring experiment using the EEDS prototype, which showed high concordance in current, electromagnetic force, and displacement. The coupled lumped parameter system enables bi-directional analysis which takes into account the interdependence between the different systems. Furthermore, it can significantly reduce the computational cost, which enables complex performance evaluation on various design variables and saves time and cost in the initial design steps.

수신측 센서를 제거한 이모빌리티 무선충전기의 와전류 손실을 고려한 출력 전압 모델링 Output Voltage Modeling in consideration of Eddy Current Loss for e-Mobility RX-Sensorless IPT Charger

https://doi.org/10.5370/KIEE.2022.71.11.1608

오승대(Seung-Dae Oh) ; 유재곤(Jae-Gon Yoo) ; 김종수(Jong-Soo Kim)

This paper presents an output voltage model considering the eddy current loss of a magnetic substance attached to a transceiver coil for precise control of the output voltage of a wireless charger for (RX-Sensorless) mobility without sensors on the receiving side. In order to accurately control the reception-side output voltage by measuring only the physical amount of the transmission side, it is necessary to minimize the error of the output voltage model. Therefore, output voltage modeling is performed to reflect an eddy current loss of a magnetic body that affects the output voltage. The validity of the derived model is verified through simulation and experimental results compared with the existing model that does not reflect the eddy current loss. The analysis result shows that the error of the proposed model is reduced by up to 3.7% compared to the existing model.

노화 가속 실험 기반 전해 커패시터 잔여 유효 수명 예측 연구 Study of Remaining Useful Lifetime Prediction for Electrolytic Capacitors based on Accelerated Aging Tests

https://doi.org/10.5370/KIEE.2022.71.11.1614

박혜진(Hye-Jin Park) ; 곽상신(Sang-Shin Kwak)

In this paper, the Remaining Useful Life (RUL) of the electrolytic capacitor is estimated through the amount of change in capacitance and ESR. RUL is predicted by the conventional model and the amount of change in capacitance and ESR according to the operating time. This paper supplements the shortcomings of the conventional model that calculates the endpoint of life according to the operating conditions of the system. Therefore, the purpose of this text is to calculate the endpoint considering the aging state and speed of the capacitor. In order to confirm the degree of aging over time, the accelerated aging experiment of capacitors was conducted under two conditions of temperature and voltage charge/discharge stress. And capacitor state parameters, Capacitance and ESR, were measured. After predicting the endpoint through the conventional model, the error with the actual measured experimental value is predicted through data fitting. As a result, both types of aging showed high accuracy when data with a large degree of aging was used. In addition, the higher the tendency of the error between the calculated value of the conventional model and the actual value of the experiment, the higher the estimation accuracy. Therefore, in this paper, when applied to the algorithm proposed for voltage charging and discharging aging rather than temperature aging, it was confirmed that the estimation performance was superior to that of the conventional model estimation value.

고전계 스트레스상에서 Cascode-GaN-FET 소자의 노화 특성 연구 Study of Aging Characteristics for Cascode-GaN-Field Effect Transistor (FET) Device under High Electric Field Stress

https://doi.org/10.5370/KIEE.2022.71.11.1624

김재창(Jae-Chang Kim) ; 곽상신(Sang-Shin Kwak)

This paper investigated changes in threshold voltage, on-resistance, turn-on delay, and turn-off delay of cascode GaN FETs under high electric field stress. As a result, the threshold voltage decreased, and the on-resistance increased under the stress of applying a positive high voltage. Also, the turn-on delay was reduced, and the turn-off delay increased. On the other hand, under the stress of applying a high negative voltage, the threshold voltage, on-resistance, and turn-on delay decreased, and the turn-off delay increased. These results imply that the conduction loss of the cascode GaN FET increases, and the dead time of the voltage source converter composed of the cascode GaN FET increases under positive high voltage stress. Also, the fact that the threshold voltage decreased under both positive and negative high voltage stress means that if the cascode GaN FET is subjected to high voltage stress, the reduced threshold voltage is more likely to turn on undesirably even at low gate voltages.

