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Song H.,Seoul National University of Science and Technology | Vovos P.N.,University of Patras | Cho K.-W.,Korea Power Exchange | Kim T.-S.,Korea Power Exchange
Journal of Electrical Engineering and Technology | Year: 2016

This paper presents a method of decision on where bus splitting is needed to reduce fault current level of power systems and to satisfy the fault current constraints. The method employs a modified fault current constrained optimal power flow (FCC-OPF) with X variables for the candidate locations of splitting and for decision making on whether to split or not, it adopts soft-discretization by augmenting inversed U-shaped penalty terms. Also, this paper discusses the procedure on the adequate selection of bus splitting locations based on the results of the modified FCC-OPF, to reduce the total number of the actions taken. © The Korean Institute of Electrical Engineers.


Nam S.-R.,Myongji University | Kang S.-H.,Myongji University | Lee J.-H.,Korea Power Exchange | Choi E.-J.,Korea Power Exchange | And 2 more authors.
Energies | Year: 2013

This paper proposes a linearized load model to evaluate the effect of conservation voltage reduction at a national level. In this model, the respective active and reactive linearizing parameters for active and reactive loads in a power system are estimated using energy management system (EMS) data resulting from conservation voltage reductions. To verify the validity of the linearized load model, PSS/E simulations were conducted for a test power system. Given that conservation voltage reductions are usually executed in the range of 2.0%-5.0%, the proposed model was found to be sufficient to accurately evaluate the effect of conservation voltage reduction. Additionally, Korean EMS data were used to estimate the linearizing parameters for aggregated loads in an actual power system. © 2013 by the authors.


Nam S.-R.,Myongji University | Kang S.-H.,Myongji University | Lee J.-H.,Korea Power Exchange | Ahn S.-J.,Chonnam National University | Choi J.-H.,Chonnam National University
Energies | Year: 2013

In this paper we propose a new method to evaluate the effects of nationwide conservation voltage reduction (CVR) on peak-load shaving, using substation operating results management system (SOMAS) data. Its evaluation is based on a national CVR factor, which is defined as the weighted average of CVR factors associated with all transformer banks and weighting coefficients are determined by the reconstructed loads corresponding to each transformer bank. To make use of the data resulting from nationwide CVR without installing additional measuring devices, we adopt a linearized static-load model with a linearizing parameter. SOMAS data are used to evaluate the effects of nationwide CVR on peak-load shaving in the Korean power system. Evaluation results show that the national CVR factor of the Korean power system has small values in the summer season and large values in the winter season. This means that the effect of nationwide CVR on peak-load shaving in the Korean power system presents stronger benefits during winter months. © 2013 by the authors; licensee MDPI, Basel, Switzerland.


Lee S.,Seoul National University of Science and Technology | Lee W.-H.,Korea Power Exchange
APAP 2011 - Proceedings: 2011 International Conference on Advanced Power System Automation and Protection | Year: 2011

In this paper, some results of power flow computation for 2010 summer peak of South Korea are presented following introduction of the Korea power network composed of 154kV, 345kV and 765kV transmission lines. They include: - total MW on 2010 summer peak time - MW demands of major load buses - MW outputs of major generators - bus voltages of significant buses. Bus angles and the angle differences between buses are important for the study of power flow, stability, protective relaying, etc. This paper shows the magnitude of voltage angles for some meaningful buses. Magnitudes of the real and imaginary part of the complex voltage angles of the buses are compared. The spread angle of the network is also observed. © 2011 IEEE.


Youn H.,Korea Power Exchange
Energy and Environment | Year: 2015

California has established aggressive Renewables Portfolio Standards (RPS) goals to increase the fraction of electricity generated from renewable energy resources and to decrease greenhouse gas emissions under AB 32. By 2010, 20% of California's electricity is required to come from renewables, and 33% has been proposed as a goal for 2020. Most of this new renewable generation will require the electric grid for delivering its electricity to customers.Renewable generators will be integrated into the electric grid at both the transmission and distribution levels, but most of them are expected to connect to the transmission system in locations remote from load centers and existing transmission infrastructure, thus requiring transmission extensions. Some of this renewable generation will exhibit properties quite different from traditional generation and loads, which pose special challenges for providing timely adequate grid delivery capacity, maintaining reliability, and avoiding economic inefficiencies. Finally, power flow constraints through transmission "gateways" into population centers must be relieved before the electricity from renewables can reach customers.In addition to constructing effective transmission interconnections between the renewable resource development areas and California's high-voltage electrical grid, it will be necessary to expand the transmission system capability between the backbone grid transmission gateways and from the transmission gateways to the local load centers.Meeting these challenges for the successful integration of renewables into the electric delivery system will require new or expanded capabilities for the grid. At higher RPS levels, the conventional "build" solutions alone will prove inadequate. New transmission technologies offer the prospect of providing a substantial portion of these new or expanded capabilities.In this report, we investigate how California is dealing with these challenges. We are covering current status, planning issues and operational issues of renewable energy. We hope this report is useful to whom studying renewable energy.Also, we will suggest the methodologies regarding Renewable Energy expansion planning in Korea. In doing so, we hope to make a solid foundation for wide spread of renewable energy.


