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Gyu-Jung Cho
Korea Railroad Research Institute, Uiwang 16105, Korea

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Journal article
Published: 21 June 2021 in Applied Sciences
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This paper presents a Scott transformer model to be applied in electromagnetic transients (EMT) programs, particularly in the absence of a detailed Scott transformer model for performing real-time simulations (RTS). Regarding a Scott transformer, a common topology for converting a three-phase network into two single-phase networks, the transformer model in EMT programs is essential to simulate large-scale electric railway systems. A code-based model has been developed to simulate the transformer in RTS directly and contain the transformer’s actual impedance characteristics. By establishing a mathematical foundation with the current injection method, we presented a matrix representation in conjunction with a network solution of EMT programs. The proposed model can handle more practical parameters of Scott transformers with a relatively low computational load. Thus, it supports the flexible computation of real-time simulators with a finite number of processor units. The accuracy of the model is verified by simulating it and comparing the simulation results with an industrial transformer’s certified performance. Furthermore, a case study involving a comparison of the results with the field measurement data of an actual Korean railway system demonstrated the efficacy of the model.

ACS Style

Choongman Lee; Gyu-Jung Cho; Joorak Kim. Development of Scott Transformer Model in Electromagnetic Transients Programs for Real-Time Simulations. Applied Sciences 2021, 11, 5752 .

AMA Style

Choongman Lee, Gyu-Jung Cho, Joorak Kim. Development of Scott Transformer Model in Electromagnetic Transients Programs for Real-Time Simulations. Applied Sciences. 2021; 11 (12):5752.

Chicago/Turabian Style

Choongman Lee; Gyu-Jung Cho; Joorak Kim. 2021. "Development of Scott Transformer Model in Electromagnetic Transients Programs for Real-Time Simulations." Applied Sciences 11, no. 12: 5752.

Journal article
Published: 20 May 2020 in Energies
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Recently, the operation of a mixed transmission system has increased due to rapid urbanization and the purpose of a good view. Therefore, a proper protection scheme for a mixed transmission system is required. Generally, when a fault occurs on a transmission line, auto reclosing is performed for the purpose of improving the continuity of service by clearing the fault and restoring the power system. However, the auto reclosing scheme should be applied to a mixed transmission system carefully because the mixed transmission system involves underground cable sections. When a fault occurs in the underground cable section, it is mostly a permanent fault. If auto reclosing is performed on a permanent fault condition, it may cause excessive overcurrent and switching surge, which can generate a serious impact on the whole transmission system and even cause an explosion. Due to this, many utilities worldwide do not allow auto reclosing or only apply it very restrictively on a mixed transmission system based on their practice. However, there is no clear guidance or standard related to auto reclosing on a mixed transmission system. Therefore, in this paper, an application of a recloser operation algorithm is proposed. Based on the proposed algorithm, reclosers can work properly and protect the transmission system. To verify the proposed algorithm, simulations were conducted using the ElectroMagnetic Transient Program (EMTP).

ACS Style

Seung-Hyun Sohn; Gyu-Jung Cho; Chul-Hwan Kim. A Study on Application of Recloser Operation Algorithm for Mixed Transmission System Based on Travelling Wave Method. Energies 2020, 13, 2610 .

AMA Style

Seung-Hyun Sohn, Gyu-Jung Cho, Chul-Hwan Kim. A Study on Application of Recloser Operation Algorithm for Mixed Transmission System Based on Travelling Wave Method. Energies. 2020; 13 (10):2610.

Chicago/Turabian Style

Seung-Hyun Sohn; Gyu-Jung Cho; Chul-Hwan Kim. 2020. "A Study on Application of Recloser Operation Algorithm for Mixed Transmission System Based on Travelling Wave Method." Energies 13, no. 10: 2610.

Journal article
Published: 10 February 2020 in IEEE Transactions on Sustainable Energy
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ACS Style

Ji-Soo Kim; Chul-Hwan Kim; Yun-Sik Oh; Gyu-Jung Cho; Jin-Sol Song. An Islanding Detection Method for Multi-RES Systems Using the Graph Search Method. IEEE Transactions on Sustainable Energy 2020, 11, 2722 -2731.

AMA Style

Ji-Soo Kim, Chul-Hwan Kim, Yun-Sik Oh, Gyu-Jung Cho, Jin-Sol Song. An Islanding Detection Method for Multi-RES Systems Using the Graph Search Method. IEEE Transactions on Sustainable Energy. 2020; 11 (4):2722-2731.

Chicago/Turabian Style

Ji-Soo Kim; Chul-Hwan Kim; Yun-Sik Oh; Gyu-Jung Cho; Jin-Sol Song. 2020. "An Islanding Detection Method for Multi-RES Systems Using the Graph Search Method." IEEE Transactions on Sustainable Energy 11, no. 4: 2722-2731.

