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    1.
    发明专利
    未知

    公开(公告)号：DE69219167T2

    公开(公告)日：1997-10-16

    申请号：DE69219167

    申请日：1992-01-10

    Applicant: HITACHI LTD

    Inventor： CHIBA TOMIO ,  KIDO MITSUYASU ,  KAWAKAMI JUNZO ,  HIRASAWA KUNIO ,  MATSUI YOSHIAKI

    IPC: H02J3/00 ,  G05B13/02 ,  H02J3/12 ,  H02J3/18 ,  H02P13/06 ,  G05F1/14 ,  G05F1/70

    Abstract: In order to control a voltage using e.g. a tap transformer (5000), the difference V between the actual voltage (V) and a reference voltage (110) is obtained (120) and integrated over time (130). That integral is then modified by at least one parameter generated by fuzzy logic (3000) from control conditions of the voltage. In this way the fuzzy logic (3000) may find the optimum control strategy which keeps the actual voltage closest to the reference voltage without an excessive number of tap position changes. The reference voltage (110) may vary with time, and therefore the control of the voltage with time may be evaluated (2000), and the control conditions varied accordingly, e.g. by fuzzy logic so that the control arrangement can exhibit learning. Normally, the integral is modified by such that when B is the parameter determined by the fuzzy logic (3000), but other control strategies may be used. The present invention is also applicable to control of reactive power.

    3.
    发明专利
    未知

    公开(公告)号：DE69219167D1

    公开(公告)日：1997-05-28

    申请号：DE69219167

    申请日：1992-01-10

    Applicant: HITACHI LTD

    Inventor： CHIBA TOMIO ,  KIDO MITSUYASU ,  KAWAKAMI JUNZO ,  HIRASAWA KUNIO ,  MATSUI YOSHIAKI

    IPC: H02J3/00 ,  G05B13/02 ,  H02J3/12 ,  H02J3/18 ,  H02P13/06 ,  G05F1/14 ,  G05F1/70

    Abstract: In order to control a voltage using e.g. a tap transformer (5000), the difference V between the actual voltage (V) and a reference voltage (110) is obtained (120) and integrated over time (130). That integral is then modified by at least one parameter generated by fuzzy logic (3000) from control conditions of the voltage. In this way the fuzzy logic (3000) may find the optimum control strategy which keeps the actual voltage closest to the reference voltage without an excessive number of tap position changes. The reference voltage (110) may vary with time, and therefore the control of the voltage with time may be evaluated (2000), and the control conditions varied accordingly, e.g. by fuzzy logic so that the control arrangement can exhibit learning. Normally, the integral is modified by such that when B is the parameter determined by the fuzzy logic (3000), but other control strategies may be used. The present invention is also applicable to control of reactive power.

    4.
    发明专利
    未知

    公开(公告)号：DE69027292T2

    公开(公告)日：1997-01-23

    申请号：DE69027292

    申请日：1990-12-31

    Applicant: HITACHI LTD

    Inventor： KIDO MITSUYASU ,  CHIBA TOMIO ,  KUDO HIROYUKI ,  KAWAKAMI JUNZO ,  KAWAI TADAO

    IPC: H02H3/02 ,  G01R19/00 ,  G01R19/25 ,  H02H1/00 ,  H02J3/00 ,  H02J13/00 ,  H03H17/00 ,  H04B14/04 ,  G01R21/133 ,  G01R23/167 ,  G11B20/10 ,  H03M1/08 ,  H03H17/02

    Abstract: A method of and system for processing a digital signal are disclosed. Disclosed also are an electric power system digital controlling system and a digital relay system which utilize the signal processing system for obtaining physical quantities of a voltage and a current inputted from the electric power system. An analog signal is sample-held. The sample-held data is converted into digital data which is then filtering-processed. Arithmetic processing is effected based on the data from a digital filter means. In this digital filter means, a blocking zone of the digital filter is set to a higher frequency zone than a passage zone of the analog signal. A sampling frequency is set so that a noise generating region is larger than the blocking zone. The synthesis noises are thereby caused in the blocking zone.

