• Journal of international Conference on Electrical Machines and Systems
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• 제2권1호
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• pp.23-30
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• 2013

This paper proposes a parametric model for inter-turn fault detection in a fault-tolerant permanent-magnet (FTPM) machine, which can predict the effect of the short-circuit fault to various physical quantity of the machine. For different faulty operations, a new effective stator inter-turn fault detection method is proposed. Finally, simulations of vector-controlled FTPM machine drives are given to verify the feasibility of the proposed method, showing that even single-coil short-circuit fault could be exactly detected.

• 대한전기학회논문지:전력기술부문A
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• 제54권6호
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• pp.315-322
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• 2005

In this article, 1 would like to explore the estimation method of time-varying voltage sags in large industrial systems considering the short circuit contributions of rotating machines. For the power distribution system of KEPCO(Korea Electric Power Corporation), the magnitude of initial symmetrical short circuit current is generally not changed. However, in industrial systems which contain a number of rotating machines, the magnitude of voltage sag is generally changed from the initial to the clearing time of a fault due to the decreasing contribution of rotating machines for a fault current. The time-varying characteristics of voltage sags can be calculated using a short circuit analysis that is considered the time-varying fault currents. For this, the prediction formulations of time-varying voltage sags are proposed using a foreign standard. The proposed method contains the consideration of generator and motor effects. For the test of proposed formulations, a simple system of industrial consumer is used for the comparison conventional and proposed estimation method of voltage sag characteristics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2203-2206
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• 2005

A load flow and short circuit fault simulation of AC electrified railway distribution systems is presented with DIgSILENT PowerFactory software. Load flow of electrified railways distribution system with concerning multi train lines and dynamic characteristics of train load is studied for different time laps. The dynamic characteristics of train load in starting and braking conditions with different starting and stopping times and its moving positions makes the load flow complicated so there is a great need in studying the effects of electrified railways on load flow. Short circuit fault transients is also studied and simulated for both power system or traction distribution system and their effects on the operation of the train sets is investigated.

• 한국초전도ㆍ저온공학회논문지
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• 제23권3호
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• pp.51-54
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• 2021

The DC system has less power loss compared to the AC system because there is no influence of frequency and dielectric loss. However, the zero-crossing point of the current is not detected in the event of a short circuit fault, and it is difficult to interruption due to the large fault current that occurs during the opening, so the reliability of the DC breaker is required. As a solution to this, an LC resonance DC circuit breaker combined a superconducting element has been proposed. This is a method of limiting the fault current, which rises rapidly in case of a short circuit fault, with the quench resistance of the superconducting element, and interruption the fault current passing through the zero-crossing point through LC resonance. The superconducting current limiting element combined to the DC circuit breaker plays an important role in reducing the electrical burden of the circuit breaker. However, at the beginning of a short circuit fault, superconducting devices also have a large electrical burden due to large fault currents, which can destroy the element. In this paper, the reactor is connected to the source side of the circuit using PSCAD/EMTDC. After that, the change of the fault current according to the reactor capacity and the electrical burden of the superconducting element were confirmed through simulation. As a result, it was confirmed that the interruption time was delayed as the capacity of the reactor connected to the source side increased, but peak of the fault current decreased, the zero-crossing point generation time was shortened, and the electrical burden of the superconducting element decreased.

• KEPCO Journal on Electric Power and Energy
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• 제6권2호
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• pp.119-122
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• 2020

With recent ESS (Energy Storage System) fire accident, the fault protection performance is becoming more important. However, there has never been any experiments with the protection performance on the faults in the ESS system level. In this study, the effect of AC ground fault and IGBT (Insulated Gate Bipolar mode Transistor) short-circuit failure on MW class ESS was performed experimentally for the first time in the world. First of all, the effect of the AC single line ground fault on battery was analyzed. Moreover, the transient voltage was investigated as a function of the battery capacity and the power level. Finally, the breaking capability and insulation performance of ESS were examined under PCS short-circuit fault condition. Through the tests, it was found that ESS protection system safely blocked the faulty current regardless of the faults, whereas the electronic parts such as IGBT and MC (Magnetic Contactor) were broken by the fault current. Also, the electrical breakdown in ESS resulted from the transient voltage during the protection process.

