| 摘要 |
PROBLEM TO BE SOLVED: To obtain a digital directional relay capable of determining direction of faults of all systems and sorting a fault phase, irrespective of balance/imbalance fault. SOLUTION: The digital directional relay periodically samples a voltage value and a current value of a power system to convert the values into digital values, and performs determination operation of an accident direction using the voltage data and the current data which are converted into digital values. The relay includes an instantaneous effective power value calculating means for calculating an instantaneous effective power for a rotary vector change of each phase from the operation values of a voltage rotary vector change calculating means 3 and a current rotary vector change calculating means 4; a rotary vector change effective power effective value calculating means 6 for calculating a rotary vector change effective power effective value of each phase; and a fault direction determining means for determining the fault direction of a system on the basis of the calculated effective power effective value of each phase. COPYRIGHT: (C)2008,JPO&INPIT
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