• Journal of Communications and Networks
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• v.14 no.6
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• pp.672-681
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• 2012

A potential breakthrough of the electrification of the vehicle fleet will incur a steep rise in the load on the electrical power grid. To avoid huge grid investments, coordinated charging of those vehicles is a must. In this paper, we assess algorithms to schedule charging of plug-in (hybrid) electric vehicles as to minimize the additional peak load they might cause. We first introduce two approaches, one based on a classical optimization approach using quadratic programming, and a second one, market based coordination, which is a multi-agent system that uses bidding on a virtual market to reach an equilibrium price that matches demand and supply. We benchmark these two methods against each other, as well as to a baseline scenario of uncontrolled charging. Our simulation results covering a residential area with 63 households show that controlled charging reduces peak load, load variability, and deviations from the nominal grid voltage.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.2
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• pp.361-370
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• 2024

In this paper, a method was studied for applying a series resonant type fault current limiter that can be manufactured at low cost to the smart grid distribution system. First, the impact of the harmonic components of the short-circuit fault current injected into the series resonance circuit of the fault current limiter on the peak value of the transient response was analyzed, and a methodology for determining the steady-state response was studied using percent impedance-based fault current computation method. Next, the effectiveness of the method was verified by applying it to a test distribution line. The test distribution system using the designed current limiter was modeled using EMTP_RV, and a three-phase short-circuit fault was simulated. In the fault simulation results, it was confirmed that the steady-state response of the fault current accurately followed the design target value after applying the fault current limiter. In addition, by comparing the fault current waveform before and after applying the fault current limiter, it was confirmed that the fault current was greatly suppressed, confirming the effect of applying the series resonance type current limiter to the distribution system.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1013-1024
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• 2022

In addition to the assessment measure of electric quality levels, load loss are also a factor in hindering the financial profits of electrical sales companies. Therefore, accurate analysis of load losses generated from distributed power networks is very important. The accurate calculation of load losses in the distribution line has been carried out for a long time in many research institutes as well as power utilities around the world. But it is increasingly difficult to calculate the exact amount of loss due to the increase in the congestion of distribution power network due to the linkage of distributed energy resources(DER). In this paper, we develop smart grid big data infrastructure in order to accurately analyze the load loss of the distribution power network due to the connection of DERs. Through the preprocess of data selected from the smart grid big data, we develop a load loss analysis model that eliminated 'veracity' which is one of the characteristics of smart grid big data. Our analysis results can be used for facility investment plans or network operation plans to maintain stable supply reliability and power quality.

• International Journal of Computer Science & Network Security
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• v.21 no.6
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• pp.89-100
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• 2021

Smart Grid Network (SGN) is a next generation electrical power network which digitizes the power distribution grid and achieves smart, efficient, safe and secure operations of the electricity. The backbone of the SGN is information communication technology that enables the SGN to get full control of network station monitoring and analysis. In any network where communication is involved security is essential. It has been observed from several recent incidents that an adversary causes an interruption to the operation of the networks which lead to the electricity theft. In order to reduce the number of electricity theft cases, companies need to develop preventive and protective methods to minimize the losses from this issue. In this paper, we have introduced a machine learning based SVM method that detects malicious nodes in a smart grid network. The algorithm collects data (electricity consumption/electric bill) from the nodes and compares it with previously obtained data. Support Vector Machine (SVM) classifies nodes into Normal or malicious nodes giving the statues of 1 for normal nodes and status of -1 for malicious -abnormal-nodes. Once the malicious nodes have been detected, we have done a trust evaluation based on the nodes history and recorded data. In the simulation, we have observed that our detection rate is almost 98% where the false alarm rate is only 2%. Moreover, a Trust value of 50 was achieved. As a future work, countermeasures based on the trust value will be developed to solve the problem remotely.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.572-575
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• 2011

It is well known that spanning tree protocol (STP) is the most commonly used protocol in switching networks for smart grid. STP selectively blocks redundancy links of the network to prevent layer 2 loops in network, and it also has a functionality of backing up links. As with the other protocols, STP has been updated with the continuing development of the network. STP is a broad concept and it does not just refer in particular to defined STP protocol in IEEE 802.1D standards, it refers to updated spanning tree protocol based on STP. Because of uneven distribution of communication traffic in root bridge, STP cannot satisfy fast converge nce while the failure occurs near the root bridge or on the root bridge in tree topologies of STP. In this paper, we propose a novel method --- Hyper Cube Spanning Tree Protocol (HCSTP) to solve uneven distribution of communication traffic. Theoretically, hyper cube in our protocol increases throughput and improves the utilization of communication. The simulation results show that HCSTP can achieve comparative and considerably higher performance than other STP protocols in terms of reconnection.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.8-19
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• 2020