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.56-59
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• 2003

As electric power systems grow to supply the increasing electric power demand short-circuit current tends to increase and impose a severe burden on circuit breakers and power system apparatuses. Thus, all electric equipment in a power system has to he designed to withstand the mechanical and thermal stresses of potential short-circuit currents. Among current limiting devices, Fault Current Limiter (FCL) is expected to reduce the short-circuit current. Especially, Superconducting Fault Current Limiters (SFCL) offer ideal performance: in normal operation the SFCL is in its superconducting state and has negligible impedance, in the event of a fault, the transition into the normal conducting state passively limits the current. The SFCL using high-temperature superconductors offers a positive resolution to controlling fault-current levels on utility distribution and transmission networks. This study contributes to the EMTDC based modeling and simulation method of DC Reactor type SFCL. Single and three phase faults in the utility system with DC reactor type SFCLs have been simulated using EMTDC in order to coordinate with other equipments, and the results are discussed in detail.

• Journal of Power Electronics
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• 제15권4호
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• pp.1074-1084
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• 2015

These days, the widespread use of sensitive loads and distributed generators makes the solid-state circuit breaker (SSCB) an essential component in power circuits to achieve a high power quality for AC Grids. In traditional AC SSCB using SCRs, some auxiliary mechanical devices are required to make the reclosing operation possible before fault recovery. However, the proposed AC SSCB can break quickly and then be reclosed without auxiliary mechanical devices even during the short-circuit fault. Moreover, its fault current breaking time is short and its SSCB reclosing operation is fast. This results in a reduction of the economic losses due to fault currents and power outages. Through simulations and experiments on short-circuit faults, the performance characteristics of the proposed AC SSCB are verified. A design guideline is also suggested to apply the proposed AC SSCB to various AC grids.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.476-479
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• 2001

Interconnection of new energy sources, such as photovoltaic generation, wind power generation, etc., into the electric power distribution system may result in the increasing short-circuit capacity when a short circuit fault occurs. The short-circuit capacity becomes over the interrupting ratings of circuit breakers, and then they fails to operate in the proper way they prevent fault currents from flowing into the distribution facilities and thus causing them serious damages. This study deals with impacts on the respective short-circuit capacity of both low voltage and extra high voltage distribution systems at which new energy sources are installed. In order to obtain more accurate and all-case values very close to reality in the complicated distribution system, computer simulation tools should be required. In this paper, however, its focus is placed on examining the varying trend of short-circuit capacity, which may happen owing to new energy source interconnection, as a previewing step for exhaustive simulation studies.

• 조명전기설비학회논문지
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• 제26권12호
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• pp.68-73
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• 2012

In this paper, the fault current limiting characteristics of a flux-lock type superconducting fault current limiter (SFCL) with peak current limiting function were analyzed through its short-circuit tests. The setting condition for the peak current limiting operation was derived from its electrical equivalent circuit, which was dependent on the inductance ratio between the third coil and the first coil. Through the analysis on the short-circuit tests for the flux-lock type SFCLs with the different inductance ratio between the third coil and the first coil, the setting value for the peak current limiting operation of the flux-lock type SFCL with peak current limiting function could be confirmed to be adjusted with the variation of the inductance ratio between the third coil and the first coil.

• 전기학회논문지
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• 제66권2호
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• pp.300-304
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• 2017

Due to the introduction of various types of dispersed generations (DGs) with larger capacity in a power distribution system, the short-circuit current is expected to be increased, which more requires for the effective fault current limiting methods. As one of the promising countermeasures, the superconducting fault current limiter (SFCL) has been noticed. However, the decreased fault current by SFCL affects the operation of the overcurrent relay (OCR), representative protective device in a power distribution system. In this paper, the operation of the overcurrent relay due to the application of a SFCL in a power distribution system with DG linked by its bus line was analysed through the short-circuit tests. To analyze the effect of the SFCL application in a power distribution system with DG, the experimental simulated circuits were designed and the short-circuit tests for the power distributed system assembled with the DG, the OCR and the SFCL were carried out. Through the analysis on the short-circuit tests, the application of the SFCL in a power distribution system with DG could be confirmed to be contributed to the operational improvement of overcurrent relay.