Cascode GaN FET 기반 EV용 V2x DAB 컨버터의 경부하 효율 분석 Analysis of light load efficiency of V2x DAB converter for EVs based on cascode GaN FET

https://doi.org/10.5370/KIEE.2022.71.11.1631

곽봉우(Bongwoo Kwak) ; 김종훈(Jonghoon Kim)

In this paper, the light-load efficiency of cascode gallium nitride (GaN) FET-based V2x dual active bridge (DAB) converters for electric vehicles(EVs) is analyzed. High efficiency and high power density are required when an on-board charger(OBC) is used in EVs. To this and a zero voltage switching (ZVS) topology, such as that observed in DAB converters, is widely applied. As for the converter requiring current enough to achieve the ZVS condition of the efficiency characteristics vary depending on whether ZVS operated or not. Therefore, in this study, the efficiency in the hard switching section is improved by applying a cascode GaN FET to a DAB converter. The ZVS characteristic is analyzed by considering the parasitic output capacitance of the switching device. Compared to the Si device, the cascode GaN FET with low parasitic output capacitance realizes ZVS under a lower load condition. To verify this, a load test is performed by applying it to a 3-kW DAB converter. The experimental results confirm that ZVS is achieved when the cascode GaN FET is applied. Moreover, a shorter dead time can be applied owing to excellent dv/dt and di/dt characteristics, which improves the overall efficiency. In conclusion, the use of GaN FET in DAB converters can improve efficiency at light loads.

전기차 운전자의 충전패턴 유형과 영향요인 분석: 잠재계층분석법의 응용 Charging Pattern of Electric Vehicle User and Affecting Factors : Latent Class Analysis Approach

https://doi.org/10.5370/KIEE.2022.71.11.1639

박지영(Jiyoung Park) ; 김찬성(Chansung Kim)

Reliable charging infrastructure is an essential element to transform the current fossil fuel-centered automobile market into electric vehicles. In Korea, the supply level of public charging infrastructure is better than that of other countries, but the residential charging infrastructure is hard to expand due to the domestic characteristics. Therefore, in order to meet the electric vehicle era in the future, charging infrastructure supply strategies suitable for the domestic situation should be prepared. This study analyzed the charging patterns of electric vehicle drivers as essential data necessary for future charging infrastructure plans and decision-making on the supply of charging facilities. This study utilized the data of one-week charging events survey of 297 electric car drivers conducted in 2021, and the Latent Class Analysis was applied to identify the charging pattern of individual driver. As a result, the charging patterns of electric car drivers were classified into four types: Mixed & Slow 69.3%, Home & Slow 16.5%, Public-centric 8.2%, and Work & Slow 6.1%. As a result of analyzing the predictive variables of the charging pattern through multi-logit analysis, accessibility by charging infrastructure type and preference by type of charging infrastructure were found to be statistically significant affecting factors for all charging patterns. For some classes of charging pattern, annual driving mileage and parking conditions at home were also found to have a significant effect.

1.2 kV 급 SiC Trench MOSFET의 게이트 산화막에서의 전계 집중 현상 억제를 위한 설계 Design of 1.2 kV SiC Trench MOSFET for suppression on Electric Field Crowding at Gate Oxide

https://doi.org/10.5370/KIEE.2022.71.11.1646

박영은(Yeongeun Park) ; 김채윤(Chaeyun Kim) ; 윤효원(Hyowon Yoon) ; 강규혁(Gyuhyeok Kang) ; 김광재(Gwangjae Kim) ; 석오균(Ogyun Seok)

SiC trench Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) has an advantage of a low on-resistance due to a small cell pitch between unit cells, and is widely used for power electronics requiring a high power conversion efficiency. However, there is a electric-field crowding problem at the gate oxide. Since the physical destruction of the gate oxide is irrecoverable, researches of a design that can improve the reliability of the trench MOSFET by suppressing the electric field of the gate oxide are needed. This paper implemented a structure in which p-shielding is added next to a trench and verified its electrical characteristics of 1.2 kV SiC trench MOSFET using Sentaurus TCAD simulation. The result showed that the specific on-resistance of 2.02 mΩ-cm2 was measured and the breakdown voltage was improved from 850 V to 1717 V.

Grassmann 공간에서 2-입력, 2-출력, 4차 시스템의 정적출력궤한 극배치 Pole Placement by Static Output Feedback for Two-input, Two-output, 4th Order Systems in Grassmann Space

https://doi.org/10.5370/KIEE.2022.71.11.1651

김수운(Su-Woon Kim) ; 송성호(Seong-Ho Song) ; 김호찬(Ho-Chan Kim)

In this paper, a parametric study of pole placement of two-input, two-output, 4th order systems with strictly proper transfer functions is investigated in real Grassmann space. To characterize the features of pole placement, the well-known Plucker matrix formula is introduced as a real constant matrix formula constructed from the static output feedback (SOF) variable’s coefficient functions of characteristic polynomial under Grassmann coordinates. It is shown that the SOF pole placement entirely depends upon the columns’ condition of a real Grassmann parameter. The results presented in this paper shows that this real Grassmannian parametrization method can generalize the existing pole placement methods for two-input, two-output, 4th order systems.

