IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Volume 139 , Issue 6
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  • Shingo Sakaeda, Mitsutoshi Asano, Shigeyuki Sugimoto, S.C. Verma, Ryos ...
    2019 Volume 139 Issue 6 Pages 410-420
    Published: June 01, 2019
    Released: June 01, 2019
    JOURNALS RESTRICTED ACCESS

    A power system with a massive PV penetration may require many conventional generating units to be disconnected in order to maintain supply-demand balance. In this situation, it may be difficult to sustain power system stability in case a system disturbance occurs. In this paper, as a countermeasure, the prototype Virtual Synchronous Generator (VSG) is developed and its effectiveness is checked experimentally using an analog simulator.

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  • Shota Ogawa, Hiroyuki Mori
    2019 Volume 139 Issue 6 Pages 421-427
    Published: June 01, 2019
    Released: June 01, 2019
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    This paper proposes a new optimal network decomposition method with Discrete Parallel Predator-Prey Brain Storm Optimization (DPPPBSO) for Voltage and Reactive Power Control (VQC) in power systems. Recently, parallel or distributed control is required for complicated power systems. To achieve that, power network decomposition plays a key role to improve VQC. The problem formulation may be expressed as one of combinatorial problems. However, it is difficult to solve them due to the NP-hard problem. In this paper, DPPPBSO is proposed to evaluate better solutions with a couple of strategies of the island model for parallel computation and discretization of solutions through the sigmoid function into PPBSO. The proposed method is successfully applied to the IEEE 57-bus system.

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  • Akinobu Go, Shinji Yasui, Takashi Tsuchida
    2019 Volume 139 Issue 6 Pages 428-434
    Published: June 01, 2019
    Released: June 01, 2019
    JOURNALS RESTRICTED ACCESS

    Special facilities such as data centers, computer centers, and hospitals with operating rooms require an extremely static electromagnetic environment. In this study, we investigated the effectiveness of an isolated type down-conductor for reduction of the magnetic field inside the building due to lightning strikes by using electromagnetic field analysis. We analyzed the four cases of the down-conductors such as building structures, bare wires, and two types of high-voltage insulated-cables which is sheath opened type and sheath shorted type. Using bare wires and sheath opened cable-type down-conductors, the internal magnetic field of the building reduced. This is because the lightning current flows in the opposite direction in the building structural pillars close to the down-conductors, and it cancel the internal magnetic fields. Comparing the bear conductor and the sheath opened cable-type conductor from the viewpoint of the overvoltage to the building structure, the overvoltage became smaller as the cace of using the cable-type duwn-conductor.

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  • Ken-ichi Kondo, Hiroki Tanaka, Yu Takeuchi, Jumpei Baba, Akihiko Yokoy ...
    2019 Volume 139 Issue 6 Pages 435-445
    Published: June 01, 2019
    Released: June 01, 2019
    JOURNALS RESTRICTED ACCESS

    Recent increase of variable renewable energy sources such as photovoltaics and wind turbines makes balancing power supply and demand difficult. One of the methods to support balancing supply and demand in power grid is demand response. In this research, demand response by use of heat pump water heater (HPWH) in spa facility was considered. To predict power consumption of HPWH, HPWH was modeled using real operation data. Hot water demand model was also made using real operation data to predict hot water consumption and avoid hot water shortage. Using both HPWH and demand model, daily operation schedule which satisfies both demand response requirement and spa users' convenience. Demand response experiment was conducted to evaluate demand control error and effect on users' convenience. From the result, daily operation schedules were generated and HPWHs were operated without water shortage. However, power consumption errors occurred due to HPWH model error, water demand error, input ambient temperature error and reheat operation. In the future, power consumption errors will be reduced to increase accuracy of input ambient temperature and consider tank heat loss into operation schedule.

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  • Yu Iwashita, Masahiro Kozako, Masayuki Hikita, Yuta Makino, Takashi Ku ...
    2019 Volume 139 Issue 6 Pages 446-454
    Published: June 01, 2019
    Released: June 01, 2019
    JOURNALS RESTRICTED ACCESS

    The authors have evaluated the possibility of deterioration diagnosis of Oil-filled (OF) cable systems by PD measurement so far. In our previous studies, we confirmed continuous occurrence of PDs even under the design electric field of 275kV OF cables. However, correlation between PD characteristics and internal conditions of the oil gap defect was not obtained. Therefore, in this study, we experimentally investigated the effects of the switching impulse voltage superimposition that can occur in practical operation of 275 OF cable systems on PD characteristics and we observed the conditions inside the oil gap defect by a CCD camera.

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