• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.107-113
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• 2008

In 22.9[kV]-y distribution systems, underground cables are provided with multiple-point ground in which each coaxial-neutral line of the distribution cable lines(A, B, C phases) is 3-wire common grounded. In the underground cable distribution systems, circulating current flows in the coaxial-neutral lines and its magnitude amounts to about $40{\sim}50[%]$ load currents, even though loads are balanced. Power loss due to the circulating current consequently reaches to about 76[%] total losses occurred in all conductor lines. This power loss provokes additional temperature rise of the underground cable lines and finally results in 20[%] reduction of the current capacity of the cables. This paper presents a new ground method to overcome such a problem. The proposed method eliminates the circulating current flowing in the coaxial-neutral line effectively. Measurement results confirmed from the practical site-test show validity and effectiveness of this research.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.585-587
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• 1998

In 22.9 kV-Y distribution lines, Several kinds of over-voltages occur. These over-voltages are usually surge types except controling the bus voltages for line voltage drop. The measuring over-voltages in 22.9 kV lines is a very difficulty skill. This paper introduces the study on the measurement system of over-voltages in 22.9kV distribution lines. It has been researching in KEPCO since 1995.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.313-315
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• 2005

Recently There has been growing interest in new renewable energy systems with high-energy efficiency due to the increasing energy consumption and environmental pollution problems. But an insertion of new distributed generation to existng power distribution systems can cause several problems such as voltage variations, harmonics, protective coordination, increasing fault current etc, because of reverse power. This paper was applied to fault location defecting a method as each Relay sensing fault current value and carried out short-circuit analysis by MATLAB and PSCAD/EMTDC programs and identity the faulted section o f22.9[kV] distribution system interconnected a large number of distributed generation. The existing protection system of 22.9[kV] power distribution system analyzed and the study on protective coordination recloser and Sectionalzer accomplished

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.46-47
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• 2006

본 논문은 CD형 초전도 케이블을 22.9kV 다중접지 배전계통에 적용한 경우 불평형 지락 고장이 초전도 케이블에 미치는 영향을 검토하고 이로 인한 중성선 전류의 변화 및 계통보호를 위한 대책을 논한다. 3상 CD형 초전도 케이블을 사용하는 경우 귀로선은 전향선과 전류가 반대이면서 거의 동일한 전류가 흐르므로 회로의 인덕턴스를 크게 줄일 수 있지만 이를 위해 회로를 단락하여 운전하는 경우 지락고장시 영상회로가 별도로 존재하지 않으면 지락전류를 저감시키는 결과를 초래하게 되어 계통보호에 영향을 주게 된다. 본 논문은 EMTDC 프로그램을 활용하여 이 현상을 XLPE 케이블 계통과 비교, 모의하는 한편, 정상적인 보호계전기 동작이 가능토록 하는 대책에 대해 논한다.

• Progress in Superconductivity and Cryogenics
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• v.12 no.3
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• pp.39-43
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• 2010

In Korea, 22.9kV hybrid SFCL (Superconducting Fault Current Limiter) has been developed and carried out long-term field tests in Gochagn power test center of KEPCO through DAPAS program. The SFCL will be installed at a distribution line of Icheon substation in Korea. For the successful application, we have to design the specifications considering real power system operation. This paper proposes a concept of the operating current based rms value for the protection coordination with protective delays and studies a proper range of the current in Korean distribution power system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.428-431
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• 2009

KPX sets up the voltage standards according to the voltage level to supply a good quality of electricity to customers. Supply voltages are divided into 4 levels - 345kV, 154kV, 22.9kV, and distribution voltage consisting of 110, 220 and 380V. In this research, we examine the optimal voltage operating level focused on 154kV system that mostly affects electricity quality, through analysing the system demand.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.266_267
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• 2009

22.9kV HTS(High Temperature Superconducting) cable and SFCL(Superconducting Fault Current Limiter) will be installed to Icheon 154kV substation for real distribution power system operation in 2010. This paper proposes CLR (Current Limiting Resistance) specification of the SFCL and fault current condition fo the HTS cable for applying to Korean power system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.195-197
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• 2007

This paper presents experimental results on the safety of persons due to a ground fault in 22.9 kV-Y distribution system In order to evaluate the touch voltages due to internal ground faults in a step down transformer based on the newly prescribed KS C IEC 60364 standard series, the verification tests in a 22.9 kV multi-grounded neutral system were carried out From the experimental results, it was found that there will be significant potential rise jeopardizing LV equipment insulation in case of separate grounding between HV and LV system and the effective measures against hazardous touch voltages due to a IN side ground fault in the common grounding system between HV and LV system are proposed. As a consequence, it was found that the equipotential bonding is an important prerequisite for the effectiveness of the protective measures for the safety of persons in the common ground system between 22.9 kV-Y and low-voltage grounding system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.505-510
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• 2001

We simulated the current limiting characteristics of a resistive superconducting fault current limiter (SFCL) for a single line-to-ground fault in the 22.9 kV system. The transient current during the fault increased to 6.33 kA, 5.80 kA and 3.71 kA without SFCL at the fault angles 0$^{\circ}$, 45$^{\circ}$ and 90$^{\circ}$, respectively, a resistive SFCL limited effectively the fault current to 2.27 kA in a half cycle without any DC components. The maximum quench resistance of an SFCL, 16Ω was suggested to be appropriate to limit the fault current in the 22.9 kV distribution system, considering the operating cooperation of a protective relay and the current limiting performance of an SFCL.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.1
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• pp.7-12
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• 2006

This paper proposes the new voltage event detection method using the weight factor of neural network and describes control system design for the DVR(Dynamic Voltage Restorer) consisted of a rectifier and series inverter applied to 22.9kV distribution system. As this method can express the fault level of each phase, we expect the proposed method can make up for disadvantage of synchronous detection method. Also, in this paper, the control system was designed using double deadbeat controller, As it has an inner current control loop and an outer voltage control loop, we can easily limit the current level during the transient intervals by using the current control loop. Simulation and experiment are performed to prove the analysis of the voltage event detection method and double deadbeat controller.