Hitachi, Ltd.

Hoya Corporation

Kouichi Hara

Masahiro Yatsu

Eisuke Kuroda

Yasuo Sato

Jun Yamazaki

Osamu Tomobe

Tetsuro Izumitani

Nao Saito

Shota Omi

Taichiro Kawahara

Ryo Yamaguchi

Chiemi Hata

Haruki Miyoshi

The setting range of the voltage and the reactive power of a power system is maintained during variations of voltage and power flow due to the output variation of renewable energy of a large number of power supplies which fluctuate due to weather. A voltage/reactive power operation assisting device is provided with a first database for storing the data to be evaluated, target value data, individual control device control method data, and individual control device data of an individual control device for adjusting the voltage/reactive power of a power system. A second database stores the device operation data of the individual control device; and the operation of the individual control device is predicted from the data stored in the first database to obtain individual control device operation prediction data. A display unit displays the individual control device operation prediction data and the device operation data in a contrastive manner.

Voltage/reactive power operation assisting device and assisting method, and voltage/reactive power operation monitoring control device and monitoring control method

A voltage stability monitoring device, which monitors voltage stability of a power system, produces a plurality of assumed change scenarios indicating a scenario of a change that is assumed based on at least one of a system configuration of the power system and a change of a tide state, calculates the voltage stability using the assumed change scenario, calculates a voltage stability margin indicating margin degree of the voltage stability, based on the voltage stability selects an assumed change scenario with high severity of the voltage stability for each assumed change scenario, based on the voltage stability margin calculates which buses in the power system are vulnerable buses that decrease voltage stability, based on the assumed change scenario which is selected, and changes a monitoring target of the voltage stability, based on information of the vulnerable bus.

Voltage stability monitoring device and method

A system stabilizing controller for estimating and controlling stability of a power grid includes a collection unit collecting grid information including a power flow amount from the power grid and a calculation unit calculating a generator shedding amount at a fault observation point on the basis of the grid information and estimating a correlation line on the basis of the power flow amount and generator shedding amount. The calculation unit determines a generator phase angle curve that is the relationship between the internal generator phase angle of a generator connected to the power grid and the power flow amount, determines a stability limit power flow amount on the basis of the amounts of generator acceleration energy and deceleration energy in the generator phase angle curve, determines a stability limit generator shedding amount corresponding to the stability limit power flow amount, and estimates a correlation line including a stability limit point.

System stabilizing control device and method

In administration based on the existing (N&#x2212;1) reliability criteria, an appropriate administration plan may be not drafted in a power system in which renewable energy increases. Accordingly, according to the invention, a power system monitoring apparatus that monitors a power system includes: an input unit that inputs assumable system breakdown data including an occurrence frequency of each assumable breakdown of the power system and assumable output change data including an occurrence frequency of each assumable output change of each generator connected to the power system; and an output unit that generates conditions by which events of the assumable breakdowns and the assumable output changes are combined based on the occurrence frequencies of the assumable breakdown and the assumable output change and outputs a control plan for each of the conditions.

Power system monitoring apparatus, power system control apparatus, and power system monitoring method employing events of assumable breakdowns and assumable output changes

A process of surface-treating a laser glass is disclosed which comprises coating a specific sol solution obtained by hydrolysis and partial polycondensation of a mixture containing a metal alcoholate on the glass surface and heating the coated glass to form a glassy coating, wherein the glass surface may be treated, prior to the coating, with an alkali aqueous solution and with an aqueous solution of phosphoric acid in sequence, or the coating and the heating may repeated to form a double- or multilayer of the same or different kind of glassy coatings. The thus treated laser glass has increased thermal shock resistance and water resistance.

Process of surface treating laser glass

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Tokyo, Japan

Kouichi Hara