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Hyun Wook Lee

Bio: Hyun Wook Lee is an academic researcher. The author has contributed to research in topics: Current transformer & Fault (power engineering). The author has an hindex of 4, co-authored 9 publications receiving 43 citations.

Papers
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Proceedings ArticleDOI
01 Jan 2013
TL;DR: A prototype AC high speed circuit breaker which could interrupt the short circuit current of 12.5kA, 25.8kV within 1 cycle of 60Hz is proposed and a prototype over current relay(OCR) which can send a trip signal within 1/2 cycle of60Hz is developed.
Abstract: In electrical power systems, especially highly networked and become smart grid recently, faster protection relay and faster circuit breaker are more desirable for system stability at short circuit accidents. Nowadays general interruption time of circuit breaker is 3~5 cycle and trip signal sending time of a protection relay is about 2 cycle for instant operation. Most cases these circuit breaker and protection relay are sufficient for protection of the power systems but some special cases faster circuit breaker and relay are required. We proposed a prototype AC high speed circuit breaker which could interrupt the short circuit current of 12.5kA, 25.8kV within 1 cycle of 60Hz. Also we developed a prototype over current relay(OCR) which can send a trip signal within 1/2 cycle of 60Hz. We carried out a short circuit test these high speed circuit breaker and OCR in combination. At making current of maximum DC components defined in IEC 62271 100 32.5kA peak, 25.8kV, current was sensed and interrupted within 1 cycle. (4 pages)

17 citations

Patent
25 Nov 2009
TL;DR: In this paper, a high speed closing switch in a power distributor includes: a case (200) forming an external appearance; a first electrode (10) provided within the case and including a through hole (14); a second electrode (20) having a receiving recess (24) facing the through hole; a moving contact point member (30) having an cylindrical portion (31) received in the throughhole (14) so as to be receivable into the receiving recess and a flange portion (33) formed at one end of the cylinrical portion; and a
Abstract: A high speed closing switch in a power distributor includes: a case (200) forming an external appearance; a first electrode (10) provided within the case and including a through hole (14); a second electrode (20) having a receiving recess (24) facing the through hole; a moving contact point member (30) having a cylindrical portion (31) received in the through hole (14) so as to be receivable into the receiving recess and a flange portion (33) formed at one end of the cylindrical portion; and a closing coil (80) wound on a base (60) of the case, wherein a damping hole (90) is formed at receiving recess of the second electrode. When the moving contact point member received into the receiving recess approaches its final position, a damping force is applied to the moving contact point member to stably and accurately control the final position.

11 citations

Patent
23 Aug 2011
TL;DR: In this article, the fault determination unit determines whether a fault occurs based on the compared result of the current determination unit and generates a trip signal when it is determined that the fault has occurred.
Abstract: An apparatus for quickly determining a fault in an electric power system includes a current transformer, a current determination unit and a fault determination unit. The current transformer detects current supplied to the electric power system and outputs a current detection voltage. The current determination unit respectively compares the current detection voltage, the first-order differential voltage of the current detection voltage and the second-order differential voltage of the current detection voltage with predetermined first, second and third reference voltages. The fault determination unit determines whether a fault occurs based on the compared result of the current determination unit and generates a trip signal when it is determined that the fault has occurred.

10 citations

Patent
01 Dec 2009
TL;DR: In this article, the authors proposed a rapid input switch of an incoming and distribution panel capable of controlling stably and precisely a final position by applying a damping force to a movable contact member by damping holes formed at the upper part of a housing hole.
Abstract: PROBLEM TO BE SOLVED: To provide a rapid input switch of an incoming and distribution panel capable of controlling stably and precisely a final position by applying a damping force to a movable contact member by damping holes formed at the upper part of a housing hole, when the movable contact member inputted into the housing hole approaches the final position. SOLUTION: The rapid input switch of an incoming and distribution panel comprises a case which forms appearance, a first electrode which is provided in the case and has a through hole, a second electrode having a housing hole opposed to the through hole, a movable contact member which has a cylindrical portion housed in the through hole capable of being inputted in the housing hole and a flange formed at one end of the cylindrical portion, and an input coil wound around at the base of the case. Damping holes are formed in the housing hole of the second electrode. COPYRIGHT: (C)2010,JPO&INPIT

4 citations

Patent
09 Mar 2012
TL;DR: In this paper, a high speed accident determining device is provided to rapidly determine whether an accident is happened or not by controlling the size of accident reference voltage of a current value, a current 1st differential value, and a current 2nd differential value.
Abstract: PURPOSE: A high speed accident determining device is provided to rapidly determine whether an accident is happened or not by controlling the size of accident reference voltage of a current value, a current 1st differential value, and a current 2nd differential value. CONSTITUTION: A current transformer(800) detects a current supplied to an electric power system. A current determining unit(810) compares differential voltage of current detecting voltage of the current transformer with reference voltage. A accident determining unit(850) determines whether an accident is happened or not by using a comparison signal of the current determining unit. The accident determining unit creates a trip signal in case the accident is happened. A plurality of light sensors is installed in a site when an electric arc accident is happened and emits light.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: A compact, efficient and dc fault-tolerant hybrid series converter (HSC) topology is proposed in this article for high-voltage direct current (HVdc) applications and its performance is compared with the prominent converter topologies.
Abstract: A compact, efficient and dc fault-tolerant hybrid series converter (HSC) topology is proposed in this article for high-voltage direct current (HVdc) applications. It contains a parallel and a series chain link (CL) per phase. The parallel CL (PCL) supports the dc-link, whereas the series CL (SCL) enables the HSC to have enhanced operating range and dc fault-tolerant capabilities. A new control technique is proposed to control the SCL submodules (SMs) capacitor voltage for its entire operating range. The performance of HSC and its control technique is evaluated using PSCAD/EMTDC for various conditions. The capability of HSC to work in the undermodulation and overmodulation index range and for HVdc system is examined. Furthermore, the response of HSC during pole-to-pole dc fault and ac faults is analyzed to substantiate its dc fault blocking and ac fault ride-through capabilities. The results obtained validate that the HSC exhibits superior performance over the existing ones. The SMs’ capacitor size design methodology in HSC and for other existing topologies is described. The loss calculation of the HSC is carried out to determine its efficiency and is compared with the prominent converter topologies. A three-phase 13-level HSC experimental setup is developed to validate its feasibility and also to reconfirm the simulation outcomes.