Journal article
Published: 25 December 2019 in Applied Sciences
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Electric railways use a single-phase system, with the line comprising a trolley wire (TF) that supplies power to the load with a neutral wire and an autotransformer (AF) feeder to absorb the return current of the rail. Testing the performance of the protective relay that detects the fault of the traction power-supply system (TPSS) and operates the circuit breaker is very important. Until now, the performance test of protective relays for the TPSS has been conducted via a simple-steady test or using an expensive real-time simulator. However, under a fast-moving environment in which the load consumes a large amount of power, the protective relay must always detect faults and operate properly. This paper proposes a digital simulator that enables the dynamic testing of protective relays without using any steady test and expensive real-time simulators. This simulator includes both external waveform import and internal waveform generation functions. Users can test the operation of the protective relay by entering the waveform generated externally or internally into the protective relay. Additionally, it has the ability to monitor the operating protection elements and pickup time when the protective relay detects a fault and orders the circuit breaker trip.

ACS Style

Joorak Kim; Gyu-Jung Cho; Jaewon Kim; Kim. Development of Railway Protective Relay Simulator for Real-Time Applications. Applied Sciences 2019, 10, 191 .

AMA Style

Joorak Kim, Gyu-Jung Cho, Jaewon Kim, Kim. Development of Railway Protective Relay Simulator for Real-Time Applications. Applied Sciences. 2019; 10 (1):191.

Chicago/Turabian Style

Joorak Kim; Gyu-Jung Cho; Jaewon Kim; Kim. 2019. "Development of Railway Protective Relay Simulator for Real-Time Applications." Applied Sciences 10, no. 1: 191.

Review
Published: 04 March 2019 in Energies
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The increased penetration of distributed generation (DG), renewable energy utilization, and the introduction of the microgrid concept have changed the shape of conventional electric power networks. Most of the new power system networks are transforming into the DG model integrated with renewable and non-renewable energy resources by forming a microgrid. Islanding detection in DG systems is a challenging issue that causes several protection and safety problems. A microgrid operates in the grid-connected or stand-alone mode. In the grid-connected mode, the main utility network is responsible for a smooth operation in coordination with the protection and control units, while in the stand-alone mode, the microgrid operates as an independent power island that is electrically separated from the main utility network. Fast islanding detection is, therefore, necessary for efficient and reliable microgrid operations. Many islanding detection methods (IdMs) are proposed in the literature, and each of them claims better reliability and high accuracy. This study describes a comprehensive review of various IdMs in terms of their merits, viability, effectiveness, and feasibility. The IdMs are extensively analysed by providing a fair comparison from different aspects. Moreover, a fair analysis of a feasible and economical solution in view of the recent research trend is presented.

ACS Style

Min-Sung Kim; Raza Haider; Gyu-Jung Cho; Chul-Hwan Kim; Chung-Yuen Won; Jong-Seo Chai. Comprehensive Review of Islanding Detection Methods for Distributed Generation Systems. Energies 2019, 12, 837 .

AMA Style

Min-Sung Kim, Raza Haider, Gyu-Jung Cho, Chul-Hwan Kim, Chung-Yuen Won, Jong-Seo Chai. Comprehensive Review of Islanding Detection Methods for Distributed Generation Systems. Energies. 2019; 12 (5):837.

Chicago/Turabian Style

Min-Sung Kim; Raza Haider; Gyu-Jung Cho; Chul-Hwan Kim; Chung-Yuen Won; Jong-Seo Chai. 2019. "Comprehensive Review of Islanding Detection Methods for Distributed Generation Systems." Energies 12, no. 5: 837.

Journal article
Published: 17 October 2018 in IEEE Power and Energy Magazine
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In South Korea (RE PUBLIC OF KOREA ), there has been a recent increase in the deployment of renewable energy sources. Concerns regarding environmental impacts from traditional fossil-fuel generation resulted in a 227% increase in renewable energy in 2015, compared to 2008. The South Korean Ministry of Trade, Industry, and Energy is considering generating 20% of the nation's electricity using renewable resources by 2030, up from 6.2% in 2017, according to the Renewable Energy 3020 Implementation Plan (signifying that in 2030 there should be 20% of energy from renewables) and the Eighth Basic Plan for Long-Term Electricity Supply and Demand, which were announced in December 2017. To aid in achieving this goal, it is expected that the capacity of renewable energy equipment to be supplied by 2030 will be 48.7 GW.

ACS Style

Gyu-Jung Cho; Chul-Hwan Kim; Yun-Sik Oh; Min-Sung Kim; Ji-Soo Kim. Planning for the Future: Optimization-Based Distribution Planning Strategies for Integrating Distributed Energy Resources. IEEE Power and Energy Magazine 2018, 16, 77 -87.