중기 전력수요 예측을 위한 LSTM 최적 모델 선정 Optimal Model Selection of Long Short-Term Memory for Mid-Term Electric Load Forecasting

https://doi.org/10.5370/KIEE.2022.71.11.1658

엄호용(Ho-Yong Eom) ; 백승묵(Seung-Mook Baek)

This paper proposes an optimal electric load forecasting technique by applying several activation functions and optimization methods in the internal structure of the Long Short-Term Memory (LSTM) algorithm to forecast mid-term electric load in Korea. As the activation function, the rectified linear unit (ReLU) and hyperbolic tangent (Tanh) are used. Optimization methods such as stochastic gradient descent (SGD) and adaptive moment optimization (Adam) are compared in the paper. In the input data, daily peak load over past seven days, maximum and minimum temperatures are used. In order to increase the efficiency of learning, special weeks and special day load data are replaced. The proposed method shows stable and great performance with small average errors, compared to the RANN based forecasting method which is a previous study. Especially, the estimated error is improved in the summer and winter where the temperature changes significantly.

이차 원뿔 제약조건을 가진 최적 제어 문제를 위한 내부점 미분 동적 프로그래밍의 확장 An Extension of Interior Point Differential Dynamic Programming for Optimal Control Problems with Second-Order Conic Constraints

https://doi.org/10.5370/KIEE.2022.71.11.1666

김민겸(Min-Gyeom Kim) ; 김광기(Kwang-Ki Kim)

This paper presents the second-order conic IPDDP (SOC-IPDDP) that modifies interior point differential dynamic programming (IPDDP) to explicitly handle second-order conic constraints. Differential dynamic programming (DDP) has been widely used to solve nonlinear optimal control problems in control and robotics. However, DDP has a big drawback that it cannot handle hard constraints and constraints are usually encoded softly as parts of the cost functions. To overcome this constraint-handling limitation of DDP, interior point differential dynamic programming (IPDDP) is proposed to deal with hard constraints using the interior point method. In this paper, we extend IPDDP to efficiently take care of second-order conic constraints by exploiting their algebraic structures. For demonstration, the performances of SOC-IPDDP are compared with IPDDP in the planar rocket landing optimal control problem. It is shown that the proposed SOC-IPDDP has a comparable convergence rate to the existing IPDDP and is less sensitive to the changes in the parameters of the cost function.

로켓모터 절단용 실시간 와이어 상태 검사 시스템 개발 Real Time Wire Condition Inspection System Development for Rocket-motor Cutting

https://doi.org/10.5370/KIEE.2022.71.11.1673

정민철(Min-Cheol Jung) ; 이정호(Jung-Ho Lee) ; 김일환(Il-Hwan Kim)

In this paper, a wire condition inspection system was developed using a high-speed camera and a spectrometer to inspect the state of diamond wire used in the cutting operation of a rocket motor in real time. During the cutting process, there is a risk that the propellant inside the rocket motor may be ignited due to excessive frictional heat of the diamond wire and sparks caused by wire breakage. At low speed, it is possible to measure wire wear using a high-speed camera and spectrometer, and at high speed using a spectrometer. Using the results of this paper, it is expected that it will be very usefully applied to the performance evaluation of guided munitions

Permutation Lempel-Ziv 복잡성 척도를 적용한 근 피로도 추정 Muscle Fatigue Estimation based on Permutation Lempel-Ziv Complexity measure

https://doi.org/10.5370/KIEE.2022.71.11.1679

이진(Jin Lee)

A new approach for quantifying muscle fatigue is presented by analyzing the deterministic complexity in the surface electromyogram(SEMG) using Permutation Lempel-Ziv(PLZ) complexity measure. The PLZ complexity measure provide a metric for the number of distinct deterministic patterns in signals by combining permutation patterns and Lempel-Ziv complexity analysis. For muscle fatigue experiment by using PLZ complexity measure, surface EMG signals from eleven subjects were recorded in biceps brachii muscle with constant isometric 20, 50, and 80%MVC contractions. The PLZ complexity measure is evaluated with the performance of muscle fatigue estimation for the SEMG signals compared to the performance of previous reported LZ complexity measure. This PLZ complexity measure has advantages that is computationally easy to compute and does not require any assumptions about the stationarity of the SEMG signal.

동공 빛 반사를 활용한 피로도 추정 Fatigue Estimation using Pupil Light Reflex

https://doi.org/10.5370/KIEE.2022.71.11.1686

김수찬(Soo-Chan Kim)

Although fatigue has been experienced more than once in a lifetime, the definition itself is ambiguous and is determined by various factors. Many researchers have studied objective and quantitative fatigue analysis methods, but standard measurement methods are still not established. In this study, we estimated fatigue using pupil light reflex providing information about the activity of sympathetic and parasympathetic nervous system among vital signs. We induced artificially fatigue through arithmetic and running, and subjective fatigue was compared with the questionnaire index at every point in time. As the results, BPD(basal pupil diameter), MCV(Maximum constriction velocity), and ACA(absolute constriction amplitude) showed the possibility of being used as factors reflecting fatigue.

