• International Journal of Aeronautical and Space Sciences
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• v.13 no.3
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• pp.398-404
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• 2012

A fault detection process is necessary for high integrity systems like satellites, missiles and aircrafts. Especially, the satellite has to be expected to detect faults autonomously because it cannot be fixed by an expert in the space. Faults can cause critical errors to the entire system and the satellite does not have sufficient computation power to operate a large scale fault management system. Thus, a fault detection method, which has less computational burden, is required. In this paper, we proposed a modified PCA (Principal Component Analysis) as a powerful fault detection method of redundant IMU (Inertial Measurement Unit). The proposed method combines PCA with the parity space approach and it is much more efficient than the others. The proposed fault detection algorithm, modified PCA, is shown to outperform fault detection through a simulation example.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.325-330
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• 2018

In this paper, we investigated the impedance method for searching fault detection point in case of an accident in the AC electric railway AT feeding system. For this purpose, simulation circuit modeling and prototype hardware are made based on the known numerical analysis. As a result of simulation modeling of the feeding system based on the numerical analysis of the impedance method confirmed that the modeling was properly implemented with an average error rate of 0.07%. Also, as a result of fault event by hardware simulator, it was confirmed that the breaker operation time is shortened and the fault current is decreased while the voltage is close to the supply voltage in the transient state as the point of the fault accident moves away from the substation(SS).

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.5
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• pp.243-248
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• 2013

Reliability evaluation is important task in embedded system. It can avoid potential failures and manage the vulnerable components of embedded system effectively. Dynamic fault tree analysis is one of the reliability evaluation methods. It can represent dynamic characteristics of a system such as fault & error recovery, sequence-dependent failures. In this paper, the steering system, which is embedded system in vehicles, is represented using dynamic fault tree. We evaluate the steering system using approximation algorithm based on Simpson's rule. A set of simulation results shows that proposed method overcomes the low accuracy of classic approximation method without requiring no excessive calculation time of the Markov chain method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.18-25
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• 2008

The paper presents a modeling of the grid-connected wind turbine generation system on MATLAB/Simulink and aims to perform simulations for analysis of the system's characteristics. It performs a pitch regulation for control of the wind generator's output with respect to wind speed variation, and presents a relationship between interconnecting transformer's connections and fault current by reviewing the variations of fault current according to transformer connections in a grid-connected wind power generation system. It also investigates the effect of grounding methods of the interconnecting transformer's neutral point on fault current variations. The simulation results show the differences of fault currents, voltages and generator's characteristics for a line-to-ground fault according to interconnecting transformer's four different connections, and the differences of fault currents of the system according to grounding methods of the transformer neutral point. Therefore, the case studies demonstrate the effectiveness of the proposed simulation model on Simulink.

• Journal of Power Electronics
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• v.13 no.4
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• pp.552-557
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• 2013

This paper proposed an analytical model for the distributed magnetic field analysis of interior permanent magnet-type blush-less direct current motors under the stator-turn fault condition using the winding function theory. Stator-turn faults cause significant changes in electric and magnetic characteristic. Therefore, many studies on stator-turn faults have been performed by simulation of the finite element method because of its non-linear characteristic. However, this is difficult to apply to on-line fault detection systems because the processing time of the finite element method is very long. Fault-tolerant control systems require diagnostic methods that have simple processing systems and can produce accurate information. Thus analytical modeling of a stator-turn fault has been performed using the winding function theory, and the distributed magnetic characteristics have been analyzed under the fault condition. The proposed analytical model was verified using the finite element method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.4
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• pp.161-166
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• 1999

We have performed an EMTDC simulation for the current limiting effects of a superconducting fault current limiter (SFCL). The fault currents in the 154 kV transmission line between the arbitrary S1 and S2 substations increased up to 39 kA during the single and double line-to-ground faults, respectively. The SFCL in the transmission line is sufficient.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.2
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• pp.122-129
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• 2016

Current differential protection relaying with second harmonic restraint is the main protection for large capacity power transformer. PSCAD simulation program is widely used for modeling of dynamic varying transients phenomena. This paper deals with a power transformer model and transients analysis using PSCAD software to develop IED for power transformer. Simulation was carried out using a three phase 40MVA, 154/22.9kV, 60Hz, two-winding transformer with Y-Y connection used in actual fields. The paper analyzed transformer magnetizing inrush, external fault, and internal fault conditions with this model in the time domain. In addition, we performed an analysis in the frequency domain using FFT during several conditions.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2278-2288
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• 2017

Multilevel converter topologies are widely used in many applications. The cascaded H-bridge multilevel inverter (CHBMI), which is one of many multilevel converter topologies, has been introduced as a useful topology in high and medium power. However, it has a drawback to require a lot of switches. Therefore, the reliability of CHBMI is important factor for analyzing the performance. This paper presents a simple switch fault diagnosis method for single-phase CHBMI. There are two types of switch faults: open-fault and short-fault. In the open-fault, the body diode of faulty switch provides a freewheeling current path. However, when the short-fault occurs, the distortion of output current is different from that of the open-fault because it has an unavailable freewheeling current flow path due to a disconnection of fuse. The fault diagnosis method is based on the zero current time analysis according to zero-voltage switching states. Using the proposed method, it is possible to detect the location of faulty switch accurately. The PSIM simulation and experimental results show the effectiveness of proposed switch fault diagnosis method.

• Steel and Composite Structures
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• v.15 no.1
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• pp.15-39
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• 2013

The sensitivities of a structural response due to variation of its design parameters are prerequisite in the majority of the algorithms used for fundamental problems in engineering as system uncertainties, identification and probabilistic assessments etc. The paper presents the concept of probabilistic sensitivity of suspension bridges with respect to near-fault ground motion. In near field earthquake ground motions, large amplitude spectral accelerations can occur at long periods where many suspension bridges have significant structural response modes. Two different types of suspension bridges, which are Bosporus and Humber bridges, are selected to investigate the near-fault ground motion effects on suspension bridges random response sensitivity analysis. The modulus of elasticity is selected as random design variable. Strong ground motion records of Kocaeli, Northridge and Erzincan earthquakes are selected for the analyses. The stochastic sensitivity displacements and internal forces are determined by using the stochastic sensitivity finite element method and Monte Carlo simulation method. The stochastic sensitivity displacements and responses obtained from the two different suspension bridges subjected to these near-fault strong-ground motions are compared with each other. It is seen from the results that near-fault ground motions have different impacts stochastic sensitivity responses of suspension bridges. The stochastic sensitivity information provides a deeper insight into the structural design and it can be used as a basis for decision-making.

• Proceedings of the KIEE Conference
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• summer
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• pp.412-414
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• 2004

In this paper, a novel algorithm of underground cable fault location based on the analysis of distributed parameter circuit is proposed. The proposed method makes voltage and current equations about core and sheath, and then establishes a function of the fault distance according to the analysis of fault conditions. Finally gets the solution of this function through Newton-Raphson iteration method. The effectiveness of proposed algorithm has been verified by Matlab program, and the cable parameters such as impedance and admittance are from EMTP simulation.