• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.64 no.1
• /
• pp.18-22
• /
• 2015

When using a secondary battery in energy storage units, if the grid is in light duty the active power is stored so it can be used when the grid is in heavy duty. This makes possible for the load equalize and make the grid optimized. Recently the government is trying to propagate this technology. Depending on its capacity this kind of electric energy storage unit is used in adjusting the frequency, break up the energy peak in summer and winter, stabilize the energy output of renewable energy which can change unstably because of the environment. Which makes it possible to stabilize the grid. It is anticipated that market of 120 trillion won will be developed worldwide in 2030. Currently in Korea a steady supply is in progress. However because of stray electromagnetic waves some other electronics are malfunctioning. This paper covers the research in the method to detect the emission noise in small electric energy storage units using lithium secondary batteries and battery management system, Power conditioning systems with CIPSR standards. And the research of a more efficient method to measure such stray electromagnetic waves.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.3
• /
• pp.1112-1118
• /
• 2014

In island and backcountry areas, electrical power is usually supplied by diesel generators. It is difficult for small scale diesel generators to have an economy of scale owing to the usage of fossil fuels to produce electricity. Also, there is a problem of carbon dioxide emissions that brings some environmental pollution to the entire region of the area. For solving those, this paper proposes a design method of autonomous micro-grid to minimize the fossil fuels of diesel generator, which is composed of diesel generator, wind turbine, battery energy storage system and photovoltaic generation system. The proposed method was verified through computer simulation and micro-grid operation system.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.1
• /
• pp.11-17
• /
• 2012

In recent years, there has been a popularity rose up on Smart TV (Smart Television) usage at home. Therefore, it is also have increase the demand on grid computing system. Smart TV has a variety of platform and usage compare to PC (Personal computer). Base on this, it is difficult to apply a traditional grid system on Smart TV. One major reason are concerning the small idle time compare to PC. To overcome this problem, this paper will propose a Javascript grid system and introducing a new scheduling policy that best suit for a smart TV. We have conduct an experiment on the proposed method. The result provides an average of 1.78 percent, which is improved compare to the traditional method which is only provides an average of 0.09 percent.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.1
• /
• pp.64-71
• /
• 2017

Considering the volatility, intermittent and random of photovoltaic (PV) generation systems, accurate forecasting of PV power output is important for the grid scheduling and energy management. In order to improve the accuracy of short-term power forecasting of PV systems, this paper proposes a prediction model based on environmental factors and support vector machine optimized by genetic algorithm (GA-SVM). In order to improve the prediction accuracy of this model, weather conditions are divided into three types, and the gray correlation coefficient algorithm is used to find out a similar day of the predicted day. To avoid parameters optimization into local optima, this paper uses genetic algorithm to optimize SVM parameters. Example verification shows that the prediction accuracy in three types of weather will remain at between 10% -15% and the short-term PV power forecasting model proposed is effective and promising.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.6
• /
• pp.1255-1260
• /
• 2011

In this paper, we study on the reliability of Very High-rate Power Line Communication (VH-PLC) for Smart Grid, so that the resultant data rate is over 400Mbps at a physical layer. Firstly, reviewing the research trend of the PLC, we discuss the required techniques for supporting the Smart Grid. Considering a pre-specification with the value of several parameters, we investigate a multi-carrier modulation technique to overcome limitations of higher rate transmission under power line channel environments. Then, we propose a system specification of the VH-PLC in the sense of enhancing two features. One is resolving the problem of the co-existence of the deployed high-speed PLC according to the published standardization of KS X 4600-1 in Korea. The other is getting better performance on the grid adopting the diverse element techniques, such as multi-carrier modulation, a subcarrier utilization mode, a variable rate LDPC (Low Density Parity Check) code, and a time and frequency diversity technique. Further, a simulation tool, composed of an Event-Driven simulator and a Time-Driven simulator, is developed for the purpose of verifying the system performance and continuously cross-checking the test bench signal of the proposed VH-PLC system.