We see an energy fucused smart city evolution of the UK along with the project of "Smart London Plan (SLP)." A theoretical logic of business model innovation has been discussed and a research framework of evolving energy focused smart city is formulated. The starting point is the silo system. In the second stage, the private investment in smart meters establishes a basement for next stages. As results, the UK's smart energy sector has evolved from smart meter installation through smart grid to new business models such as water-energy nexus and microgrid. Before smart meter installation of the government, the electricity system was centralized. However, after consumer engagement plan has been set to make them understand benefits that they can secure through smart meters, the customer behavior has been changed. The data analytics firm enables greater understanding of consumer behavior and it helps energy industry to be smart via controlling, securing and using that data to improve the energy system. In the third stage, distribution network operators (DNOs)' access to smart meter data has been allowed and the segmentation starts. In the fourth stage, with collaboration of Ofwat and Ofgem, it is possible to eliminate unnecessary duplication of works and reduce interest conflict between water and electricity. In the fifth stage, smart meter and grid has been integrated as an "adaptive" system and a transition from DNO to DSO is accomplished for the integrated operation. Microgrid is a prototype for an "adaptive" smart grid. Previous steps enable London to accomplish a platform leadership to support the increasing electrification of the heating and transport sector and smart home.

• Journal of the Korea Society for Simulation
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• v.24 no.1
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• pp.17-24
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• 2015

Smart grid is a modernized electrical grid that uses information and communication technologies to gather and act on information, such as information about the behaviors of suppliers and consumers, in an automated fashion to improve the efficiency, reliability, economics, and sustainability of the production and distribution of electricity. However, with the advent of cyber crime, there are also concerns on the security of the infrastructure, primarily that involving communications technologies. In this work, we make an in-depth investigation on the issue of security services and network loads on Smart grid. Through simulation, we analyze the relations between security services and network loads. The experimental results of this study will contribute toward designing an advanced Smart grid system that offers better quality of services. Also, the approach proposed in this study can be utilized to derive new and valuable insights in security aspects.

• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.605-612
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• 2011

As the power grids are integrated into one big umbrella called a "smart grid," communication protocol plays a key role in successful operations. The successful deployment of smart grid interoperability is a major hurdle that must be overcome. The micro grid, a small power system that distributes energy resource, is operated in diverse regions. Different vendors use different communication protocols in the operation of the micro grid. Recently, the IEC 61850 has been legislated to solve the interoperability problems in power utility automation. The present paper presents a micro grid system based on the IEC 61850 protocol. It consists of a micro grid monitoring system, a protocol converter that transforms serial data to IEC 61850 data, and distributed energy resource controllers for diverse DER nodes. A developed communication gateway can be deployed for DER controllers with serial links to exchange data with IEC 61850-based devices. The gateway can be extended to IEC 61850-based distribution automation systems, substation automation systems, or SCADA.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.2
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• pp.80-89
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• 2014

In this paper, we conceive a context-aware recommendations system for water distribution in future smart water grids, with taking the end users' profiles, water types, network conditions into account. A spectral clustering approach is developed to cluster end users into different communities, based on the end users' common interests in water resources. A back-propagation (BP) neural network is designed to obtain the rating list of the end users' preferences on water resources and the water resource with the highest prediction rating is recommended to the end users. Simulation results demonstrate that the proposed scheme achieves the improved accuracy of recommendation within 2.5% errors notably together with a better user experience in contrast to traditional recommendations approaches.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.737-743
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• 2013

This paper describes the overvoltage through lightning surge analysis on underground system in DC combined distribution systems. It is considered that operating micro grid including distributed generation with smart grid can make possibility of composing new distribution system different from existing one. However, there are many papers about low voltage DC distribution in grids or buildings but not many about replacement or distributing 22.9kV AC distribution system to DC system. Among many research need for DC system development, overvoltage is studied in this paper. Overvoltage is simulated on DC cable when lightning strikes to overhead grounding wire which is installed at the nearest location from power cable section. Analysis as well as modeling is performed in EMTP/ATPDraw. It is evaluated that analysis results can be used to design of DC underground distribution power cable system.