    PARTIAL DISCHARGE DETECTION APPARATUS AND PARTIAL DISCHARGE DETECTION METHOD
    7.
    发明专利
    PARTIAL DISCHARGE DETECTION APPARATUS AND PARTIAL DISCHARGE DETECTION METHOD 未知

    公开(公告)号：SG11202104904RA

    公开(公告)日：2021-06-29

    申请号：SG11202104904R

    申请日：2019-08-22

    Applicant: HITACHI LTD

    Inventor： TAKAMI KAZUHISA ,  YOSHIDA SHOJI ,  KIDO MITSUYASU ,  MARUYAMA TATSUYA

    IPC: G01R31/12

    Abstract: A partial discharge detection apparatus includes a low-speed AD converter, a high-speed AD converter, and a partial-discharge-detection digital signal processing unit. The low-speed AD converter converts an analog signal of an AC waveform flowing through a power cable into a digital signal. The high-speed AD converter converts an analog signal of a partial discharge current into a digital signal. The analog signal is in a plurality of Nyquist frequency domains defined for each of two different types of sampling frequencies. The partial-discharge-detection digital signal processing unit detects partial discharge based on the maximum value or the sum of a current value obtained from the digital signal of the partial discharge current, which is obtained by the conversion of the high-speed AD converter, for each phase of the AC waveform, which is obtained from the digital signal of the AC waveform flowing in the power cable. The digital signal is obtained by the conversion of the low-speed AD converter.

    9.
    发明专利
    未知

    公开(公告)号：DE69028225D1

    公开(公告)日：1996-10-02

    申请号：DE69028225

    申请日：1990-02-21

    Applicant: HITACHI LTD

    Inventor： CHIBA TOMIO ,  KIDO MITSUYASU ,  KUDO HIROYUKI ,  KAWAKAMI JUNZO ,  YAMANAKA YOSHIKAZU ,  YOKOYAMA KAZUYUKI ,  MATSUYAMA TAKAKAZU ,  KAWAI TADAO ,  MORI SHIGERU

    IPC: H02H3/02 ,  H02H3/00 ,  H02H3/05 ,  H02J3/00 ,  H02J3/18

    Abstract: A power signal processing system high in expandability and versatility is disclosed, in which a signal representing the conditions of a power system is taken in and subjected to digital computation processing, and a signal is produced for protecting or controlling the power system on the basis of the computation result. The power signal processing system comprises a plurality of processing units (2, 3, 4, 5, 6, 7, 8, 9) for executing a series of processings from signal input to signal output based on the computation result in divided fashion in accordance with the processing functions. A system control unit (1) has a function of controlling the units to assure sequential data transfer therebetween according to the divided processing functions, thereby standardizing the power signal processing system.

    PARTIAL DISCHARGE DETERMINATION APPARATUS AND PARTIAL DISCHARGE DETERMINATION METHOD
    10.
    发明专利
    PARTIAL DISCHARGE DETERMINATION APPARATUS AND PARTIAL DISCHARGE DETERMINATION METHOD 未知

    公开(公告)号：SG11202111087QA

    公开(公告)日：2021-11-29

    申请号：SG11202111087Q

    申请日：2020-04-23

    Applicant: HITACHI LTD

    Inventor： YAMADA HIROMICHI ,  MARUYAMA TATSUYA ,  KIDO MITSUYASU

    IPC: G01R31/12

    Abstract: A distribution pattern of a combination of a charge quantity and an occurrence phase angle of each of the partial discharges occurring in one or a plurality of cycle periods of an applied voltage of the power transmission cable is generated, differential data including a difference between the numbers of occurrences of the partial discharge for each combination of the charge quantity and the occurrence phase angle in two or more latest distribution patterns is generated, and the degree of progress of the partial discharge is determined based on data of the latest distribution patterns and the differential data.

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