AMA Style

Gyu-Jung Cho, Chul-Hwan Kim, Yun-Sik Oh, Min-Sung Kim, Ji-Soo Kim. Planning for the Future: Optimization-Based Distribution Planning Strategies for Integrating Distributed Energy Resources. IEEE Power and Energy Magazine. 2018; 16 (6):77-87.

Chicago/Turabian Style

Gyu-Jung Cho; Chul-Hwan Kim; Yun-Sik Oh; Min-Sung Kim; Ji-Soo Kim. 2018. "Planning for the Future: Optimization-Based Distribution Planning Strategies for Integrating Distributed Energy Resources." IEEE Power and Energy Magazine 16, no. 6: 77-87.

Journal article
Published: 26 September 2018 in IEEE Transactions on Power Delivery
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In general, an autotransformer (AT) is used to improve the voltage sag and inductive interference in power lines and communication lines in the Korean AC electric railway feeding system. In particular, the Korean AT feeding system has a different configuration compared to those of other countries, such as Japan or France; therefore, it has certain distinctive characteristics. However, a fault locator imported from other countries have been used in Korea, and the settings of these equipment should be modified and reflect the distinct characteristics of the Korean AT feeding system. Thus, the development of a novel fault-location scheme for the Korean railway system is required. Herein, we analyzed the fault current and developed a specific relationship for use in our new algorithm. We presented the current magnitude of each branch, expressed by the boosting current of the ATs; further, the novel fault-location scheme using this relationship is developed. The novel scheme performance is verified through power system computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) and the field measured data.

ACS Style

Gyu-Jung Cho; Chul-Hwan Kim; Min-Sung Kim; Dong-Hyun Kim; Seung-Hoon Heo; Hyun-Dong Kim; Myung-Hwan Min; Tae-Pung An. A Novel Fault-Location Algorithm for AC Parallel Autotransformer Feeding System. IEEE Transactions on Power Delivery 2018, 34, 475 -485.

AMA Style

Gyu-Jung Cho, Chul-Hwan Kim, Min-Sung Kim, Dong-Hyun Kim, Seung-Hoon Heo, Hyun-Dong Kim, Myung-Hwan Min, Tae-Pung An. A Novel Fault-Location Algorithm for AC Parallel Autotransformer Feeding System. IEEE Transactions on Power Delivery. 2018; 34 (2):475-485.

Chicago/Turabian Style

Gyu-Jung Cho; Chul-Hwan Kim; Min-Sung Kim; Dong-Hyun Kim; Seung-Hoon Heo; Hyun-Dong Kim; Myung-Hwan Min; Tae-Pung An. 2018. "A Novel Fault-Location Algorithm for AC Parallel Autotransformer Feeding System." IEEE Transactions on Power Delivery 34, no. 2: 475-485.

Journal article
Published: 03 May 2017 in Energies
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High-speed auto-reclosing is used in power system protection schemes to ensure the stability and reliability of the transmission system; leader-follower auto-reclosing is one scheme type that is widely used. However, when a leader-follower reclosing scheme responds to a permanent fault that affects a transmission line in the proximity of a generation plant, the reclosing directly impacts the turbine-generator shaft; furthermore, the nature of this impact is dependent upon the selection of the leader reclosing terminal. We therefore analyzed the transient torque of the turbine-generator shaft according to the selection of the leader-follower reclosing end between both ends of the transmission line. We used this analysis to propose an adaptive leader-end reclosing algorithm that removes the stress potential of the transient torque to prevent it from damaging the turbine-generator shaft. We conducted a simulation in actual Korean power systems based on the ElectroMagnetic Transients Program (EMTP) and the Dynamic Link Library (DLL) function in EMTP-RV (Restructured Version) to realize the proposed algorithm.

ACS Style

Gyu-Jung Cho; Ji-Kyung Park; Seung-Hyun Sohn; Se-Jin Chung; Gi-Hyeon Gwon; Yun-Sik Oh; Chul-Hwan Kim. Development of a Leader-End Reclosing Algorithm Considering Turbine-Generator Shaft Torque. Energies 2017, 10, 622 .

AMA Style

Gyu-Jung Cho, Ji-Kyung Park, Seung-Hyun Sohn, Se-Jin Chung, Gi-Hyeon Gwon, Yun-Sik Oh, Chul-Hwan Kim. Development of a Leader-End Reclosing Algorithm Considering Turbine-Generator Shaft Torque. Energies. 2017; 10 (5):622.

Chicago/Turabian Style

Gyu-Jung Cho; Ji-Kyung Park; Seung-Hyun Sohn; Se-Jin Chung; Gi-Hyeon Gwon; Yun-Sik Oh; Chul-Hwan Kim. 2017. "Development of a Leader-End Reclosing Algorithm Considering Turbine-Generator Shaft Torque." Energies 10, no. 5: 622.