Kong S.,Korea University | Kim Y.,Korea University | Joo S.-K.,Korea University | Kim J.H.,Korea Power Exchange
Digest of Technical Papers - IEEE International Conference on Consumer Electronics | Year: 2014

This paper presents Cepstrum smoothing-based feature extraction method to reduce the variation of the characteristic signals of home appliance for Nonintrusive Load Monitoring (NILM). In this paper, a data acquisition system is also developed to obtain only characteristic signals of appliances and to filter the noise inputted from the power supply. Testing results are provided to demonstrate the effectiveness of the proposed method. © 2014 IEEE.


Lee S.-H.,Yonsei University | Son S.-E.,Yonsei University | Lee S.-M.,Korea Power Exchange | Cho J.-M.,Korea Power Exchange | And 2 more authors.
Journal of Electrical Engineering and Technology | Year: 2012

So far, the importance for an accurate load model has been constantly raised and its necessity would be further more emphasized. Currently used load model for analysis of power system in Korea was developed 10 years ago, which is aggregated by applying the statistically estimated load compositions to load models based on individual appliances. As modern appliances have diversified and rapidly changed, the existing load model is no longer compatible with current loads in the Korean power system. Therefore, a measurement based load model is more suitable for modern power system analysis because it can accurately include the load characteristics by directly measuring target load. This paper proposes a ZIP model employing a Kalman-filter as the estimation algorithm for the model parameters. The Kamlan-filter based parameter identification offers an advantage of fast parameter determination by removing iterative calculation. To verify the proposed load model, the four-secondinterval real data from the Korea Energy Management System (K-EMS) is used.


Kim S.G.,Korea Power Exchange | Hur S.I.,Korea Power Exchange | Chae Y.-J.,Korea Power Exchange
Journal of Electrical Engineering and Technology | Year: 2010

Recently, smart grid has been considered a very important new energy delivery technology, and one that can help ensure a cleaner environment by making use of information and communication technology (ICT) in countries around the world. The many technological benefits smart grid offers is expected to bring about a huge change in the electric energy supply chain. In particular, smart grid with advanced ICT is likely to allow market agents to participate in the decision-making process in the restructured electricity industry, easily facilitating Homeostatic Utility Control. In this paper, we examine smart grid as a market externality, and then illustrate issues from the commercial market perspective as it relates to electricity market design. Finally, our paper identifies some of the impacts of smart grid on electricity market design, which may possibly be incorporated into the evolution of the electricity market, thus ensuring market efficiency.


Kang S.-G.,Korea University | Seo S.,Korea University | Lee B.,Korea University | Joo J.-Y.,Korea Power Exchange
Journal of Electrical Engineering and Technology | Year: 2010

This paper presents a new algorithm for determining generator operation point for maintaining stability considering generator faults in Jeju-Haenam HVDC system. As the HVDC system consumes reactive power for the transmission of active power substantially, compensation of reactive power is essential. And the HVDC system is operated on frequency control mode. That is to say, the HVDC system almost manages system frequency. Therefore, we recognized that the Jeju system could be unstable if the reactive power consumed by the HVDC is insufficient when out-of-step occurs with large generators. When the solution of power flow analysis does not converge due to the unstable system phenomenon, we have difficulty in establishing countermeasures as the post-fault information is not available. In this paper, for the purpose of overcoming this difficulty in establishing countermeasures, we introduce the CPF(Continuation Power Flow) algorithm. This paper suggests an algorithm for calculating the output limitation of the generator to maintain the stability in case of generator fault in the Jeju system.


Patent
Korea Power Exchange | Date: 2010-06-04

The invention relates to a graphic processing apparatus for stock/futures trading conditions is configured by systematically linking and deploying: a computing module capable of deriving various pieces of stock/futures trading information reflecting stock/futures trading conditions by stock/futures trading times and prices, within a communication pipeline at an exchange system; a computing module capable of producing a screen with stock/futures trading times and prices on a horizontal axis and on a vertical axis, and arranging CRIs (Cells for Recording Stock/Futures Trading Information) corresponding to stock/futures trading times and prices in a matrix configuration on the screen; and a computing module capable of generating an ST (Stock/Futures Trading Information Relation Graph Tag) conforming to stock/futures trading information by stock/futures trading times and prices, inputting the generated ST into the CRIs, and inducing the display of stock/futures trading information by stock/futures trading times and prices.

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