• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.1921-1929
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• 2015

The smart substation is the heart of a transmission system, which is particularly emphasized as the most significant composition of smart grids in China. In order to assess the functionality performance of substation technologies, this paper presents methods used to identify the most promising solutions for smart substation design and to evaluate the technical levels of available technologies. The multi-index optimization model is presented to address the issue of smart substation planning. A mathematical model of the planning decision problem is established with multiple objectives consisting of economic, reliability, and green key indices, and many kinds of concerns including physical and environmentally friendly operations are formulated as a set of constraints. With respect to the assessment of the technical level regarding integration of advanced technologies into a substation, a modified grey whitenization weight function is adopted to structure a novel grey clustering method. The proposed grey clustering approach is used to overcome the difficulty of insufficient quantitative assessment capacity for traditional methods. The evaluation of technical effects provides the classification definition for the development phase and the maturity level of the smart substation. The effectiveness of the proposed approaches in planning decision-making and evaluation of construction efforts is demonstrated with case studies involving the actual smart substation projects of Wenchongkou substation in China Southern Power Grid (CSG) and Mengzi substation in State Grid Corporation of China (SGCC).

• ETRI Journal
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• 제42권3호
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• pp.366-375
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• 2020

The network traffic prediction of a smart substation is key in strengthening its system security protection. To improve the performance of its traffic prediction, in this paper, we propose an improved gravitational search algorithm (IGSA), then introduce the IGSA into a wavelet neural network (WNN), iteratively optimize the initial connection weighting, scalability factor, and shift factor, and establish a smart substation network traffic prediction model based on the IGSA-WNN. A comparative analysis of the experimental results shows that the performance of the IGSA-WNN-based prediction model further improves the convergence velocity and prediction accuracy, and that the proposed model solves the deficiency issues of the original WNN, such as slow convergence velocity and ease of falling into a locally optimal solution; thus, it is a better smart substation network traffic prediction model.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.981-987
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• 2017

In this paper, we estimate the economic benefits of Energy Storage Systems (ESSs) for peak load shaving in an urban railway substation using the annual cost. The annual investment cost of ESSs is estimated using Net Present Value (NPV) and compared with the cost reduction of electricity by the ESS. The optimal capacities of the battery and Power Converting System (PCS) are determined for peak load shaving. The optimal capacity of the ESS and the peak load shaving is determined to maximize the profit by the ESS. The proposed method was applied to real load data in an urban railway substation, and the results show that electric power costs can be reduced. Other aspects of the ESS, such as the lifetime and unit price of the battery, are also investigated economically.

• 한국인터넷방송통신학회논문지
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• 제17권1호
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• pp.115-121
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• 2017

스마트 그리드 응용에서 ICT(Information and Communication Technologies) 활용은 전력망을 효율성 있고 신뢰성 있게 구축할 수 있다. 전력 시설 내에서 필요한 정보를 교환하는 스마트 그리드 표준으로 IEC 61850이 채택되었다. 그러나 이더넷을 사용하는 IEC 61850과 같은 기술을 소규모 배전 변전소 자동화에 직접 적용하면, 소규모 배전 변전소 그 자체의 가치보다 더 많은 비용이 소요될 수 있다. IEEE 802.15.4 기술은 적은 설치비용과 설치의 용이성으로 인해 전력 설비 자동화 분야에서 관심을 받고 있다. 다소 덜 엄격한 성능이 요구되는 D1 소규모 배전 변전소에 IEEE 802.15.4를 이용하는 연구들이 진행되고 있다. 본 논문에서는 소규모 배전 변전소에 IEEE 802.15.4를 적용하고, 실제 장비들을 이용하여 성능분석을 수행 하였다. 성능 분석 결과를 IEC 61850 메시지 유형과 비교 분석하여 IEEE 802.15.4 적용 범위를 결정하였다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1425-1437
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• 2018

