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이중퀜치를 이용한 자속구속형 초전도한류기의 과도전류제한 특성
최상재,임성훈,Choi, Sang-Jae,Lim, Sung-Hun 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.2
In this paper, the flux-lock type superconducting fault current limiter (SFCL) using double quench was suggested and its transient current limiting characteristics were analyzed. The suggested flux-lock type SFCL using double quench consists of two magnetically coupled windings and two $high-T_{c}$ superconducting (HTSC) elements connected in series with each winding. To analyze the transient current limiting characteristics of the flux-lock type SFCL using double quench, the short-circuit tests according to the fault angles, which affect the transient component of the fault current right after the fault occurs, were executed. From the comparative analysis for the short-circuit tests at both $0^{\circ}$ and $90^{\circ}$ fault angles, the useful transient current limiting operations of the suggested flux-lock type SFCL through the double or the single quench occurrence were confirmed.
최상재,임성훈 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1
The newly increased electrical energy is needed around the metropolitan area, and therefore, the transmission system is needed to be reorganized. MVDC (medium voltage direct current) system is an attractive one for constructing these new systems. This MVDC system, which is composed of two or more VSCs (voltage-sourced converters), prevents the degradation of system reliability due to renewable energy resource and is contributed to making it more stable for power supplying companies to supply the electrical power. Furthermore, to connect the increased renewable energy resource with larger capacity into the main grid through this MVDC system, the regulations such as FRT (fault ride through) for the grid have been more and more required. According to the FRT, the VSC system is required to supply the reactive current to grid when the grid voltage drops below the allowed voltage range. However, the FRT operation can cause the DC-link voltage in the MVDC system to increase. If the DC-link voltage exceeds the nominal voltage, the damage to the DC-related application may occur. In this paper, as the method to solve this problem, the application of the APTC (active power tracking control) into the MVDC system was proposed. The APTC is based on the principle that the DC-link voltage is determined by the power balance between the incoming and the outgoing active powers into the DC-link. If the outgoing active power decreases due to the short circuit in grid side, the DC-link voltage rises with the constant incoming active power. However, if the incoming active power is controlled to be reduced by the APTC performance of the MVDC system at the same time, the DC-link voltage is expected to be maintained at a constant level. The efectiveness of the suggested APTC application was verifed through the PSCAD (power system computer aided design)/EMTDC (electro magnetic transient design and control) simulation.
Current Limiting and Interrupting Operation of Hybrid Self-Excited Type Superconducting DCCB
최상재,임성훈 한국초전도저온학회 2018 한국초전도저온공학회논문지 Vol.20 No.4
Currently, the development of industry makes needs larger electric supply. Providers must consider the efficiency about losses and reliability of the system. In this case, DC power system can save electrical energy; long-distance transmission line losses. Relevance to switch technology with a voltage-source converter (VSC) in AC-DC conversion system have been researched. But, protection device of DC-link against fault current is still needed to study much. VSC DC power system is vulnerable to DC-cable short-circuit and ground faults, because DC-link has a huge size of capacitor filter which releases extremely large current during DC faults. Furthermore, DC has a fatal flaw that current zero crossing is nonexistence. To interrupt the DC, several methods which make a zero crossing is used; parallel connecting self-excited series LC circuit with main switch, LC circuit with power electronic device called hybrid DC circuit breaker. Meanwhile, self-excited oscillator needs a huge size capacitor that produces big oscillation current which makes zero crossing. This capacitor has a quite effective on the price of DCCB. In this paper, hybrid self-excited type superconducting DCCB which are using AC circuit breaker system is studied by simulation tool PSCAD/EMTDC.
단일·이중소자를 이용한 자기결합 초전도 한류기의 자화특성 및 누적에너지 비교분석
최상재,김보희,임성훈,Choi, Sang-Jae,Kim, Bo-Hee,Lim, Sung-Hun 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.2
In this paper, the magnetization characteristics and the stored energy of magnetically coupled superconducting fault current limiter (SFCL)s using single and double high-Tc superconducting (HTSC) elements were compared. To analyze the magnetization characteristics and the stored energy, the magnetizing current and the flux linkage, which were derived from the electrical equivalent circuit of the SFCL using single and double HTSC elements, were calculated from the voltages and the current measured in the short-circuit tests. Through the comparative analysis on the magnetization characteristics and the stored energy for SFCL using sing and double HTSC elements, the magnetically coupled SFCL using double HTSC elements was shown to be more effective than the SFCL using single HTSC element from the point of view of the magnetic saturation.