| 摘要 |
PROBLEM TO BE SOLVED: To determine a line constant highly accurately by utilizing a regular tidal current. SOLUTION: Protection control measuring devices 110 for taking an electrical quantity are provided on both ends of transmission lines 101A-C which are measuring objects, a time synchronizing means 112 for taking synchronously the electrical quantity in the protection control measuring devices 110 on both ends, and a line constant calculation means 113 for calculating a line constant from the electrical quantity taken from the protection control measuring devices 110 on both ends are also provided. The line constant calculation means 113 is provided with a zero-phase portion detection means 114 for detecting that a fixed quantity or more of the zero-phase portion is included in the taken electrical quantity in the protection control measuring devices 110. The line constant calculation means is started on condition that the detected zero-phase portion reaches a fixed value or more, in the zero-phase portion detection means 114. A constant calculation means calculates a contact of a transmission line based on each electrical quantity taken at at least two or more points of time and its zero-phase portion. The line constant calculation means 113 regards the transmission line as aπ-type equivalent circuit or a distributed constant circuit. COPYRIGHT: (C)2011,JPO&INPIT |
