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

온도 데이터를 이용한 다양한 포설 방식에서의 지중케이블의 동적 용량 산정 시스템에 대한 연구 A Study on the Dynamic Rating System of Underground Cables in Various Installation Methods Using Temperature Data

https://doi.org/10.5370/KIEE.2020.69.3.381

남용현(Yong-Hyun Nam) ; 이향범(Hyang-Beom Lee) ; 강지원(Ji-Won Kang) ; 김정훈(Jung-Hoon Kim)

When operating the power system, instantaneous supply and demand imbalance can occur and become transient. In order to prevent system instability, the system is always operated with room for transmission capacity, if necessary, additional transmission lines may be constructed. However, if more current flows momentarily during an emergency time, there is no need to construct additional transmission lines because of the flexible system operation. In this paper, we propose a new dynamic rating system(DRS) that calculates the allowable current by reflecting the real-time situation instead of the IEC standard which calculates the allowable current assuming the most severe situation in the utility tunnel. This new DRS was developed with the idea that parameter changes are not significant in the most severe and actual situations, based on the calculation of allowable current in IEC 60287. A linear correction factor mathmatical model is proposed that can be applied to underground cable in various installation methods. In the case study with the measured conductor temperature estimated by the FEM thermal analysis, the utility is proved by obtaining a mathematical model of correction coefficient with low error.

ESS 기반 신재생에너지 패키지 변전소의 계통 영향 평가를 위한 모델링 및 적용에 관한 연구 A Study on Modeling and Application for an Evaluation of Impact by ESS-based Package Substation for Renewable Energy

https://doi.org/10.5370/KIEE.2020.69.3.388

송성윤(Sungyoon Song) ; 유연태(Yeuntae Yoo) ; 문희성(Heesung Moon) ; 김준호(Joonho Kim) ; 조윤성(Yoon-sung Cho) ; 정승민(Seungmin Jung) ; 장길수(Gilsoo Jang)

The expansion of renewable energy in recent electric power systems has affected the associated networks, and their speed is gradually increasing. Renewable generators that do not have their own reserve capacity produce variable amounts of power that often generate balancing issues in grid operation. Therefore, a high penetration of the renewable generator is expected to impact on the stability of the power system greatly. As a countermeasure against these issues, a proposal has been derived to use the energy storage system (ESS) to contribute to the stability of the power system. An ESS, which is planned to be composed at the point of connection of renewable generators, must be evaluated in advance to meet its own objectives. In this paper, based on structural analysis, progress has been made in the development of a user-defined model dedicated to power system analysis tools for use in stability analysis. Based on IEEE 1547, the active response capability for ESS is configured and verified through the simulation based on PSS/e software tool.

차단 실패 시 정전구간 최소화를 위한 기반 변전소 복구 방식 개선방안 연구 A Study on Improvement of IEC 61850-Based Substation Restoration Scheme for Minimizing Outage Area in case of Breaker Failure

https://doi.org/10.5370/KIEE.2020.69.3.396

김민수(Min-Soo Kim) ; 강상희(Sang-Hee Kang)

This paper presents a study on improvement of IEC 61850-based substation restoration scheme for minimizing outage area in case of breaker failure. It utilizes voltage, current, and contact information of each circuit breaker and disconnect switch of transmission line and bus. In the event of a fault on a transmission line or a transformer or a bus, the IEC 61850-based substation restoration scheme for minimizing outage area proposed in this paper is explained, assuming that a breaker failure of a line or transformer has occurred, and the bus breakers are fully opened.

동적송전용량 산정을 이용한 송전선로 보호용 거리계전기 과부하 영역 설정에 관한 연구 A Study on Distance Relay Overload Zone Setting for Transmission Line Protection Using Dynamic Line Rating

https://doi.org/10.5370/KIEE.2020.69.3.402

김영근(Yeong-Geun Kim) ; 김민수(Min-Soo Kim) ; 강상희(Sang-Hee Kang)

A distance relay overload zone setting for transmission line protection using dynamic line rating considering the ambient temperature around the transmission line is proposed in this paper. If the ambient temperature around the transmission line is high, the proposed overload zone becomes narrower as the line allowable current becomes smaller. If the ambient temperature is low, the overload zone expands as the line allowable current increases. In the same power system situation, the overload zone that depends on the ambient temperature around the transmission line is operated by the apparent impedance calculated at the relay point together with the fault determination zone of the existing distance relay to provide the system operator with the line overload information. To verify the proposed method, air temperature data from regional detailed observation data provided by Korea Meteorological Administration AWS(Automatic Weather System) and real system PSS/E data were used.

