• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.115-120
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• 2004

Most of the LV customer have been applied the distribution system of 3-phase four wire system because of its advantage of supplying both of 1-phase & 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But uneven load distribution or unclean voltage quality has occurred various problems such as do-rating, losses increase and vibration, etc. In this paper, voltage, current and power waveform in the actual fields have measured and analyzed in relation with internationally allowable voltage unbalance limits and compared the current unbalance factor with the load unbalance factor.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.447-454
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• 1998

This paper describes a modeling and current control techniques of Distribution static condenser (D-STATCON) for power factor compensation. The current control is based on the predictive and the space vector PWM scheme. The predictive current controlled PWM D-STATCON can maintain its performance with power factor compensation and fixed switching frequency. By using the space vector control low ripple and offset in the current and the voltage as well as fast dynamic responses are achieved with a small DC link capacitance employed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.100-107
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• 2011

Since transmission and distribution neutral wires are connected with a substation grounding grid, it is very difficult to measure grounding resistance of isolated substation grounding grid after the substation is energized. It is impractical to isolate the grounding grid from other parallel connections such as distribution line neutrals and overhead ground wires for grounding resistance measurement only. In this paper, we proposed and demonstrated a novel measurement method of grounding resistance of isolated substation grounding grid. For this method, grounding current division factor and conventional FOP(Fall-Of-Potential) profiles were measured at power supplying 154[kV] substation. The obtained FOP profile was processed with the measured grounding current division factor to produce the grounding resistance of isolated grounding grid. Simulated FOP profile agreed well with the measured one showing the validity of the proposed method.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.32-36
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• 2008

An HTS conductor with parallel HTS tapes is essential for a large power HTS device to flow a large current. One of the most important factor for this conductor is a current distribution. Non-uniform current distribution in parallel tapes makes the critical current of the conductor low and the AC losses high. In this paper we proposed a non-contact method which measured each current in parallel tapes by using an array of Hall sensors. A matrix can be derived from this array for calibration. The current distributions of 4 and 6 parallel tapes were measured.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.159-163
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• 2015

Recently squirrel cage induction generator has been steadily applied to many small hydro power plants. Induction generator needs a reactive power for magnetization. The reactive power of induction generator is being supplied from the supply side mostly. The use of induction generators in the power distribution grid can affect the power factor. The power factor of induction generator is fixed already during production. The power factor in the distribution system is due to the increase or decrease of the load rather than due to the induction generator. In this study, we analyzed that how the increase or decrease of D/L load impacts at the change of power factor and power flow.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.40-45
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• 2010

In order to establish the electric distribution system economically and operate efficiently, it becomes important to calculate energy losses of the system more accurately. This importance is not only related for the engineering of utilities' power network but also for the consumers' electric system. The Distribution Loss Factor (DLF) is the fundamental element of calculating the energy losses occurred through the electric system including the electric lines and equipments. Up to now, the DLF is calculated by empirical formulas using the correlation between the DLF itself and Load Factor. However, these methods have some limitations to reflect the various characteristics of the system and the load. In this regard, the novel method proposed here is developed to yield more accurate result of DLF which actively interacting with the characteristics and load patterns of the system. The improvement of accuracy is very significant according to the results of verification presented at the end of this paper.

• Progress in Superconductivity
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• v.4 no.2
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• pp.184-188
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• 2003

Voltage-current characteristics of High Temperature Superconductor(HTS) tapes after applying the current beyond their critical current was investigated. When over-current is applied, the current begins to flow through the metal sheath instead of superconductor. The HTS tapes quenched were analyzed using V-I curve with various magnitudes of current. Two kinds of tapes were compared with each other to examine the influence of critical current on quench development. As a result, it was found that the resistance of superconductors and joule heat due to the over-current affect current distribution in HTS tapes. Critical current of HTS tapes was considered as a main factor deciding over-current characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.52-58
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• 2012

In this study, we have investigated the effect of the solar power generation facilities on the power quality of interconnected solar power generation system. When the solar power generation facility was connected to the distribution system, whether the solar power generation is under operation or not, Peak factor of current was increased to 0.033[%], Frequency is deviated from $60{\pm}0.2$[Hz] and also Short term flicker indication($P_{st}$) increased to 0.213[p.u.] compare with the disconnected situation. Harmonic current [%] in orders was 11.42[%] maximum under 11th orders and was 7.861[%] between 11th and 17th orders. These values were about 3 or 4 times compared with "the power system interconnection technique standards" at the same situation above. Therefore, we could confirmed that the solar power generation facility, when it was connected to the existing distribution system, made bad influence on the power qualities such as the peak factor of current, frequency regulation, short term flicker indication($P_{st}$) and harmonic current [%] in orders etc.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.34-40
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• 1998

Conductive metal matrix composite(MMC) material of 30% silicon carbide particulated based on aluminum matrix was machined by die sinking electrical discharge machining(EDM) process according to different current and duty factor for reverse polarity of electrode. Material removal rate(MRR) was examined by process under various operation conditions. The surface morphology was evaluated by surface roughness parameter and scanning electron microscopy(SEM) research. The MRR was suddenly increased over 11 ampere of current, and it was slightly changed over 0.3 of duty factor. The maximum surface roughness of EDMed surface was affected by the duty factor. The SEM photograghs of EDMed surface showed wide recast distribution region of melting materials as increased of current and duty factor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.57-64
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• 2011

Most of the user has been used linear load and non-linear load. The former is usually inductive load which is needed power factor compensation, the latter is power conversion system device. Actually two kinds of load is used together in the customer application. Generally capacitor is used for power-factor compensation of inductive load and reduction harmonics of non linear load with reactor. Non-linear load generates harmonic current for its energy conversion process. If harmonic current pass along the low impedance side of distribution system, the magnification of voltage and current is appeared by the series and parallel resonance. As a result, condenser has received a bitter electrical stress by the harmonic component. In this paper, we analyzed that how resonance is changed by the 5-th harmonic current pattern and proposed an alternative plan for non-magnification.