20 citations

Journal ArticleDOI
01 Jan 2020-Energies
TL;DR: In this article, the authors focus on the potential application of the IEC 61850 generic object-oriented substation event (GOOSE) protocol in the AC microgrid for adaptive protection.
Abstract: The IEC 61850 communication standard is getting popular for application in electric power substation automation. This paper focuses on the potential application of the IEC 61850 generic object-oriented substation event (GOOSE) protocol in the AC microgrid for adaptive protection. The focus of the paper is to utilize the existing low-voltage ride through characteristic of distributed generators (DGs) with a reactive power supply during faults and communication between intelligent electronic devices (IEDs) at different locations for adaptive overcurrent protection. The adaptive overcurrent IEDs detect the faults with two different preplanned settings groups: lower settings for the islanded mode and higher settings for the grid-connected mode considering limited fault contributions from the converter-based DGs. Setting groups are changed to lower values quickly using the circuit breaker status signal (XCBR) after loss-of-mains, loss-of-DG or islanding is detected. The methods of fault detection and isolation for two different kinds of communication-based IEDs (adaptive/nonadaptive) are explained for three-phase faults at two different locations. The communication-based IEDs take decisions in a decentralized manner, using information about the circuit breaker status, fault detection and current magnitude comparison signals obtained from other IEDs. However, the developed algorithm can also be implemented with the centralized system. An adaptive overcurrent protection algorithm was evaluated with PSCAD (Power Systems Computer Aided Design) simulations, and results were found to be effective for the considered fault cases.

15 citations

Patent
John J. Shea1
05 Aug 2011
TL;DR: An arc flash arrester includes a fixed contact; a movable contact; an actuator mechanism structured to close the movable and fixed contacts; and insulation disposed between the fixed and movable contacts in an open position of the arc flash ARrester as mentioned in this paper.
Abstract: An arc flash arrester includes a fixed contact; a movable contact; an actuator mechanism structured to close the movable and fixed contacts; and insulation disposed between the fixed and movable contacts in an open position of the arc flash arrester. The insulation is selected from the group consisting of liquid insulation; SF 6 ; a gas, other than SF 6 or air, at a pressure of at least about one atmospheric pressure; and solid insulation.

13 citations

Proceedings ArticleDOI
01 Oct 2015
TL;DR: In this article, the analysis of Thomson coil actuator and the dynamic characteristics is presented, which is necessary to the fast switch of HVDC circuit breaker, and experiments are performed for the prototypes with simple contacts and a vacuum interrupter.
Abstract: In this paper, the analysis is performed on Thomson coil actuator and the dynamic characteristics is presented, which is necessary to the fast switch of HVDC circuit breaker. For analysis, electromagnetic and dynamic equations are simultaneously solved using commercial code. Whole geometry with a drive coil is simplified and applied to analysis by considering the cylindrical shape of the actuator for simulation. In calculation of current flowing through the coil as the component of electric power circuit for operation of the actuator, the resistance and the inductance are taken into account, including stray component. The calculated current is used to predict the repulsive force on the plate, and the stroke of the actuator is deduced from solving the dynamic equation by considering the forces by spring and the gravity besides friction. Through simulation, dynamic variables are calculated such as inductance of a drive coil, force on a repulsive plate, and so on. Also, flux lines, induced current density, and magnetic flux density are predicted to time. In order to confirm the simulation results, experiments are performed for the prototypes with simple contacts and a vacuum interrupter, which is designed for fast switch. Experimental results are compared with simulation and the characteristics are discussed.

12 citations

Patent
10 Oct 2013
TL;DR: In this paper, the fault current detecting circuit includes a current detection unit, a differentiator, and a trip determining unit that outputs a trip control signal only when the first output signal and the second output signal are maintained to be received and the third output signal is not received.
Abstract: The fault current detecting circuit includes: a current detection unit that outputs a current detection signal; a first comparing circuit unit that compares the current detection signal with a predetermined reference current value and outputs a first output signal; a differentiator that differentiates the current detection signal to output a change slope of the current detection signal; a second comparing circuit unit that compares the change slope with a predetermined reference change slope value and outputs a second output signal; a third comparing circuit unit that compares the current detection signal with a predetermined current detection limit reference value and output a third output signal; and a trip determining unit that outputs a trip control signal only when the first output signal and the second output signal are maintained to be received and the third output signal is not received.

12 citations