인접변전소의 시각 비동기 데이터를 이용한 역상전류 차동방식 기반 IEC-61850 송전선로 후비보호에 관한 연구 Transmission Line Backup Protection Based on Negative Sequence Current Differential Algorithm Using IEC-61850 Asynchronous Data from an Adjacent Substation

https://doi.org/10.5370/KIEE.2020.69.3.409

이선우(Sun-Woo Lee) ; 이남호(Nam-Ho Lee) ; 남순열(Soon-Ryul Nam)

This paper presents to study the construction of a centralized environment based on IEC 61850 data and to propose the back-up protection algorithm of the central IED to be used for transmission line protection, which is one of the essential elements of the power system. it also shows how to use rgoose communication for data acquisition based on IEC 61850 90-5 TR(Technical Report)

외철형 배전용 변압기의 손실 감소를 위한 철심 최적설계 Optimum Design of Core for Loss Reduction of Shell Type Distribution Transformer

https://doi.org/10.5370/KIEE.2020.69.3.414

김상현(Sang-Hyun Kim) ; 이향범(Hyang-Beom Lee)

In this paper, we propose the design of a transformer with four cores arranged radially to reduce the stray load loss of a 100kVA shell type transformer. Also, the design of the four cores used a magnetic equivalent circuit method taking into account the nonlinear properties. The optimized design reduced no-load losses to 2.29% and stray load losses of the transformer tank to 77.30%.

역 프라이자흐 모델을 이용한 히스테리시스 전동기의 동기 진입 후 루프 시뮬레이션 B-H Loop Simulation of Hysteresis Motor after Entering Synchronous Speed Using Inverse Preisach Model

https://doi.org/10.5370/KIEE.2020.69.3.419

한지훈(Ji-Hoon Han) ; 최동진(Dong-Jin Choi) ; 박상욱(Sang-Uk Park) ; 홍선기(Sun-Ki Hong)

The output of the hysteresis motor decreases after entering the synchronous speed. This means that the area of the rotor B-H loop is reduced to fit the load. For the dynamic analysis of this motor, the loop area needs to be calculated to determine the output. However, the studies so far did not consider the variation of the hystreresis loop after synchronization or just simplifies the minor loops as a line with constant permeability. In this study, an algorithm that can simulate the actual loop variance is proposed using the inverse Preisach model for more realistic simulation. When the motor speed becomes synchronous speed, the phase of flux density is reduced, then for each point the minor loop is calculated and the corresponded magnetic field intensity is calculated. It was confirmed that more realistic synchronous entry loop simulation can be performed by comparing with the Kataoka approach.

축 전압 저감 구조 모터의 축 전압 주파수 응답 특성 분석 Frequency Response Analysis in Motors with Shaft Voltage Mitigation Methods

https://doi.org/10.5370/KIEE.2020.69.3.427

임준혁(Jun-Hyuk Im) ; 박준규(Jun-Kyu Park) ; 허진(Jin Hur)

In PWM based inverter driven motor, shaft voltages usually cause bearing fault. Many methods to mitigate the shaft voltages have been proposed. Since the high frequency components are hazardous to bearing, it is necessary to analyze the frequency responses for each shaft voltage mitigation method. In this paper, frequency responses of three shaft voltage mitigation methods are analyzed and compared. First, equivalent circuit models regarding geometric shape of motor are presented. Second, modified models of each equivalent circuit containing shaft voltage reduction methods are proposed. Finally, the comparison of the frequency responses for each shaft voltage mitigation method is presented.

Bipolar HVDC MMC 전송을 위한 비대칭 혼합 회로구성 Circuit Configuration of Asymmetric Mixed MMC in Bipolar HVDC Transmission Systems

https://doi.org/10.5370/KIEE.2020.69.3.435

정재정(Jae-Jung Jung)

Among the MMC topologies for bipolar HVDC systems, the asymmetric mixed MMC is considered as promising and attractive circuit due to the cost saving, less loss, DC fault ride-through capability, and free and quick DC bus voltage regulation. In this paper, the reasonable circuit configuration of an asymmetric mixed MMC in bipolar HVDC transmission system is introduced. In the application of asymmetric mixed MMC for the bipolar HVDC system, the induced DC bias voltage into AC transformer at normal operation according to the placement of submodules is investigated and discussed. Furthermore, the optimal submodule arrangement is proposed considering the busbar single line-to-ground fault at AC side of MMC.