In this paper, a methodology was proposed to reduce the electrical level and spatial size of the smart grid with distributed generations (DGs) to a scale in which the electrical phenomena and control strategies for disturbances on the smart grid could be safely and freely experimented and observed. Based on the design methodology, a micro smart grid simulator with a substation transformer capacity of 190VA, voltage level of 19V, maximum breaking current of 20A and size of $2{\times}2m^2$ was designed by reducing the substation transformer capacity of 45MVA, voltage level of 23kV and area of $2{\times}2km^2$ of the smart grid to over one thousandth, and also reducing the maximum breaking current of 12kA of the smart grid to 1/600. It was verified that the proposed design methodology and designed micro smart grid simulator were very effective by identifying how all of the fault currents are limited to within the maximum breaking current of 20A, and by confirming that the maximum error between the fault currents obtained from the fault analysis method and the simulation method is within 1.8% through the EMTP-RV simulation results to the micro smart grid simulator model.

• 전기학회논문지
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• 제60권7호
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• pp.1324-1330
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• 2011

This paper presents the development of gateway for smart grid for the interoperable communication between IEC 61850 station leveled devices and one of legacy Modbus, DNP3, and IEC60870-5-101/104/103 communication protocol devices of bay level in substation or for the exchange of information between IEC 61850 substation and SCADA control center. The data-mapping model is designed for the exchange of information and the gateway configuration tool is developed for generating meta-data based on XML Schema. this paper is mostly concerned with the design and realization of gateway system for the interoperable data communication between a legacy protocol device and IEC61850 based devices or systems.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.320-329
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• 2012

The Load Tap Changing (LTC) transformer and Shunt Capacitor (SC) bank are major devices for voltage and reactive power control in a distribution substation. Thus, the coordination operation of a LTC transformer and a SC bank is required to achieve better voltage and reactive power compensation at a distribution substation in the same time. This paper proposes coordinate control method of LTC transformer and SC bank to achieve better voltage and reactive power compensation and operation times of these two devices in the same time. The mathematical formulations of the proposed coordinate control method are introduced. Sample case studies are shown to verify the effectiveness of the proposed coordinate control method.

• 조명전기설비학회논문지
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• 제21권9호
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• pp.76-80
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• 2007

For a more efficient and economical management of substations of power system areas, the concept of substation automation has been introduced using intelligent and ubiquitous IT techniques. In this paper, ubiquitous IT prototype hardware, functions and communication interfaces on an embedded platform for substation automation are proposed. Also, operating system architecture is suggested for the effective implementation of substation automation.

• 전기학회논문지
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• 제65권3호
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• pp.404-410
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• 2016

This paper proposed a program of an energy storage system(ESS) for peak shaving of high-speed railway substations The peak shaving saves cost of equipment and demand cost of the substation. To reduce the peak load, it is very important to know when the peak load appears. The past data based load profile forecasting method is easy and applicable to customers which have relatively fixed load profiles. And an optimal scheduling method of the ESS is helpful in reducing the electricity tariff and shaving the peak load efficiently. Based on these techniques, MS. NET based peak shaving program is developed. In case study, a specific daily load profile of the local substation was applied and simulated to verify performance of the proposed program.

• 전기학회논문지
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• 제63권1호
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• pp.27-34
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• 2014

The paper proposed a sizing method of an energy storage system(ESS) for peak shaving of high-speed railway substations based on load profile patterns of substations. A lithium based battery ESS was selected since it can produce high-power at high speed that peak shaving requires, and also takes up a relatively smaller space for installation. Adequate size of the ESS, minimum capacity which can technically meet a peak shaving target, was determined by collectively considering load patterns of a target substation, characteristics of the ESS to be installed, and optimal scheduling of the ESS. In case study, a local substation was considered to demonstrate the proposed sizing method. Also economic analysis with the determined size of ESS was performed to calculate electricity cost savings of the peak shaving ESS, and to offer pay-back period and return on investment.