ESS 화재예방을 위한 전력품질과 발열의 상관관계 연구 A Study of Correlation between Power Quality and Heat for ESS Fire Prevention

https://doi.org/10.5370/KIEE.2022.71.11.1692

이현우(Hyeon-Woo Lee) ; 김현식(Hyun-Sik Kim) ; 이재윤(Jae-Yoon Lee) ; 장경배(Kyung-Bae Jang)

Recently, ESS facilities are used in that connected with renewable energy facilities or photovoltaic facilities. Accordingly number of ESS facilities are increasing continuously. there were 32 fire accidents until last may, and various causes were pointed out. Although the cause of the accident is being studied individually, fire accidents are happened to complex reasons in field. Mostly the fire ignition occurs ESS battery or PSC parts. Main causes of accidents are insufficient management and battery protection system of the operating environment. In this paper, the cause that has the greatest influence on fire accidents was studied. linear regression analysis was performed for each cause of fire and graph was expressed for comparison.

고속철도 신호기계실의 접지전류 개선 효과에 관한 연구 A Study on the Improvement Effect of Ground Current in a Signal Machine Room of High Speed Rail

https://doi.org/10.5370/KIEE.2022.71.11.1700

윤용기(Yong-Ki Yoon) ; 김성진(Sung-Jin Kim) ; 고경준(Kyeong-Jun Ko) ; 신영인(Young-In Shin) ; 김용규(Yong-Kyu Kim)

Through construction of high-speed railways and railway electrification projects in Korea, individual(or independent) grounding methods were replaced with common grounding methods. Common grounding methods can eliminate potential difference between equipments connected with common grounding wires, but the wires are used as return current paths such as rails. A track circuit cable consists of signal wires and shielding conductors, and connects track circuit devices installed along tracks, transmitters and receivers located in a signal machine room. Shielding conductors at one end of the track circuit cable are connected to the common earth wire, and the conductor at the other end are connected to a grounding terminal of the signal machine room. It was confirmed through measurements that impulse surge current invades to the signal machine room through shield conductors of a track circuit cable connected to grounding wires. Also, it was confirmed that steel frame grounding was used as a path for another impulse surge current to enter the room. Therefore, in this paper, the ground current status of the signal room is analyzed, the improvements of grounding facilities in the signal room are listed, and the improvement effects of the ground current are presented.

전기철도 배전망을 활용한 팬터그래프 방식 충전시스템에 관한 연구 A Study on Pantograph Charging System using Electric Railway Power Network

https://doi.org/10.5370/KIEE.2022.71.11.1709

신승권(Seung-Kwon Shin) ; 정호성(Ho-Sung Jung)

In the industrial fields have being accelerated the development of alternative energy resources because of restriction of environment pollution and increasing oil price at the world. Most of conventional vehicles are reason of environment pollutions. For these reason, interest in electric vehicles are increasing because of which is solution of reducing the environment pollution issues. Although a local autonomous entity had tried to replaced CNG buses for operating electrical buses, electrical buses have intrinsic problems such as charging/discharging sequences, connector issues and charging time. For these reason pantograph-type automatic charging technology is being developed for mating the environment of bus garages in nation. However, that has some problems such as initial price, room of charging infrastructure and electric power supply. In this paper, therefore, proposes methodology of using railway power supply system. It has been verified under suitability and balidity of charging and discharging scenario using electric bus charging system simulation model based on MATLAB Simulink and PSIM.

분산전원이 있는 배전계통에서 딥러닝을 통한 고저항 지락사고 판별 High-resistance Ground Fault Detection through Deep Learning in a Distribution System with Distributed Generation

https://doi.org/10.5370/KIEE.2022.71.11.1715

박종영(Jong-young Park) ; 이한민(Hanmin Lee) ; 조규정(Gyu-Jung Cho) ; 정호성(Hosung Jung) ; 한문섭(Moonseob Han)

This paper proposes a method to detect a high-resistance ground fault in a distribution system with complicated configuration such as installation of a distributed generation. A method to detect high-resistance ground fault accidents by converting the fault current into visual data and applying the CNN technique to this is presented and verified. The data for learning the CNN technique was generated through simulation of the model system. Simulations were performed for data generation by changing the fault resistance, the size, location of faults and amount of distributed power generation, in the case of a high-resistance ground fault and an increase in load in the model system. The generated data was transformed into graphic data by applying Morlett wavelet transform, and then learning was performed by applying CNN. As a result of the learning, high-resistance ground faults were identified with 98.29% accuracy, and a protective algorithm including this result that can respond to high-resistance ground faults occurring in the distribution system was proposed.