다출력 공진형 컨버터의 변압기 누설 인덕턴스를 고려한 특성 분석 Analysis of Cross-regulation Characteristic in Multi-Output LLC Resonant Converter Considering Transformer Leakage Inductance

https://doi.org/10.5370/KIEE.2020.69.3.442

김성재(Sung-Jae Kim) ; 김종수(Jong-Soo Kim)

This paper presents analysis and experimental results of cross-regulation characteristics in multi-output LLC resonant converter focus on transformer leakage inductance. The detail leakage inductance is extracted using the multi-winding transformer equivalent model, and the effects of leakage inductance on the cross-regulation characteristics under two load conditions are investigated. The analytical results are verified through an experiment results using 240W 4-output LLC resonant converter. Furthermore, the solution for reducing the cross-regulation error is discussed.

캐리어 수명시간과 온도에 따른 수직형 절연 게이트 바이폴러 트랜지스터의 Forward Biased Safe Operating Area를 위한 설계 및 시뮬레이션 Design and Simulation for Forward Biased Safe Operating Area of Vertical Insulated Gate Bipolar Transistors with Carrier Lifetimes and Temperatures

https://doi.org/10.5370/KIEE.2020.69.3.450

정현준(Hyunjoon Jeong) ; 김태은(Taeeun Kim) ; 하민우(Min-Woo Ha)

The forward biased safe operating area of insulated gate bipolar transistors (IGBTs) is important for stable and reliable operations. A parasitic thyristor latch-up has limited the on-state operation of the devices. In this manuscript, we reported the forward biased safe operating area of the vertical punch through IGBTs with various N buffer layers, carrier lifetimes, and temperatures. Increasing the thickness and doping concentration of the N buffer layer decreased the forward current and improved the forward biased safe operating area. The low forward current suppressed a parasitic thyristor latch-up. Reducing the carrier lifetime increased the forward bias safe operating area due to the enhanced recombination in the N buffer layer. At the high temperature, two conflicting mechanisms of the forward bias safe operating area were found. As the temperature rised, the forward bias safe operating area increased due to the channel scattering and forward current reduction. The forward biased safe operating area rather decreased at the high temperature because the parasitic thyristor easily triggered at the low collector voltage.

코로나 방전의 방향탐지를 위한 전기적 빔 조향 기반 라디오미터 시스템 연구 Study of Radiometer System Based on Electrical Beam Steering for Direction Detection of Corona Discharge

https://doi.org/10.5370/KIEE.2020.69.3.454

김수민(Sumin Kim) ; 천창율(Changyul Cheon)

In this study, we designed and fabricated a radiometer using electric beam steering to improve the problems of the conventional corona discharge detection. The research was then conducted to image the data so that direction of corona discharge could be detected. When a corona discharge occurred, heat was generated around it and the electromagnetic wave generated by the heat was detected to detect the direction of the corona discharge. In addition, by selecting the electric beam steering using a phase shifter, the stability of the system is increased and the data is imaged to increase the accuracy of the detection of the measurement object. In particular, by showing the possibility of direction detection using electric beam steering, it laid the foundation for the possibility of direction detection of corona discharge.

시계열 예측을 위한 이동평균 변화율 기반 퍼지 시스템 TSK A TSK Fuzzy System Based on the Rate of Change of Moving Average for Time Series Prediction

https://doi.org/10.5370/KIEE.2020.69.3.460

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

It is very difficult for nonstationary or nonlinear time series to establish a proper prediction model. In this paper, we propose a TSK FPS that uses the rate of change of MA of data as the predictor input. The LPF property of the MA stabilizes statistical characteristics of time series and the rate of change of them removes the monotonic increasing/decreasing tendency of the data, thereby overcoming the rule bias of the data. For the fuzzy partitioning of input space, CBKM using the correlation coefficient as the similarity index is applied. As a result, more appropriate rules to the attribute of data can be obtained. In order to verify the validity of the proposed method, simulations were performed on representative cases of nonstationary and nonlinear time series, respectively. The result of the simulation shows excellent performance and effectiveness of the proposed method.

객체 인식 알고리즘 기반 소의 특이행동 검출 Detecting Abnormal Behavior of Cattle based on Object Detection Algorithm

https://doi.org/10.5370/KIEE.2020.69.3.468

채정우(Jung-woo Chae) ; 조현종(Hyun-chong Cho)

Detection of abnormal behavior and unusual signs of cattle has been an important factor for managers in the livestock farming. Among them, it is of great interest for livestock farmers to detect estrus of cattle, which are unusual behaviors related to breeding management. Most studies on detecting estrus combined with IT technologies have been based on sensors attached to the neck or leg of cattle. But sensor-type devices have the potential to cause stress on the cattle by attaching them, and there are additional cost issues for maintenance. In this study, to solve the above problems, we present a estrus detection system which used regular CCTV and applied the object detection algorithm based on the deep learning model. To run real-time detection in video stream, the activity detection is performed within a single image frame and makes prediction with a single network evaluation. The results of the proposed system showed 97% precision and 96% accuracy.

