Electrical transmission or interconnection systems – Plural supply circuits or sources
Patent
1995-04-12
1997-11-11
Shoop, Jr., William M.
Electrical transmission or interconnection systems
Plural supply circuits or sources
307 31, 307 32, 307 52, 307 38, 361186, 361187, 363 2, 363 13, H02J 306
Patent
active
056867662
ABSTRACT:
Even when a plurality of dispersed power generation systems are connected to a utility gride, an islanding-operation prevention apparatus can easily and assuredly prevent an islanding operation of each dispersed power supply constituting the corresponding dispersed power generation system. The apparatus includes a breaker provided between the utility gride and a dispersed power supply, an electric-power-value detector for detecting a value of electric power from a power line connected to the utility gride, a switch for electrically connecting or disconnecting an electric-power changing device for changing the value of electric power to the power line in accordance with an output from a pulse circuit, and a controller for controlling the breaker in accordance with the width of fluctuations of the value of electric power during the connection or the disconnection. A dispersed power generation apparatus and a dispersed power generation system uses such an apparatus. By further providing a synchronous circuit for synchronizing the output of the pulse circuit with a signal output from a reference-signal source, even if the amount of the generated power and the amount of a load are in a complete equilibrium state during an islanding operation, the islanding operation can be assuredly prevented with a short time period until the stop of the islanding operation and without using large-scale equipment.
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"Method For Preventing Islanding Phenomenon On Utility Grid With A Number of Small Scale PV Systems" H. Kobayashi et al., 22 IEEE Photovoltaic Specialists Conference--1991, vol. 1, 7 Oct. 1991, USA, pp. 695-700.
"Utility Intertied Photovoltaic System Islanding Experiments" J. Stevens, 19 IEEE Photovoltaic Specialists Conference--1987, 4 May 1987, USA, pp. 1134-1138.
Canon Kabushiki Kaisha
Paladini Albert W.
Shoop Jr. William M.
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