| 摘要 |
PURPOSE:To eliminate errors employing commercial frequency voltage and current when the distance to a fault point is located, in a transmission line comprising three terminals by computing the impedance to the fault point using measured values of voltage and current detected at two terminals when a fault occurred therein. CONSTITUTION:When a positive phase voltage and current of terminals B and C, terminals A and C and terminals A and B can be measured at the terminals A, B and C respectively, the impedance containing no resistance at the fault point is determined. In other words, when voltage and current vector values at terminals A-C are VA and IA-VC and IC and impedance from the terminals to branch points ZA-ZC respectively, the distance to the fault point is located as follows: If the requirement of VA-ZAIA<VC-ZCIC<VB- ZBIB is met, the fault point is estimated to be between the terminal A and the fault point and the distance to the fault point from the terminal A is located based on the impedance determined by the formula I . If the requirement of VB-ZBIB<VA-ZAIA<VC-ZC is met, the fault point is estimat ed to be between the terminal B and the branch point, and the distance to the fault point from the terminal B is located based on the impedance determined by the formula II. If the requirement of VC-ZCIC<VB-ZBIB<VA-ZAIA is met, the fault point is estimated to be between the terminal C and the branch point and the distance to the fault point from the terminal C is located based on the impedance determined by the formula III. |