딥러닝을 이용한 영상 기반의 화재 위치 감지 Detecting Location of Fire in Video Stream Environment using Deep Learning

https://doi.org/10.5370/KIEE.2020.69.3.474

김윤지(Yun-ji Kim) ; 조현종(Hyun-chong Cho)

To avoid the large scale of damage of fire occurred, it is necessary to have a system to detect the incident as soon as possible. Traditional sensors and vision based systems for fire detection is limited in indoors and need more computational time and memory, restricting its implementation. In this paper, we propose a video-based fire detection system using deep learning to solve these problems. To run real-time detection in video stream, the activity detection is performed within a single image frame and makes prediction with a single network evaluation. The object detection algorithm we applied can tell the location as well as the presence of fire. It allows us to analyze the cause of the fire through video and monitor extensive areas efficiently. The results of the proposed system showed 99% precision, 99% accuracy and 100% recall. Experimental results show that the proposed method has excellent fire detection performance.

머신러닝 해석 기법을 이용한 전력 수요 예측 모델 해석 Interpretation of Load Forecasting Using Explainable Artificial Intelligence Techniques

https://doi.org/10.5370/KIEE.2020.69.3.480

이용건(Yong-Geon Lee) ; 오재영(Jae-Young Oh) ; 김기백(Gibak Kim)

Artificial intelligence (AI) is getting popular and has been successfully applied to many applications. However, in many cases, AI is considered as a ‘black box’ which is hard to interpret. Recently, researchers have been attempting to explain AI systems and various explainable AI techniques have been developed. In this paper, we apply explainable AI techniques to interpret the load forecasting based on machine learning method. For load forecasting, we employ XGBoost which is decision tree based gradient boosting algorithm. The XGBoost based load forecasting approach was analyzed in terms of feature importance and partial dependence plot. The experimental results show that the performance can be improved by selecting features which were found to have high importance in the SHAP analysis.

컨볼루션 희소 코딩을 사용한 기반 반사율 분해 Retinex based Reflectance Decomposition Using Convolutional Sparse Coding

https://doi.org/10.5370/KIEE.2020.69.3.486

윤종수(Jongsu Yoon) ; 최윤식(Yoonsik Choe)

Color constancy is a feature of the human visual system, which detects the relative inconsistency of the perceived color of an object so that the perceived color may not be changed under various illumination conditions, even when the conditions for observing color are changed. Thus, the Retinex theory was designed in consideration of this color constancy. The physics based Retinex algorithms have been popularly used to effectively decompose the illumination and reflectance of the object. However, if there are many detail areas in the image or the illumination changes rapidly, the illumination and reflectance may not be decomposed properly, because of the violation of the smoothness constraint on illumination. In this paper, we use the convolutional sparse coding model to represent the reflectance in more detail. This allows the reflectance component to provide improved visual quality over conventional methods, as shown in experimental results. Consequently, we can decompose Retinex based illumination and reflectance more precisely, then, reduce the perception gap between humans and machines.

대역확산 기법을 사용한 단일 채널 중계기 개발 Development of On-Channel Repeater Using Spread Spectrum Technique

https://doi.org/10.5370/KIEE.2020.69.3.495

김종민(Jong-Min Kime) ; 장경배(Kyung-Bae Jang)

This paper describes the elimination of feedback signals to implement a stable on-channel repeater regardless of input signals in the frequency bandwidth desired by the user. Toward this objective, the spread spectrum technique is applied to an adaptive filter, in which the least mean square algorithm removes the frequency characteristics of input signals. OCRs have been commercialized using adaptive filters based on the LMS algorithm in existing mobile communication services, including in GSM, CDMA, WCDMA, and LTE. However, in current mobile communication networks, various services with different signal characteristics can become mixed in the user’s frequency band, and bands with no signals may also exist. If the integrated bandwidth and the occupied bandwidth do not coincide, a bandpass filter cannot completely suppress other bands. Because the LMS algorithm is affected by the frequency characteristics of input signals as well as the feedback path of the object to be removed, feedback signals cannot be canceled for the entire band. Therefore, in this paper, the SS technique is applied to the existing LMS method to remove the frequency characteristics of input signals, thereby eliminating feedback signals in a more stable manner. The performance of the proposed scheme is verified through simulation and experiments.