• Journal of Power Electronics
• /
• v.17 no.1
• /
• pp.172-180
• /
• 2017

The repetitive control (RC) strategy is widely used in AC power systems because of its high performance in tracking period signal and suppressing steady-state error. However, the dynamic response of RC is determined by the fundamental period delay $T_0$ existing in the internal model. In the current study, a ($nk{\pm}i$)-order harmonic RC structure is proposed to improve dynamic performance. The proposed structure has less data memory and can improve the tracking speed by n/2 times. $T_0$ proves the effectiveness of the ($nk{\pm}i$)-order RC strategy. The simulation and experiments of ($6k{\pm}1$)-order and ($4k{\pm}1$)-order RC strategy used in the voltage source inverter is conducted in this study to control the harmonic current source, which shows the validity and advantages of the proposed structure.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1921-1922
• /
• 2008

전 세계적인 환경에 대한 요구를 충족시키기 위한 노력 및 정책에 따라 전력 에너지 산업 또한 커다란 변화의 요구에 부응하고 있다. 즉, 기존의 전력망에 IT를 접목하고 새로운 종류의 연료를 사용하는 전력원의 개발, 그리고 새로운 방법의 고객 참여 등을 통한 효율적인 에너지의 사용을 골자로 하는 정책들이 그것이다. 대표적인 정책은 바로 미국 의회가 지난 2007년 12월 '스마트그리드(Smart Grid)'라는 프로젝트를 법제화하여 지원방안을 연방법안으로 통과시킴으로서 주목을 받고 있는 'The Energy Independence and Security Act of 2007'이다. 법안은 2008년부터 2020년까지 스마트그리드에 대한 연구개발, 시범사업 등을 국가 정책사업으로 추진한다는 내용을 담고 있으며, 매칭 펀드 등 자금지원 내용도 포함하고 있다. 스마트그리드는 IT를 기존 전력기술에 적용해 송전, 배전망(파워그리드)을 지능형으로 만들자는 개념으로, 2003년 DOE(Development of Energy)가 발표한 2030년까지의 전력인프라 발전 계획인 '그리드2030(Grid2030)'의 실천 전략으로 볼 수도 있다. 이러한 미국의 정책 방향에 따라 각 주마다 다양한 스마트그리드 관련 기술들을 적용하고, 요소 기술들을 축적시키고 있다. 본 논문에서는 Xcel Energy가 미국 최초로 추진하는 'Smart Grid City' 내용을 토대로 관련 기술과 추진전략 등을 살펴보기로 한다.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.4
• /
• pp.1759-1768
• /
• 2018

The energy density, power density and ohm resistance of battery change significantly as results of battery aging, which lead to decrease in the accuracy of the equivalent model. A parameter identification method of the equivale6nt circuit model with 3 R-C branches based on the test database of battery life cycle is proposed in this paper. This database is built on the basis of experiments such as updating of available capacity, charging and discharging tests at different rates and relaxation characteristics tests. It can realize regular update and calibration of key parameters like SOH, so as to ensure the reliability of parameters identified. Taking SOH, SOC and T as independent variables, lookup table method is adopted to set initial value for the parameter matrix. Meanwhile, in order to ensure the validity of the model, the least square method based on variable forgetting factor is adopted for optimizing to complete the identification of equivalent model parameters. By comparing the simulation data with measured data for charging and discharging experiments of Li-ion battery, the effectiveness of the full life cycle database and the model are verified.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.24 no.3
• /
• pp.547-560
• /
• 2014

Smart Grid, which maximize the efficiency of energic utilization by applying Information and Communication Technology to Power Grid, requires high availability. Attacks, such as DDoS, which cause suspension of service and lead to social disruptions have recently been increasing so that systematic management over availability becomes more important. In this paper, we presents a new evaluation criteria of Korean Smart Grid by comparing availability assessment items of international standards specified in management system and then overcome the limitations of availability evaluation of existing information security management system.

• International Journal of Computer Science & Network Security
• /
• v.22 no.4
• /
• pp.1-12
• /
• 2022

In order to overcome the power fluctuation issues in photovoltaic (PV) smart grid-connected systems and the inverter nonlinearity model problem, an adaptive backstepping command-filter and a double second order generalized Integrators (DSOGI) controller are designed in order to tune the AC current and the DC-link voltage from the DC side. Firstly, we propose to present the filter mathematical model throughout the PV system, at that juncture the backstepping control law is applied in order to control it, Moreover the command filter is bounded to the controller aiming to exclude the backstepping controller differential increase. Additionally, The adaptive law uses Lyapunov stability criterion. Its task is to estimate the uncertain parameters in the smart grid-connected inverter. A DSOGI is added to stabilize the grid currents and eliminate undesirable harmonics meanwhile feeding maximum power generated from PV to the point of common coupling (PCC). Then, guaranteeing a dynamic effective response even under very unbalanced loads and/or intermittent climate changes. Finally, the simulation results will be established using MATLAB/SIMULINK proving that the presented approach can control surely the smart grid-connected system.