통계적 추론을 이용한 불규칙 발생 오류의 수정 결과 판단 기법 Decision Making Method of Random Fault Correction Using Statistical Inference

https://doi.org/10.5370/KIEE.2020.69.3.503

박해리(Haerhee Park) ; 황익호(Ick Ho Whang)

The complex system to consist of several subsystems is developed by correcting errors or faults found through many kinds of tests. These errors can be classified into two categories according to regularity; systematic error and the random error. Systematic errors are always occurred at the same condition, same time and same period. But random error is occurred occasionally and may be occurred or not at the same condition. Therefore the suitable method for decision making of random fault correction is needed. In this paper, the statistical method to find whether random fault is corrected or not is proposed. First, random faults are modeled stochastically and the method using statistical hypothesis test is presented to decide that random errors of the system is corrected. Also, the way to obtain the minimum test number for verifying correction of system is showed. Finally, usefulness and validity of proposed method is proved by applying some examples.

국내 태양광발전시스템 적합성 평가를 위한 기술기준 Technical Standard for Conformity Assessment of PV Power Generation System in Korea

https://doi.org/10.5370/KIEE.2020.69.3.510

윤용호(Yong-Ho Yoon)

Currently, KS certification system for new and renewable energy facilities in Korea is operated at the level of issuing KS certification mark through factory audit and performance audit by individual product unit. Therefore, the technical standards and performance evaluation when constructing the system by organically integrating each subsystem such as PV inverter, photovoltaic module, photovoltaic junction box, and monitoring device. In this regard, it is not currently reflected in the KS certification system for new and renewable energy facilities in Korea. In addition, domestic photovoltaic power generation system construction is being supplied to public institutions and government offices through the Public Procurement Service's excellent product system. Only the GS-certified product registered in the copyright and technology development successful product of R&D business is applied, but the performance evaluation of the technical standard of each system unit is not made. As a result, most of the domestic photovoltaic power generation system builders are evaluated for the performance of the photovoltaic power generation system by issuing a report through their own test evaluation by a domestic accredited testing institute for the purpose of registering the successful product development of the R&D business of the excellent product system. Therefore, in this paper, we propose a specification related to system diagnosis evaluation through status information in case of interoperation and abnormality between subsystems.

배전선로의 분산전원 연계용량 기준 상향을 위한 분석 연구 An Analysis Study on the Proposal for Increasing Hosting Capacity in Distribution Feeders

https://doi.org/10.5370/KIEE.2020.69.3.516

임현옥(Hyeonok Lim) ; 김현진(Hyeonjin Kim) ; 심준보(Junbo Sim) ; 조성수(Seongsoo Cho)

With Korean Government’s Renewable energy 3020 plan, the penetration of DERs in Korean grid will raise to 20 percent of the total generation rate by 2030. Especially, with Interconnection guarantee policy for small generators by Korea’s power corporation, KEPCO, established in Oct, 2016, DERs interconnection delay due to lack of allowable distribution hosting capacity occurred and reduction of expanding cost for distribution facilities where 70% of DERs in South Korea are installed became one of important issues of KEPCO. Therefore, KEPCO needs to extract reasonable measures to increase feasible hosting capacity of distribution feeders in order to reduce expanding facilities cost under the condition of no matter in distribution system operation. This paper proposes feasible hosting capacity of distribution feeders that can be adopted and the status of DER installation in distribution system, PV generation data, minimum load data in distribution feeders.

귀선전류 고조파에 의한 자동열차정지장치 영향 분석 Analysis of the Effect of Automatic Train Stop(ATS) by the Return Current Harmonics

https://doi.org/10.5370/KIEE.2020.69.3.523

백종현(Jong-Hyen Baek) ; 창상훈(Sang-Hoon Chang) ; 곽우현(Woo-Hyun Kwak)

The use of ATS(Automatic Train Stop) has been restricted recently with the introduction of a onboard ETCS(European Train Control System) Level 1 ATP(Automatic Train Protection). However, ATS are still installed and operated on most of Korea's existing lines. Data may not be transmitted from ground equipment of ATS due to the effect of the return current harmonics. In such a case, the onboard ATS on the vehicle may cause emergency braking or malfunction and cause problems such as delays in train operation or accidents. For these reasons, the Railroad Safety Act obligates the government to verify the performance of a facility after the new installation of the ATS device. In this paper, the measurement and analysis method of whether these return current harmonics can affect the ground equipment of ATS is presented. In addition, the test results of electric railway vehicle operation are presented.